@prefix vivo: . @prefix edm: . @prefix ns0: . @prefix dcterms: . @prefix skos: . vivo:departmentOrSchool "Science, Faculty of"@en, "Zoology, Department of"@en ; edm:dataProvider "DSpace"@en ; ns0:degreeCampus "UBCV"@en ; dcterms:creator "LeDuc, Janice Irene"@en ; dcterms:issued "2010-01-21T22:38:23Z"@en, "1974"@en ; vivo:relatedDegree "Master of Science - MSc"@en ; ns0:degreeGrantor "University of British Columbia"@en ; dcterms:description "A number of studies on small mammals have shewn that changes in the frequency of alleles at polymorphic loci are correlated with population fluctuations. To determine whether this association between demography and genetics is causal, I altered gene frequencies in two field populations of M. townsendi Using starch gel electrophoresis, I detected a leucine aminopeptidase (LAP) polymorphism in M. townsendi. The fast allele, LAP-F, was present in a control population at a frequency of about .35 from July 1971 to July 1973. By removing homozygous SS voles from one experimental population I maintained an LAP-F frequency of about .75. Removal of FF homozygotes from a second population resulted in an LAP-F frequency of about .25. I monitored demographic variables of the populations while the selection was being applied. The populations went through increasing and peak phases and then declined sharply during the spring of 1973. There were indications that different genotypes had an advantage in survival and reproduction during different phases of population density. The selection that maintained the polymorphism on the control area could be correlated with population density. However, the overall fitness of each experimental population was not affected by its genotypic composition at this locus."@en ; edm:aggregatedCHO "https://circle.library.ubc.ca/rest/handle/2429/18877?expand=metadata"@en ; skos:note "DEMOGRAPHIC CONSEQUENCES OF ARTIFICIAL SELECTION AT THE LAP LOCUS IN VOLES jHICBOTUS TORNSENDI) by JANICE IRENE leCDC B.Sc, , u n i v e r s i t y of A l b e r t a , 1971 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE CF MASTER OF SCIENCE i n the Eepartment of Zoology We accept t h i s t h e s i s as conforming to the r e g u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA AUGUST, 1974 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 r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Co lumb ia , I ag ree 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 r e f e r e n c e and s tudy . I f u r t h e r agree 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 t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r 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 that c o p y i n g o r p u b l i c a t i o n o f 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 thout my w r i t t e n p e r m i s s i o n . Department o f _ / a The U n i v e r s i t y o f B r i t i s h Co lumbia Vancouver 8, Canada Date Jejrfi- I X /97V ABSTRACT A number of s t u d i e s on s m a l l mammals have shewn that changes i n the frequency of a l l e l e s a t polymorphic l o c i are c o r r e l a t e d with p o p u l a t i o n f l u c t u a t i o n s . To determine whether t h i s a s s o c i a t i o n between demography and g e n e t i c s i s c a u s a l , I a l t e r e d gene f r e q u e n c i e s i n two f i e l d p o p u l a t i o n s of M*. townsendi^ Using s t a r c h g e l e l e c t r o p h o r e s i s , I detected a l e u c i n e aminopeptidase (LAP) polymorphism i n M_. townsendi_. The f a s t a l l e l e , LAP-F, was present i n a c o n t r o l p o p u l a t i o n at a frequency of about .35 from J u l y 1971 to J u l y 1973. By removing homozygous SS v o l e s from one experimental p o p u l a t i o n I maintained an LAP-F frequency of about .75. Removal of FF homozygotes from a second p o p u l a t i o n r e s u l t e d i n an LAP-F frequency of about .25. I monitored demographic v a r i a b l e s of the p o p u l a t i o n s while the s e l e c t i o n was being a p p l i e d . The p o p u l a t i o n s went through i n c r e a s i n g and peak phases and then d e c l i n e d s h a r p l y during the s p r i n g of 1973. There were i n d i c a t i o n s t h a t d i f f e r e n t genotypes had an advantage i n s u r v i v a l and r e p r o d u c t i o n during d i f f e r e n t phases of p o p u l a t i o n d e n s i t y . The s e l e c t i o n t h a t maintained the polymorphism on the c o n t r o l area c o u l d be c o r r e l a t e d with p o p u l a t i o n d e n s i t y . However, the o v e r a l l f i t n e s s of each experimental population was not a f f e c t e d by i t s genotypic composition at t h i s l o c u s . TABLE OF CONTENTS I n t r o d u c t i o n 1 Methods Study Area . 4 Trapping Schedule 5 E l e c t r o p h o r e s i s . . 6 T r a n s f e r s 7 Sources Of E r r o r 8 R e s u l t s 11 Population Density 11 A l l e l e Frequency . 12 A l l e l e Frequency And Density 13 Demography And Genotypes 15 S u r v i v a l And Genotype . 16 Breeding C o n d i t i o n And Genotype 17 Eody Weights And Growth Rates 19 LAP And Demography 20 D i s c u s s i o n ; . 21 L i t e r a t u r e C i t e d 61 LIST OF TABLES Table 1. LAP Types For Colony Crosses Of M.. townsendi Tested For Chi-square Goodness Of F i t . 