Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Population differentiation of the three-spined stickleback (Gasterosteus aculeatus) Black, E. A. (Edward Adam) 1977

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1978_A6_7 B59.pdf [ 5.43MB ]
Metadata
JSON: 831-1.0103869.json
JSON-LD: 831-1.0103869-ld.json
RDF/XML (Pretty): 831-1.0103869-rdf.xml
RDF/JSON: 831-1.0103869-rdf.json
Turtle: 831-1.0103869-turtle.txt
N-Triples: 831-1.0103869-rdf-ntriples.txt
Original Record: 831-1.0103869-source.json
Full Text
831-1.0103869-fulltext.txt
Citation
831-1.0103869.ris

Full Text

POPULATION DIFFERENTIATION OF TH1 THREE-SPINED STICKLEBACK ( GASTEROSTEUS ACUTEATUS ) By EDWARD ADAM BLACK B . S c . , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1974 A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES ( D e p t . Of Z o o l o g y ) Be a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e g u i r e d s t a n d a r d THE UNIVERSITY OF BR I T I S H COLUMBIA November, 1977 S~\ Edward Adam B l a c k , 1977 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements for an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f th i s thes is f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d tha t c o p y i n g or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f ^ _ Q O < - Q ^ f The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1WS Date / ? ArRn- art ABSTRACT The three general body armour forms of Gasterosteus aculeatus (Linnaeus), high, intermediate and low plate count forms, are found in nonbreeding marine populations. In breeding season i n i t i a l l y the population i n the nontidal portion of Bonsall Creek consisted of the low and intermediate plate count forms. Later when the t i d a l zone was occupied by breeding sticklebacks a l l three body armour forms were present and from the l i m i t of the t i d a l influence the low and intermediate forms became less frequent seaward. In Chase Creek there exists an anadromous breeding population but there was no adjoining freshwater population. In Chase Creek however there did e x i s t a zone where a l l three body armour form were present. Therefore, the development of the pattern of plate v a r i a t i o n in the creek's t i d a l zone does not appear to be dependent upon the presence of both freshwater and marine population tyrjes. In Bonsall Creek where both a freshwater and a marine population bred, low plate count individuals from the freshwater zone and high plate count indivi d u a l s from the adjoining t i d a l zone were r e c i p r o c a l l y transferred in wire baskets. M o r t a l i t i e s of transferred f i s h were shown to be s i g n i f i c a n t l y higher than those of the controls indicating a possible barrier to gene exchange between the two populations. However, the presence of the intermediate plate count form i n t h e f r e s h w a t e r z o n e o f B o n s a l l c r e e k s t r o n g l y i m p l i c a t e s gene f l o w b e t ween t h e s e two g r o u p s o f f i s h e s . a l l t h r e e f o r m s c o l l e c t e d f r o m t h e t i d a l z o n e o f C h a s e C r e e k . Showed t h e same m o r t a l i t y r a t e when p l a c e d i n f r e s h w a t e r . T h i s s u g g e s t s t h a t t h e l o w and i n t e r m e d i a t e p l a t e c o u n t f i s h b r e e d i n g i n t h e t i d a l p o r t i o n of C h a s e C r e e k were o f m a r i n e o r i g i n . Ten m o r p h o l o g i c a l c h a r a c t e r s w e re c o m b i n e d i n a d i s c r i m i n a n t f u n c t i o n a n d used t o c l a s s i f y b r e e d i n g i n d i v i d u a l s f r o m B o n s a l l C r e e k . The d i s c r i m i n a n t f u n c t i o n showed a g r a d u a l c h a n g e i n m o r p h o l o g y o f t h e f i s h d i s t r i b u t e d f r o m m a r i n e t o f r e s h w a t e r . I t i s c o n c l u d e d t h a t w h i l e t h e r e was c o n s i d e r a b l e d i f f e r e n t i a t i o n b e t w e e n a d j o i n i n g f r e s h w a t e r and a n a d r o m o u s b r e e d i n g p o p u l a t i o n s o f G a s t e r o s t e u s a c u l e a t u s , no e v i d e n c e o f a m o r p h o l o g i c a l d i s c o n t i n u i t y as w o u l d be e x p e c t e d o f s e p a r a t e s p e c i e s . However, t h e p r e s e n c e s o f t h e h y b r i d f o r m i n t h e f r e s h w a t e r z o n e o f B o n s a l l C r e e k s t r o n g l y i m p l i c a t e s gene f l o w b e t w e e n t h o s e f r e s h w a t e r and m a r i n e g r o u p s o f f i s h . E l e v e n p o p u l a t i o n s r a n g i n g g e o g r a p h i c a l l y f r o m t h e A l a s k a P e n i n s u l a t o C h e h a l i s B i v e r i n W a s h i n g t o n S t a t e were s i m i l a r l y s u b j e c t t o d i s c r i m i n a n t f u n c t i o n a n a l y s i s . T h e s e s a m p l e s d i d n o t show c l i n a l v a r i a t i o n i n t h e i r s c o r e s , t h o u g h t h e s c o r e s o f t h e p o p u l a t i o n s w e r e s i g n i f i c a n t l y d i f f e r e n t s u g g e s t i n g l o c a l a d a p t a t i o n and p o s s i b l e r e s t r i c t i o n o f gene f l o w w i t h i n t h e m a r i n e e n v i r o n m e n t . TABLE OF CONTENTS ABSTRACT . i i TABLE OF CONTENTS i v L I S T OF TABL ES v i L I S T OF FIGURES v i i i ACKNOWLEDGEMENTS i x DEDICATION X INTRODUCTION 1 MATERIALS AND METHODS 7 1 S t u d y S i t e s 7 2 F i e l d D a t a ,.. 7 3 D i s c r i m i n a n t F u n c t i o n A n a l y s i s And The D e t e r m i n a t i o n Of P o p u l a t i o n D i f f e r e n t i a t i o n 13 RESULTS 18 1 F i e l d I n v e s t i g a t i o n s I n t o S p e c i a t i o n I n C r e e k s ... 18 2 M o r p h o l o g i c a l I n d i c a t i o n s Of S p e c i a t i o n s I n C r e e k s 29 3 B i o g e o g r a p h y Of M o r p h o l o g y And V a r i a t i o n 40 DISCUSSION ............................ 52 1 E v i d e n c e Of Gene F l o w Between F r e s h w a t e r And M a r i n e P o p u l a t i o n s ................................ 52 I I n t r d o u c t i o n 52 I I i n f e r e n c e s From F i e l d D a t a On P h y s i o l o g i c a l Forms And L a t e r a l P l a t e C o u n t Forms ............ 52 I I I I n f e r e n c e s From G e n e r a l M o r p h o l o g y Of The 9 V F r e s h w a t e r And M a r i n e P o p u l a t i o n s 59 2 R e l a t i v e V a r i a b i l i t y Of F r e s h w a t e r and M a r i n e B r e e d i n g Gas t e r o s t eus A c u l e a t u s 64 CONCLUSIONS 68 LITERATURE CITED 72 APPENDIX I 77 APPENDIX I I . 80 v i LIST OF TABLES TABLE I Representation Of The Body Armour Forms Of Sticklebacks In Schools And In Eelgrass Breeding Communities . . . , . . , 19 TABLE II Distribution Of Body Armour Forms Of G. aculeatus In Bonsall Creek. 21 TABLE III Distribution Of Body Armour Forms Of G. aculeatus In Chase Creek. 22 TABLE IV Distribution Consistency Of Bonsall Creek Freshwater Stickleback Plate Count Forms In 1975 ftnd 1976 25 TABLE V Effect Of Breeding G. aculeatus In T i d a l Zone On Dis t r i b u t i o n Of Forms i n The Freshwater Zone In Bonsall Creek. 26 TABLE VI Survival Of Fish Transferred Within Bonsall Creek. 27 TABLE VII The F Values For Differences Between Sample Means In The Discriminant Analysis Of Bonsall Creek Sticklebacks For Year-location Morphological Types 31 TABLE VIII The A P o s t e r i o r i C l a s s i f i c a t i o n Of Samples In The Discriminant Analysis Of Bonsall Creek Sticklebacks For Year-location Morphological Types 32 TABLE IX The F Values For The Difference Between Sample Means In The Discriminant Analysis Of Bonsall Creek Sticklebacks For The Year-sex-location Morphological Types 34 TABLE X The A P o s t e r i o r i C l a s s i f i c a t i o n In The Discriminant Analysis Of Bonsall Creek Sticklebacks For Year-sex-location M o r p h o l o g i c a l T y p e s ..................................... 35 TABLE XI The I m p o r t a n c e Of Each C h a r a c t e r I n The D i s c r i m i n a t i o n A n a l y s e s Of B o n s a l l C r e e k F i s h e s 36 TABLE X I I The F V a l u e s F o r D i f f e r e n c e s B e t w e e n The S a m p l e Means I n The D i s c r i m i n a n t A n a l y s i s F o r L o c a t i o n M o r p h o l o g i c a l T y p e s I n M a r i n e S t i c k l e b a c k s 41 TABLE X I I I C a n o n i c a l V a r i a b l e s E v a l u a t e d A t Group Means I n The A n a l y s i s Of The M o r p h o l o g y Of The F r e s h w a t e r S t i c k l e b a c k s E x p r e s s e d As M a r i n e S t i c k l e b a c k s M o r p h o l o g i c a l L o c a t i o n T y p e s ........... 42 TABLE XIV The A P o s t e r i o r i C l a s s i f i c a t i o n I n The D i s c r i m i n a n t A n a l y s i s F o r G e o g r a p h i c M o r p h o l o g i c a l T y p e s Of M a r i n e S t i c k l e b a c k s I n d i c a t i n g T e m p o r a l V a r i a t i o n 43 TABLE XV The F V a l u e s F o r D i f f e r e n c e s Between Sample Means I n The D i s c r i m i n a n t A n a l y s i s F o r L o c a t i o n - s e x M o r p h o l o g i c a l T y p e s I n M a r i n e S t i c k l e b a c k s 44 TABLE XVI The A P o s t e r i o r i C l a s s i f i c a t i o n I n The D i s c r i m i n a n t A n a l y s i s F o r L o c a t i o n - s e x M o r p h o l o g i c a l T y p e s Of M a r i n e S t i c k l e b a c k s 45 TABLE X V I I The I m p o r t a n c e Of E a c h C h a r a c t e r I n The D i s c r i m i n a n t A n a l y s e s Of B i o g e o g r a p h i c F i s h S a m p l e s ..... 46 TABLE X V I I I The F V a l u e s F o r D i f f e r e n c e s Between Sample Means I n The D i s c r i m i n a n t A n a l y s i s F o r M a r i n e G e o g r a p h i c M o r p h o l o g y T y p e s 49 TABLE XIX M o r p h o l o g y Of F r e s h w a t e r S t i c k l e b a c k s E x p r e s s e d As M a r i n e S t i c k l e b a c k s M o r p h o l o g i c a l L o c a t i o n T y p e s 51 v i i i LIST OF FIGURES FIG. 1 Diagram Of Gasterosteus Aculeatus ................ 2 FIG. 2 Geographic L o c a t i o n Of Sample S i t e s Along The P a c i f i c Coast Of North America 10 FIG..3 L o c a t i o n Of Sample S i t e s In B o n s a l l Creek ........ 11 FIG. 4. D i s t r i b u t i o n Of Adult S t i c k l e b a c k Body S i z e In B o n s a l l Creek 24 FIG. 5. Freshwater M o r t a l i t i e s Of S t i c k l e b a c k J u v e n i l e s And Adult P l a t e Forms From The Chase Creek Sympatric Zone ... 29 FIG. 6 M o r p h o l o g i c a l V a r i a t i o n Of S t i c k l e b a c k Males And Females In B o n s a l l Creek 38 FIG. 7 M o r p h o l o g i c a l V a r i a t i o n Of S t i c k l e b a c k Male And Females In B o n s a l l Creek E x c l u s i v e Of Sympatric Zone I n d i v i d u a l s Of The Low P l a t e Form 39 FIG. 8 V a r i a t i o n In Standard Body Length Of Breeding Gasterosteus Aculeatus Along The P a c i f i c Coast Of North America ................................................. 48 i x ACKNOWLEDGEMENTS C o m p l e t i o n o f t h i s t h e s i s w o u l d h a v e been h i n d e r e d w i t h o u t t h e s u p p o r t o f many p e o p l e . T h e r e i s n o t s p a c e e n o u g h t o a c k n o w l e d g e a l l o f t h e a s s i s t a n c e g i v e n , h o w e v e r I w o u l d l i k e t o p a r t i c u l a r l y a c k n o w l e d g e t h e c o n t r i b u t i o n s o f s e v e r a l p e o p l e . I w o u l d l i k e t o t h a n k Dr. J.D, M c P h a i l w i t h o u t whom t h i s work c o u l d n o t h a v e been a c c o m p l i s h e d , and D r . P.A. L a r k i n whose s u p p o r t and a d v i c e d u r i n g t h e a n a l y s i s and w r i t i n g p r o v e d i n v a l u a b l e . I w o u l d l i k e a l s o t o t h a n k D r , N.J. W i l i m o v s k y , D r . C. D. L e v i n g s and Mr. D. P e a c o c k f o r t h e i r s u g g e s t i o n s and p r o o f r e a d i n g o f t h e m a n u s c r i p t . Much o f what i s r e p o r t e d h e r e i n was d e p e n d e n t upon t h e s w e a t and t o i l o f p e o p l e who a i d e d me i n t h e f i e l d work. I n p a r t i c u l a r I w o u l d l i k e t o t h a n k Mr. P.R. B l a c k and Mr. D. L e v y . X DEDICATION To the memory of Francesco S i z i vho, i n rebuttal to Galileo's suggestion that several s a t e l l i t e s c i r c l e d Jupiter r e p l i e d : 0 There are seven windows in the head, two n o s t r i l s , two ears, two eyes and a mouth; so i n the heavens there are two favorable stars, two unpropitious, two luminarie and Mercury alone undecided and i n d i f f e r e n t . From which and many other s i m i l a r phenomena of nature such as the seven metals, ect., which i t were tedious to enumerate, we gather that the number of planets i s necessarily seven.... Moreover, the s a t e l l i t e s are i n v i s i b l e to the naked eye and therefore can have no influence on the earth and therefore would be useless and therefore do not exist. 1 INTRODUCTION Some f i s h s p e c i e s tend to be c o n s e r v a t i v e i n the shape and placement of body armour. For example, i n the Poacher fa m i l y (Agonidae) the e x t e r n a l bony p l a t e s are so i n v a r i a b l e t h a t the r e p o s i t i o n i n g o f a s i n g l e p l a t e i s s u f f i c i e n t t o d i f f e r e n t i a t e between two s p e c i e s ( Asterotheca alascana and i n f r a s p i n a t a }. S i m i l a r l y i n the L o r i c a r i i d a e (a f a m i l y o f c a t f i s h e s ) many of the s p e c i e s are d i f f e r e n t i a t e d by smal l d i f f e r e n c e s i n body armour. In c o n t r a s t , the t h r e e - s p i n e d s t i c k l e b a c k G a s t e r p s t e u s a c u l e a t u s L., i s s t r i k i n g l y v a r i a b l e i n i t s e x t e r n a l body armour. One extreme form has bony p l a t e s c o v e r i n g the e n t i r e l ength of both s i d e s of the body. In a d d i t i o n t h i s form has an e x t e r n a l p e l v i c g i r d l e t h a t supports a p a i r of e r e c t i l e p e l v i c s p i n e s , and middorsal p l a t e s that support three e r e c t i l e d o r s a l s p i n e s ( FIG. 1 ) . At the o t h e r extreme are p o p u l a t i o n s which l a c k a l l d o r s a l and v e n t r a l s p i n e s , the p e l v i c g i r d l e and the l a t e r a l p l a t e s ( B e l l 1976). Other p o p u l a t i o n s show some combinations of the above c h a r a c t e r s and some p o p u l a t i o n s possess s e v e r a l d i f f e r e n t morphological forms each r e c o g n i z a b l e by t h e i r d i s t i n c t i v e body armour. The amount, maintenance, and o r i g i n of such v a r i a b i l i t y has i n t r i g u e d s c i e n t i s t s and l e d to a c o n s i d e r a b l e l i t e r a t u r e on G, a c u l e a t u s . The o r i g i n of t h i s v a r i a b i l i t y i s , however, a matter f o r c o n j e c t u r e . There e x i s t s some g e n e t i c and some e c o l o g i c a l data on three body armour forms. However most of FIGURE 1. The m o r p h o l o g i c a l c h a r a c t e r s o f G a s t e r o s t e u s  a c u l e a t u c used i n t h i s s t u d y were: 1.Standard body l e n g t h , 2.Number of d o r s a l f i n r a y s , 3.Number of a n a l f i n r a y s , 4.Body de p t h , 5 . V e n t r a l s p i n e l e n g t h ( l e f t s i d e o n l y ) , 6.Head l e n g t h , 7.Distance between the a n t e r i o r two d o r s a l s p i n e s , 8 . Distance between the p o s t e r i o r two d o r s a l s p i n e s . A l s o measured were mouth w i d t h ( t h e w i d t h a c r o s s the p o s t e r i o r l i m i t s o f the m a x i l l a r i e s ) , g i l l r a k e r l e n g t h ( o f the t h i r d v e n t r a l g i l l r a k e r on the lower l i m b o f the f i r s t l e f t g i l l a r c h ) , and the number of g i l l r a k e r s on t h a t g i l l a r c h . P l a t e count forms i n c l u d e the h i g h p l a t e count form i n the diagram(30-35 p l a t e s per s i d e ) , the low p l a t e count form(0-7 o f the s t i p l e d p l a t e s i n the d i a g r a m ) , and a form i n t e r m e d i a t e between these two forms. 