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Geographical variation in wolves (Canis lupis L.) of northwestern North America Jolicoeur, Pierre 1958

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GEOGRAPHICAL VARIATION IN WOLVES (Canis lupus L. OF NORTHWESTERN NORTH AMERICA by PIERRE JOLICOEUR B.A., Uniyersite de MDntreal, 1953 B.Sc, Universite' de Montreal, 1956  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n the Department of ZOOLOGY  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1958  i  ABSTRACT Five hundred wolf specimens were studied. They represent populations from Alaska to Keewatin and from Vancouver Island to Manitoba. Pelage color varies nearly from black to white. There are no discrete color phases. Pale wolves are more numerous and dark wolves less numerous toward the tundra (northeastward) between Great Slave Lake and Great Bear Lake. Judging from color variation, wolf populations intermingle by associating with caribou at migration. Male wolves are larger than females (approximately K$> i n linear s k u l l dimensions). Northeastern individuals have a shorter and r e l a t i v e l y broader s k u l l than southwestern ones. Multivariate divergence i n twelve s k u l l dimensions i s approximately proportional to geographical separation. This may express genetic differentiation "by incomplete i s o l a t i o n . But the pronounced northeastward zonation of the environment may have direct influences upon growth processes. Interpretations i n terms of genetic a f f i n i t i e s are hypothetical and taxonomic conclusions are postponed. Simultaneous analysis of biometrical data appears indispensable to disclose major trends of geographic variation.  In p r e s e n t i n g the  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  r e q u i r e m e n t s f o r an advanced degree at the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t freely  a v a i l a b l e f o r r e f e r e n c e and  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 f o r s c h o l a r l y purposes' may  study.  I further  copying of t h i s  be g r a n t e d by the Head o f  Department o r by h i s r e p r e s e n t a t i v e .  Department  be a l l o w e d w i t h o u t my w r i t t e n  of  The U n i v e r s i t y o f B r i t i s h Columbia, Vancouver^S, Canada.  my  I t i s understood  t h a t c o p y i n g or 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 g a i n s h a l l not  thesis  financial  permission.  ii TABLE OF CONTENTS Text Abstract Table of contents  i .  i i  Introduction  1  Material and data  3  Techniques of analysis  ........  8  Variation i n pelage coloration  10  Variation i n s k u l l size and form : bivariate analysis  13  Variation i n s k u l l dimensions : multivariate analysis  18  Interpretations and conclusions  28  .......  References  . ..  • 32  Figures Fig. 1 Geographical o r i g i n of the samples  h  Fig. 2 Skull dimensions and coded designations  7  Fig. 3 Relative; frequency of pale wolves Fig. h Variation i n overall s k u l l size and proportions  11 ......  lU  Fig. 5 Variation i n a r e l a t i v e growth rate  16  Fig. 6 Interbullar breadth and upper carnassial length  17  Fig. 7 K 1 : K 2 multivariate configuration  23  Fig. 8 K 1 : K 2 biometrical overlapping  2k  Fig» 9 K 3 : K h multivariate configuration  25  Tables Table 1 Sample sizes and sex-compositions  k  Table 2 Discriminant functions  20  Table 3 Group means i n discriminant analysis . . . . ,  21  1 INIRCDUCTION Bie l a s t comprehensive taxonomic study of North American wolves (Canis lupus L.) was that of Goldman (Young and Goldman, 19kk). I t consisted largely of qualitative s k u l l and pelage descriptions and such procedures f a i l e d to show clearly geographic variation i n the species as a whole. Large collections of wolves have been made during recent control operations i n northwestern Canada by the Canadian W i l d l i f e Service and the Manitoba Game Department. Qhis material has been deposited i n the Museum of Zoology of the University of B r i t i s h Columbia. I t forms the main object of the present study. Comparisons were made with B r i t i s h Columbia, Alaska and High Arctic material, some of which was borrowed from the B r i t i s h Columbia Provincial Museum, the National Museum of Canada and Dr. R. Rausch, Anchorage, Alaska. Much of the limitations of previous studies appears to be due to i n e f f i c i e n t methods of analysis. Finding optimum biometrical techniques has therefore been a major aim of t h i s investigation. Hie author worked under the