26 Table 2. Number Of T r a n s f e r r e d M._ townsendi Remaining On The Experimental G r i d s U n t i l At Lea s t The Next Trapping S e s s i o n . . ; 27 Table 3. Percentage Maximum T r a p p a b i l i t y Of Tagged Mj_ townsendi Grouped By Time Of Year. 2 8 Table 4. Mean Body Weight At The Time Of F i r s t Capture Of M_j_ townsendi On The C o n t r o l G r i d I. 29 Table 5. Instantaneous Rates Of P o p u l a t i o n Increase For Ik i2«£sendi On A l l G r i d s Expressed As Percent Per Week. _30 Table 6. Percent Bi-weekly Change In LAP-F Frequency For Hi townsendi.. . 31 Table 7. C o r r e l a t i o n Of Density And LAP-F Frequency In !k i o a i j s e n d i ^ 3 2 Table 8. Minimum Two-week S u r v i v a l Rates In B, townsendi On G r i d G. 3 3 Table 9. Minimum Two-week S u r v i v a l Rates F c r M._ townsendi On G r i d H. I I 34 Table 10. Minimum Two-week S u r v i v a l Rates For MA townsendi On C o n t r o l G r i d I . 35 Table 11. Percentage Of Adult M^ townsendi Males With S c r o t a l T e s t e s On G r i d G. 36 Table 12. Percentage Of Adult |, townsendi Males With S c r o t a l Testes On G r i d H. _ _ 37 Table 13. Percentage Of Adult townsendi Males With S c r o t a l T e s t e s On C o n t r o l G r i d I. 38 Table 14. Percentage Of Adult M.. townsendi Females L a c t a t i n g On G r i d G. 39 Table 15. Percentage Of Adult fU townsendi Females L a c t a t i n g On G r i d H. 40 Table 16. Percentage Of Adult M. townsendi Females L a c t a t i n g On C o n t r o l G r i d I. . 41 Table 17. Mean Body Weight Of Male MA townsendi On Gr i d G i i i For Each Season. 42 Table 18. Mean Body Weight Of Male M^ townsendi On Gri d H For Each Season. 43 Table 19. Mean Body Weight Of Male MA townsendi On G r i d I For Each Season. 44 Table 20. Average Growth Bates {% Per Day.) Adjusted By Regression To A Standard 35 G Vole, Of M_. townsendi Males On G r i d G. ~_ \" _ ~ Z Z Z 4 5 Table 21. Average Growth Rates {% Per Day) Adjusted By Regression To A Standard 35 G Vole, Of M_. townsendi Males On G r i d H. ~ 46 Table 22. Average Growth Rates (% Per Day) Adjusted By Regression To A Standard 35 G Vole, Of M.. townsendi Males On C o n t r o l G r i d I . LIST OF FIGURES F i g u r e 1. Westham I s l a n d R e c e i v i n g S t a t i o n : L o c a t i o n Of Study G r i d s . 48 F i g u r e 2. S t a r c h Gel Showing LAP S t a i n i n g P a t t e r n In Mi c r o t u s Townsendi Serum. 4 9 Fi g u r e 3. P o p u l a t i o n Density Of Microtus Townsendi On G r i d G. . ZZZZZ—Z—ZZZ ~ ~ 5 0 F i g u r e 4. P o p u l a t i o n D e n s i t y Of Microtus Townsendi On G r i d H. ZZZZZZZ ZZZ—ZZZZ 5 1 F i g u r e 5. P o p u l a t i o n Density Of Microtus Townsendi On G r i d I. Z Z Z , Z 52 F i g u r e 6. A l l e l e Frequency Of F On Grid G, From Which A l l SS Voles Were Removed. 53 Fi g u r e 7. A l l e l e Frequency Of F On G r i d H, From Which A l l FF Voles Were Removed, 54 F i g u r e 8. A l l e l e Frequency Of F On G r i d I, The C o n t r o l G r i d . 55 Fi g u r e 9. Histogram Of Mean Bi-weekly S u r v i v a l Rates Of Male Microtus Townsendi During The Three Summers. 56 Fi g u r e 10. Histogram Of Mean Bi-weekly S u r v i v a l Rates Of Female Microtus Townsendi During The Three Summers. 57 F i g u r e 11. Histogram Of Body Weight D i s t r i b u t i o n s Of Male Microtus Townsendi On G r i d G. 58 Fi g u r e 12. Histogram Of Body Weight D i s t r i b u t i o n s Of Male MiSSSiSS Townsendi On G r i d H. 59 F i g u r e 13. Histogram Of Body Weight D i s t r i b u t i o n s Of Male Microtus Townsendi On G r i d I. _ _ 60 1 INTRODUCTION M i c r o t i n e rodents undergo p e r i o d i c f l u c t u a t i o n s i n p o p u l a t i o n d e n s i t y which are not d i r e c t l y r e l a t e d to known changes i n the environment of the p o p u l a t i o n ( C h i t t y 1960; Krebs 1966; Krebs et a l 1969). The absence of obvious e x t r i n s i c r e g u l a t i o n of such p o p u l a t i o n s has l e d C h i t t y (1967,1969) to suggest that g e n e t i c changes are a necessary p a r t of the c o n d i t i o n s l e a d i n g to numerical f l u c t u a t i o n s . During the p e r i o d of low numbers and p o p u l a t i o n i n c r e a s e , so the s t o r y gees, c e r t a i n genotypes are favored by s e l e c t i o n . As d e n s i t y i n c r e a s e s , an a g g r e s s i v e genotype gains the s e l e c t i v e advantage through the e l i m i n a t i o n from the breeding p o p u l a t i o n of those l e s s able to withstand crowding. A d e c l i n e i n numbers w i l l occur when the i n c r e a s i n g s e l e c t i o n f o r a g g r e s s i v e i n d i v i d u a l s has decreased the t o t a l p o p u l a t i o n f i t n e s s with regard to f o r c e s other than i n t r a - s p e c i f i c c o m p e t i t i o n . The above hypothesis assumes t h a t the p o p u l a t i o n c o n t a i n s g e n e t i c v a r i a t i o n capable of responding to short-term s e l e c t i v e p r e s s u r e s . E l e c t r o p h o r e t i c s t u d i e s of p r o t e i n s have r e v e a l e d l a r g e amounts of a p p a r e n t l y p e r s i s t e n t a l l e l i c v a r i a t i o n i n n a t u r a l p o p u l a t i o n s (e.g., Lewontin and Hubby 1966; Selander e t a l 1971). Evidence t h a t s e l e c t i o n does maintain such v a r i a t i o n and can be e f f e c t i v e over s h o r t p e r i o d s has been found (Yarbrough and Kojima 1967; Kojima