3 the l i t e r a t u r e on G. aculeatus i s descriptive and either documents the d i s t r i b u t i o n of various forms or new and rare variations on the three generalized body armour forms. Past workers recognized a difference i n the d i s t r i b u t i o n of the two extreme armour forms: the low plate form tends to occur i n freshwater streams, and high plate count form mainly occurs i n the ocean(Munzing 1 9 6 3 } . High plate count ocean populations usually have 3 0 - 3 5 l a t e r a l bony plates per side. In contrast the generalized stream form has 1 - 7 l a t e r a l bony plates per side. This d i s t r i b u t i o n a l difference between plate forms i s not absolute, and freshwater l o c a l i t i e s are known where populations have either of the above forms, or a form with intermediate plate count, or any combination of these forms. Populations t o t a l l y lacking l a t e r a l plates, or spines and pelvic g i r d l e are rare. For convenience in assaying phenotypes three l a t e r a l plate forms are recognised: high, intermediate and low. A l l three are known to be inherited. H a g e n { 1 9 6 7 ) , Hay and Mc P h a i l ( 1 9 7 5 ) , Mc P h a i l ( 1 9 6 9 ) and H e u t s { 1 9 4 7 ) demonstrated that the high and low plate count forms are true breeding and that hybridization of these two forms produces the intermediate plate count form i n the f i r s t hybrid generation. However, t h i s pattern of inheritance is inadeguate to explain some of the combinations of plate forms found i n freshwater populations. Populations are known where only the intermediate and one extreme plate count form are present(Hagen and Gilbertson 1 9 7 2 ) . Also populations are 4 known where both extreme plate count forms are present (Bell 1976) , or only the intermediate form i s present (M unzing 1963). This suggests that the plate inheritance model i s not as general as suggested by the previous researchers. Data on the l o c a l i z a t i o n and v a r i a b i l i t y of anadrcmous populations on the P a c i f i c Coast of North America are scarce. In other regions of the world the data are often u n i n t e l l i g i b l e i n the context of l a t e r a l plate inheritance. However, for a l l known European and North American anadrcmous populations of sticklebacks the inheritance pattern suggested by Hagen (1967) i s adequate to to explain present data. The morphology of an animal is composed of two components, a biogeographic component derived from the history of the species and a component that i s the resu l t of the loc a l i z e d interaction of sel e c t i o n and gene flow. Analysis of v a r i a b i l i t y in European three-spined stickleback suggest h i s t o r i c a l events provide a plausible explanation for the or i g i n and d i s t r i b u t i o n of plate count forms along the continent's coast (Munzing 1963). No systematic search for such a h i s t o r i c a l explanation for the variation in coastal populations along the P a c i f i c Coast of North America has been published. The h i s t o r i c a l component having been dealt with, interpretation of the remaining v a r i a b i l i t y involves determining to what degree gene flow has been r e s t r i c t e d between groups of ind i v i d u a l s , and selec t i v e pressures which are operating to modify the morphology i n l o c a l areas. 5 I s o l a t i n g m e c h anisms t h a t h a v e f o r m e d b e t w e e n s p e c i e s may a l s o b r e a k ( H u b b s 1955) . I n t e r m s o f t h e t o t a l number o f f i s h s p e c i e s h y b r i d i z a t i o n i s n o t common b u t h y b r i d s do o c c u r . Most h y b r i d i z a t i o n i s between f r e s h w a t e r s p e c i e s b u t some i s a l s o r e c o g n i z e d b e t w e e n m a r i n e s p e c i e s . S p a r s e e v i d e n c e i n t h e l i t e r a t u r e and t h e i m p r e s s i o n s o f s c i e n t i s t s i n t e r e s t e d i n s t i c k l e b a c k v a r i a t i o n l e a d s t o c o n j e c t u r e t h a t i s o l a t i n g m e c h a n i s m s between m o r p h o l o g i c a l l y d i f f e r e n t i a t e d p o p u l a t i o n s o f G a s t e r o s t e u s a c u l e a t u s may n o t a l w a y s be e f f e c t i v e ( M i l l e r a n d Hubbs 1969) . H a g e n f s (1967) work on t h e C a m p b e l l B i v e r s u g g e s t s t h e main i s o l a t i n g mechanism b e t w e e n a n a d r o m o u s and f r e s h w a t e r p o p u l a t i o n s o f G a s t e r o s t e u s a c u l e a t u s i s h a b i t a t i s o l a t i o n . T h i s i s a mechanism t h a t c o n c e i v a b l y may f a i l a s a r e s u l t o f c h a n g e i n g s e l e c t i v e p r e s s u r e s . I n i t i a l l y I s e t o u t t o s e e i f s i m i l a r h a b i t a t i s o l a t i o n was common t o s e v e r a l c r e e k s i n t h e S t r a i t o f G e o r g i a r e g i o n o f B r i t i s h C o l u m b i a . However, p r e l i m i n a r y work o n s e v e r a l s m a l l d r a i n a g e s l o c a t e d on V a n c o u v e r I s l a n d ( B o n s a l l , C h a s e and L a r d C r e e k s , L i t t l e R i v e r and t h e d r a i n a g e c a n a l o f t h e Comox a i r base) s u g g e s t e d t h a t h a b i t a t i s o l a t i o n o f t h i s t y p e was n o t c o n s t a n t . The p u r p o s e o f t h i s t h e s i s i s t o r e - e x a m i n e t h e p a t t e r n o f m o r p h o l o g i c a l v a r i a t i o n i n c r e e k b r e e d i n g s t i c k l e b a c k s t o d e t e r m i n e i f t h e r e i s e v i d e n c e o f r e p r o d u c t i v e i s o l a t i o n b e t w een m a r i n e and f r e s h w a t e r p o p u l a t i o n s i n a d r a i n a g e o t h e r t h a n C a m p b e l l R i v e r , and a l s o t o d e t e r m i n e i f t h e m o r p h o l o g i c a l p a t t e r n i s c o n s t a n t f r o m y e a r t o y e a r . I 6 also attempt to locate any pattern in the variation that night suggest a h i s t o r i c a l explanation . 7 MATERIALS AND METHODS 1 S t u d y S i t e s T h r e e c o a s t a l c r e e k s w e re u s e d i n t h i s s t u d y . B o n s a l l C r e e k on V a n c o u v e r I s l a n d was t h e p r i m e s t u d y s i t e . T h i s c r e e k d r a i n s a g r i c u l t u r e l a n d and d u r i n g t h e b r e e d i n g s e a s o n i s a b o u t 4.4 km l o n g . T h i s d i s t a n c e i s f r o m t h e s t a r t o f t h e c r e e k c h a n n e l i n t i d a l g r a s s e s t o i t ' s i n t e r m i t t e n t end a b o u t 400 m w e s t o f t h e I s l a n d H i g h w a y . A n o t h e r s t u d y s i t e C h a s e C r e e k d r a i n s a f o r e s t e d w a t e r s h e d a n d t h e n r u n s t h r o u g h a r e s i d e n t i a l s e c t i o n o f Nanaimo c i t y t o t h e o c e a n . I t ' s a p p r o x i m a t e l e n g t h i s 12.5 km. C a m p b e l l R i v e r i s on t h e B r i t i s h C o l u m b i a m a i n l a n d c l o s e t o t h e U.S., Canada b o r d e r . T h i s 26.5 km l o n g r i v e r d r a i n s a g r i c u l t u r a l l a n d . A l l o f t h e s e c r e e k s c r o s s r e l a t i v e l y f l a t l a n d o v e r most o f t h e i r l e n g t h . They a l l h a v e v e g e t a t e d and mud-sand b o t t o m a r e a s s c a t t e r e d a l o n g t h e i r l e n g t h . C h a s e C r e e k h a s a l a k e o n i t where t h e Nanaimo w a t e r d i s t r i c t has c o n s t r u c t e d a s m a l l r e s e r v o i r . G e n e r a l l y t h e s e c r e e k s a n d t h e r i v e r a p p e a r v e r y s i m i l a r e x c e p t t h a t t h e l o n g e r d r a i n a g e s have s l i g h t l y f a s t e r f l o w s . 2 F i e l d D a t a F i s h were c o l l e c t e d f r o m t h r e e t y p e s o f l o c a t i o n s . I n t h e w i n t e r a t t e m p t s t o c o l l e c t f i s h e s i n B o n s a l l C r e e k above and b e l o w t h e l i m i t o f t i d a l i n f l u e n c e f a i l e d t o p r o d u c e 8 r e s u l t s . D u r i n g t h i s p e r i o d a s i n g l e f i s h was c o l l e c t e d i n b e d s o f Z o s t e r a m a r i n a a t t h e mouth o f B o n s a l l C r e e k . T h i s f i s h was n o t i n b r e e d i n g c o n d i t i o n . O t h e r c o l l e c t i o n s o f G. a c u l e a t u s b e t w e e n t h e months o f November and M a r c h were done i n t h e v i c i n i t y o f w h a r f s . H e r e t h e f i s h e x h i b i t e d s c h o o l i n g b e h a v i o r and were f o u n d n o t t o be i n b r e e d i n g c o n d i t i o n . W i n t e r c o l l e c t i o n s w e r e made a t t h e Comox p u b l i c w h a r f u s i n g a l o n g h a n d l e d .75 m d i p n e t (2.8 mm s g . M e s h ) , a t t h e P a c i f i c E n v i r o n m e n t a l I n s t i t u t e i n V a n c o u v e r u s i n g a 3.00 x 1.25 m e t e r p o l e s e i n e (2.8 mm s g . m e s h ) , and a t t h e M a p l e Bay p u b l i c w h a r f u s i n g a 13.4 x 2.68 m e t e r b e a c h s e i n e w i t h a 2.15 x 2.68 m e t e r c e n t r e c o l l e c t i o n bag o f 2.68 m e t e r d e p t h ( e n t i r e l y o f 3.6 mm s g , mesh). A l s o used was a U.B.C. F i s h Museum c o l l e c t i o n o f G. a c u l e a t u s c o l l e c t e d 9 March 1968 a t Mc Kay Cormock S h i p y a r d s i n V i c t o r i a h a r b o u r . From J u n e t h r o u g h S e p t e m b e r s t i c k l e b a c k s were n o t o b s e r v e d a r o u n d t h e w h a r f s a n d t h e r e f o r e no a t t e m p t s were made t o c o l l e c t a t t h i s t i m e . However d u r i n g t h i s p e r i o d f i s h were common i n Z o s t e r a b e d s and i n c r e e k s t h r o ughou t t h e S t r a i t o f G e o r g i a . I n B o n s a l l C r e e k a n d C a m p b e l l R i v e r f i s h were f o u n d a b o v e t h e l i m i t o f t i d a l i n f l u e n c e , I n B o n s a l l C r e e k . C a m p b e l l R i v e r , and i n C h a s e C r e e k f i s h wer e f o u n d b r e e d i n g f r o m t h e u p p e r l i m i t o f t i d a l i n . f l u en c e s e a w a r d t o , and i n c l u d i n g , t h e Z._ m a r i n a b e d s i n t h e e s t u a r i e s. At t h i s t i m e most o f t h e a d u l t f i s h c a u g h t a b o v e and b elow t h e u p p e r l i m i t o f t i d a l i n f l u e n c e w e re i n b r e e d i n g c o n d i t i o n . 9 In two successive summers extensive attempts were made to c o l l e c t three-spined sticklebacks from waters above the zone of t i d a l influence in Chase Creek. None were caught i n 1976 and only two were caught in 1975. The two caught in 1975 were taken only one hundred and f i f t y meters above the l i m i t of t i d a l influence. A l l creeks were sampled using the pole seine. During the summer of 1975 Z.. marina beds at Porpoise Bay, Bamfield I n l e t , Comox public wharf and the mouths of Campbell River and Bonsall Creek were sampled. at these locations Casterosteus aculeatus i n breeding condition were c o l l e c t e d , by beach seining. Museum c o l l e c t i o n s containing a large proportion of gravid females were used i f the c o l l e c t i o n was taken from saline waters . The U.B.C. Fish Museum specimens (museum catalogue numbers i n parenthesis) were from King Salmon River ( BC60-409), Koitoi Bay (BC58-206) , Turnagain Slough(BC58-198), Twin Glaciers (BC58-394), and Chehalis River(uncatalogued). ( See FIG. 2 ) . Transfer experiments using l i v e G. aculeatus were done across the upper l i m i t of t i d a l influence i n Bonsall Creek ( FIG. 3 ). The high plate count form was coll e c t e d from about the 0 and 2500 m points i n Bonsall. They were moved i n buckets containing water from their c o l l e c t i o n point to the 2580 and 3548 m points respectively. A c o l l e c t i o n of high plate count in d i v i d u a l s was also made at the 25 80 m location and transferred to the 0 m point.. Similarly the low plate FIGURE 2. The P a c i f i c coast sampling s t a t i o n s used i n t h i s study and the approximate c o a s t a l distance of each s t a t i o n from King Salmon R i v e r , A l a s k a ( S t a t i o n 1). The s t a t i o n s sampled were; l . K i n g Salmon River (OKm), 2 . K o i t o i Bay(1340Km) 3.Turnagain Slough(1550Km), 4.Taku River (2850Km), 5.Comox River (4010Km), 6.Porpoise Bay (4110Km), 7.Qualicum River (4110Km), 8.Campbell River (4130Km), 9. B o n s a l l Creek (4130Km), lO.Bamfield I n l e t (4130Km), and 11.Connor Creek (4550Km). Locations of data taken from the published l i t e r a t u r e i n c l u d e ; 12.Rogue River (5050Km), 13.Smith River (5110Km), 14.Kalamath River (5150Km), 15.Mattole River (5270Km) and 16.Ten M i l e River (5370Km). FIGURE 3. A map o f the B o n s a l l Creek s a m p l i n g s i t e s . The numbers i n d i c a t e the d i s t a n c e i n meters from the most seaward s a m p l i n g s i t e . 12 count form collected at the 3548 ra point was transferred across the upper l i m i t of t i d a l influence to 2580 m In addition other f i s h were coll e c t e d as above but were not transferred. They were l e f t i n v buckets for a time equivalent to the time i t took to do the transfers and then both transferred f i s h and the nontransferred control group were placed in separate "Gee's Common Sense Minnow Traps" and reimmersed in the creek. These traps had their ends wired closed. The traps were removed afte r f i v e days and the mortalities recorded. One hundred meters below the upper l i m i t of t i d a l influence i n Chase Creek a sample of a l l plate forms (297 individuals) were coll e c t e d from a small side channel. These f i s h were put in a large p l a s t i c garbage p a i l with water collected from the same area. Compressed oxygen was bubbled through the water and the f i s h were transported to the University of B r i t i s h Columbia. At U.B.C. the f i s h were put in a .90 x .90 x .45 m wire cage of 2.8 mm galvanized mesh. The cage rested in a large cement pond with a continuous supply of fresh water. The purpose of t h i s was to determine i f the physiological response of the three plate forms to freshwater was d i f f e r e n t . Along side t h i s cage was an i d e n t i c a l cage containing a sample of a polymorphic population of G. aculeatus from a freshwater lake. M o r t a l i t i e s were recorded from both cages. The mortalities of each plate form was recorded for Chase Creek f i s h and includes those f i s h that died in t r a n s i t from Vancouver Island. Only the number of 13 m o r t a l i t i e s o f a l l f o r m s was r e c o r d e d f o r t h e f r e s h w a t e r l a k e f i s h . They were c o n s i d e r e d a s a c o n t r o l a g a i n s t t o x i c a n t s i n t h e s y s t e m . 3 D i s c r i m i n a n t F u n c t i o n A n a l y s i s a n d t h e D e t e r m i n a t i o n o f EofiMliiisa D i f f e r e n t i a t i o n A l l f i s h u s e d i n t h e d i s c r i m i n a n t f u n c t i o n a n a l y s i s were i n i t i a l l y f i x e d i n 10% f o r m a l i n . Museum s p e c i m e n s were s u b s e q u e n t l y washed and p r e s e r v e d i n 3 7 % I s o p r o p a n o l . C o l l e c t i o n s made s p e c i f i c a l l y f o r t h i s t h e s i s r e m a i n e d i n t h e f o r m a l i n s o l u t i o n . To a i d i n c o u n t i n g m e r i s t i c c h a r a c t e r s a s t a i n was u s e d . S p e c i m e n s were f i x e d f o r a t l e a s t one week i n f o r m a l i n and t h e n r i n s e d f o r 24 h r . i n c o l d w a t e r . S a m p l e s were t h e n i m m e r s e d o v e r n i g h t i n a m i x t u r e o f n i n e p a r t s w a t e r t o one p a r t dye s o l u t i o n . The dye s o l u t i o n c o n s i s t e d o f one gram A l i z a r i n Red i n a l i t r e o f 2 0 % KOH. S h r i n k a g e o f s p e c i m e n s d u r i n g p r e s e r v a t i o n c a n o c c u r h o w e v e r , s h r i n k a g e o f a l l s p e c i m e n s c o l l e c t e d f o r t h i s s t u d y s h o u l d have b e e n e q u a l a s a l l were p r e s e r v e d i n t h e same manner. I t i s assumed t h a t s h r i n k a g e i n t h e museum s p e c i m e n s was n o t s i g n i f i c a n t l y d i f f e r e n t f r o m t h a t i n t h e o t h e r s a m p l e s . E l e v e n c h a r a c t e r s were measured and c o u n t e d . They i n c l u d e s t a n d a r d body l e n g t h , head l e n g t h , l e n g t h o f l e f t p e l v i c s p i n e , l e n g t h o f t h i r d v e n t r a l g i l l r a k e r on t h e l o w e r l i m b o f t h e f i r s t l e f t g i l l a r c h , d i s t a n c e b e t w e e n t h e two a n t e r i o r d o r s a l s p i n e s , d i s t a n c e b e t w e e n t h e two p o s t e r i o r 14 dorsal spines, number of g i l l rakers on the f i r s t l e f t g i l l arch, number of anal f i n rays, number of dorsal f i n rays, and counts of l a t e r a l plates on both sides of the body (see Fig. 1) • ft ten power binocular microscope was used in making a l l counts and an ocular micrometer was used to measure g i l l raker length. Other lengths were measured with c a l i p e r s . A l l fishes used were over 3 3 mm i n length. Discriminant function analysis was completed on an I.B.I!. 370 computer using a U.B.C. adapted version of the U.C.L.A., BHD 07M stepwise discriminant analysis