guidance of Dr. I. McT. Cowan, Department of Zoology, University of B r i t i s h Columbia. F i e l d aspects of the problem were discussed with several members of the Canadian Wildlife Service. Dr. S. W. Nash, Department of Mathematics, gave numerous explanations on multivariate analysis. Help i n mathematics was received from Marcel Banville, Dept. of Ehysics, W. R. Knight and Bomshik Chang, Dept. of Mathematics and many others. Most calculations were done a t the Computing Centre,  2  with much assistance from the personnel. The author i s indebted to Dr. I. McT. Cowan for a c r i t i c a l reading of the manuscript and to other members of the Department of Zoology for advice on i l l u s t r a t i o n s . Discussions with fellow graduate students lead to c l a r i f i c a t i o n of several ideas. Financial support came from the Wildlife Conservation Fund of the Canadian Industries Limited. A l l of this i s gratefully acknowledged.  •3 MATERIAL and DATA Specimens vere grouped by l o c a l i t i e s of o r i g i n ( f i g . l ) . The number of specimens a t hand and t h e i r most obvious characteristics were considered i n delimiting the groups. Sample size and sex composition were taken into account throughout the analysis (table l ) . There was only half a dozen juvenile specimens (estimated younger than six months) and they were excluded. Only four areas are represented by large samples : B r i t i s h Columbia (group K), Manitoba ( I ), and the Northwest Territories between Great Slave Lake and Great Bear Lake ( groups D, E and G). Two arrows have been lined up on these large samples i n the map ( f i g . l ) and i n some subsequent graphs. They point approximately northeastward and northwestward and help to refer biometrical differences to t h e i r geographical context. Skulls were available for most specimens while there were pelage and body data f o r only part of the collection. The analysis of geographic variation was therefore based primarily on s k u l l dimensions. Photographic transparencies of the carcasses were available for four samples of the Northwest Territories and the frequencies of types of pelage coloration were compared. Twelve s k u l l dimensions were measured. They were chosen for their descriptive value and f o r the ease with which they could be measured consistently. They are refered to by coded designations ( L i , Wi, Ci and Ti ) and defined as follows :  If  Figure 1 : Geographical o r i g i n of the samples.  Sable 1 : Sample sizes and sex-compositions. Locality High Arctic Alaska Keewatin Northwest territories Manitoba Vancouver Island Interior B. C. Rocky Mountains  group A B C D E F G .H I J K L  males  females  11 3 •5  8 3 3 39  Ul  hi  12 33  -  73 5 15 6  undetermined  19 9  . _  •  3 6  lk  -  1+0.  8 33 -  5 12 . 3  -  •  9  -  18  total  '  • 80 81 20 66 9 137 10 ^5 • 9 H99  5  ( L i ) : MEASUREMENTS OF LENGTH ( L 1 ) : Condylobasal length : Distance from the anterior t i p of the premaxillae to the plane of the posterior border of the o c c i p i t a l condyles. ( L 2 ) : Palatal length : Distance from the alveolus of the median upper incisor on one side to the notch of the posterior. edge of the palatal shelf on the same side. ( L 3 ) : Post-palatal length : Distance from the notch of the posterior edge of the palatal shelf on one side to the posterior face of the ventral l i p of the foramen magnum on the median l i n e .  ( ¥ i ) : MEASUREMENTS OF WIDTH ( W 1 ) : Zygomatic width : Greatest distance across the zygomatic arches. ( W 2 ) : Palatal width at M 1 : Greatest distance between the outer edges of the a l v e o l i of the f i r s t upper molars. ( W 3 ) : Palatal width at Pm 2 : Least distance between the inner edges of the a l v e o l i of the second upper premolars. ( W h ) : Interglenoid width : Least distance between the postglenoid foramina. ( W 5 ) : Interorbital width : Least distance across the frontal bones between the orbits.  6 ( C i ) : MEASUREMENTS EXPRESSING BRAINCASE DEVELOPMENT ( C 1 ) : Least width of the cranium : Least distance across the frontal hones behind the postorbital processes. ( C 2 ) : Interbullar "breadth : Distance between the auditory bullae where they angle with the b a s i o c c i p i t a l bone. ( T i ) : TOOTH MEASUREMENTS ( T 1 ) : Length of the upper carnassial : Distance from the anterior surface of the upper carnassial to i t s posterior surface at the l e v e l of emergence from the alveolus. ( T 2 ) : Length of the f i r s t upper molar : Greatest distance from the anterior surface of the f i r s t upper molar to i t s posterior surface at the l e v e l of the crown and i n the axis of the two outer cusps.  