and T o b a r i 1969). It i s at l e a s t reasonable, then, to use e l e c t r o p h o r e t i c v a r i a n t s as g e n e t i c markers when one i s i n v e s t i g a t i n g the i m p l i c a t i o n s of 2 C h i t t y 1 s hypothesis of p o p u l a t i o n r e g u l a t i o n through g e n e t i c change. S e v e r a l authors have monitored e l e c t r o p h o r e t i c markers durin g d e t a i l e d demographic s t u d i e s on f l u c t u a t i n g p o p u l a t i o n s . Semeonoff and Robertson (1968) found that the a l l e l e frequency of an e s t e r a s e polymorphism changed during a p o p u l a t i o n d e c l i n e of Microtus a g r e s t i s ^ Canham (1969) reported that the r e l a t i v e f i t n e s s e s of the genotypes of a t r a n s f e r r i n and of an albumin polymorphism were r e l a t e d to changes i n d e n s i t y of Peromyscus manjculatus and Clethriononjys FS>SS) f o r percentages of each genotype i n breeding c o n d i t i o n . During that p e r i o d the LAP-F frequency i n c r e a s e d on g r i d I, but I found no such r e l a t i o n s h i p between breeding and a l l e l e .frequency change during any other p e r i o d of the study. The most n o t i c e a b l e p a t t e r n i n breeding performance was the d i f f e r e n c e between the years of the study. Breeding was maintained at a low l e v e l on a l l g r i d s throughout the winter of 1971-1972, but had stopped by the end of September 1972. 19 However, the percentages of v o l e s i n breeding c o n d i t i o n were not d i f f e r e n t between summers. No d i f f e r e n c e s were apparent between the g r i d s i n the obvious year-to-year v a r i a t i o n of length of breeding seasons. Body Weights and Growth Bates The d i s t r i b u t i o n of male body weights changed on each g r i d d u r i n g the study (Figures 11, 12, and 13). The change was most n o t i c e a b l e on g r i d I , where the average weight of males went from about 50 g durin g summer 1971 and winter 1971-72, to about 60 g during summer 1972, then down to about 45 g i n winter 1972-73 and back up to about 56 g i n summer 1973 (see Tables 17, 18, and 19). On the two experimental g r i d s the average weights were not as high as on the c o n t r o l during summer 1972, but d i d drop to about 46 g during winter 1972-73.' except f c r summer 1972, the changes i n body weight d i s t r i b u t i o n were c o n s i s t e n t between a l l three g r i d s throughout the study. Instantaneous r e l a t i v e growth r a t e s , adjusted to a standard 35 g vo l e by r e g r e s s i o n , were c a l c u l a t e d f o r males (see Krebs e t a l 1969). The mean growth r a t e s f o r each p e r i o d and genotype are shown i n Tables 20, 21, and 22. During a l l three summers on g r i d I, growth r a t e s were lowest f o r the FF homozygotes. Growth r a t e s f o r the heterozygotes were lower than those f o r the SS homozygote duri n g a l l t h r e e summers on g r i d H and during the summers of 1971 and 1972 on g r i d I. On g r i d G, the growth r a t e of FF homozygotes was higher than t h a t of the heterozygotes i n 20 summer 1971, but lower during summer 1973. Growth r a t e s were not c o n s i s t e n t l y d i f f e r e n t between g r i d s f o r any genotype. LAP and Demographer My experiment was based on c o r r e l a t i v e evidence from other s p e c i e s t h a t a l l e l e f r e q u e n c i e s of e l e c t r o p h o r e t i c polymorphisms are r e l a t e d t o demography. I w i l l now summarize the evidence from my c o n t r o l g r i d f o r such a r e l a t i o n s h i p between LAP and p o p u l a t i o n processes i n M.. townsendi^ During the study there was a p o s i t i v e c o r r e l a t i o n between numbers and LAP-F a l l e l e frequency, although t h i s was s i g n i f i c a n t only f o r the males. T h i s a s s o c i a t i o n was most ev i d e n t d u r i n g s p r i n g 1972 and. s p r i n g 1973 when numbers were dropping, and there was s e l e c t i o n i n fa v o r of the LAP-S a l l e l e . During summer 1973 a steep d e c l i n e i n numbers {-3.5% per week) was fo l l o w e d by a r a p i d i n c r e a s e (1.69? per week). Male heterozygotes s u r v i v e d very p o o r l y during both phases, both male and female FF homozygotes showed an enhanced s u r v i v a l during the i n c r e a s e , and SS homozygotes a decreased s u r v i v a l (Table 8). During summer 1971, when numbers were i n c r e a s i n g there were fewer SS homozygotes i n breeding, c o n d i t i o n i n both males and females, and a corresponding r i s e i n LAP-F frequency was e v i d e n t . So there was some evidence t h a t the d i f f e r e n t genotypes of LAP had v a r i a b l e f i t n e s s e s a s s o c i a t e d with demographic events on the c o n t r o l g r i d d u r i n g my study. 