program. Regression analysis was done on a PDP 11 computer. In G. aculeatus spawning in a creek there may e x i s t several reproductively isolated populations. Given time and d i f f e r e n t i a l s e l e c t i o n . I f a complete and temporally stable i s o l a t i n g mechanism existed a detectable morphological discontinuity should develop. Discriminant analysis allows a combination of characters to be used to represent the composite morphology of individuals. Such analysis should be capable of detecting any discontinuity in the d i s t r i b u t i o n of a l l e l e s or i n the manner i n which the genes are interpretted. Discriminant analysis i s designed to maximize differences by creating a series of orthoginal functions with seguentially l e s s power to make the discrimination. The resultant discriminant variables (canonical variates) r e f l e c t variation of each of the character in a l l samples i n r e l a t i o n to the variation among a l l samples. Such a morphological index 15 should allow d e f i n i t i o n of multivariate c l i n e s and detection of d i s c o n t i n u i t i e s not apparent from single characters. Further, i f af t e r the rotation of the axes by the discriminant analysis , the variance associated with any single variable does not approximate the variance amongst group means then that discriminant function w i l l have the power to discriminate between the groups. If an F value i s derived from the variance associated with each of the variables, then these F values may be considered a crude indicator of the r e l a t i v e importance of each variable i n the discrimination. These calculations are done s e r i a l l y with the variation associated with the highest F value removed before the next highest F value i s calculated. Therefore i t i s not possible to compare more than the f i r s t two or possibly three highest F values due to the dependency of each subsequent F value on the variation previously removed. Such calculations were done and the re s u l t s are l i s t e d in tables VII and VIII. To answer the question, "Are individual anadromous populations morphologically a random subset of a l l marine populations along the coast?" (implying panmixis) i t i s necessary to perform the equivalent of an analysis of variance on the f i r s t discriminant function score. This c r i t e r i o n of t e s t a b i l i t y for s i g n i f i c a n c e i s also met. Discriminant function analysis allows f o r an approximate F t e s t . Discriminant function analysis meets a l l requirements for the analysis proposed. The actual mathematical technique i s b r i e f l y described by Polqar(1975) and in i t s e n t i r e t y by 16 Cooley and Lohnes(1971). The data for analysis consists of a l l morphological parameters with the exception of l a t e r a l bony plates and standard body length. The reason for the exclusion of these characters are explained l a t e r . A l l scalar characters were regressed using standard body length as the independent variable. The residuals from these regressions were then used as standardized variables for these characters i n the discriminant analysis. In Bonsall Creek analysis groups are defined as either coming from the anadromous zone (that zone below the upper l i m i t of t i d a l influence) or from the freshwater zone. The Bonsall Creek f i s h are also divided by year collected and by sex. Only the f u l l y plated form and the low plate form were analysed. This makes any s t a t i s t i c a l errors i n hypothesis te s t i n g more l i k e l y to be type 1 errors. A second analysis on Bonsall Creek data excludes a l l low plate form indivi d u a l s sympatric with the high plate form. In the large scale geographic analysis groups were defined by location sampled and sex. Rs several of the characters are known to be inherited i t i s of interest to determine which in d i v i d u a l characters show the e f f e c t s of selection, Characters were i n d i v i d u a l l y analysed using an F test to test the equivalence of variance in a composite sample of ten marine samples and i n a composite sample of three freshwater samples. Then an approximate »t f test was used to test for differences between the means of the two composite samples. The marine samples were those used in 17 the multivariate analysis of d i f f e r e n t i a t i o n i n marine populations. The freshwater samples included those collected as the extreme landward sample i n Bonsall Creek i n 1975 and i n 1976, and a sample from the freshwater zone in Campbell River. 18 RESULTS 1 F i e l d I Investigations Into SjJeciation in Creeks Previous work(Hagen 1967, Narver 1969) on the P a c i f i c coast of North America assumed marine populations of G. aculeatus are exclusively the high plate count form. However, a l l of my samples of sticklebacks taken from f i s h schools near wharfs early i n the year, indicate nonbreeding schools contain a l l three of the body armour types(Table I) . Clearly, the high count form predominates and the intermediate and low plate count forms are i n such low frequencies (4.9 and 1.6 % respectively) that they might be missed in small samples. Reguarding l a t e r a l plates inheritance; none of the genetic models for l a t e r a l plate inheritance can explain the occurrence of certain plate count forms i n some lakes. However, Hagen's 1967 model i s adeguate to explain the d i s t r i b u t i o n of plate count forms found i n coastal l o t i c systems and the ocean. A character of marine populations i s that they breed i n places other than in streams, creeks and r i v e r s . Samples of male and female Gasterosteus aculeatus in breeding condition were coll e c t e d over two summers from Fostera marina beds i n several d i f f e r e n t estuaries ( For a description of the Zostera marina habitat see appendix 1.) , Adults and very young sticklebacks were collected i n th i s vegetation. The density of the grass though, makes observation of mating impossible 19 1— i f T T -1 11 SCHOOLING | F I S H I N 1 ! 1 11 J || TOTALS| • * FISHES | Z A M a r i n a | HIGH T T J I ! ! j OBSERVED | J 4 1 7 7 ! 5 9 7 1 i I | PLATE j | | \ 11 i « | i 4 7 7 4 j | COUNT j j EXPECTED || 4 2 1 0 . 4 7 | 5 6 3 . 5 3 1 1 I \ FORM !! !! ! J INTERMEDIATE j i ; j l l ! i OBSERVED | j 2 1 9 I 1 i I I ! PLATE i | ] | 11 1 -j--).- -•H 2 2 0 I | COUNT • 1 1 1 \ FORM 1 EXPECTED | | 1 9 4 . 0 3 | 2 5 . 9 7 1 1 1 _„„ ] l T — 1 i — ! i i J J LOW | | 1 j 1 1 i | OBSERVED || 7 2 I o ) 1 1 | PLATE | | I 1 1 t | 1 J 7 2 1 I I 1 * 1 COUNT • 1 I I | FORM ! EXPECTED | 1 6 3 . 5 0 1 8 . 5 !! 1 i X J j = 3 9 . 1 1 P < . 0 0 1 i , _ J l&BLE I Probabil i t y that the forms of G A aculeatus are equally represented i n schooling nonbreeding f i s h compared with their representation i n Eelgrass where they are breeding. 20 and v i s u a l location of nests d i f f i c u l t . However, i n Porpoise Bay two nests were observed and males i n reproductive condition were seen fanning water at the nests with their pectoral f i n s . One point needs to be c l a r i f i e d . Eelgrass beds where G. aculeatus breed are often associated with r i v e r s , streams or creeks entering the ocean. However, breeding sticklebacks were abundant in the Zostera marina at the Porpoise Bay c o l l e c t i o n s i t e though there was no apparent freshwater surface flow i n the area. Because of the low frequency of the intermediate and low plate count forms of marine G. aculeatus i t i s possible that small sample sizes are responsible for the apparent s c a r c i t y of such i n d i v i d u a l s in c o l l e c t i o n s from eelgrass beds. However a contingency table (Table I) suggests the frequency of these forms was s i g n i f i c a n t l y d i f f e r e n t in winter schools and in eelgrass beds. The pattern of high plate count individuals at the mouth of the creek and an increasing proportion of the low plate count individuals upstream was apparent i n both Bonsall and Chase Creeks.. In both creeks intermediate plate count individuals were present i n that area of the creeks where the high and low count forms were sympatric( Table II and Table I I I ) . The upper l i m i t of t h i s zone of sympatry appeared, i n the creeks investigated, to be equivalent to the l i m i t of t i d a l influence in the creek. Above this zone i n Bonsall Creek the low and intermediate 2 1 \ DISTANCE FROM OCEAN (METERS) I | | 0 | 8 0 0 | 1 9 3 5 J 2 5 8 0 | 2 9 0 0 J 3 5 4 8 J 5 0 0 0 J , T f x + 1 1 r + + 1 \ r- H- — 4 H 4 4 4 + 4 I I HIGH I I ] I I 1 ] I j | | PLATE || | | | | | I | | | COUNT | | 1 0 0 | 1 0 0 | * * * J 2 7 . 3 | 7 . 1 | 0 | 0 | I I FORM || | | | | | I | | 1 | INTERMEDIATE || | | | | | | | | | PLATE M | | I I I I I | 9 | COUNT || 0 | 0 | * * * | 9 . 1 | 2 8 . 6 | 8 . 1 | 0 J I I FORM || | | | | I I I , 7 J- I -T -I 1 -I + - -I + -I I I IOW || | | | | | | I I 5 | PLATE H I I I I I I I | | COUNT || 0 | 0 | * * * J 6 3 . 6 J 6 4 . 3 | 9 1 . 9 | 1 0 0 | I I FORM || | | | | | ! | | i 4-+ +~ r - r !~ + 4 4 i I SAMPLE I I I I S I I I I J J SIZE |] 2 5 | 9 | 0 | 1 1 | 1 4 | 1 3 6 | 1 2 | 1 r ++ 4~ h + r - + -I 4 , + + + j _ V r _ T _ + + I I HIGH || | | | | | | I | | PLATE || | J 1 | 1 1 I | | COUNT || 1 0 0 | 1 0 0 | 1 0 0 | * * * ( 1 3 . 1 | 0 | 0 | | | FORM || 1 | | | | | I I f— 4 + 4 4~ + \ + 4 4 | 1 |INTERMEDIATE || I I I I | i I | | PLATE || | | | | i | | I | 9 | COUNT || 0 | 0 | 0 | * * * | 3 0 . 0 | 7 . 4 I 1 . 4 I | | FORM I I I I I I I I I | 7 ] +4- i r r V -I 4 4 | j LOW | ] | | I | I I I | 6 | PLATE || | | | | f I I | | COUNT || 0 | 0 | 0 | * * * | 5 6 . 9 j 9 2 . 8 | 9 8 . 6 j I I FORM || | | | | | ! J i r + + 4 + -j ^ ^ -+ -i | | SAMPLE || | | | | I I I | | S I Z E || 7 4 | 1 0 | 5 | 0 | 1 3 0 | 6 8 | 7 2 | I r 1-+ - i 1 4- 4- h 4- 4 I I L J I 1 J J 1 L _ i TABLE I I D i s t r i b u t i o n o f t h e p e r c e n t a g e s of body a r m o u r f o r m s i n B o n s a l l C r e e k d u r i n g t h e 1 9 7 5 and 1 9 7 6 b r e e d i n g s e a s o n s . S t a t i o n s a t 3 5 4 8 and 5 0 0 0 m e t e r s f r o m t h e o c e a n a r e a b o v e t h e z o n e o f t i d a l i n f l u e n c e . 22 I T T T "1 T 1 | 1 9 7 5 || S E I N E 1 | SEINE 2 | SEINE 3 | SEINE 4 | 1 -H- f 1- + i *; + J r j . h 1 | HIGH M I I | I | PLATE || | | | | | COUNT || 80.0 | 47.4 | 7.2 j 0 | I POEM || | | | | , 4-4- L._ }._ ., j |INTERMEDIATE || | | | | | PLATE H | | I | | COUNT || 12.5 | 32.9 | 46.4 | 0 | I FORM || | | | | 1- ++ 1- 1- + 4 I LOW || | | 1 | | PLATE | j | j | | | COUNT I! 7.5 \ 19.7 j 46.4 | 100 | | FORM || | \ | | j -H-- j r- H J , -14- f- 1-- + i | SAMPLE 11 | \ 1 | | S I Z E || 40 | 76 | 28 | 2 | l l _ l J 1 L I TABLE I I I D i s t r i b u t i o n o f p e r c e n t a g e of body a r m o u r f o r m s i n C h a s e C r e e k d u r i n g t h e 1975 b r e e d i n g s e a s o n . S e i n e 4 was t h e t o t a l r e s u l t a n t o f s e i n i n g and t r a p p i n g s e v e r a l k i l o m e t e r s o f c r e e k a b o v e t h e t i d a l z o n e . The two i n d i v i d u a l s c a u g h t were b o t h c a u g h t 150 m e t e r s a b o v e t h e l i m i t o f t h e t i d a l z o n e . S e i n e s 3, 2 and 1 were r e s p e c t i v e l y 200, 350 and 500 m e t e r s d o w n s t r e a m . S e i n e 1 was a t t h e c r e e k s mouth. 2 3 f o r m s were p r e s e n t . M o v i n g u p s t r e a m t h e p r o p o r t i o n o f i n t e r m e d i a t e c o u n t i n d i v i d u a l s d e c r e a s e d s i g n i f i c a n t l y ( T a b l e I V ) . I n B o n s a l l C r e e k t h e r e was a l s o a c l i n a l d e c r e a s e i n body s i z e u p s t r e a m f r o m t h e o c e a n ( F i g . 4 ) . I n C h a s e C r e e k t h e p r e s e n c e o f s t i c k l e b a c k s a b o v e t h e s y m p a t r i c z o n e i s n o t c o n s t a n t . I n B o n s a l l C r e e k t h a t p o r t i o n o f t h e G. a c u l e a t u s b r e e d i n g c o m m u n i t y f o u n d a b o v e t h e t i d a l p o r t i o n o f t h e c r e e k was p r e s e n t a n d i n b r e e d i n g c o n d i t i o n b e f o r e b r e e d i n g t h r e e -s p i n e d s t i c k l e b a c k w e re p r e s e n t i n t h e t i d a l p o r t i o n o f t h e c r e e k . C o m p a r i s o n o f t h e p r o p o r t i o n o f l o w a n d i n t e r m e d i a t e p l a t e c o u n t i n d i v i d u a l s i n t h i s f r e s h w a t e r z o n e b e f o r e a n d a f t e r t h e a p p e a r a n c e o f a b r e e d i n g p o p u l a t i o n i n t h e t i d a l p o r t i o n o f t h e c r e e k showed no s i g n i f i c a n t c h a n g e i n t h e f r e q u e n c y o f t h e t w o f o r m s ( T a b l e V ) i W i t h i n B o n s a l l C r e e k t r a n s f e r s o f G. a c u l e a t u s were made t o d e t e r m i n e i f t h e h i g h a n d l o w p l a t e c o u n t f o r m s were p h y s i o l o g i c a l l y c a p a b l e o f s u r v i v i n g t h r o u g h o u t t h e c r e e k . T a b l e V I i n d i c a t e s t h e h i g h p l a t e c o u n t f o r m and t h e f r e s h w a t e r l o w p l a t e c o u n t f o r m were a t a d i s a d v a n t a g e when moved a c r o s s t h e l i m i t s o f t i d a l i n f l u e n c e . I n c o n t r a s t , h i g h p l a t e c o u n t i n d i v i d u a l s c o l l e c t e d i n t h e e e l g r a s s b e d s ( h i g h s a l i n i t y ) and t r a n s f e r r e d t o t h e t i d a l p o r t i o n o f t h e c r e e k (low s a l i n i t y ) s u r v i v e d w e l l . I n C h ase C r e e k a d i f f e r e n t p a t t e r n o c c u r r e d . a f t e r f o u r a t t e m p t s i n v o l v i n g e x t e n s i v e s , e i n i n g and o b s e r v a t i o n o v e r two y e a r s , no r e s i d e n t f r e s h w a t e r p o p u l a t i o n o f t h r e e - s p i n e d 2 4 FIGURE 4. The d i s t r i b u t i o n of adult stickleback body size i n Bonsall Creek during the 1975 (A) and 1976 (B) breeding season. 1375 VARIATION IN BODY LENGTH WITHIN BONSAL CREEK DISTANCE FROM THE OCEAN (METERS) ho -J> > 1976 VARIATION IN BODY LENGTH WITHIN EGNSAL CREEK Y = 6 1 6 - 7 + - 0 - 3 7 3 0 E - 0 1 * X N = 105 BOO-7 5 0 - L 700 - . 0 - 500- 1000- 1500- SOOO- 5500- 3000- 3500- 4000- 4500- 5000 - 5500-DISTANCE FROM THE OCEAN (METERS) 2 5 "TT ++ LOW PLATE COUNT FORM INTERMEDIATE PLATE COUNT FORM OBSERVED EXPECTED OBSERVED EXPECTED TOTALS T fx 3 5 4 8 M. FROM OCEAN — T T 5 0 0 0 M. FROM OCEAN 1 8 8 1 9 2 16 1 2 2 0 4 84 80 —++ 8 5 -+ TOTALS 2 7 2 17 2 8 9 r — -XJ .AA. X - "-567 P < . 0 5 Ik^LE I V The p r o b a b i l i t y t h a t d u r i n g t h a t p e r i o d G, a c u l e a t u s i s b r e e d i n g i n t h e t i d a l z o n e o f B o n s a l l C r e e k , t h e c o m b i n e d d a t a f r o m 1 9 7 5 a n d 1 9 7 6 i n d i c a t e s t h a t t h e p r o p o r t i o n o f i n t e r m e d i a t e p l a t e f o r m i n d i v i d u a l s i s c o n s t a n t i n t h e z o n e 3 5 4 8 t o 5 0 0 0 m e t e r s f r o m t h e o c e a n . 26 TT LOW PLATE COUNT FOB H INTERMEDIATE PLATE COUNT FORM OBSERVED EXPECTED OBSERVED EXPECTED +4 BEFORE F I S H BREEDING IN HYBRID ZONE 193 192.75 8.25 AFTER FI S H BREEDING I N HYBRID ZONE 134 134.25 5. 75 TOTALS 327 14 TOTALS .1 201 P > . 90 140 341 TABLE V P r o b a b i l i t y t h a t i n 1976, b e f o r e a n d a f t e r t h e p r e s e n c e o f G._ a c u l e a t u s b r e e d i n g i n t h e t i d a l z o n e o f B o n s a l l C r e e k t h e p r o p o r t i o n o f i n t e r m e d i a t e p l a t e c o u n t i n d i v i d u a l s i n t h e non t i d a l p o r t i o n o f t h e c r e e k r e m a i n s c o n s t a n t . 27 B 0 D a Y N D C A a R L D M 0 G 0 C H U A T R T I a T 0 T Y N p E BODY ARMOUR TYPE AND LOCATION TRANSFERRED TO f+-METERS 2580 METERS 3548 METERS HIGH PLATE COUNT FORM HIGH PLATE COUNT FORM LOW PLATE COUNT FORM J | METERS |HIGH PLATE ! j COUNT FORM LOST f+ 25 80 METERS HIGH PLATE COUNT FORM 20 / 20 1 1 / 2 0 3548 METERS LOS PLATE COUNT FORM +-1 1 / 2 0 TABLE V I S u r v i v a l o f f i s h e s t r a n s f e r r e d i n B o n s a l l C r e e k . C o n t r o l s a r e f i s h e s c a u g h t , h a n d l e d and p u t b a c k i n w i r e c a g e s a t t h e p l a c e t h e y w e r e c o l l e c t e d . The number b e f o r e t h e d i a g o n a l l i n e r e p r e s e n t s t h e number o f s u r v i v i n g f i s h i n t h e t r a n s f e r r e d b a s k e t . The number a f t e r t h e t h e d i a g o n a l l i n e i s t h e number o f s u r v i v i n g f i s h i n t h e c o n t r o l b a s k e t . A l l b a s k e t s s t a r t w i t h 20 f i s h e s . P o s i t i o n i n t h e c r e e k i s r e p r e s e n t e d a s d i s t a n c e f r o m t h e o c e a n . The l i m i t o f t i d a l i n f l u e n c e i s 3000 m e t e r s f r o m t h e o c e a n . 