These twelve s k u l l measurements are i l l u s t r a t e d i n figure number two.  7  Figure 2 : Skull dimensions measured and coded designations.  8  TECHNIQUES OF ANALYSIS In the physico-chemical sciences variation arises mostly from errors of measurements. Biological variation on the other hand results largely from objective factors. In b i o l o g i c a l s t a t i s t i c s therefore, describing variation concisely i s more important than assessing the probability that sets of observations f i t a single hypothesis. Associating biometrical data between themselves and/or with age data i s generally necessary to bring out t h e i r f u l l meaning. In the analysis of animal form large use has been made of arbitrary age estimates and of ratios of dimensions. Age estimates of wild mammals are generally f a r less precise than bone measurements except for a few species exhibiting "growth-rings" or other definite c r i t e r i a of age. Ratios express a proportion by a single figure but they dissociate form from size and they are i n e f f i c i e n t for more than two dimensions. Bivariate scatter diagrams or t h e i r multivariate version (Anderson, 195*0 are the best simple a n a l y t i c a l t o o l . However multiassociated data usually y i e l d more information through multivariate analysis (Hotelling, 1954; Quenouille, 1952; Yates, 1950). The l a t t e r takes into account a l l intercorrelations of the variables. Animal form can thus be analysed without age estimates save f o r a broad preliminary c l a s s i f i c a t i o n of the material. Multivariate techniques permit the analyst to express information with maximum conciseness. Most recent applications have unfortunately featured too abstract  a presentation. Expressing the results of a study i n terms of the original variables i s preferable i n practise. Multivariate analysis i s now within the reach of biologists thanks to Murdoch's excellent introduction (1957) to linear algebra and analytic geometry.  10  VARIATION IN PELAGE COLORATION Pelage coloration of wolves i s highly variable i n intensity, i n hue and i n pattern. There are no obviously discrete color phases as i n some polymorphic species. Detailed verbal descriptions are clearly unsuitable for large samples. The photographic transparencies examined for pelage coloration were classified into four arbitrary types according to the general darkness of pigmentation : dark, darkish, whitish and white. Such arbitrary types do not correspond i n the wolf to actually discrete color phases. Such a classification i s also only approximate and f i t s adequately only the present material. It does disclose however a gradual change i n color-type frequencies analogous to the clines i n color-phase frequencies of the red fox and the black bear (Cowan, 1938). The relative frequency of pale wolves increases i n a northeastward direction (toward the tundra) between Great Slave Lake and Great Bear Lake i n the Northwest Territories (fig. 3)» There are gradually more white and whitish and fewer dark and darkish individuals i n samples F, D, E, and G successively. Samples D and E differ l i t t l e from each other but differ significantly from the two extreme samples (95$ chi squared). Recent barren-ground caribou studies (Banfield, 195^J Kelsall, 1957) have shown caribou to migrate more through areas D and E than through areas F and G.Differences of pelage coloration between wolf populations appear therefore to be inversely proportional to the local importance of caribou migrations. But wolves are often observed  34 1  Great Bear Lake  fTTTTTS  45 10 niiiinii  17 43  12 i  8 » Great Slave Lake North  5  7  dark darkish Absolute  6  : 11111 • 1111  white whitish frequencies  West  East  South  Geographical  localities  Figure 3 Northeastward increase i n the r e l a t i v e frequency o f pale wolves between Great Slave Lake and Great Bear Lake ( toward the tundra ) . :  12  with caribou herds (Banfield, 1951)* This suggests that wolf populations intermingle by associating with caribou a t migration. A r e l a t i v e l y higher frequency of dark individuals has been reported for the Rocky Mountains (Cowan, 19^7)• The shortdistance cline exhibited by the present material may therefore be part of a long-distance cline going a t least from the Rockies to the Northwest Territories. More data on the pelage coloration of wolves may eventually show analogy with the pattern of geographical variation of color-phase frequencies of the red fox and the black bear (Cowan, 1938j Butler, 19^7).  