21 DISCUSSION The o v e r a l l c o n c l u s i o n must be t h a t the a l t e r e d a l l e l e f r e q u e n c i e s on the experimental g r i d s d i d not produce any c o n s i s t e n t e f f e c t s on demography. Any d i f f e r e n c e s between the genotypes on the c o n t r o l g r i d were i n g e n e r a l not r e f l e c t e d i n demographic d i f f e r e n c e s between the experimental g r i d s . The changes i n LAP-F frequency had no d i s c e r n a b l e e f f e c t on the changes i n numbers on g r i d G and g r i d H. There was an obvious p a t t e r n of changes between years i n numbers, breeding c o n d i t i o n , and body weights of v o l e s on a l l g r i d s and no g r i d d e v i a t e d p a r t i c u l a r l y from t h i s p a t t e r n . The s i g n i f i c a n t d i f f e r e n c e s t h a t I found between genotypes and g r i d s f o r demographic v a r i a b l e s d i d not a f f e c t the o v e r a l l p a t t e r n of change between years. Owing to p o s s i b l e i n t e r f e r e n c e with r e p r o d u c t i o n and s o c i a l s t r u c t u r e , the t r a n s f e r r i n g of animals throughout the study may have been a major e r r o r i n experimental des i g n . One might p o s t u l a t e that the i n t r o d u c t i o n of a l i e n FU_ townsendi onto the experimental g r i d s produced some s o c i a l d i s t u r b a n c e i n the p o p u l a t i o n s . Davis and C h r i s t i a n (1956) claimed t h a t the i n t r o d u c t i o n of animals i n t o expanding po p u l a t i o n s of r a t s would stop the i n c r e a s e , and i n t r o d u c t i o n s i n t o s t a t i o n a r y p o p u l a t i o n s would r e s u l t i n d e c l i n e s , o n g r i d H i n t h i s study, i n t r o d u c t i o n s formed 7.9% of the t o t a l p o p u l a t i o n , and t h i s l e v e l of d i s t u r b a n c e may have been a f a c t o r i n keeping p o p u l a t i o n d e n s i t i e s low. I n t r o d u c t i o n s to g r i d G formed only 1.7% of the t o t a l p o p u l a t i o n , and d e n s i t i e s were c e r t a i n l y no d i f f e r e n t from 22 those on the c o n t r o l g r i d . In g e n e r a l , few were t r a n s f e r r e d d u r i n g any one t r a p p i n g period, and whatever s o c i a l e f f e c t s were produced by the strange v o l e s would presumably have d i s s i p a t e d by the next t r a p p i n g . Terman (1962) reported that the i n t r o d u c t i o n of a l i e n Perom^yscus would i n h i b i t homing behavior i n r e s i d e n t s f o r only the f i r s t two days a f t e r i n t r o d u c t i o n . The p o p u l a t i o n t h a t the voles were r e l e a s e d i n t o appeared to have an e f f e c t on r e c r u i t m e n t of the t r a n s f e r s . Orr (1966) found t h a t removing r e s i d e n t s before r e l e a s i n g a l i e n Peronryscus r e s u l t e d i n 40% r e c r u i t m e n t of the new mice. In t h i s study, 27% of the mice t r a n s f e r r e d to g r i d G stayed u n t i l the next t r a p p i n g p e r i o d , and 59% o f those t r a n s f e r r e d to g r i d H stayed u n t i l a t l e a s t the next t r a p p i n g p e r i o d . The r e l a t i v e l y high p o p u l a t i o n d e n s i t y on g r i d G was probably r e s p o n s i b l e f o r the poor r e c r u i t m e n t of the t r a n s f e r s . The voles t r a n s f e r r e d - to g r i d H were suddenly exposed t o a l e s s crowded area and t h i s change i n t h e i r environment might account f o r the r e l a t i v e l y high r a t e of r e c r u i t m e n t . Experimental attempts a t t e s t i n g C h i t t y ' s hypothesis have i n v o l v e d the cropping of a d u l t r e s i d e n t s from popu l a t i o n s of m i c r o t i n e s (Krebs 1966, Smyth 1968). T h e i r experiments were undertaken e x p r e s s l y to have an e f f e c t on the s o c i a l processes i n the p o p u l a t i o n s . While the cropping of animals was done on a much l a r g e r s c a l e by those authors, I d i d not c o n s i d e r the p o s s i b i l i t i e s of s o c i a l d i s r u p t i o n through the removal of r e s i d e n t s i n t h i s experiment, A more i n f o r m a t i v e design would be t o a l t e r the a l l e l e f r e q u e n c i e s o n l y at the beginning o f the 23 study r a t h e r than to continue the s e l e c t i o n process throughout. As w e l l as minimizing the s o c i a l d i s t u r b a n c e , such an experiment would r e t a i n a l l genotypes on the g r i d s , one could t h e r e f o r e compare d i r e c t l y between g r i d s using t o t a l v alues f o r demographic v a r i a b l e s . The r e t u r n to o r i g i n a l a l l e l e f r e q u e n c i e s , i f i t occurred, c o u l d i n d i c a t e s p e c i f i c s e l e c t i o n p r e s s u r e s on the polymorphism. v A number of authors have shown t h a t the a l l e l e frequency of an e l e c t r o p h o r e t i c marker can determine the f i t n e s s of an i n d i v i d u a l i n a p o p u l a t i o n . Yarbrough and Kojima (1967) found the s e l e c t i v e advantage among the genotypes of an E s t e r a s e 6 l o c u s i n Droso£hila JSglanogaster cage p o p u l a t i o n s to depend upon the frequency of the a l l e l e s i n the p o p u l a t i o n . Kojima and T o b a r i (1969) found t h a t e i t h e r homozygote of an a l c o h o l dehydrogenase l o c u s i n D r o s o p h i l a melanogaster had an enhanced v i a b i l i t y i f present at a low frequency, but had reduced v i a b i l i t y i f present i n a high frequency. There were i n d i c a t i o n s i n M^, townsendi t h a t d i f f e r e n t genotypes had the r e l a t i v e advantage at d i f f e r e n t p e r i o d s , but such d i f f e r e n c e s apparently had l i t t l e e f f e c t on the demographic events of the p o p u l