28 stickleback was found i n t h i s creek. The two i n d i v i d u a l s obtained by seining t h i s area were presumed to have originated in the zone of sympatry. I f a l l three body armour forms present in the t i d a l portion of the creek were of marine o r i g i n , then the re s u l t s from the Bonsall Creek transfers suggest that i f they were placed in freshwater they would die and a l l forms would die at the same rate. This hypothesis was tested by transporting adults from the t i d a l portion of Chase Creek to a freshwater environment. In Figure 5 mortalities are recorded. A l l three forms of adults died at the same rate. However, juveniles (under 3cm.) which cannot be c l a s s i f i e d according to body armour type, died at a much increased rate. The mortalities were not due to toxicants i n the system as other three-spined stickleback l i v i n g i n another cage i n the same water at the same time showed no increase i n mortality rate during the test period. 2 Morphological Indications of Speciatign i n Creeks As discussed e a r l i e r , discriminant analysis was chosen as the method for analyzing stickleback morphology. Table XI l i s t s the F values associated with the residual variation of each variable in each of the three discriminant analyses done on Bonsall Creek data (Rohlf and Sokal(1969) l i s t e d the c r i t i c a l F value at alpha egual to .05 used i n tables XI and XVIII). Using Bonsall Creek f i s h an equation was produced that 29 FIGURE 5. Freshwater s u r v i v a l of j u v e n i l e and of the a d u l t p l a t e forms of threespine s t i c k l e b a c k s from the t i d a l zone of Chase Creek. Open c i r c l e s represent s u r v i v o r s of 100 low p l a t e count f i s h e s , boxes represent s u r v i v o r s of 119 intermediate p l a t e count f i s h e s , t r i a n g l e s represent s u r v i v o r s of 60 high p l a t e count f i s h e s , and the s o l i d c i r c l e s represent s u r v i v o r s from 18 j u v e n i l e f i s h e s . The f i r s t p o i n t on the graph in c l u d e s m o r t a l i t i e s during t r a n s i t . o t> a > o t>cn can oca Ota o o o o o O OO <£) ^ C M dIHSdOAIAdnS ! N 3 0 H 3 d 30 not only d i s c r i m i n a t e d between f i s h breeding i n marine and freshwater but a l s o d i s c r i m i n a t e d between years f o r each group. The d i s c r i m i n a n t scores f o r B o n s a l l Creek i n d i c a t e a l l groups were s i g n i f i c a n t l y d i f f e r e n t (F values above the c r i t i c a l value f o r a .05 p r o b a b i l i t y ) {Table V I I ) , though there was o v e r l a p i n the d i s t r i b u t i o n of d i s c r i m i n a n t s c o r e s ( T a b l e V I I I ) . To t e s t the d i s c r i m i n a t i n g power of t h i s f u n c t i o n the equation was computed using data from f i s h c o l l e c t e d i n Campbell l i v e r . The Campbell R i v e r f i s h were completely separated and no f i s h were assigned to i n c o r r e c t groups. S i m i l a r l y i n a n a l y s i s as 'marine types' i t was apparent t h a t the Campbell R i v e r samples had d i s j u n c t d i s c r i m i n a n t score d i s t r i b u t i o n s whereas s i m i l a r samples from B o n s a l l Creek were not d i s j u n c t (Table XIX). In B o n s a l l Creek an a n a l y s i s i n c l u d i n g sex as a grouping c r i t e r i a i n d i c a t e d t h a t males and females had s i g n i f i c a n t l y d i f f e r e n t means i n t h e i r d i s c r i m i n a n t f u n c t i o n s c o r e s ( T a b l e I X ) , but t h a t the d i s t r i b u t i o n of t h e i r s c o r e s overlapped(Table X). T a b l e XI i n d i c a t e s t h a t i n the a n a l y s i s f o r l o c a t i o n and year the c h a r a c t e r s , v e n t r a l s p i n e l e n g t h and a n a l ray counts were the s t r o n g e s t c o n t r i b u t o r s to the d i s c r i m i n a t i o n . The t h i r d most important c o n t r i b u t o r was head l e n g t h . In the a n a l y s i s t h a t a d d i t i o n a l l y d e f i n e d the groups by sex, the f i r s t and second most important c h a r a c t e r s were head l e n g t h and v e n t r a l s p i n e l e n g t h . T h i s occurred i n both the a n a l y s i s t h a t i n c l u d e d , and the a n a l y s i s that excluded, the c o n t e n t i o u s TABLE V I 1 The F v a l u e s f o r d i f f e r e n c e s b e t w e e n s a m p l e means i n t h e d i s c r i m i n a n t a n a l y s i s o f B o n s a l l C r e e k s t i c k l e b a c k s when a n a l y z e d f o r l o c a t i o n a n d y e a r m o r p h o l o g i c a l t y p e s . A l l v a l u e s a r e s i g n i f i c a n t a t °C=.05. The l a b e l n u m e r a l i n d i c a t e s t h e y e a r , 8 ( 1 9 6 8 ) , 5 ( 1 9 7 5 ) , 6 ( 1 9 7 6 ) , and t h e l a b e l s ' p o s t s c r i p t i n d i c a t e w h e t h e r t h e s a m p l e i s f r o m above (F) o r b e l o w (M) t h e l i m i t o f t h e t i d a l i n f l u e n c e i n t h e c r e e k . / / — / / / / / / • / / / Sample / / 8M / 5M / 5F / 6M // / / / / / / / / / / / 5M / / / / 3. 24 / / / / 5F / / / / 3. 12 10.38 / / / / 6M / / / / 2. 60 7.72 6. 95 / / / / 6F / / / / 4.35 13.03 3 . 51 3.51 / / / / TABLE V I I I A p o s t e r i o r i c l a s s i f i c a t i o n o f B o n s a l l Creek s a m p l e s u s e d i n t h e d e r i v a t i o n o f l o c a t i o n and y e a r m o r p h o l o g y t y p e s . The l a b e l s a r e as i n T a b l e V I I . // Per c e n t a g e C l a s s i f i e d as // O r i g i n a l // M o r p h o l o g i c a l Type : // // ________ // Sample / / / / / / / / Sample // 8M / 5M / 5F / 6M / 6F // Group / / / / / / / / S i z e // // 8 M / / 3 2 2 4 1 8 1 8 9 / / 3 4 // // 5 i M / / 1 4 5 6 9 1 4 8 / / 8 0 //. // 5 F / / 1 5 5 4 6 8 2 6 / / 3 9 / / / / 6 M / / 1 9 1 9 1 0 3 1 2 1 / / 7 0 7 / / / 6 F / / 1 0 2 1 0 1 8 6 0 / / 4 0 / / / / 33 low plate count individuals from the sympatric zone. In the analysis including the low plate count i n d i v i d u a l s mouth width was the t h i r d most important character. In the analysis excluding them g i l l raker length was t h i r d . This s h i f t was not unlikely as Aneer(1973) noted that in populations from the B a l t i c coast t h i s character was sexually dimorphic. The l i t e r a t u r e includes a few examples demonstrating multivariate analysis of population d i f f e r e n t i a t i o n (for a review see Gould and Johnston 1972) however, r a r e l y i s temporal variation taken into consideration. In t h i s study evidence of such variation e x i s t s . From 197 5 to 1976 6 815 of the Bonsall Creek marine samples changed their morphological location type (Table VIII) and the assignment of the Bonsall Creek freshwater f i s h for these years was even more di s s i m i l a r . Further, the sexual dimorphism of the characters was not constant over time i n the freshwater groups. The 1976 probability that the characters used in the analysis did not exhibit sexual dimorphism was .0299 while i n 1975 the probability was 0.731( Table IX). Bonsall Creek freshwater and marine populations were morphologically di f f e r e n t and as the degree and d i r e c t i o n of t h i s difference changed from year to year i n the analysis, no combination of data years was done to increase sample si z e . The derived discriminant scores for location (freshwater or marine) , year and sex groupings in --Bonsall Creek are plotted against the distance from the ocean where each f i s h was caught to determine i f there was any pattern of variation TABLE I X The F v a l u e s f o r d i f f e r e n c e s b e t w e e n s a m p l e means i n t h e d i s c r i m i n a n t a n a l y s i s o f B o n s a l l C r e e k s t i c k l e b a c k when a n a l y z e d f o r s e x , l o c a t i o n and y e a r m o r p h o l o g i c a l t y p e s . V a l u e s w i t h a s t r o k e t h r o u g h them a r e n o t s i g n i f i c a n t a t °c = .05. The l a b e l s a r e as i n T a b l e V I I b u t a r e p r e f i x e d t o i n d i c a t e m a le (M) o r f e m a l e ( F ) . / / -// / / / / / / mple // M8M / F8M / M5M / F5M / M5F / F5F / M6M // / / / / / / // F8M // // 2.98 M5M V / // 7 .34 F5M / / // 4.65 3 . 88 11. 27 M5F // // 3 .67 6. 15 9 . 39 F5F // / / 2.50 2 .53 7.44 8 . 54 CWiT9 M6M // // 2 .41 7.73 6 . 79 17 .35 3 . 39 5.52 F6M // // 4 . 13 4 .12 11.23 6.26 8 .55 6 .90 13 . 70 M6F // // 2.78 5 .02 7 . 09 12 . 60 2.33 1.95 3.31 F6M // // 3,01. 2.94 9 . 52 7 . 31 3.55 2 . 3 9 7 .70 // / / // / F6M / M6F // / / // / / / / / / / / / / / / . / / / / / / / / / / / / / / / / / / 6.3 0 / / / / 2.3 8 2.0 4 / / // > TABLE X A p o s t e r i o r i c l a s s i f i c a t i o n o f B o n s a l l C r e e k s a m p l e s u s e d i n t h e d e r i v a t i o n o f s e x , l o c a t i o n and y e a r m o r p h o l o g y t y p e s . The l a b e l s a r e as i n T a b l e I X . O r i g i n a l // P e r c e n t a g e C l a s i f i e d as M o r p h o l o g i c a l Type / / Sample // / / / / / / / F 6 F // M-8M / F 8 M / M5M / F 5 M / MSF / F 5 F / M6M / F 6 M / M6F / Group // / / / / / / / / / // M8M // 7 14 14 7 14 14 7 14 0 7 // 10 F 8 M // // •5 45 10 15 10 0 0 0 5 M5M // 18 6 46 4 0 4 14 4 2 2 // 10 F 5 M // 7 13 7 40 0 7 0 17 0 // 22 M5F // 6 6 1 1 1 1 1 1 1 1 1 1 6 6 // 10 F 5 F // 5 10 5 0 38 10 5 5 14 // 20 0 M6M // 10 0 13 0 7 0 50 0 // 20 F 6 M // 5 13 8 10 0 0 0 45 0 // 20 M6F // 0 15 0 0 10 5 5 0 45 // 35 F 6 F // 5 10 5 0 0 5 . 0 25 15 / / - / / // Samole // // S i z e // // / / // / / / / //' // / / / / // // // // // // / / // // // / / // 14 20 50 30 18 21 30 40 20 20 0 36 F VALUES ASSOCIATED WITH INDIVIDUAL I N CHARACTERS I N ANALYSIS OF GROUPS DEFINED BY; + LOCATION, YEAR AND SEX LOCATION YEAR AND SEX LOCATION AND YEAR C R I T I C A L VALUE OF F 1.96 C R I T . VALUE OF F 2.37 VARIABLES HD.L V.S.L MO. WD ANL. R L.G.RK BOD. D W.P2DS W.A2DS DOR. R N.G,RK TIDAL ZONE LOW PLATE COUNT F I S H , INCLUDED TIDAL ZONE LOW PLATE COUNT F I S H , EXCLUDED 14.56 7. 35 4. 16 3. 94 3.67 3. 43 2.30 0,97 0.91 0.77 8.25 5.88 2.88 2.38 5.44 4.26 1.25 0.95 0.75 0.47 CRIT. VALUE OF F 2.37 TIDAL ZONE LOW PLATE COUNT F I S H , INCLUDED 5. 93 9. 22 3. 10 8. 01 3. 24 4. 93 2.23 1.77 1. 55 0. 55 TABLE X I F v a l u e s a s s o c i a t e d w i t h i n d i v i d u a l c h a r a c t e r s i n d i s c r i m i n a n t a n a l y s e s o f B o n s a l l C r e e k d a t a . The v a r i a b l e s a r e ; HD.L , head l e n g t h ; V.S.L , v e n t r a l s p i n e l e n g t h ; DOR.R , number o f r a y s i n t h e d o r s a l f i n ; W.A2DS , w i d t h b e t w e e n t h e a n t e r i o r two d o r s a l s p i n e s ; BOD.D , body d e p t h ; MO.WD ,mouth w i d t h ; ANL.R number o f r a y s i n t h e a n a l f i n ; W.P2DS , w i d t h b e t w e e n t h e p o s t e r i o r two d o r s a l s p i n e s ; N.G.RK , number o f g i l l r a k e r s on t h e l e f t f i r s t g i l l a r c h ; L.G.RK , l e n g t h o f t h e t h i r d v e n t r a l g i l l r a k e r on t h e l o w e r l i m b o f t h e l e f t f i r s t g i l l a r c h . 37 i n the creek. When the d i s c r i m i n a n t scores from a n a l y s i s of the sex groupings of each year were p l o t t e d a g a i n s t d i s t a n c e up B o n s a l l Creek s e v e r a l i n t e r e s t i n g t r e n d s were apparent; 1 . The s e l e c t i o n moving upstream i s f o r d i f f e r e n t forms of male and female; 2. T h i s ,pattern though i t v a r i e s between years i s continuous; 3. Only i n females i s the pattern not of a c l i n a l n a t u r e { F i g . 6). Because the a n a l y s i s i n c l u d e s a l l f i s h from the sympatric zone the p o s s i b i l i t y e x i s t s t h a t i t may i n c l u d e some migrants from the freshwater zone. S i n c e t h e d i s c r i m i n a n t f u n c t i o n i s dependent upon which f i s h are i n i t i a l l y assigned to each group i t i s p o s s i b l e to i n a d v e r t a n t l y bias the f u n c t i o n through i n j u d i c i o u s assignment of data t o the groupings. The a n a l y s i s was redone with the low p l a t e i n d i v i d u a l s from the sympatric zone excluded from the data. The r e s u l t a n t data are almost i d e n t i c a l ( F i g . 7) the only notable change i s t h a t the d i s c r i m i n a n t f u n c t i o n s c o r e s f o r both sexes was c l i n a l . The a n a l y s i s so f a r i s not unexpected. There were d i f f e r e n c e s between freshwater and marine p o p u l a t i o n s of §asterosteus a c u l e a t u s . F u r t h e r the d i s c r i m i n a n t f u n c t i o n f o r d i f f e r e n t i a t i n g these groups has a strong g e n e t i c component. 38 FIGURE 6. The d i s t r i b u t i o n of the v a r i a t i o n of a morphological composite of Gasterosteus aculeatus (represented by the f i r s t c a n o n i c a l v a r i a t e of a d i s c r i m i n a n t function) i n B o n s a l l Creek. The f i g u r e s are males 1975 (A) and 1976 (B), and females 1975 (C) and 1976 (D). This a n a l y s i s includes low p l a t e d f i s h from the zone of sympatry. The arrow i n d i c a t e s the l i m i t of t i d a l i n f l u e n c e i n the creek. FIRST CANONICAL VARIATE in o O « o. o o tn. o o ru o. o o ffl. o o B. o o LO 01. o o * o o i i L u r u H - O H - r U L O H r- H 1 — X X X X X X X3KSXHJOB88KX X X X X X XM X X Ln -< it i o o HI W i o * Ln , 8 ^ o X X3K X XX< o BDNSAL CREEK MALES 137E Y = - 1 - 7 7 5 + CM7E5E -03*X N' = 50 < i—i > i—i i—i LL. 5 -500- 1000. 1500- E000- 2500- 3000- 3500- 4000- 4500- 5000 - 5500-DISTANCE FROM OCEAN CMETERS) C O EONSAL CREEK FEMALES 1975 Y = 2 -443 + - 0 - 5 2 i _ 3 _ - 0 3 * X N = 51 5 -< i—i > U L. 0 . 500- 1000- 1500- EOOO- S500- 3000 - 3500 - 40O0- 4500- 5000 - 5500-•ISTANCE FROM OCEAN (METERS) L O 0 0 o. r FIGURE 7. The d i s t r i b u t i o n of the v a r i a t i o n of a m o r p h o l o g i c a l composite o f Gasterosteus a c u l e a t u s (represented by the f i r s t c a n o n i c a l v a r i a t e of a d i s c r i m i n a n t f u n c t i o n ) i n B o n s a l l Creek The f i g u r e s are; males 1975 (A) and 1976 (B), and females 1975 (C) and 1976 (D). T h i s a n a l y s i s excludes low p l a t e d f i s h from the zone of sympatry. The arrow i n d i c a t e s the l i m i t of t i d a l i n f l u e n c e i n the creek. EDNSAL CREEK MALES 1S75 DISTANCE FROM OCEAN (METERS) EDNSAL CREEK MALES 1S7S Y = - 2 - E 2 4 + 0 .50S7E -03^X N = 33 1 1 1 1 —I =H —1 1 1 1 1 0 . 500- 1000. 1500. 2000. 5500 - 3300 - 3500 . 4000 - 4500 - 5000 . 5500 DISTANCE FROM OCEAN (METERS) BDNSAL CREEK FEMALES 1375 Y = 1 - 1 1 3 + - 0 - 7 0 8 4 E - 0 4 * X N = 39 < > 5 -4-__ 3-.. S 0 - . . - 1 - . . X -A-.. - 5 X x 8 X X -X-X X X + g T 0- 500- 1000- 1500- 2000- 2500- 3000- 3500- 4000. 4500- 50C0- 5500-DISTANCE FROM OCEAN (METERS) C O so O E D N S A L C R E E K F E M A L E S 1 3 7 E < > _ LL Y = 0 - 5 9 2 3 5 -4-__ X 3-.. £•__ I— - 2 « „ - 3 - . . - 4 - . . - 5 1 x 8 + + + 0 -1130E-03*X N = 5 1 X X X + X X X A -X" X X N + 0 - 500 - 1000- 1500- 2000- 2500- 3000- 3500- 4000- 4500- 5000- 5500-DISTANCE FROM DCEAN (METERS) C O V D o 40 3 B i o g e o g r a p h y o f Morohglgciy. and V a r i a t i o n S p o t s a m p l e s f r o m m a r i n e b r e e d i n g f i s h w e r e u s e d t o d e t e r m i n e m a r i n e l o c a t i o n t y p e s f o r t h r e e - s p i n e d s t i c k l e b a c k ( T a b l e X I I ) . When s p o t s a m p l e s f r o m a l l o p a t r i c f r e s h w a t e r p o p u l a t i o n s were c l a s s i f i e d i n t o t h e s e m a r i n e l o c a t i o n t y p e s i t was f o u n d t h a t t h e y w e r e n o t w i t h i n t h e v a r i a t i o n d e s c r i b e d by t h e m a r i n e b r e e d i n g f i s h ( T a b l e X I I I ) . F u r t h e r , s a m p l e s o f f i s h f r o m one c r e e k more c l e a r l y r e s e m b l e a n a d r o m o u s G. a c u l e a t u s f r o m o t h e r c r e e k s t h a n t h o s e o f t h a t p a r t i c u l a r c r e e k . I f t h e r e was a s i n g l e p a n m i c t i c m a r i n e p o p u l a t i o n o n l y l o c a l l y a f f e c t e d by gene f l o w w i t h f r e s h w a t e r p o p u l a t i o n s , where gene f l o w o c c u r s m a r i n e f i s h f r o m t h a t c r e e k s h o u l d more r e s e m b l e f r e s h w a t e r f i s h f r o m t h a t c r e e k t h a n any o t h e r m a r i n e s a m p l e . T h i s s u p p o r t s s u g g e s t i o n s t h a t l o c a l a d a p t a t i o n i s a p r i m a r y s o u r c e o f v a r i a b i l i t y i n m a r i n e p o p u l a t i o n s o f t h r e e - s p i n e d s t i c k l e b a c k . A n a l y s i s was done t o d e t e r m i n e i f any m o r p h o l o g i c a l d i f f e r e n t i a t i o n e x i s t s b e t w e e n s a m p l e s o f G a s t e r o s t e u s a c u l e a t u s t a k e n f r o m p o p u l a t i o n s b r e e d i n g i n s a l i n e e n v i r o n m e n t s . A g a i n d i s c r i m i n a n t f u n c t i o n a n a l y s i s was u s e d . I n most i n s t a n c e s t h e r e a p p e a r s t o be s i g n i f i c a n t d i f f e r e n c e s b e t w een p o p u l a t i o n s ( T a b l e X I I ) . T h e s e p o p u l a t i o n s were a l s o a n a l y s e d by s e x . The F p r o b a b i l i t i e s i n d i c a t e d s i g n i f i c a n t m o r p h o l o g i c a l d i f f e r e n c e s b e t w e e n s e x e s ( T a b l e X V ) , a t l e a s t where s a m p l e s i z e i s s u f f i c i e n t ( s e e a p p e n d i x 2. f o r e s t i m a t i o n o f s a m p l e s i z e ) f u r t h e r t h e d i s c r i m i n a t i o n f o r s e x d i d n o t r e d u c e t h e o v e r l a p b e t ween l o c a t i o n g r o u p s ( T a b l e X V I ) . 