13  VARIATION IN SKULL SIZE AND FORM : BIVARIATE ANALYSIS Overall s k u l l size can be s a t i s f a c t o r i l y described by condylobasal length (L l ) and zygomatic width (W l ) . Bivariate dot diagrams of these two dimensions were made and 9 5 $ equal-frequency ellipses were calculated following the procedure discussed by Defrise-Gussenhoven  (1955)*  Figure h summarizes the most important information : males reach a s k u l l size approximately b$> greater than females (in linear dimensions). This agrees with Hildebrand's  (1952)  conclusions regarding the body size of Canidae. Other facts brought out are the lesser maximum s k u l l size (they are closer to the l e f t lower corner of the graph) and the greater relative breadth (they are closer to the l e f t upper corner of the graph) of northeastern wolves. Groups L, • I, D + E + G, and A are successively closer to the l e f t side of the graph. This ordering of samples according to s k u l l size and relative breadth i s s t r i k i n g l y similar to the ordering of the l o c a l i t i e s of geographical o r i g i n projected upon a l i n e of northeastward direction. Such gradual geographic variation was termed "clines" by Huxley  (1938).  The same shortness and greater relative breadth of s k u l l of northeastern wolves shows i n a scatter diagram (figure 5 ) of interglenoid width (\l k) on post-palatal length (L 3 ) . The skulls of wolves from the Northwest Territories ( G ) are shorter and broader than those of wolves from B r i t i s h Columbia ( K ) with respect to these two dimensions. But here the difference of proportion increases with size. This i s a difference of relative growth rate.  mm.  220  230  240  250  260  L|  Figure h : Sexual and geographic variation i n overall s k u l l size and proportions as i l l u s t r a t e d by condylobasal length (L 1) and zygomatic width (W l)  Equal-frequency ellipses f i t the data s a t i s f a c t o r i l y ; there i s no obvious trend curvature and no need f o r a logarithmic transformation. Rates of relative growth are of considerable b i o l o g i c a l interest (Huxley, 1932) and a multivariate analysis of growth i n wolf skulls i s planned f o r the near future. A t h i r d bivariate association shows geographical variation (figure 6) : interbullar breadth ( C 2 ) against carnassial length ( T 1 ). The wolves from Manitoba ( I ) and the Northwest Territories ( D + E ) are a t the center of this graph and constitute the average. The wolves from B r i t i s h Columbia ( K ) have a shorter carnassial than the average and those from Vancouver Island ( J ) a narrower interbullar space. Simple examination of the skulls confirms what the graphical analysis summarizes. Distinct spaces show i n between the small teeth of B r i t i s h Columbia wolves and the ten Vancouver Island specimens have markedly "inflated" bullae with a narrow interval. Surprisingly i n t h i s graph the Vancouver Island wolves d i f f e r the most from those to which they are the closest geographically. Further discussion of this w i l l follow the j o i n t multivariate analysis of a l l twelve s k u l l dimensions.  Figure 5 : Geographical variation i n a relative growth rate. Interglenoid width (W h) against post-palatal length (L 3).  Figure 6 : Geographical variation i n interbullar breadth (C 2) and upper carnassial length (T l ) .  £j  18 VARIATION IN SKULL DIMENSIONS : MULTIVARIATE ANALYSIS Several multivariate techniques are available for j o i n t biometrical variation. Some lead to o v e r a l l estimates of betweensample differences ("distance functions"); others lead to combinations of measurements revealing the pattern of divergence or "configuration" of groups ("discriminant functions"). Distance functions express variation as a whole. Discriminant  functions  disclose the p r i n c i p a l components of variation underlying the .intercorrelations of the variables. Discriminant analysis was carried on here following Rao's (1952 :370-378) procedure. Sexual s k u l l differences having shown to be mostly size differences ( f i g . h), sexes were kept together to emphasize geographical variation i n s k u l l proportions. The withingroup product matrix W, generated by the individuals around t h e i r group means, came from the U09 specimens of the four largest samples (K, G, D + E, and I ). The between-group product matrix B, generated by the group means around the grand mean came from eleven geographical groups t o t a l l i n g U99 specimens. The