a t i o n s . When I began t h i s experiment, I had no evidence t h a t the l e u c i n e aminopeptidase polymorphism i n f l u e n c e d demography. Other s t u d i e s have shown that the a l l e l e f r e q u e n c i e s of e l e c t r o p h o r e t i c markers chosen e s s e n t i a l l l y a t random are c o r r e l a t e d with demographic events. B e d f i e l d (1972), from a study on c o l o n i z i n g blue grouse, found t h a t both age of h a b i t a t and the d e n s i t y of the p o p u l a t i o n were c o r r e l a t e d with the 24 frequency of the heterozygotes of an Ng l o c u s . Tamarin and Krebs (1969) found that a d e f i n a b l e ' i n c r e a s e ' genotype e x i s t e d i n both Microtus ochrogaster and M i c r c t u s i e n n s ^ l v a n i c u s ^ T h i s t r a n s f e r r i n genotype was s e l e c t e d f o r during i n c r e a s i n g and peak p e r i o d s of d e n s i t y , and s e l e c t e d a g a i n s t during the d e c l i n e . These ' i n c r e a s e ' and ' d e c l i n e ' genotypes were again d e f i n e d by Gaines (1970) f o r t r a n s f e r r i n and l e u c i n e aminopeptidase. The above s t u d i e s i n d i c a t e d t h a t a s e l e c t i v e advantage can be d e t e c t e d f o r a p a r t i c u l a r e l e c t r o p h o r e t i c genotype although the b i o c h e m i c a l b a s i s f o r the advantage i s not known. However, i n an experimental a n a l y s i s of the r e l a t i v e f i t n e s s e s of t r a n s f e r r i n genotypes i n Microtus o c h r o ^ a s t e r ^ Gaines et a l (1971) found no s i g n i f i c a n t e f f e c t of t r a n s f e r r i n genotype cn r a t e of p o p u l a t i o n i n c r e a s e , percentage of l a c t a t i n g a d u l t s , recruitment index, or s u r v i v a l r a t e o f v o l e s i n fenced e n c l o s u r e s . The r e s u l t s of my study i n d i c a t e t h a t the a l l e l e frequency of l e u c i n e aminopeptidase i n the ^ townsendi p o p u l a t i o n had no e f f e c t on the p o p u l a t i o n processes during the experiment. T h e r e f o r e , any a s s o c i a t i o n s of a l l e l e frequency and numbers were probably an e f f e c t of numbers on the polymorphism r a t h e r than the converse. The d i f f e r e n c e s I found between genotypes f o r s u r v i v a l , r e p r o d u c t i o n , and growth r a t e s i n d i c a t e that the a l l e l e frequency changes on the c o n t r o l g r i d were due to the s e l e c t i o n which maintains the polymorphism. Apparently, s e l e c t i o n does a c t on the v a r i o u s genotypes of e l e c t r o p h o r e t i c markers, yet these genotypes dc not have an a b s o l u t e f i t n e s s . Sved, Reed, and Bodmer (1966) were the f i r s t to suggest that great numbers of genetic polymorphisms i n a 25 p o p u l a t i o n would tend to obscure the optimal genotype. With some hundreds of independently s e g r e g a t i n g l o c i , there would be thousands of i n d i v i d u a l s i n a p o p u l a t i o n with e s s e n t i a l l y the same f i t n e s s . King (1967) makes the point t h a t the l o s s of f i t n e s s s u f f i c i e n t to maintain a polymorphism need not s i g n i f i c a n t l y reduce the f i t n e s s of a p o p u l a t i o n . Therefore changes i n a l l e l e frequency a t such l o c i during numerical f l u c t u a t i o n s would be determined by the degree of f a v c r a b i l i t y of the environment, and the polymorphism i t s e l f would have no e f f e c t on the demographic processes of the p o p u l a t i o n . My work with LAP was e s s e n t i a l l y a 'shot-in-the-dark» approach, although i t was a l o g i c a l next step i n i n v e s t i g a t i n g the c o r r e l a t i o n s of a l l e l e frequency with demography. In the l i g h t of t h i s study, an e x p l a n a t i o n that a l l e l e frequency change causes demographic change cannot be accepted. However, t h i s does not n e c e s s a r i l y i n d i c a t e a g e n e r a l r e l a t i o n s h i p s i n c e LAP may have been a bad c h o i c e of marker. LAP was chosen f o r the same reason that other polymorphisms have been s t u d i e d : the f a c i l i t y of t y p i n g i t i n the l a b . T h e r e f o r e , the s t u d i e s tc date which have invoked e l e c t r o p h o r e t i c polymorphisms as markers f o r demographic change c o n t a i n no i n f o r m a t i o n on g e n e t i c i n f l u e n c e s on demography. An e f f o r t must be made to determine the g e n e t i c a l b a s i s of p o p u l a t i o n processes, such as a g g r e s s i o n , which are thought to be d i r e c t l y i n v o l v e d i n numerical f l u c t u a t i o n s , b e f o r e the hypothesis t h a t g e n e t i c change i n f l u e n c e s numerical f l u c t u a t i o n s i n m i c r o t i n e s can be evaluated. 