41 TABLE X I I The F v a l u e s f o r d i f f e r e n c e s b e t w e e n s a m p l e means i n t h e d i s c r i m i n a n t a n a l y s i s o f m a r i n e s t i c k l e b a c k s when a n a l y z e d f o r m o r p h o l o g i c a l l o c a t i o n t y p e s . The l a b e l s r e p r e -s e n t s , B o n s a l l C r e e k ; PB, P o r p o i s e B a y ; BA, B a m f i e l d ; C O , Coraox; QA, B i g Q u a l i c u m R i v e r ; KS, K i n g S almon R i v e r ; BK, K o i t o i B a y ; TG, T w i n G l a c i e r s ; TA, T u r n a g a i n Arm; CH, C h e h a l i s R i v e r ; LC, L i t t l e C a m p b e l l R i v e r , A l l v a l u e s a r e s i g n i f i c a n t a t CC = . 05 . // / / / / / / / / / // imple // // B / / PB / / BA / / CO / / QA / / KS / / BK / / TG / / 'TA / / CH // // // // PB //• // 4. 08 . // // BA // // 13. 58 15.56 // // CO // // 17 . 46 15. 05 6. 10 // // QA //• // 2. 40 6.61 9.99 13 .62 // // KS // // 7. 65 8.90 4 . 60 6 . 84 6.56 // // BK // // 3. 37 5.12 26.-31 25. 35 6. 13 13 . 33 // // TG // // 5 . 62 7.38 13 .30 13.18 3.75 3.41 6 .70 // // TA // // 7 . 16 5.21 11.3 4 9 .42 8. 13 4 .73 9. 18 4 .46 // // CH // // 3. 0 4 6.45 18.02 24 .03 7 .08 9. 16 4 . 77 8 .49 9. 67 // // LC // 5 . 00 7. 13 5 . 09 11. 06 4 .74 6.51 12 .30 9 . 15 10 . 17 7.IS // / / 42 TABLE X I I I C a n o n i c a l v a r i a b l e s e v a l u a t e d a t g r o u p means f o r t h e a p o s t e r i o r i c l a s s i f i c a t i o n o f T a b l e X I X . // C a n o n i c a l V a r i a b l e // S a m p l e // / / / / / / / / / // G r o u p // 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 // // / / / / / / / / / // // 0' '052 // B5M // 0 . 5 3 3 0 . 7 6 7 0 . 4 9 0 0 . 0 1 0 0 . 2 5 7 - 0 . 0 1 7 0 . 512 0 . 099 0 . 0 8 2 // PB // - 0 . 0 4 8 0 . 6 1 7 - 1 . 0 9 5 - 0 . 1 9 4 0 . 2 3 0 0 . 3 1 6 - 0 . 172 - 0 . 021 0 . 1 1 1 0 . 0 2 8 // BA // - 2 . 5 4 4 0 . 1 0 6 0 . 7 2 2 - 0 . 0 2 2 0 . 2 7 6 - 0 . 0 8 8 - 0 . 230 0 . 032 0 . 1 1 3 - 0 . 0 1 8 // CO // - 2 . 5 4 0 - 0 . 6 0 - 0 . 8 6 4 - 0 . 1 9 4 - 0 . 4 1 6 0 . 0 2 8 0 . 264 0 . 098 - 0 . 0 9 6 - 0 . 0 1 1 // QA // 0 . 4 3 3 - 0 . 2 3 4 0 . 6 9 1 - 0 . 3 4 2 - 0 . 4 2 0 - 0 . 1 7 4 - 0 . 156 0 . 614 0 . 1 0 0 - 0 . 0 2 5 // KS // - 0 . 2 4 3 - 1 . 0 2 3 0 . 8 5 2 0 . 5 9 8 0 . 2 2 9 0 . 4 7 0 0 . 196 - 0 . 211 0 . 0 4 6 - 0 . 1 0 0 // BK // 2 . 3 9 2 - 0 . 2 0 5 - 0 . 4 9 9 - 0 . 0 2 6 - 0 . 4 5 3 - 0 . 2 0 7 0 . 105 - 0 . 144 0 . 1 2 5 - 0 . 0 6 7 // TG // 1 . 0 3 3 - 1 . 3 1 8 0 . 3 6 5 0 . 252 - 0 . 3 0 6 0 . 1 8 7 - 0 . 213 - 0 . 050 - 0 . 0 5 1 - 0 . 1 0 1 // TA // 0 . 484 - 1 . 1 1 0 - 0 . 4 7 0 0 . 1 4 0 0 . 7 6 7 - 0 . 7 6 7 - 0 . 046 - 0 . 015 - 0 . 0 5 7 - 0 . 0 0 1 // CH // 0 . 3 5 7 1 . 4 4 5 - 0 . 1 8 2 1 . 1 8 8 - 0 . 0 8 8 - 0 . 0 0 3 - 0 . 111 0 . 159 - 0 . 1 3 3 - 0 . 0 2 9 // LC // - 1 . 0 8 6 0 . 9 6 5 0 . 4 7 4 - 0 . 1 8 9 - 0 . 4 1 0 - 0 . 3 1 9 - 0 . 081 - 0 . 450 - 0 . 0 1 3 0 . 0 2 6 // B6M // 1 . 1 8 5 0 . 5 2 5 0 . 3 9 6 - 0 . 0 6 7 0 . 202 0 . 1 8 2 - 0 . 057 - 0 . 001 - 0 . 1 7 2 - 0 . 0 4 4 // LCFW // 4 . 513 - 1 . 4 1 4 1 . 8 5 2 - 0 . 3 6 1 0 . 047 - 1 . 7 2 8 - 0 . 132 1 . 058 - 0 . 0 8 8 - 1 . 3 3 3 // B5FW // 4 . 8 2 2 - 2 . 6 9 8 2 . 4 2 8 - 0 . 4 3 5 - 0 . 5 2 0 - 1 . 4 1 2 - 1 . 184 0 . 800 1 . 1 8 0 - 1 . 0 8 7 // B6FW // 2 . 9 8 5 - 2 . 3 8 0 3 . 2 4 1 - 0 . 1 6 2 0 . 351 - 1 . 5 5 3 - 1 . 288 1 . 151 0 . 1 6 5 - 0 . 4 9 8 // TABLE XIV A p o s t e r i o r i a s s i g n m e n t o f m a r i n e s t i c k l e b a c k s t o m a r i n e g e o g r a p h i c m o r p h o l o g y t y p e s s h o w i n g . T e m p o r a l v a r i a t i o n i n m a r i n e s t i c k l e b a c k s i n r e l a t i o n t o t h e m o r p h o l o g y . L a b e l s a r e as i n T a b l e X I I . The l a s t s a m p l e , B5M ( B o n s a l l 1975 f r o m t h e a r e a b e l o w t h e l i m i t o f t i d a l i n f l u e n c e ) was n o t i n c l u d e d i n t h e d a t a u s e d t o d e r i v e t h e d i s c r i m i n a n t f u n c t i o n . O r i g i n a l // Percentage C l a s s i f i e d as M o r p h o l o g i c a l Type : II ti- •// Sample ll / / / / / / TG / / / / // Sample II PB / BA / CO / QA / KS / BK / / TA / CH / LC / B6M // Group II / / • / ' / / / / / / / // S i z e II // PB II II 33 3 10 0 5 20 5 3 8 ,10 5 // // 40 BA II II 0 41 17 0 24 0 0 3 0 14 0 // // 29 CO II II 3 21 55 0 6 0 3 9 0 0 3 // // 33 QA II 5 0 0 55 0 5 10 10 5 10 0 // 20 ll // KS II II . 5 5 9 9 4 5 0 14 9 0 5 0 // // 22 BK II II 3 0 0 7 0 57 17 7 3 0 7 // // 30 TG II II 5 0 • 3 18 12 3 44 12 3 0 0 // // 34 TA II II 3 0 7 0 0 3 17 63 7 0 0 // // 30 CH II II 3 0 0 7 7 7 7 3 55 7 3 // // 29 ' LC II II 7 4 0 11 4 0 4 4 0 63 4 // // 27 B6M II 19 6 0 13 0 0 6 3 6 0 45 // 31 II // B5M II II 3 3 0 16 3 6 3 9 9 13 34 // // 32 TABLE XV The F v a l u e s f o r d i f f e r e n c e s b e t w e e n means i n t h e d i s c r i m i n a n t a n a l y s i s o f m a r i n e s t i c k l e b a c k s when a n a l y z e d f o r s e x a n d g e o g r a p h i c m o r p h o l o g y t y p e s . V a l u e s w i t h s t r o k e s t h r o u g h them a r e n o t s i g n i f i c a n t a t OC =.05 . The l a b e l s a r e as i n T a b l e X I I b u t a r e p r e f i x e d t o i n d i c a t e m a l e (M) o r f e m a l e ( F ) . Sample // MB / PB / HPB / FPB / MBA / PBA / MCO / PCO / MQA / PQA / MKS / FK3 / MBK / FBK / MTO / PTG / MTA / PIA / MCH / PCH / MLC // FB / / 2.17 // MPB // 3.02 2.84 // FPB / / 6.66 J~*T S.51 / / MBA / / 10.69 4.29 8.25 11.59 // FBA // 15.41 2.79 17.22 9.75 8.11 // MCO // 11.63 5.79 7.61 9.75 3.28 12.60 / / FCO // 18.20 3.58 16.90 9.48 7.82 5.46 8.29 // // / / MQA // 2.40 1.96 3.74 4.71 5.70 7.98 5.76 10.50 // FQA // 3.10 ir«S 7.36 3.88 9.55 6.31 10.31 9.08 1.98 / / MKS / / 6.85 4.26 5.54 9.62 3.48 .11.43 4.18 19.98 3.66 7.42 // FKS // 3.71 JV?» 3.30 4.19 IrOt 3.51 3.06 3.52 2.05 3.51 VrSt // // 3.14 3.76 3.08 6.76 16.07 23.50' 11.93 22.73 4.44 6.53 9.33 6.39 / / MCH // 5.70 7.98 5.76 9.55 6 31 10 313.48 .11.43 4.18 3.51 3.06 16.07 23.50' 11.93 14.74 11.91 14.66 9.30 17.64 7.04 6.47 6.03 9.24 6.00 15.95 5.47 5.92 8.18 7.13 8.50 13.40 9.98 11.65 12.23 13.83 3.21 5.23 4.99 11.74 2.78 16.50 MBK FBK // 4.39 Jrr*T 7.25 3.48 14.66 13.25 4.86 2.57 10.43 4.74 4.97 // MTG // 4.04 3.75 4.73 8.69 17.64 7.04 17.16 1.90 5.22 2.97 3.23 3.84 7.27 // FTG // 7.93 3^*1 8.43 4.17 8 6.03 9.24 6.31 4.29 3.71 4.95 2.31 9.48 3.64 6.07 // MTA / / 5.69 3.03 2.31 6.75 5.47 12.69 3.86 7.72 3.05 2.42 4.97 8.27 2.92 5.63 / / FTA // 7.96 i < 4 T 6.64 4.03 4.96 5.69 5.39 6.31 2.17 9.09 5.11 7.54 2.65 3.67 // // lrt?T 2.36 1»*T 5.70 14.97 3.51 5.22 5.77 3.07 2.78 3.58 4.66 6.30 3.96 5.98 // FCH '/', 3 62 5.59 5.89 11.65 .23 .83 16.68 4.60 4.39 7.92 3.07 6.67 2.41 8.09 4.71 8.05 6.27 J ^ T // MLC // 2 62 J-*T 2.72 2.97 3.21 3 9 6.46 U « 2.65 2.81 M I 6.09 4.38 3.64 3.27 3.42 3.58 2.84 2.93 // // „ . , . , « j ii i i an l is 19 23 6 99 17-75 6.84 17.01 8.37 9.84 7.68 4.68 // PLC // 11.17 1.89 15.14 7.53 11.74 2.78 16.50 8.47 B.35 4.46 13.98 4.36 19.23 6.99 f / // > 45 TABLE XVI A p o s t e r i o r i c l a s s i f i c a t i o n o f m a r i n e s a m p l e s u s e d i n t h e d e r i v a t i o n o f s e x and g e o g r a p h i c m o r p h o l o g y t y p e s . L a b e l s a r e as i n T a b l e XV. otigin.i / / .PaIf!;hSi!!-i!i!--"---~--i~-----^ -- - - // S a n P l e Barnpla C r o u p //-// // // KB / / / PB / / / MPB / / / m / I / MSA / PBA / / / / HCO / / / PCO / / / / HQA / / / POA / / MK9 / / / / PKS / / / MBK / / / PBK / / / MTO / / / pro / / / MTA / / / PTA / / / KCM / / / PCH / / / / // PLC // // S i ze MD // // JJ 0 29 0 0 0 0 0 < 0 0 0 6 ' « 6 0 0 0 0 11 0 « // // // 18 PB // // 25 0 0 0 0 0 0 0 0 0 0 0 0 0 0 23 0 23 0 0 0 23 // // 4 HPt // // 3 0 40 0 0 0 0 0 9 0 0 0 3 0 3 0 13 0 20 0 5 0 // // 20 TPB // // 0 10 9 33 0 9 0 3 0 3 0 0 20 3 0 0 0 5 0 0 0 5 // // 20 MBA // // 0 0 0 0 20 7 27 0 0 0 13 13 0 0 0 0 0 0 0 0 0 0 // // 15 F B A // // 0 0 0 0 0 71 0 14 0 0 0 0 0 0 0 7 0 0 . 0 0 0 7 // // 14 MCO // // 0 0 0 0 23 0 6 2 0 0 0 0 0 0 . 0 0 0 8 8 0 •'0 0 0 // // 13 FCO // // 0 0 0 5 0 35 15 15 0 0 0 0 0 0 0 5 0 20 0 0 0 5 // // 2 0 M3A // // 0 0 0 10 0 0 0 0 50 10 0 0 0 0 10 0 ' 0 10 0 0 10 . 0 // // 10 rOA // // 10 10 0 io. 0 0 0 0 10 40 0 0 0 10 0 0 0 0 0 10 0 0 // // 10 MXS // // 0 0 0 6 13 0 0 0 19 0 38 13 0 0 0 0 6 0 0 6 0 0 // // 16 F K S // // 0 0 0 0 17 0 0 17 0 0 17 0 0 0 0 0 0 33 0 0 0 17 // // 6 M B K // // 6 0 12 0 0 0 0 0 0 0 0 0 53 0 24 0 6 0 0 0 0 0 // // 17 F3K // // 0 3 0 8 0 0 0 0 0 8 0 0 15 23 0 15 8 0 8 0 0 8 // // 13 MTG // // 10 0 0 0 0 0 0 0 19 0 14 0 S 0 . 24 5 14 0 0 5 5 0 // // 21 n o // // 0 0 0 8 0 0 0 0 0 0 0 IS 0 8 0 62 0 8 0 0 0 0 // // 13 MTA // // 6 0 < 0 0 0 0 0 0 0 0 6 0 0 17 6 50 6 0 6 0 0 // // 18 PTA // // 0 0 0 0 0 0 0 B 0 0 0 8 0 0 8 17 0 58 0 0 0 0 // // 12 MCH // // 10 0 0 0 0 0 0 0 10' 0 10 10 0 0 0 0 0 0 40 20 0 0 // // 10 TCH // // 0 0 0 0 s 0 0 0 0 11 0 0 0 26 0 11 0 0 11 32 5 0 // // 19 HLC // // B 0 8 17 0 0 0 0 17 0 8 17 0 0 0 0 0 0 0 0 25 0 // // 12 FLC // // 0 0 0 0 0 7 0 0 0 0 0 7 0 0 0 0 0 0 0 0 0 87 // 15 O n > 46 F VALUES ASSOCIATED WITH INDIVIDUAL CHARACTERS I N ANALYSIS OF GROUPS DEFINED BY; I VARIABLES LOCATION AND SEX —+ C R I T I C A L VALUE OF F 1.91 LOCATION C R I T I C A L VALUE OF F 1.66 MO.WD | 14. 97 HD. L j 9. 33 BOD.D | 6.76 A NL.R | 3.64 W.P2DS | 3. 61 V.S.L | 3. 25 L.G.RK | 2. 89 W.A2DS I 2. 57 N.G.RK I 1. 25 DOR. R | 1. 17 29.79 6.20 11.22 5.45 5.67 4.42 4.21 3.99 1.17 1.23 l i i L E X V I I F v a l u e s a s s o c i a t e d w i t h c h a r a c t e r s v a r i a b l e s i n t h e two d i s c r i m i n a n t a n a l y s e s d o n e on t h e d a t a f r o m m a r i n e Q.*. a c u l e a t u s f o u n d b r e e d i n g i n %± m a r i n a b e d s . The v a r i a b l e s a r e a s d e s c r i b e d i n t h e l a b e l t o TABLE XI . 47 Analysis of the F values associated with r e s i d u a l variation in each of the characters (Table XVII) indicated that In d i f f e r e n t i a t i n g the location and in d i f f e r e n t i a t i n g the location and sex of the sample the three most important characters in the discrimination were: head length, ventral spine length, and mouth width. Along the P a c i f i c Northwest Coast there does not appear to be c l i n e s i n the t o t a l morphology of Gasterosteus aculeatus as represented by discriminant function scores or i n the i n d i v i d u a l characters except for adult body size which shows c l i n a l v a r i a t i o n over t h i s geographic range ( FIG. 8 ). If i t were decided that discriminant analysis did not s u f f i c i e n t l y describe the nature of v a r i a t i o n within or between populations the alternate arguement might be; I f there i s no evidence in the i n d i v i d u a l characters of t o t a l reproductive i s o l a t i o n between the two groups of f i s h then any differences i n means and variances, p a r t i c u l a r l y of the genetically determined characters, are the r e s u l t of d i f f e r e n t i a l s e l e c t i o n . In a l l cases whether character expression i s known to be primarily under environmental control, under genetic control, or has unknown genetic and environmental components, there i s a difference i n the means of a l l characters between marine and freshwater breeding individuals(Table XVIII). Further in four of the characters of the freshwater f i s h there was a s i g n i f i c a n t reduction i n the variances of the sample. Three FIGURE 8. Mean a d u l t b ody l e n g t h o f t h e t h r e e s p i n e s t i c k l e b a c k i n r e l a t i o n t o t h e c o a s t a l d i s t a n c e s o u t h f r o m K i n g S a l m o n R i v e r , A l a s k a . S o l i d s q u a r e s r e p r e s e n t d a t a f r o m t h i s s t u d y , s o l i d c i r c l e s a r e d a t a f r o m Howe(1973) and t h e open c i r c l e r e p r e s e n t s d a t a f r o m C h r i s t i e ( 1 9 7 4 ) . S T A N D A R D B O D Y L E N G T H O F A D U L T S ( m m ) O O > CD CO > o o o o Ul o o o o o o -4-00 o o CO —i > z o m n ZD O in O O 2 O u o. o o 30 < m 33 > CO > Ul o" o Ul in O " o 49 __ V A R I A B L E S CALCULATED i p i VALUE C R I T I C A L VALUE OF • F • 1.41 N.G.RK | 1. 88 | 27.6 5 DOR.R j 0.97 | 15.54 ANL. R | 0.83 | 14.26 BOD.D | 1. 97 | 3.10 V.S.L J 1.60 | 26.46 L. G. RK ! 1.24 | 16.09 MO.WD | 1.36 | 5.86 FID. L | 1.41 | 4.42 W.A2DS | 0.90 | 29.55 W.P2DS | 1.38 | 9.79 CALCULATED APPROX. • T • VALUE CRITICAL VALUE OF * T' 2.06 TABLE X V I I I F and a p p r o x i m a t e * t * v a l u e s a s s o c i a t e d w i t h s i n g l e c h a r a c t e r c o m p a r i s o n s b e t w e e n s p o t s a m p l e s o f f r e s h w a t e r and m a r i n e b r e e d i n g G a s t e r o s t e u s a c u l e a t u s . V a r i a b l e l a b e l s a r e a s d e s c r i b e d i n TABLE X I . 50 o f t h e s e , g i l l r a k e r number, body d e p t h a n d v e n t r a l s p i n e l e n g t h a r e known t o be g e n e t i c a l l y d e t e r m i n e d . TABLE X I X A p o s t e r i o r i a s s i g n m e n t o f f r e s h w a t e r s t i c k l e b a c k s t o m a r i n e s t i c k l e b a c k g e o g r a p h i c a l m o r p h o l o g y t y p e s s h o w i n g t e m p o r a l v a r i a t i o n . L a b e l s a r e as i n T a b l e X I I . The l a s t t h r e e s a m p l e s LCFW, B6FW and B5FW were n o t i n c l u d e d i n d a t a u s e d t o d e r i v e t h e d i s c r i m i n a n t f u n c t i o n . // _ _ — _ _ ._// // / / / / / / / / / // Sample // B / PB / BA / CO / QA / KS / BK / TG / TA / CH // // / / / / / / / / / // // // PB // 4.08 // // // BA // 13.58 15.56 // / / / / CO // 17.46 15.05 6.10 // // // QA // 2.40 6.61 9.99 13.62 // // // KS // 7.65 8.90 4. 