B and W matrices were therefore divided by ^99 and k09 respectively^efore calculation of the discriminant functions. Inspecting the means of the twelve s k u l l dimensions i n the eleven geographical groups (table 3) permits a rapid check upon the r e a l i t y of the trends of j o i n t variation disclosed by discriminant functions. Tabulating other s t a t i s t i c s or the o r i g i n a l data would consume too much space without making anything e x p l i c i t . Discriminant functions K (also c a l l e d characteristic,  19 canonical, latent or eigen-vectors) and their variance components D (characteristic roots or eigen-values) are defined by the following matrix equation : KB = DKW . They were calculated on an electronic d i g i t a l computer by matrix operations (Murdoch, 1957 :l65-l66) corresponding to the transformations suggested by Rao (1952 :357>367). Matrices were diagonalized following Jacobi's method. The within-group variances and covariances of the discriminant functions checked ( KWK' = I ) to two or three significant d i g i t s , which i s acceptable. A l l of these mathematical manipulations correspond to the analysis of between-group variation taking within-group variation as a unit of measurement. This standardization should minimize the effects of differences i n age-composition of the samples. A l l components of standardized between-group variation add up to  I.5U6U . The f i r s t five add up to  1.4533 and account  for 9*$ of the t o t a l . Tb each of these f i v e components correspond twelve coefficients for the o r i g i n a l variables i n the discriminant functions (table 2)« She s t a t i s t i c a l significance of these variance components was tested as prescribed by Rao (1952 :372) for large samples taking k09 as t o t a l number of observations. The probability of such large components under a n u l l hypothesis i s less than 1$ for the f i r s t four and less than 5$ for the f i f t h . She configuration of groups i n the two f i r s t discriminant functions, (figure 7) i s recognizably similar to the disposition of the l o c a l i t i e s of origin on a geographical map. Northern samples congregate i n the- l e f t upper corner of the graph, eastern samples i n the  Table 2 : Discriminant functions. Variance components and coefficients of the s k u l l dimensions. Function  K 1  K2  K 3  Kl+  K5  variance component.  .80kQ  .2761  .181+6  .1221  .0657  $ of t o t a l variance  52$  18$  12$  8$  1+$  L 1  -.1557  .06^5  .231+5  .0728  L 2  -.0198  -.161+0  -.31+80  -.0302  .37^  L 3  -.0097  .0755  -.2077  -.11+02  .1201+  ¥ 1  .0538  -.0^98  -.0786  -.0137  -.I65O  Coefficients of  W2  .0172  -.01+1+2  -.1125  -.0182  -.0332  the s k u l l  W3  -.0080  -.0080  .6301  .3135  .01+72  dimensions  Wk  .2271  .0993  .01+28  -.1227  .11*59  W5  .1712  -.11+20  .0910  -.1803  .1783  C 1  -.1261  .001+1+  -.0952  .1221  '-.0366  C2  -.1970  .132^  .0908  -.271+1  -.1258  T 1  .5036  .7033  -.2729  .1+297  .2522  T2  .1781*  -.31+66  .3857  -.1+070  .181+8  -.1623  Table 3 : Group means of the s k u l l dimensions i n discriminant analysis. GROUP N  L 1  L 2  A  19 231.63 113.84  B  9 245.67 i 2 3 . l l  C  14  234.14 U6.79  D+E 161 234.73 117.30  L 3 98.84  W1  W5  c 1  C2  T1  T2  45.44 40.08 19.20 25.77 17.54 24.40 17.70  98.50 135.29 78.72 33.67 64.01 45.71 40.52 18.70 24.50 17.33 98.49 138.56 78.37 33.58 63.78 46.37 41.28 18.45  G  66  79.63 33.79 65.07 45.64  41.64  99.00 137.76 78.13 33.18 64.05 46.08 41.03  9 243.33 120.89 102.89 140.22 79.59 34.39 64.34 137 237.20 117.75  J  10 236.30 119.60  K  45 240.18 119.36 101.40  23.99 17.28  19.67 25.13 17.42 18.59 24.42  46.27 40.49 20.54  99.88 136.52 78.63 34.01 63.82 45.11 41.15  I  L  W4  102.22 140.45 81.33 35.36 65.65 46.86 43.06 19.46  20 242.15 119.55 103.15 140.75  H  W3  139-37 80.32 32.90 65.84  F  235.98 118.35  W2  17.36  23.91 17.19  19.03 24.61 17.34  98.30 136.70 77.73 31.85 61.15 44.13 41.94 17.03 24.82 16.70 135.27 76.92 32.97 62.49 44.07 42.16 19.50 23.28 16.80  9 251.00 123.45 106.33 139.67 79.91 32.73 66.10 47.51 42.61 22.23 25.23 17.76  right upper corner and inversely for southern and western samples. The two arrows of northeastward and northwestward directions correspond to those of the map ( f i g . l ) and help to evaluate the s i m i l a r i t y of the pattern of biometrical divergence with the pattern of geographical origin. Discrepancies come mostly from small samples. The major one i s the respective position of Alaska ( B ) and Vancouver Island ( J ) wolves. But the group configuration of the t h i r d and fourth discriminant functions (figure 9) compensates largely that discrepancy : Vancouver Island wolves contrast sharply with a l l others and Alaska wolves are further from the southern ones than a l l other northern ones. The f i r s t component of multivariate variance ( D 1 = 52$ of t o t a l ) corresponds very closely to a northeastward direction and i s markedly greater than the next largest one ( D 2 = 18$ of t o t a l ) .