26 T a b l e 1. LAP t y p e s f o r c o l o n y c r o s s e s of M., t o w n s e n d i t e s t e d f o r c h i - s q u a r e goodness of f i t . LAP No. o f No. of C r o s s : L i t t e r s : O f f s p r i n g : SS FS FF SS x SS 40 SS x FS 11 53 51 >.98 SS x FF 3 15 0 FS x FS 6 FS x FF 11 15 20 10 >.50 22 >.90 FF x FF 34 27 Table 2. Number of t r a n s f e r r e d M. townsendi remaining cn the experimental g r i d s u n t i l at l e a s t the next t r a p p i n g s e s s i o n . T o t a l number t r a n s f e r r e d i n parentheses. To G r i d G To G r i d H Males Females Males Females Summer 1971 0 (5) 1 (3) 8 (9) 4 (8) Winter 1971-72 6 (9) 3 (4) 6 (11) 9 (10) Summer 1972 3 (16) 3 (9) 6 (16) 7 (13) Winter 1972-73 0 (2) 2 (10) 12 (17) 5 (13) Summer 1973 0 (4) 1 (<0 1 (3) 3 (3) T o t a l s 10 (30) 9 (36) 33 (56) 28 (47) 28 Table 3. Percentage maximum t r a p p a b i l i t y of tagged M.. townsendi grouped by time of year. The minimum number known to be a l i v e i n parentheses. G r i d G G r i d H G r i d I Males Females Males Females Males Females J u l y - S e p t 1971 91 88 88 96 100 97 (54) (118) (42) (68) (24) (34) Oct 71-Jan 72 82 84 93 86 85 98 (325) (430) (194) (212) (456) (508) Feb-May 1972 94 90 96 91 94 92 (322) (509) (249) (369) (408) (727) June-Sept 1972 85 83 91 84 87 81 (51 1) (630) (310) (430) (415) (702) Oct 72-Jan 73 83 91 90 88 89 86 (883) (908) (497) (512) (618) (1007) Feb-May 1973 96 95 92 95 92 93 (375) (454) (180) (283) (224) (460) Jun-July 1973 89 91 93 90 91 89 (164) (222) (94) (144) (1 18) (173) Average 87 89 92 90 91 92 29 Table 4. Mean body weight at the time o f f i r s t capture of townsendi on the c o n t r o l g r i d I. Number of vo l e s i n parentheses. Males Females Summer 1971 FF 46.00 ± 4.94 (7) 40.50 ± 6.07 (6) FS 43. 31 ± 2. 47 (26) 38.93 ± 2.15 (29) SS 47.94 ± 3.80 (17) 41.14 ± 2.87 (21) Winter 71-72 FF 37. 80 ± 5.05 (5) 38.27 + 2.11 (11) FS 42.48 + 1 .84 (42) 35.24 ± 1.00 (46) SS 42. 05 2. 53 (22) 33.04 ± 1.59 (26) Summer 1972 FF 57.69 + 1.95 (13) 41.06 ± 2.77 (17) FS 51 .15 ± 1 .42 (72) 40.28 ± 1.68 (57) SS 45. 45 ± 1.57 (64) 40.22 + 1.44 (68) Winter 72-73 FF 39.67 + 3.31 (18) 34.06 ± 2. 15 (17) FS 41. 96 ± 1.57 (52) 37.12 ± 1.07 (77) SS 39.79 + 1.71 (43) 38.72 ± 1.73 (39) Summer 1973 FF 51.00 + 4. 52 (8) 43.00 ± 6.03 (3) FS 44. 15 + 2. 36 (26) 38.00 ± 2.20 (26) SS 43.52 ± 2.71 (25) 35.83 + 2.07 (29) 3 0 Table 5. Instantaneous r a t e s of p o p u l a t i o n i n c r e a s e f o r Hi i2*£5§Sdi on a l l g r i d s expressed as percent per week. Grid G G r i d H G r i d I Summer 1971 3.5 3.0 9.6 Winter 71-72 3.2 3.2 1.5 Summer 1972 1.6 0.8 -0.6 Winter 71-72 1.2 0.2 0.6 Summer 1973 * (a) -3.6 -2.8 -3.5 (b) 2.4 3.1 1.6 * Voles were breeding during summer 1973, but a d e c l i n e i n numbers on a l l g r i d s was pronounced enough to warrant my s e p a r a t i n g the pe r i o d i n t o \" d e c l i n e \" and \" i n c r e a s e \" phases given i n (a) and (b). Table 6. Percent bi-weekly change i n LAP-F frequency f o r M. townsendi. G r i d G Grid H Grid I Summer 1971 2.24 -3.82 1.67 Winter 71-72 1.20 -0. 11 0.78 Summer 1972 0.09 0.24 -0. 10 Winter 72-73 -0.05 -0.67 0.09 Summer 1973 (a) 1 .35 1.06 1.63 (b) 0.03 -0.46 0.05 A verage* 0. 53 -0.83 0.16 Average** 0.37 -0.32 0.03 * From J u l y 1971 to J u l y 1973 ** From September 1971, when experiment began, to end. Table 7. C o r r e l a t i o n of a e n s i t y ana LAP-F freguency Ha. fowi}SS£dii. Number of sampling p e r i o d s i n parentheses. G r i d G Grid fi Gria I N r N r N r Summer 1971 Males (8) .15 (8) -.18 (6) .58 Females (8) .37 (8) -.59 (7) .42 Winter 71-72 Males (7) .23 (7) -.42 (7) .58 Females (7) .46 (7) .79* (7) .89** Summer 1972 Males (16) -.43 (16) .51* (16) -.21 Females (16) .80** (16) -. 57* (16) -.53* Winter 71-72 Males (10) -.39 (10) .00 (10) .82** Females (10) .23 (10) -.13 (10) .25 Summer 1973 Males (12) -.58* (12) -. 59* (12) .60 Females (12) -.14 (12) .32 (12) .66 T o t a l s Males (53) . 17 (53) -.64** (51) .34* Females (53) .43* (53) -.55** (52) . 25 * p < 0.05 ** p < 0.01 33 Table 8. Minimum two-week s u r v i v a l r a t e s i n M A townsendi on g r i d G. Number of v o l e s r e l e a s e d i n parentheses. Voles were breeding duri n g Summer 1973, but a d e c l i n e i n numbers was pronounced enough to warrant my s e p a r a t i n g the pe r i o d i n t o • d e c l i n e * and • i n c r e a s e ' phases g i v e n i n (a) and (b). G r i d G Males FF FS Females FF FS Summer 1971 Winter 71-72 Summer 1972 Winter 72-73 Summer 1973 (a) (b) .82 (44) .84 (106) .76 (276) .92 (366) .74 (102) .76 (112) .55** (40) .79 (117) .76 (330) .88 (400) .70 (101) .74 (147) .79 (58) .89 (118) .84 (409) .88 (370) .89 (95) .89 (82) .84 (90) .87 (176) .84 (440) . 88 (482) .86 (144) .86 (112) ** p < .01 34 Table 9. Minimum two-week s u r v i v a l r a t e s f o r M. townsendi on g r i d H. Number of v o l e s r e l e a s e d i n parentheses. Voles were breeding during summer 1973, but a d e c l i n e i n numbers on a l l g r i d s was pronounced enough-to warrant my s e p a r a t i n g the p e r i o d i n t o ' d e c l i n e ' and ' i n c r e a s e phases given i n (a) and (b). G r i d H Males Females SS FS SS FS Summer 1971 .71 .59** .70 .70 (14) (29) (23) (30) Winter 71-72 .84 .85 .82 .90 (50) (52) (61) (71) Summer 1972 .65 .71 .85 .86 (199) (174) (331) (201) Winter 72-73 .87 .85 .90 .86 (233) ( 169) (250) (161) Summer 1973 (a) .47 .79** .84 . 84 (32) (48) (79) (67) (b) .75 .62 .82 . 