60 6.84 6.56 //-// // BK // 3.37 5.12 26.31 25.35 6.13 13.33 // // // TG // 5.62 7.38 13.30 13.18 3.75 3.41 6.70 // / / / / TA // 7.16 5.21 11.34 9.42 8.13 4.73 9.18 4.46 // // // CH // 3.04 6.45 13.02 24.03 7.08 9.16 4.77 8.49 9.67 // / / / / LC // 5.00 7.13 5.09 11.06 4.74 6.51 12.30 9.15 10.17 7.18 // V/ . // > 52 DISCUSSION 1 Evidence of gene flow between freshwater and marine populations I Introduction Our knowledge of Gasterosteus aculeatus suggests i t has two types of l i f e history: one i s resident year round in freshwater, and the other i s anadromous with adults spending most of their l i f e in the sea. During the summer both population types breed i n freshwater. Their breeding periods and ranges p a r t i a l l y overlap. The l o t i c freshwater and marine environments represent dif f e r e n t s e l e c t i v e pressures. The se l e c t i o n presumably i s disruptive. Such disruptive selection can lead to reproductive i s o l a t i o n between the two selected forms(Thoday 1972). This study was concerned with the e f f e c t on var i a t i o n among marine populations of reproductive i s o l a t i o n between l o t i c freshwater and marine populations. The key to any such discussion i s the existence of hybrids, and therefore the question of whether intermediate plated f i s h represent interpopulation hybrids w i l l be discussed at length. II Inferences from f i e l d data on physiological forms and l a t e r a l plate count forms 53 F r e s h w a t e r p o p u l a t i o n s o f t h e t h r e e - s p i n e d s t i c k l e b a c k a r e m o r p h o l o g i c a l l y v a r i a b l e , and l a k e p o p u l a t i o n s a p p e a r t o be more v a r i a b l e t h a n s t r e a m p o p u l a t i o n s ( H o o d i e 1 S 7 2 a , L a r s o n 1976, and Hagen a n d G i l b e r t s o n 1 9 7 2 ) . T o a v o i d c o n f o u n d i n g t h e a f f e c t s o f i n t e r a c t i n g l o t i c a n d l e n t i c s e l e c t i o n I e x c l u d e d f r o m a n a l y s i s a n y s t r e a m s w i t h l a k e s c o n t a i n i n g s t i c k l e b a c k s . W i t h r e g a r d t o gene f l o w b e t w e e n a n a d r o m o u s m a r i n e p o p u l a t i o n s a n d r e s i d e n t f r e s h w a t e r p o p u l a t i o n s , two p r e v i o u s p u b l i c a t i o n s a r e r e l e v a n t , Hagen (1967) s u g g e s t e d t h a t i n t h e C a m p b e l l R i v e r r e p r o d u c t i v e i s o l a t i o n b e t w e e n t h e s e f o r m s i s b a s e d p a r t l y o n d i f f e r e n t i a l c h o i c e o f b r e e d i n g s i t e s . He d e t e r m i n e d t h e g e o g r a p h i c p a t t e r n o f t h e v a r i o u s p l a t e f o r m s w i t h i n t h e s t r e a m . I n c l u d e d i n t h i s p a t t e r n i s a z o n e where h i g h , low a n d i n t e r m e d i a t e p l a t e c o u n t f o r m s b r e e d s y m p a t r i c a l l y . He d e s i g n a t e d t h i s a r e a t h e " h y b r i d z o n e " . T h i s d e s i g n a t i o n i m p l i e s t h a t t h e i n t e r m e d i a t e f o r m s a r e a r e s u l t o f i n t e r p o p u l a t i o n h y b r i d i z a t i o n , h o w e v e r a s p e c t s o f my d a t a s u g g e s t t h i s h y b r i d z o n e i s n o t n e c e s s a r i l y due t o s u c h h y b r i d i z a t i o n . F i r s t , t h e t h r e e p l a t e f o r m s a r e p r e s e n t i n n o n b r e e d i n g m a r i n e p o p u l a t i o n s a n d t h i s s u g g e s t s t h a t some o f t h e s o c a l l e d h y b r i d s may be o f m a r i n e o r i g i n . S e c o n d , s u c h a " h y b r i d " zone c a n e x i s t w i t h o u t a f r e s h w a t e r p o p u l a t i o n ( i e . C h a s e R i v e r ) , a n d a g a i n t h i s s u g g e s t s a n o n - h y b r i d o r i g i n . F i n a l l y , t h e r e s u l t s f r o m t r a n s f e r e x p e r i m e n t s a n d f r e s h w a t e r s u r v i v o r s h i p s u g g e s t t h a t t h i s z o n e i s n o t n e c e s s a r i l y o f h y b r i d o r i g i n ( T a b l e s I I I a n d V I and F i g . 4 ) . An a l t e r n a t e 5 4 explanation of t h i s "hybrid" zone i s that i t i s a zone of sympatry between the various plate forms a l l of which may have originated from either the freshwater or marine environment (Tables III and VI, and Fig. 4). However, data for the Campbell River strongly suggest that the area occupied by a l l plate forms was indeed a zone of hybridization between populations. Hagen used a morphological index based on seven characters to investigate hybridization in the Campbell River, and demonstrated that three of his index characters ( l a t e r a l plates, g i l l rakers and the r a t i o of body depth to standard length) are largely under genetic control. In these characters and in muscle protien electrophoretic patterns the a l l o p a t r i c populations were d i s t i n c t . For a l l these t r a i t s however f i s h from the hybrid zone were intermediate. These data indicate that the hybrid zone i n the Campbell River was indeed a zone of hybridization between populations. McPhail (1969) worked on Connor creek, lashington State, with a di f f e r e n t form of three-spined stickleback. This population was resident in freshwater and had black breeding color in males i n contrast to the normal red coloration of breeding males. Though s i m i l a r coloration now i s known in other freshwater populations (Moodie 1972 (b), and McPhail pers. comm.) i t i s unknown i n marine populations. McPhail demonstrated that breeding coloration, number of g i l l rakers, and the r a t i o of the distance between the anterior two dorsal spines compared to that between the posterior two were a l l 55 under genetic control. Further that the ranges of values f o r these characters was d i f f e r e n t i n both populations. Using these characters he indicated a zone of hybridization between the two populations. He further suggested that in the creek character displacement in g i l l raker counts existed. Hagen and Mc Phail both suggest incomplete i s o l a t i n g mechanisms and agree that i n t h e i r respective study areas reproductive i s o l a t i o n r e l i e d upon selection against hybrids. Hagen*s evidence that this occurs i s based upon the existence of character displacement. McPhail, while able to show the existence of the expected character displacement, also demonstrated mechanisms increasing the mortality and decreasing the v i a b i l i t y of hybrid offspring. The mechanism of reproductive i s o l a t i o n in both instances was therefore of a survivorship type. Such an i s o l a t i n g mechanism may be disrupted by natural population fluctuations. In both the Campbell River and Connor Creek no intermediate plate count f i s h occur in the freshwater zone (the area above t i d a l influence), however i n Bonsall Creek intermediate plate count i n d i v i d u a l s were found in t h i s zone and they increased in abundance as you approached the upper l i m i t of t i d a l influence . If such intermediate i n d i v i d u a l s are part of a persistent d i s t r i b u t i o n of plate forms, then sticklebacks of marine o r i g i n presumably must interbreed with the freshwater f i s h as the marine f i s h were the only source of high plate count f i s h located. 56 The l a c k o f f r e s h w a t e r f i s h i n C h a s e C r e e k and t h e s i m i l a r i t y o f m o r t a l i t y r a t e s i n f r e s h w a t e r o f a l l p l a t e c o u n t f o r m s f r o m t h e z o n e o f s y m p a t r y ( F i g , 4) i m p l i c a t e s a m a r i n e o r i g i n f o r t h e f i s h o f t h e C h a s e C r e e k h y b r i d z o n e . F u r t h e r C h a s e C r e e k d a t a s u g g e s t s t h e d i s t r i b u t i o n o f p l a t e c o u n t f o r m s i n t h e t i d a l z o n e was d e r i v e d t h r o u g h i n t e r a c t i o n s o t h e r t h a n t h o s e a s s o c i a t e d w i t h t h e p r e s e n c e o f f i s h i n t h e f r e s h w a t e r z o n e o f t h e c r e e k . T i m i n g and d i s t r i b u t i o n o f p l a t e f o r m s i n B o n s a l l and C h a s e C r e e k s s u g g e s t s d i f f e r e n t b r e e d i n g s i t e s e x i s t f o r t h e d i f f e r e n t p l a t e c o u n t f o r m s . T h i s d i s t r i b u t i o n w h i c h was i n d e p e n d e n t o f i n p u t by a d j a c e n t f r e s h w a t e r o r m a r i n e p o p u l a t i o n s , g u e r i e s w h e t h e r o r n o t t h e two p o p u l a t i o n s were c a p a b l e o f i n v a d i n g e a c h o t h e r s h a b i t a t f o r t h e p u r p o s e o f b r e e d i n g . I n B o n s a l l C r e e k r e c i p r o c a l t r a n s f e r s were made u s i n g l o w p l a t e c o u n t i n d i v i d u a l s f r o m t h e a l l o p a t r i c f r e s h w a t e r p o p u l a t i o n and h i g h p l a t e c o u n t i n d i v i d u a l s f r o m b o t h s y m p a t r i c and a l l o p a t r i c m a r i n e h a b i t a t s . The r e s u l t s i m p l y no p h y s i o l o g i c a l b a r r i e r p r e v e n t i n g t h e m a r i n e h i g h p l a t e c o u n t f o r m f r o m e n t e r i n g t h e t i d a l p o r t i o n o f t h e c r e e k . However h i g h p l a t e c o u n t i n d i v i d u a l s f r o m t h e t i d a l z o n e ( j u s t b e l o w t h e l i m i t o f t i d a l i n f l u e n c e ) d i d n o t s u r v i v e i n t h e f r e s h w a t e r z o n e a s w e l l as t h e r e s i d e n t ( c o n t r o l ) f r e s h w a t e r f i s h . C o n v e r s e l y l o w p l a t e c o u n t i n d i v i d u a l s f r o m f r e s h w a t e r were l e s s v i a b l e i n t h e t i d a l z o n e . M o r t a l i t i e s i n t h e s e t r a n s f e r e x p e r i m e n t s were r e c o r d e d f o r s e v e n d a y s . T h i s i s 57 the period required for stickleback eggs to hatch at 18 degrees centigrade and, as some survived i t i s conceiveable that both forms could mate and tend eggs in the alternate environment. Mc Phail(1969) indicated that for freshwater sticklebacks in his study area s a l i n i t y was a barrier to invasion of marine habitats and that s a l i n i t y tolerance i s inherited. He did not find as complete a barr i e r existed f o r marine f i s h invading freshwater habitats. Over seven days 33% and 21% of his marine f i s h survived i n freshwater while a l l of his freshwater f i s h in saline waters died i n t h i s period. Corroborative evidence i s presented by Heuts{1947) who demonstrated shorter s u r v i v a l times of the European low plate count form i n marine water compared to the high plate count marine form's su r v i v a l in freshwater, A l l such studies indicate some physioloqical b a r r i e r exists, and that t h i s b a r r i e r probably involves s a l i n i t y tolerance. A l l except t h i s study suggests a stronger (more complete) barrier exists against freshwater f i s h invading t i d a l and marine waters than exists against movement of f i s h i n the opposite d i r e c t i o n . Those r e s u l t s are si m i l a r but not d i r e c t l y comparable to those of t h i s study. The l i t e r a t u r e data were was taken from transfers involving moving animals from f u l l y marine water to freshwater or the reverse, the c r i t i c a l data of t h i s investigation involves moving the animals across the l i m i t of t i d a l influence , a movement that at most involves a s a l i n i t y change of only a few parts per thousand. The results i n general though, are s i m i l a r . 58 Recapitulating, a common feature i n a l l coastal creeks where marine G, aculeatus was found breeding was a zone where high, intermediate and low plate count i n d i v i d u a l s breed sympatrically. In transect from t h i s zone to the sea intermediate and low plate count forms decreased i n frequency. Only the high plate count form was found breeding i n the sea (in the Zostera marina beds ) . The development and maintenance of t h i s pattern was independent of the presence of an adjacent resident freshwater population. Where G. aculeatus was present, a pattern of plate counts was found in the freshwater zone. The low plate count form increased in abundance away from the sympatric zone. My data suggests that the formation of t h i s pattern was not dependent upon the t i d a l zone being occupied by an anadromous breeding population i n that the presence of an anadromous breeding population did not a l t e r the proportions of low and intermediate forms i n the freshwater zone. However, the existence of intermediate indiv i d u a l s i n the freshwater population was taken as evidence that the marine population somehow contributed to the maintenance of the pattern. Sympatric zone high plate count f i s h had an increased mortality rate in the t i d a l zone and conversely low plated freshwater individuals showed increased mortality in the t i d a l section of the stream. However, there was no evidence suggesting d i f f e r e n t s a l i n i t y tolerances for f i s h from the sympatric zone compared to marine breeding f i s h . In addition low, intermediate and high plate count forms from ' the 59 s y m p a t r i c z o n e showed t h e same t o l e r a n c e t o f r e s h w a t e r . O t h e r t h a n p l a t e c o u n t , s i z e was t h e o n l y d e t e c t e d d i f f e r e n c e f o r f i s h i n t h e o c e a n and t h o s e i n t h e s y m p a t r i c z o n e . M a l e s o f b o t h p o p u l a t i o n t y p e s t h e n , were s e v e r e l y s e l e c t e d a g a i n s t when t h e y a t t e m p t e d t o b r e e d i n t h e o t h e r p o p u l a t i o n ' s b r e e d i n g z o n e . B a r r i e r s t o b r e e d i n g o f anadromous f e m a l e s i n t h e n o n t i d a l a r e a were n o t a p p a r e n t a n d t h e i r e g g s a p p e a r c a p a b l e o f s u r v i v i n g t o h a t c h i n g i n t h e f r e s h w a t e r (Mc P h a i l 1 9 6 9 ) . a l t h o u g h e v i d e n c e o f r e p r o d u c t i v e i s o l a t i o n b e t w e e n t h e s e two p o p u l a t i o n t y p e s i s s t r o n g i n C a m p b e l l R i v e r and C o n n o r C r e e k , i n B o n s a l l C r e e k t h e r e i s no e v i d e n c e o f c o m p l e t e i s o l a t i o n e i t h e r on t h e b a s i s o f morph d i s t r i b u t i o n s o r on t h e b a s i s o f s a l i n i t y t o l e r a n c e s . An i n d e p e n d e n t m o r p h o l o g i c a l r e a s s e s s m e n t o f t h i s s i t u a t i o n w i l l now be p r e s e n t e d . I l l I n f e r e n c e s f r o m g e n e r a l m o r p h o l o g y o f t h e f r e s h w a t e r and m a r i n e p o p u l a t i o n s A n a l y s i s o f m o r p h o l o g i c a l c h a r a c t e r s i n d i c a t e d f r e s h w a t e r and m a r i n e s a m p l e s were d i f f e r e n t a n d t h a t t h e d i f f e r e n c e i n v o l v e d n o t o n l y a c h a n g e i n t h e mean v a l u e o f i n d i v i d u a l c h a r a c t e r s b u t a l s o a c h a n g e i n some of t h e c h a r a c t e r s v a r i a n c e . I n s t u d y i n g f i s h p o p u l a t i o n s t h e a n a l y s i s o f a s i n g l e g e n e t i c a l l y d e t e r m i n e d c h a r a c t e r o f t e n i s i n s u f f i c i e n t t o 60 i n f e r presence or absence of gene flow. Heuts* 1955 paper demonstrated th i s . Analysis of his freshwater and marine populations by plate count suggested a single population occupied both habitats. However, analysis of another genetically determined character ( s a l i n i t y tolerance) argued for two separate populations. While one or even two characters i s often i n s u f f i c i e n t , to discriminate genetically i s o l a t e d stocks, i t i s impractical to try to determine the inheritance of a large number of characters. If data from a large number of characters, some known to be primarily under genetic c o n t r o l , are pooled and analyzed i t i s reasonable to expect a clearer indication of whether there i s gene flow between populations. Hubbs and Kuhne(1937) proposed a hybrid index as a method of combining characters. Hagen(1967) used th e i r method in his study of the Campbell River. The method suffers i n that a l l characters are given the same weight, or they are subjectively weighed, and no attempt i s made to determined i f the characters are correlated. The f i r s t f a u l t assumes either egual a b i l i t y of the characters to discriminate the groupings or the experimenter's talent i n sorting out the importance of the various characters. The i n a b i l i t y to adjust for correlated characters can result in bias caused by redundant information i n two or more characters. Discriminate function analysis overcomes these objections and i s the technique used here to i n f e r the p o s s i b i l i t y of gene flow between freshwater and marine populations i n Bonsall Creek. Since l a t e r a l plates and 6 1 physiological types are not considered i n t h i s analysis i t represents an independent reassessment of the s i t u a t i o n . The p o s s i b i l i t y of temporal variation confounding the re s u l t s of the morphological analysis was investigated. My re s u l t s indicate temporal variation was s i g n i f i c a n t . The only other report of temporal variation i n the multivariate typing of f i s h i s the report of H i l l (1959) on the American Shad ( sa£idissima ) . Here temporal variation amounted to one sixth the variation seen between two populations. Meristic variables affected by weather ( i . e . temperature a f f e c t s on developing zygotes) may be responsible f o r these changes. Another manner in which the data may be confounded i s by sexual dimorphism. Evidence that sexually dimorphic variation occurs at a multivariate l e v e l i s available from the studies of Johnston, Niles and Rohwer(1972) on the house sparrow ( Passer domesticus ) . The p o s s i b i l i t y of confounding effects of sexual and temporal morphological v a r i a b i l i t y must be considered in any such analysis. In Bonsall Creek males and females were found to have s i g n i f i c a n t l y d i f f e r e n t composite morphologies, however the d i s t r i b u t i o n of the composite morphologies was not disjunct. The i n a b i l i t y to discriminate wholly d i s t i n c t morphological types may have resulted from the discriminant function being derived to at the same time discriminate between sexes and freshwater or marine o r i g i n of the fi s h e s . 