78 (28) (56) (82) (60) ** p < .01 35 Table 10. Minimum two-week s u r v i v a l r a t e s f o r M.. townsendi on c o n t r o l g r i d I. Number of voles r e l e a s e d i n parentheses. Voles were breeding d u r i n g summer 1973, but a d e c l i n e i n numbers on a l l g r i d s was pronounced enough t o warrant my s e p a r a t i n g the p e r i o d i n t o • d e c l i n e * and 'i n c r e a s e phases given i n (a) and (b). G r i d I Males Females FF FS SS FF FS SS Summer 1971 Winter 71-72 .85 .89 .85 (13) (53) (39) • 86 • 88 • 88 (35) (213) (116) .78 .94 .89 (9) (65) (76) .94 .92 .88 (49) (242) (162) Summer 1972 Winter 72-73 Summer 1973 (a) (b) .72 .72 .76 .80 .86 .84 (47) (339) (287) (107) (564) (475) .80 .83 .86 .87 .86 .88 (88) (259) (241 ) (111) (485) (343) .87 .67 .84 .66 .78 .88* (14) (4U) (62) (22) (138) (98) .91 .53 .76** .90 .80 .82 (24) (38) (63) (10) (94) (95) ** p < .01 36 Table 11. Percentage of a d u l t |L townsendi males with s c r o t a l t e s t e s on g r i d G. T o t a l number of a d u l t males i n parentheses. G r i d G FF FS T o t a l s Summer 1971 Winter 71-72 Summer 1972 Summer 1973 97 N (31) 53 N (79) 72 N (260) Winter 72-73 13 N (263) 84 N (212) 97 (30) 48 (87) 77 (299) 16 (254) 74* (142) 97 (61) 49 (166) 75 (559) 15 (517) 80 (354) * p < .05 37 Table 12. Percentage of a d u l t H A townsendi males with s c r o t a l t e s t e s on g r i d H. T o t a l number of a d u l t males i n parentheses. G r i d H SS FS T o t a l s Summer 1971 95 89 92 N (21) (18) (39) Winter 71-72 55 65 59 N (62) (46) (112) Summer 1972 82 80 80 H (212) (154) (366) Winter 72-73 16 29* 21 N (169) (97) (266) Summer 1973 75 84 80 N (76) (98) (174) * P < :05 38 Table 13. Percentage of ad u l t townsendi males with s c r o t a l t e s t e s on c o n t r o l g r i d I. T o t a l number of a d u l t males i n parentheses. G r i d I FF FS SS TotaIs Summer 1971 100 94 69** 84 .\"N (10) (32) (32) (74) Winter 71-72 26 46 51 45 N (30) (160) (84) (278) Summer 1972 87 83 77 81 U (46) (313) (255) (614) Winter 72-73 17 10 9 11 S (53) (146) (150) (349) Summer 1973 88 74 78 79 N (44) (77) (122) (243) ** p < .01 39 Table 14. Percentage of a d u l t H._ townsendi females l a c t a t i n g on g r i d G. T o t a l number of ad u l t females i n parentheses. G r i d G FF FS T o t a l s Summer 1971 42 N (43) Winter 71-72 Summer 1972 Winter 72-73 Summer 1973 27 8 (88) 25 N (346) 6 H (176) 38 N (187) 47 (76) 41 (69) 39** (338) 9 (221) 43 (184) 45 (119) 33 (157) 32 (684) 8 (397) 40 (371) ** p < .0 1 40 Table 15. Percentage of a d u l t EL townsendi females l a c t a t i n g on g r i d H. T o t a l number of a d u l t females i n parentheses. G r i d H SS , FS T o t a l s Summer 1971 15 36 22 N (27) (14) (41) Winter 71-72 17 28 21 N (54) (39) (93) Summer 1972 40 38 39 N (365) (181 ) (546) Winter 72-73 7 6 7 N (161) (80) (241) Summer 1973 36 32 34 N (140) (93) (233) 41 Table 16. Percentage of a d u l t M A townsendi females l a c t a t i n g on c o n t r o l g r i d I. T o t a l number of a d u l t females i n parentheses. G r i d I FF FS SS T c t a I s Summer 1971 75 H (4) 48 (48) 27** (59) 38 (111) Winter 71-72 H (24) 21 (112) 20 (101) 19 (237) Summer 1972 35 H (85) 34 (470) 32 (387) 33 (942) Winter 72-73 6 (32) 5 (182) 5 (151) 5 (365) Summer 1973 33 (21) 33 (132) 39 (139) 36 (292) ** p < .01 42 Table 17. Mean body weight of male Mj_ townsendi on g r i d G f o r each season. T o t a l number of males i n parentheses. G r i d G FF FS Summer 1971 49.14 ± 1.72 53.64 + 1.82 (42) (36) Winter 1971-72 49.34 ± 1.17 51.76 ± 1.26 (122) (117) Summer 1972 54.62 ± 0.68 55.85 ± 0.56 (315) (333) Winter 1972-73 48.01 + 0.48 47.15 ± 0.55 (375) (400) Summer 1973 55.02 ± 0.71 53.45 ± 0.77 (245) (168) 43 Table 18. Mean body weight of male M._ townsendi on g r i d H f o r each season. T o t a l number of males i n parentheses. G r i d H FS SS Summer 1971 50.31 ± 2.05 50.96 ± 2.43 (26) (26) Winter 1971-72 54.55 ± 1.74 48.29 ± 1.31 (55) (103) Summer 1972 56.07 ± 0.74 52.44 ± 0.82 (175) (281) Winter 1972-73 45.71 ± 0.99 44.50 ± 0.61 (170) (296) Summer 1973 52.29 ± 1.04 50.06 ± 1.14 (117) (99) i 44 Table 19. Mean body weight of male M_. townsendi cn g r i d I f o r each season. Number of males i n parentheses. G r i d I FF FS SS Summer 1971 47.29 ± 2.58 47.96 ± 1.59 52.23 ± 2.05 (14) (54) (39) Winter 1971-72 52.48 ± 2.06 50.71 ± 0.74 52.03 ± 1.17 (35) (213) (116) Summer 1972 64.13 ± 1.11 60.79 ± 0.58 55.75 ± 0.66 (47) (339) (289) Winter 1972-73 46.06 ± 1.24 44.28 ± 0.60 45.28 ± 0.63 (88) (254) (244) Summer 1973 60.85 ± 1.46 55.41 ± 1.22 55.44 ± 0.98 (46) (93) (142) 45 Table 20. Average growth r a t e s {% per day) adjusted by r e g r e s s i o n to a standard 35 g v o l e , of M A tojjnsendi males on g r i d G. Sample s i z e i n parentheses. G r i d G FF FS Summer 1971 1.87 ± .21 1.20 ± 34 (31) (19) Winter 71-72 0.64 ± .11 0.84 + .13 (94) (91) Summer 1972 1.08 ± .12 1.09 ± .15 (213) (240) Winter 72-73 0.25 ± .08 0.22 ± .06 (334) (349) Summer 1973 0.51 ± .13 0.85 ± .16 (160) (106) 46 Table 21. Average growth r a t e s (f per day) ad j u s t e d by r e g r e s s i o n to a standard 35 g v o l e , of H._ townsendi males on g r i d H. Sample s i z e i n parentheses. G r i d H FS SS Summer 1971 0.75 ± .35 1.19 ± .36 (17) (13) Winter 71-72 0.76 + .18 0.79 ± .12 (82) (43) Summer 1972 0.56 ± .16 1.70 + .11 (181) (123) Winter 72-73 0.41 ± .09 0.31 ± .08 (249) (141) Summer 1973 1.30 ± .22 1.65 ± .23 (55) (71) d_ ; 47 Table 22. average growth r a t e s (% per day) adjusted by r e g r e s s i o n to a standard 35 g v o l e , of M._ townsendi males on c o n t r o l g r i d I. Sample s i z e i n parentheses. G r i d I FF FS SS Summer 1971 0.84 ± .34 1.25 ± .19 1.64 ± .21 (1 1) (42) (32) Winter 71-72 0.75 ± .21 0.66 ± .09 0.71 ± .10 (30) (178) (99) Summer 1972 0.41 + .40 0.54 + .10 1.29 ± .12 (34) (241) (213) Winter 72-73 0.19 ± .13 0.18 ± .08 0.29 ± .07 (68) (210) (202) Summer 1973 0.79 ± .40 1.59 ± .30 1.32 ± .19 (34) (49) (99) 4 8 F i g u r e 1. Westham I s l a n d r e c e i v i n g s t a t i o n : l o c a t i o n of study g r i d s . The c e n t r a l g r i d , I , was the c o n t r o l . Homozygous FF v o l e s were removed from g r i d H and t r a n s f e r r e d to g r i d G, and homozygous SS v o l e s were moved i n the opposite d i r e c t i o n . H :^I-AV\"1V^ /I:/-'''I->W-\"'!'\" -'. 1 I . ' N i ' V. / ' - ' I ix r „ \\ , • _' -O ' station farmland 1 cm = 1 2 5 ft 00 4 9 F i g u r e 2. S t a r c h g e l showing LAP s t a i n i n g p a t t e r n i n M i c r o t u s townsendi serum. 49a • 5 0 F i g u r e 3 . P o p u l a t i o n d e n s i t y of K i c r o t u s townsendi on g r i d G. 3 \" .3 3 E oj CD — CO CD . CO • MINIMUM NO. ALIVE < m > DO 51 F i g u r e 4. P o p u l a t i o n d e n s i t y of Microtus townsendi on g r i d H. ® 3 3 » 03 CD — CO 0 CO • MINIMUM NO. A L I V E -< m > 33 F i g u r e 5. P o p u l a t i o n d e n s i t y of H i c r o t u s townsendi on g r i d LU > < o males D females 2 5 Of 100f 5 0 1 2 5 f 10 .. H:::::: n . \\ / • \\ /::H: m :::: / a . : . : . • • : : : : / • a • • a-•... : o : a , j 1 : 1 r; \\ B' . \\ / c • • • • • „ Sept Dec Mar Jun Sept Dec 1971 1972 YEAR Mar Jun 1973 53 F i g u r e 6. A l l e l e frequency of F on g r i d G, from which a l l SS v o l e s were removed. — H CD 3 3 oj 0) CD CO L A P - F CD CO • • o . ai L A P _ F A L L E L E F R E Q U E N C Y O L 54 F i g u r e 7. A l l e l e frequency of F on g r i d H, from which a l l FF v o l e s were removed. > o z LU =) O LU CC LL LU _J LU LL I Q_ < .751 o • o .50 h .25 m a l e s f e m a les o o o o \\ MM** o °o° °° o o o o o o O' o / .... n«¥rT . . . . o o : : : : Q : . < r > a . . 0 . . . Sept Dec Mar Jun Sept Dec 19 71 1972 YEAR Mar Jun 1973 F i g u r e 8 . A l l e l e frequency of F on g r i d I, the c o n t r o l g r i d . Bgc 56 F i g u r e 9. Histogram of mean bi-weekly s u r v i v a l r a t e s of male Mic r o t u s townsendi during the three summers. ** p < .01 * p < .05 56a < > > rx 100-90 -80 -70 60- n G S U M M E R 1971 F S F F H G S S * < > > cn Z) if) 100] 90] 80-70 6 0 F S S U M M E R 1972 F F G I H G I S S H I < > > DC z> CO 100^ 90-80-6 0 i S U M M E R 1 9 7 3 F S F F S S G I H G I H I 57 F i g u r e 10. Histogram of mean bi-weekly s u r v i v a l r a t e s of female Microtus townsendi during the three summers. ** p < .01 5 7 a < > > DC co 100 90 80 70 60 S U M M E R 1971 F F G I H G I S S H _1 100 • < 90-> > 80-DC 70-CO •\\* 60-_ l 100\" < > go-> so\"-DC Z) 70-CO 60-S U M M E R 1972 F S F F S S G l H G I S U M M E R F S F F H I 1973 S S G I H G H I 5 8 F i g u r e 11. Histogram of body weight d i s t r i b u t i o n s of male Microtus townsendi oh g r i d G. 58a CL i r r r m T h O \" r-v-n r->-^ ~i „n m • r-r-i <-n ( I—i i f i i _JD n rm n i-i - n — rr-r-n -» n r-C - 3 03 CO CD JT~lnir-iM O Q a CO r-m-n ,m-n-m. n-. J~Lrtn X L m:n-i: -in,. XfcLi (^•^^•••••nnH •—' rVn - . •-. i~i' i-i PI r-i r-i c 03 n n n n XL. XI *-» n r-r-i C - n m r h n • O CD Q a CO - f — o CO - 4 -o CD + — f -o -+— o CM I S- < CD •IAI0 uj -IAA 59 F i g u r e 12. Histogram of body weight d i s t r i b u t i o n s of male Microtus townsendi on g r i d H. 59a n — -J 3 = - n r - f l r f T H - i n-TTh-n r f T h - r h n-v— CD c ZD t CC o CD Q CO CD n i T*\\ 11 -a- a co n rHtM-^n iin — i . r m J T h r-i n~t-3_ r - n - i - i c 03 C\\J DC < L U >-• f U T T . •irri-n O n r f t ^ ^ • - 1 • IT\"! - i i ifT-\"^\"!\"**--- i i •fTi—n- :rvjh'f-i \" ^ i r i : : : IA n. H : '/-jfT-TTTH-wJ JlW-itii o CD a r-m a n r~i H I 1 -I o CO. —f— o CD — f -O — I — o CM CL CD CO CD •IAI0 U| » 1 M 60 F i g u r e 13. Histogram of body weight d i s t r i b u t i o n s of male Microtus townsendi on g r i d I . 6 0 a r~r-r-T-(~n~l r W h fTr-i — X L r r U T T -- n r f f l o_ r - r r - t -^rw. rT-t-rn-. i •JTlTili 11 iiih •rtTTT-rfTJi-. TTTrviraa^: X L rrf-r-TVfTTr-t • rt~i I H - —(~1 __TJL -n-rTVi- J 11 n Q_ r-f~0~>-i f-i-i rnJ\"h m. 1 llnl I I I i n d I I PI I - n r-i r-n-i —f— o CO O CD — r -O C D 03 O CD Q CL CD CO c Z3 03 O CD Q a CD CO o CM CO CD CM DC < LU >-•l/MO u ! 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Ecology 43:216-223 Ts u y a k i , H. , E. Roberts, R. H. Kerr, and A. P. Ronald. 1966 j o u r n a l of f i s h . Res. Board of can. Micro s t a r c h g e l e l e c t r o p h o r e s i s . 23 (6) 929-933. Yarbrough, K. M. And K. I. Kojima. 1967. The mode of s e l e c t i o n a t the polymorphic esterase-6 l o c u s i n cage popu l a t i o n s of 2£5§2£iiilS 1122^2ter_j_ G e n e t i c s 57:677-686 "@en ; edm:hasType "Thesis/Dissertation"@en ; edm:isShownAt "10.14288/1.0093052"@en ; dcterms:language "eng"@en ; ns0:degreeDiscipline "Zoology"@en ; edm:provider "Vancouver : University of British Columbia Library"@en ; dcterms:publisher "University of British Columbia"@en ; dcterms:rights "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en ; ns0:scholarLevel "Graduate"@en ; dcterms:title "Demographic consequences of artificial selection at the LAP locus in voles Microtus townsendi"@en ; dcterms:type "Text"@en ; ns0:identifierURI "http://hdl.handle.net/2429/18877"@en .