62 I n d i s c r i m i n a t i n g f o r two t y p e s o f g r o u p i n g s c h a n g e s i n t h e i m p o r t a n c e o f i n d i v i d u a l c h a r a c t e r s may s t r e n g t h e n o r weaken c o n f i d e n c e i n t h e d e r i v e d d i s c r i m i n a n t f u n c t i o n s . I n t h e two g r o u p t y p e s a n a l y z e d , o n e b a s e d o n l o c a t i o n - y e a r a n d t h e o t h e r b a s e d on a l o c a t i o n - y e a r - s e x g r o u p i n g , t h e r e s u c h c h a n g e s i n t h e i m p o r t a n c e o f v a r i o u s c h a r a c t e r s i n t h e d i s c r i m i n a n t f u n c t i o n . I n t h e B o n s a l l C r e e k a n a l y s i s o f l o c a t i o n - y e a r m o r p h o l o g i c a l t y p e s t h e two most i m p o r t a n t c h a r a c t e r s i n c o n t r i b u t i n g t o t h e d i s c r i m i n a t i o n were v e n t r a l s p i n e l e n g t h and a n a l r a y c o u n t . V e n t r a l s p i n e l e n g t h i s known t o be g e n e t i c a l l y d e t e r m i n e d (Mc P h a i l 1 9 7 7 b ) , and i n c r e a s e d s p i n e l e n g t h a t any g i v e n body l e n g t h i s a s s o c i a t e d w i t h t h e p r e s e n c e o f p r e d a t o r s (Hagen and G i l b e r t s o n 1972, M o o d i e a nd R e i m e c h e n 1 9 7 3 ) . a l s o d e c r e a s e d p r e d a t o r s u c c e s s i s a s s o c i a t e d w i t h l o n g e r s p i n e s ( M c P h a i l 1977a) . The most l i k e l y p r e d a t o r s o n B o n s a l l C r e e k s t i c k l e b a c k s a r e a d u l t Co t t us asp_er i n t h e c r e e k a n d, L§££ocottus a r m a t u s a nd s a l m o n i d s i n t h e e s t u a r y . I n a d d i t i o n t o t h e s e p r e d a t o r s t h e m a r i n e t h r e e - s p i n e d s t i c k l e b a c k i s p r o b a b l y e x p o s e d t o p r e d a t i o n by a d i f f e r e n t s e t o f p r e d a t o r s when s c h o o l i n g d u r i n g t h e n o n b r e e d i n g s e a s o n . V a r i a t i o n i n d o r s a l r a y c o u n t s was shown n o t t o be u n d e r g e n e t i c c o n t r o l by Hagen (1967) . , L i n d s e y (196 2) d i d ho w e v e r i n d i c a t e t h a t l e v e l s o f o b s e r v e d n a t u r a l v a r i a t i o n i n d o r s a l r a y c o u n t s c o u l d be a l t e r e d by c o n t r o l l i n g t h e t e m p e r a t u r e a t w h i c h G. a c u l e a t u s d e v e l o p e d . E s t u a r i n e w a t e r s t h o u g h 63 thermally variable l i k e l y have cooler o v e r a l l summer temperatures than coastal creeks and r i v e r s . Variation i n proportional head length has unknown genetic and environmental components. In the discrimination for year,location and sex groupings ventral spine length remained important. However, a change was the inclusion of head length as the most important character in the discrimination. Such a s h i f t i s not unreasonable as head length has been noted to be sexually dimorphic i n B a l t i c populations of G. aculeatus (Aneer 1973). In these analyses while i t i s not possible to say which character i s more important i n each of the grouping c r i t e r i a , i t i s not unreasonable that the suggested characters are important. Selection for d i f f e r e n t ecotypes in estuarine and l o t i c environments should result in a different pattern of morphological types than i f reproductive i s o l a t i o n occurred between these groups of individuals. If s e l e c t i o n for d i f f e r e n t ecotypes occurs without reproductive i s o l a t i o n then the pattern of morphological variation should be continuous between the two environments. The v a r i a t i o n need not be c l i n a l but must be continuous. In contrast i f t o t a l reproductive i s o l a t i o n occurs between the two groups, then competition or other unknown mechanisms should cause the indivi d u a l s i n the zone of overlap to be more d i s s i m i l a r than those i n a l l o p a t r i c areas. 6 4 P l o t s of d i s c r i m i n a n t s c o r e s a g a i n s t d i s t a n c e up B o n s a l l Creek i n d i c a t e d t h at v a r i a t i o n i n the composite morphology of B o n s a l l Creek s t i c k l e b a c k s was c l i n a l f o r a l l sex and year groups examined. The l a c k of any d i s c o n t i n u i t y l e a d s to the s u p p o s i t i o n of gene flow between the freshwater and marine f i s h e s . Such a c o n c l u s i o n i s i n agreement with other r e s u l t s of t h i s study. In summary, there e x i s t d i f f e r e n c e s i n morphology between marine and freshwater s t i c k l e b a c k s i n B o n s a l l creek. These d i f f e r e n c e s as d e s c r i b e d by the d i s c r i m i n a n t f u n c t i o n have a l a r g e g e n e t i c component. The p a t t e r n of t h i s morphological v a r i a t i o n i s d i f f e r e n t f o r males and females, but i n both cases i s continuous and c l i n a l . These o b s e r v a t i o n s support the c o n c l u s i o n s d e r i v e d from the p r e v i o u s s e c t i o n , t h a t i n B o n s a l l Creek there i s no evidence of a t o t a l b a r r i e r to gene flow. However, t h e r e i s evidence of s e l e c t i o n f o r two d i f f e r e n t ecotypes: one i n freshwater, and the other i n marine p o p u l a t i o n s with a gradual s h i f t from one type to the other. 2 R e l a t i v e v a r i a b i l i t y o f freshwater and marine breeding Gasterosteus a c u l e a t u s Evidence o f gene flow and r e p r o d u c t i v e i s o l a t i o n between p o p u l a t i o n s of s t i c k l e b a c k s s h o u l d be framed i n the context of geographic v a r i a t i o n of s t i c k l e b a c k s . Are marine and freshwater s t i c k l e b a c k s g e n e r a l l y d i s t i n c t at t h e i r i n t e r f a c e ? Is the morphology of marine s t i c k l e b a c k s a t one l o c a t i o n d i s t i n c t from t h a t o f marine s t i c k l e b a c k s at other l o c a t i o n s 65 or does t h e i r conformity suggest panmixis? Of the variation present amongst marine samples, i s i t random or patterned such that i t would suggest i t had a h i s t o r i c a l origin? Is the pattern of marine variation dependent on the differences between freshwater populations or i s marine variation independent of freshwater variation? These questions are important in an overview of stickleback evolution and to which some of my data are pertinent. If reproductive i s o l a t i o n occurred between two groups of individuals and s e l e c t i v e pressures were very d i f f e r e n t i n th e i r respective habitats, in time selection would produce two sets of autonomous coadapted genomes. Further environmental e f f e c t s on gene expression i n the d i f f e r e n t environments would l i k e l y create an even larger d i f f e r e n t i a l i n the phenome. The f i v e inherited characters mentioned e a r l i e r were; body depth, ventral spine length, g i l l raker number, the width between the anterior two dorsal spines and the width between the posterior two dorsal spines. K sixth character, head length, i s suggested but not proven to be an inherited character. In the analysis of the i n d i v i d u a l characters a l l characters had s i g n i f i c a n t l y d i f f e r e n t means i n the freshwater and marine samples, but only four characters had s i g n i f i c a n t l y d i f f e r e n t variances. These four were g i l l raker number, body depth, ventral spine length and head length. In a l l cases the samples with the reduced v a r i a b i l i t y were the freshwater samples. Three of the characters with s i g n i f i c a n t l y d i f f e r e n t variances have a known genetic basis and the fourth i s 66 suspected to be under s i m i l a r c o n t r o l . In the m u l t i v a r i a t e d i s c r i m i n a t i o n f o r marine or freshwater o r i g i n and i n the d i s c r i m i n a t i o n of l o c a t i o n i n marine samples, three of the four most important c h a r a c t e r s i n the d i s c r i m i n a t i o n were from t h i s group of p o s s i b l e g e n e t i c c h a r a c t e r s . Body depth and head l e n g t h were i n the f o u r most important c h a r a c t e r s i n both d i s c r i m i n a t i o n s . In the freshwater-marine d i s c r i m i n a t i o n f o r B o n s a l l Creek f i s h v e n t r a l spine length was the t h i r d i n h e r i t e d c h a r a c t e r . In the d i s c r i m i n a t i o n of marine l o c a t i o n the t h i r d c h a r a c t e r was the width between the a n t e r i o r two d o r s a l s p i n e s . The data as analyzed f o r marine l o c a t i o n - s e x groupings i n d i c a t e s t h a t i n a l l cases where sample s i z e was adequate; 1. the sexes a r e d i s t i n c t ; 2. both sexes are i d e n t i f i e d under the same l o c a t i o n type; and 3. t h e r e i s no r e d u c t i o n i n the o v e r l a p between l o c a t i o n types by s u b d i v i s i o n i n t o sex groupings. As l o c a t i o n t y p i n g i s the only necessary c r i t e r i a i n t h i s part of the a n a l y s i s , and as s u b d i v i s i o n i n t o sexes r e s u l t s i n marginal sample s i z e s , the r e s t of the a n a l y s i s i s done using d i s c r i m i n a n t f u n c t i o n s whose a p r i o r i grouping c r i t e r i o n i s l o c a t i o n alone. The two most important c h a r a c t e r s i n c o n t r i b u t i n g t o the d i s c r i m i n a t i o n of l o c a t i o n were mouth width and body depth thus, the l o c a t i o n d i s c r i m i n a n t f u n c t i o n has a strong g e n e t i c component. 67 Sticklebacks from d i f f e r e n t marine locations had dif f e r e n t composite morphologies, however a great deal of overlap existed between these d i s t r i b u t i o n s . , These overlapping d i s t r i b u t i o n s might have been caused by gene flow between two h i s t o r i c a l marine populations. Such an assumption would not be supported by my data as there was no evidence of a gradual change i n composite morphology along the coast, nor was any gradual s h i f t observed i n any of the i n d i v i d u a l characters used in the discriminant function analysis. Adult length however did show a tendency to decrease to the south. Spot samples from marine breeding f i s h were used to determine marine location types for three-spined stickleback. When spot samples from a l l o p a t r i c freshwater populations were c l a s s i f i e d into these marine location types i t was found that they did not sort out within the v a r i a b i l i t y described by the marine breeding f i s h and, samples of freshwater f i s h from one creek more c l e a r l y resemble anadromous three-spined stickleback from other creeks than those of that p a r t i c u l a r creek. This supports suggestions that l o c a l adaptation i s a primary source of v a r i a b i l i t y . These results would seem to imply that the freshwater l o t i c environment i s far more rigorous i n i t s selection of a phenotype than the marine environment and that the marine location types show no pattern of v a r i a b i l i t y that can be attributed to h i s t o r i c a l events or to gene flow with freshwater populations. These marine populations are however variable and l o c a l l y d i f f e r e n t i a t e d suggesting that l o c a l 68 s e l e c t i o n i s more i m p o r t a n t t h a n gene f l o w i n d e t e r m i n i n g t h e p a t t e r n o f v a r i a t i o n i n p o p u l a t i o n s o f m a r i n e G a s t e r o s t e u s a c u l e a t u s i n t h e P a c i f i c N o r t h w e s t . CONCLUSIONS The end o f t h e l a s t g l a c i a l p e r i o d o n t h e w e s t c o a s t o f N o r t h A m e r i c a r o u g h l y c o i n c i d e d w i t h t h e end o f g l a c i a t i o n i n E u r o p e . I s o l a t i o n i n s e p a r a t e g l a c i a l r e f u g i a a n d p o s t g l a c i a l d i s p e r s a l a r e c r i t i c a l f a c t o r s i n e x p l a i n i n g t h e o r i g i n o f b i o g e o g r a p h i c v a r i a t i o n i n t h e E u r o p e a n t h r e e - s p i n e d s t i c k l e b a c k ( M u n z i n g 1 9 6 3 ) . However, a l t h o u g h t h e g e o g r a p h i c p a t t e r n s o f v a r i a t i o n i n E u r o p e a n G a s t e r o s t e u s a c u l e a t u s c a n be s u c c e s s f u l l y e x p l a i n e d i n t h i s way i t was n o t p o s s i b l e t o f i n d a ny s u c h p a t t e r n i n d i s t r i b u t i o n o f p l a t e f o r m s i n t h e c o a s t a l w a t e r s o f t h e P a c i f i c N o r t h w e s t . T h i s l a c k o f a d i s c e r n a b l e p a t t e r n may be r e a l , o r i n p a r t a r e s u l t o f t h e d a t a l a c k i n g r i g o r i n t w o a s p e c t s : 1) t h e e x t e n t o f s a m p l i n g , and 2) t h e l o c a t i o n o f i n d i v i d u a l s a m p l e s . At t h e h e i g h t o f most r e c e n t g l a c i a t i o n ( t h e W i s c o n s i n G l a c i a l P e r i o d ) most o f t h e we s t c o a s t o f N o r t h A m e r i c a was c o v e r e d b y t h e C o r d i l l e r a n I c e S h e e t . F o r a n a d r c m o u s s p e c i e s s u c h a s s t i c k l e b a c k s t h e r e were p r o b a b l y two a r e a s f r o m w h i c h t h e w e s t c o a s t c o u l d be r e c o l o n i z e d , t h e B r i s t o l Bay r e g i o n o f A l a s k a , a n d t h e t h e u n g l a c i a t e d p o r t i o n o f t h e c o a s t s o u t h o f P u g e t Sound. The p r e s e n t d i s t r i b u t i o n o f G a s t e r o s t e u s a c u l e a t u s i s f r o m S t . L a w r e n c e I s l a n d , A l a s k a , t o B a j a C a l i f o r n i a . The s a m p l e s I u s e d t o d e t e c t b i o g e o g r a p h i c 69 variation covered most of the glaciated zone, but few i f any, were from the unglaciated areas. In Europe the southern unglaciated zone i s characterized by having few marine sticklebacks. A si m i l a r s i t u a t i o n i s said to exist along the coast of C a l i f o r n i a {Miller and Hubbs 1969). I t i s possible that any inte r f a c e between the two groups of populations occurred to the south of my sampling area. My evidence suggests that i n the breeding populations dif f e r e n t forms are associated with d i f f e r e n t positions i n the t i d a l zone of the creek. The museum specimens used i n the analysis of biogeographic variation are of marine o r i g i n , but they do not a l l come from the same position in the t i d a l zone. The Twin Glaciers Lake samples probably came from the upper end of the breeding d i s t r i b u t i o n of f i s h of marine o r i g i n while the Big Ko i t o i Bay f i s h are as l i k e l y to have come from the lower extreme of t h i s zone. This s i t u a t i o n may have led to serious confounding of the biogeographic an a l y s i s . While the biogeographic data are perhaps " s o f t " , the data on d i f f e r e n t i a t i o n of l o c a l populations are concrete. Two schools of thought have attempted to explain that variation i n G. aculeatus that cannot be accounted f o r by h i s t o r i c a l events. One school attributes the observed variation to introgression and intergradation between high and low plate count populations (Miller and Hubbs 1969). The other claims the variation has arisen primarily through adaptation to l o c a l environmental conditions (Hagen and Mc Phail 1970). The only r e a l difference between these suggestions i s that to have introgression or intergradation there must f i r s t exist separate genomes, while the adaptation theory derives the various plate forms through s e l e c t i v e pressures and therefore can s t a r t from any population type. The existence of d i s t i n c t , geographically separated, genetic types such as in the Connor Creek and Campbell River studies, i s undeniable. However, the u n i v e r s a l i t y of these types i s in doubt. There also i s evidence that these population types which are reproductively i s o l a t e d i n some locations may, i n other locations, be maintained as separate population types though there i s gene flow between the two groups of individuals. This appears to be the case i n Bonsall Creek. The process of selection of a genotype occurs too slowly to be p r a c t i c a l l y shown by experiments with Gasterosteus §cul§§.|u§/ therefore i t i s necessary to make inferences from what may be observed i n nature. Several observation are pertinent; (1)In lakes without predators the l a t e r a l plate count i s between 0 and 7. In lakes containing predatory f i s h and where no high plate count G. aculeatus are present l a t e r a l plate count has a mean at seven and a d i s t r i b u t i o n which includes individuals with plate counts between 8 and 28(Hagen and Gilbertson 197 2). Further i t has been shown experimentally that predators select against sticklebacks with less than seven l a t e r a l plates(Moodie 1972a and 1972b, and Hoodie, Mc Phail and Hagen 1973. (2)There exist populations of three-spined stickleback monitored over 71 several years in which the f i s h are monomorphic for the "hybrid" intermediate plate count form (M unzinq 1963 ). (3)Stickleback populations schooling i n the ocean contain a l l three plate count forms. During breeding season, but before the anadromous population starts breeding, there are no sticklebacks i n the t i d a l portion of the creek although upstream the freshwater population may be breeding. When the anadromous populations do begin breeding, high, low and intermediate forms are present in a pattern that c h a r a c t e r i s t i c a l l y has an increasing proportion of the low and intermediate forms as you approach the freshwater zone. Evidence from Chase Creek suggests t h i s pattern i s independent of the occurrence of an adjacent freshwater population. Although the data are largely circumstantial these observations suggest that s e l e c t i v e forces such as predation may cause l o c a l adaptation in populations of G. aculeatus and further that within marine populations there may be selection for d i f f e r e n t plate count forms at the opposite s a l i n i t y extremes of t h e i r breeding range. 7 2 LITERATURE CITED Aneer G. 1973 Biometric c h a r a c t e r i s t i c s of the three-spined stickleback ( Gasterosteus aculeatus Linnaeus ) from the Northern B a l t i c proper. Zool. Scr. 2(4): 157-162 B e l l , M. A. 1976 The evolution of phenotypic d i v e r s i t y in Gasterosteus aculeatus subspecies on the P a c i f i c coast of North America. Syst. Zool. 25(3) pp.211-227 Cooley, W. W. , and P, R. Lohnes 1971 Multivariate data analysis. John Wiley and Sons, New York, N. Y. C r i s t i e , M. T. 1974 Control of v i s u a l pigment proportions i n two anadromous fishes., Ph.D. Thesis, University of Oregon, Eugene, Oregon Gould, S. J . , and R. F. Johnson 1972 Geographic v a r i a t i o n . Ann. Rev. Ecol. Syst. 3: 457-498 Hagen, D. W. 1967 I s o l a t i n g mechanisms in three-spined sticklebacks (Gasterosteus) . , Jour. Fish. Res. Board of Canada 24: 1637-1692 Hagen, D. W., and L. G. Gilbertson 1972 Geographic variation and environmental s e l e c t i o n i n Gasterosteus aculeatus i n P a c i f i c Northwest America. Evolution 26: 32-51 73 Hagen, D, W., and J . D. Mc P h a i l 1970 The s p e c i e s p r o b l e m w i t h i n G a s t e r o s t e u s a c u l e a t u s on t h e P a c i f i c c o a s t o f N o r t h A m e r i c a . J o u r . F i s h . R es. B o a r d o f Canada 27: 147-155 Hay, D. D., and J . D. Mc P h a i l 19 75 Mate s e l e c t i o n i n ( G a s t e r o s t e u s ) . C a n . t h r e e - s p i n e d s t i c k l e b a c k s J . Z o o l 5 3 ( 4 ) ; 44 1-450 H e u t s , M. J . 1947 E x p e r i m e n t a l s t u d i e s on a d a p t i v e e v o l u t i o n i n G a s t e r o s t e u s a c u l e a t u s . E v o l u t i o n 1: 89-102 H e u t s , M. J . 1955 T e m p e r a t u r e a d a p t a t i o n s i n G a s t e r o s t e u s a c u l e a t u s L.. P u b b l . S t a z . Z o o l . N a p o l i . 28: 44-61 H i l l , D. H. 1959 Some u s e s o f s t a t i s t i c a l a n a l y s i s on c l a s s i f y i n g r a c e s o f a m e r i c a n s h a d ( A l o s a s a p i d i s s i m a ) . U. S. F i s h a n d W i l d l i f e S e r v i c e , F i s h e r i e s B u l l e t i n 59: 269-286. Howe, K. M. 1973 S y s t e m a t i c s o f t h e G a s t e r o s t e u s c o m p l e x ( P i s c e s : G a s t e r o s t i d a e ) i n N o r t h e r n C a l i f o r n i a . M. A. T h e s i s , C a l i f . S t a t e C o l l . , Sonome, C a l i f . H u b b s, C. C. 1955 H y b r i d i z a t i o n b e t w e e n f i s h s p e c i e s i n n a t u r e . S y s t . Z o o l . 4: 1-20 Hubbs, C. C. And E. B. Kuhne 1937 A new f i s h o f t h e g e n u s Apocope f r o m a Wyoming warm s p r i n g . O c c . P a p e r s Mus. Z o o l . U n i v . M i c h i g a n 3 4 3 : 1-21 74 Hubbs, C. C 1955 H y b r i d i z a t i o n between f i s h s p e c i e s i n nature. Syst. Z o o l . 4: 1-20 Johnson, R. F., D. W. U i l e s and S. A. Rohwer 1972 Herman Bumpus and n a t u r a l s e l e c t i o n i n the house sparrow Passer domesticus ., E v o l u t i o n 26: 20-31 Larson, G. L. 1976 S o c i a l behavior and feeding a b i l i t y of two phenotypes of Gasterosteus a c u l e a t u s i n r e l a t i o n t o t h e i r s p a t i a l and t r o p h i c s e g r e g a t i o n i n a temperate l a k e . Can. Jour . Z o o l . , 54: 107-121 Lindsey, C. C. 1962 Experimental study of m e r i s t i c v a r i a t i o n i n a po p u l a t i o n of three-spined s t i c k l e b a c k s , Gasterosteus a c u l e a t u s ., Can. J o u r . Z o o l . 40: 271-312 Mc P h a i l , J . D. 1969 P r e d a t i o n and t h e e v o l u t i o n of a s t i c k l e b a c k {Gasterosteus) . Jour. F i s h . Res. Board of Canada 26: 3183-3208 Mc P h a i l , J . D. MS 1977a s p i n e s , s t i c k l e b a c k s and predators - a study o f the d e t e r r e n t e f f e c t s of d i f f e r e n t s i z e d s p i n e s . Mc P h a i l , J . D. MS 1977b I n h e r i t e d i n t e r p o p u l a t i o n d i f f e r e n c e s i n spine l e n g t h i n t h r e e - s p i n e d s t i c k l e b a c k . M i l l e r , R. R. , and C. L. Hubbs 1969 Systematics of Gasterosteus a c u l e a t u s with p a r t i c u l a r r e f e r e n c e t o i n t e r g r a d a t i o n and 75 i n t r o g r e s s i o n a l o n g t h e P a c i f i c c o a s t o f N o r t h A m e r i c a : A commentary on a r e c e n t c o n t r i b u t i o n . , C o p e i a 1969: 52-69 M o o d i e , G. E. E. 1972 (a) P r e d a t i o n , n a t u r a l s e l e c t i o n and a d a p t a t i o n i n a n u n u s u a l t h r e e - s p i n e d s t i c k l e b a c k . H e r e d i t y 2 8 ( 2 ) : 155- 167 M o o d i e , G. E. E. 1972 (b) M o r p h o l o g y , l i f e h i s t o r y , and e c o l o g y o f an u n u s u a l s t i c k l e b a c k ( G a s t e r o s t e u s a c u l e a t u s ) i n t h e Queen C h a r l o t t e I s l a n d s , C a n a d a . Can. J o u r . Z o o l . 50: 721-732 E. E. , J . D. Mc P h a i l and D. W. Hagen E x p e r i m e n t a l d e m o n s t r a t i o n o f s e l e c t i v e p r e d a t i o n on G a s t e r o s t e u s a c u l e a t u s . B e h a v i o r 47: 9 5-105 M o o d i e , G. E. E. And T. E. R e i m e c h e n 1973 Endemism and c o n s e r v a t i o n o f s t i c k l e b a c k s i n t h e Queen C h a r l o t t e I s l a n d s . Can. F i e l d - n a t u r a l i s t 87: 173-175 M u n z i n g , J . 1963 The e v o l u t i o n o f v a r i a t i o n and d i s t r i b u t i o n a l p a t t e r n s i n E u r o p e a n p o p u l a t i o n s o f t h e t h r e e -s p i n e d s t i c k l e b a c k , G a s t e r o s t e u s a c u l e a t u s . E v o l u t i o n 17: 320-332 N a r v e r , D. W. 1969 P h e n o t y p i c v a r i a t i o n i n t h e t h r e e - s p i n e d s t i c k l e b a c k s ( G a s t e r o s t e u s a c u l e a t u s ) o f t h e C h i g n i k R i v e r s y s t e m , A l a s k a . J o u r . F i s h . Res. B o a r d o f Canada 26: 40 5-412 M o o d i e , G. 1973 76 Polgar T. T. 1975 Characterization of bent hie community response to environmental variation by multiple discriminant analysis, In: Fisheries and energy production: a symposium, Ed S.B. S a i l a . , Lexington Books, Lexington Massachusetts, pp. 267-2 94 Rohlf, F. J . , ana B. E. Sokal 1969 S t a t i s t i c a l tables. W. H. Freeman, San Francisco Thoday, J. M. 1972 Disruptive selection. Proc. B. Soc. Lond. B 182:109-143 77 APPENDIX I The Zostera marina Environment It i s important to outline something of the character of these Zj. marina beds as they may represent a much more extensive breeding zone for the marine three-spined stickleback than do the streams, creeks and r i v e r s of t h i s coast. Zostera marina (Eelgrass) i s a grasslike angiosperm. I t i s found in association with low s a l i n i t y coastal waters. Able to survive on a sand or mud substrate the seeds of this plant w i l l only germinate in waters of 4.5 to 9.0 parts per thousand s a l t s . Vegetative growth occurs between 10 and 30 parts per thousand, and temperatures between 10 and 20 degrees centigrade . Waters above 20 degrees are believed to constitute thermal stress to the p l a n t ( P h i l l i p s 1974) The di s t r i b u t i o n of t h i s plant i s limited between mean low water and t h i r t y meters (Thayer, Wolfe and Williams 1975). __ carina constitutes some of the most productive area known on this planet. In Puget Sound, Washington Eelgrass growth i s known to average 581 gm. dry wt./ sg.m. Annually, of which 34 to 66 % becomes detritus ( p h i l l i p s 1974). Large communities of invertebrates and f i s h are also found i n beds of Z t marina. A break down of the Eelgrass community i n the Newport River estuary, Beaufort, N.C. i s as follows ; Eelgrass 40 gm./sg.m., d e t r i t a l feeding macr oinvertebrates 3.23 gm./sg.m., carnivorous macroinvertebrates 1.67 gm./sg.m., 78 herbivorous macroinvertebrates 1.63 gm./sg.m. , omnivorous fishes 1,33 gm./sq.m. and zooplankton 0.04 gm./sg. m. (Thayer, Wolfe and Williams 1975) It i s l i k e l y that the high productivity of invertebrates by "L±. f a r i n a beds allows stickleback females using these areas to attain a greater fecundity than those females which use the creek breeding areas. Females experiencing a more abundant food supply are known to have more eggs per clutch(Wooton 1973a) and produce more clutches in a breeding season (Wooton 1973b). Further, the dense vegetation would mitigate possible damaging e f f e c t s of currents and surf in addition to providing both adults and young shelter from many larger piscivorous fishes. LITERATURE CITED P h i l l i p s , R. C. 1974 Temperate Eelgrass Flats. In; Coastal ecoloqical systems of the U.S.., Ed: H. T. Odum, B. J. Copeland, and E. A. Mc Mahon., vol. 2, 244-299 Thayer, G. W., D. A. Wolfe, and R. B. Williams 1975 The impact of man on seagrass systems. American S c i e n t i s t , 63 (3): 288-296 Wooton, R. J. 1973a The effect of s i z e of food ration on egg production i n the female three-spined stickleback, Gasterosteus aculeatus L. . J. Fish B i o l . 5, 89-96 79 Wooton, S. J. 1973b Fecundity of the three-spined s t i c k l e b a c k , Gasterosteus aculeatus L. . J . F i s h B i o l . 5, 683-688 80 APPENDIX I I C a l c u l a t i o n Of Sample S i z e For D i s c r i m i n a n t A n a l y s i s F a i l u r e t o r e j e c t the n u l l hypothesis does not i n d i c a t e that the samples have been proven t o be s i m i l a r , but only that with the data s u p p l i e d you cannot prove the observed d i f f e r e n c e s would not have o c c u r r e d with a p r o b a b i l i t y l e s s than i f there had been no d i f f e r e n c e . What i s l e f t i s the choice of a c c e p t i n g the n u l l hypothesis, o r assuming t h a t the sample s i z e was t o s m a l l to show that the d i f f e r e n c e was r e a l . In most u n i v a r i a t e a n a l y s i s f o r d i f f e r e n c e s between means, even though s t a t i s t i c a l methods e x i s t f o r a p r i o r i e s t i m a t i o n of s u f f i c i e n t sample s i z e s , a p o s t e r i o r i between samples of Gasterosteus a c u l e a t u s taken from p o p u l a t i o n s Representation of m u l t i d i m e n s i o n a l d i s c r i m i n a n t a n a l y s i s i n two dimensions i s too much of an over s i m p l i f i c a t i o n to a l l o w a s i m i l a r a n a l y s i s . T h i s inadequacy o f two or three dimensional p l o t s i s a major d i f f i c u l t y i n the development of a s i m i l a r a p o s t e r i o r i approach to d e c i p h e r i n g the reason f o r f a i l u r e t o d e t e c t a d i f f e r e n c e between two sample means. Further the a d d i t i o n of data i n the d e r i v a t i o n of a d i s c r i m i n a n t f u n c t i o n changes the r e l a t i o n s h i p between the orthogonal a x i s thereby negating the comparison between d i f f e r e n t t e s t s which i s necessary i n order to formulate an a p r i o r i e s t i m a t i o n of s u f f i c i e n t sample s i z e . However i t s t i l l i s o f t e n d e s i r e a b l e to be a b l e t o p o i n t a f i n g e r a t what may 81 have been the reason f o r the f a i l u r e to detect a s i g n i f i c a n t difference between group means. The method outlined below i s not a s t a t i s t i c a l l y rigorous method which allows d e f i n i t i o n of certainty, however i t i s a considerable improvement over making an inference based on your 'gut* reaction to the data. I t starts by the researcher a p r i o r i delineating an extreme sample size. This i s a sample size beyond which i f larger sized samples are necessary, the experimenter would consider any difference between means b i o l o g i c a l l y i n s i g n i f i c a n t . Then the discriminant analysis i s done. I f the n u l l hypothesis must be accepted formula 2 may be used to i n f e r the reason for f a i l u r e to detect a difference between groups. The formulation of the a p o s t e r i o r i analysis i s derived from the 'Approximate F* test used to determine i f differences between discriminant analysis group means are s i g n i f i c a n t . The formula i s as follows: (X) F(m#l) = N-G-R+1/R * 1 / N - G * N (m) N (1) /N (m) +N (1) * C (m,i)-C ( l , i ) * X (ra, i)-X ( l , i ) Where: F{m,l) - the F value for comparison of discriminant groups m and 1. N(m) - the number of cases in group m N(l) - the number of cases i n group 1. N - the t o t a l number of cases used i n the derivation of the discriminant function. G - the number of groups to be discriminated. 82 E - the number o f c h a r a c t e r s analyzed from each i n d i v i d u a l case. C (m ri) - the c l a s s i f i c a t i o n c o e f f i c i e n t f o r v a r i a b l e I of group m C ( l , i ) - the c l a s s i f i c a t i o n c o e f f i c i e n t f o r v a r i a b l e I of group 1. X(m,i) - the mean value of c h a r a c t e r I i n group m X ( l , i ) - the mean value of c h a r a c t e r I i n group 1. The formula i s then r e c o n s t r u c t e d with sample s i z e s on the l e f t of the e g u i v a l e n t s i g n as below (£) N (m) N (1)/N (m)+N (1) = Fc * H/N-G-E+1 * N-G/ < C (m,i)-C (1,1) * X(m, i) -X ( l , i ) ) Where Fc i s the t a b u l a t e d c r i t i c a l F s t a t i s t i c f o r R and (N-G-R*1) degrees of freedom From our knowledge t h a t at the t e s t e d sample s i z e the sample means cannot be proven to be d i f f e r e n t and using the c a l c u l a t e d value of N (m) N (1) / (N (m)+N (1)) i t i s p o s s i b l e t o a s s i g n the t e s t e d sample s i z e to one of two areas. That area where the value t e s t e d samples i s l e s s than the a p o s t e r i o r i c a l c u l a t e d value. I n t h i s region sample s i z e would be c o n s i d e r e d a p o s s i b l e reason f o r f a i l u r e to d e t e c t d i f f e r e n c e s between group means. The area where the t e s t e d sample s i z e r e s u l t s i n a value l a r g e r than t h e a p o s t e r i o r i c a l c u l a t e d v a l u e r e p r e s e n t s an area where i t would be i m p o s s i b l e to decide the reason f o r f a i l u r e to d e t e c t a d i f f e r e n c e between d i s c r i m i n a n t group means. 83 A l l comparison of means done in my data the value of N (m) N (1) /N {m) +N (1) calculated had an upper l i m i t for b i o l o g i c a l l y s i g n i f i c a n t r e s u l t s set at 100. In a l l instances where the 'approximate F 1 test was not s i g n i f i c a n t , by the above i n f e r e n t i a l method sample size was implicated as the reason for f a i l u r e to detect a s i g n i f i c a n t difference between the means of discriminated groups.needless to say t h i s implication could be inappropriate. With increased sample sizes the n u l l hypothesis could be accepted and no difference demonstrated. With the formulation above the chance of the n u l l hypothesis at a sample size of 100 would be 50% . 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0103869/manifest

Comment

Related Items