> Sets of vectors ("arrows") bearing the coded designations of the s k u l l dimensions indicate their contributions to the discriminant functions. Each vector shows the change i n the discriminant plane that the corresponding dimension would generate i f i t varied independently (by 1 standard deviation i n f i g . 9 and by 2 i n f i g . 7)-» Such i s not the case of course and these vectors must be considered j o i n t l y rather than separately. Northeastern wolves d i f f e r generally from southwestern ones ( f i g . 7) by a decrease i n s k u l l length ( L I and L 3 ) and i n braincase development ( C 1 and C 2 ) opposed to an increase i n s k u l l breadth ( W 1, W h  }  and W 5 ), Eastern wolves have a longer upper  i  5  r  6  7  K  2  Figure 7 : Group configuration ( l e f t ) i n the f i r s t two discriminant functions ( K 1 and K 2 ) and v a r i a t i o n of the s k u l l dimensions (right) j N-W and N-E arrows correspond to those of the map ( f i g . 1); see text f o r explanations.  i  i  i  -  r  rr  r~  f  4 5 6 7 8 9 K 2 10 Figure 8 : Biometrical overlapping i n discriminant functions K 1 and K 2 i l l u s t r a t e d by 95> equal-frequency e l l i p s e s ; crosses and dots represent group means and individuals respectively; letters refer to closest symbols.  Figure 9 : Group configuration ( l e f t ) i n discriminant functions K 3 and K h and variation of the s k u l l dimensions (right); 95$ equal-frequencye l l i p s e of group K ; see text for explanations.  K>  26  carnassial ( T 1 ) and a shorter palate ( L 2 ) than western ones. Such East-West variation had not shown up with simpler analytical techniques. Vancouver Island wolves ( J ) d i f f e r very much from others (figure 9) "by s i x s k u l l dimensions (greater T 1, C 1; lesser T 2, C 2, W k and W 5) and very l i t t l e with respect to the s i x others. The role of these two groups of dimensions i s contrasted not only by the directions but also by the lengths of their vectors. Vancouver Island wolves are much further from the grand mean than the arrows ( 1 standard deviation each ) of their discriminators are long. The amount of biometrical overlapping can be shown s a t i s f a c t o r i l y by the individual observations of small samples and by 95$ equal-frequency ellipses of large samples. B r i t i s h Columbia wolves ( K ) overlap by approximately 50$ (figure 8) with Manitoba ( I ) and Northwest Territories wolves ( D + E ). Ihe wolves from the Rocky Mountains ( L ) are intermediary and overlap largely both with those from B r i t i s h Columbia and those from Manitoba. High Arctic wolves ( A ) overlap by approximately 50$ with those from the mainland. Ihe lowermost point of sample A represents a subadult female from Coronation Gulf which should have been grouped with mainland specimens and i s r e l a t i v e l y narrow-skulled. Save for this exception, High Arctic wolves do not overlap with those from the Rockies. Larger samples would probably do to some extent however. Vancouver Island wolves overlap ( f i g . 9) by approximately 50$ with others. To sum up, this material shows northeastern wolves to • have generally shorter and r e l a t i v e l y broader skulls than  southwestern  27 ones and eastern wolves to have a shorter palate and a longer carnassial tooth than western ones. Such a generalization i s approximate however : the correspondence "between the patterns of biometrical divergence and of geographical separation i s imperfect and the f i r s t two discriminant functions account for only  of t o t a l  variance. More variance.is associated with a northeastward direction than with any other one. Vancouver Island wolves d i f f e r markedly from others by s i x s k u l l dimensions but very l i t t l e with respect to the s i x others. The amount of biometrical divergence and overlapping between a l l groups i s approximately proportional to the degree of geographical separation by distance, i n s u l a r i t y , etc.  28 INTERPRETATIONS AND CONCLUSIONS The proportionality of biometrical divergence to geographical separation could readily be interpreted i n terms of .population genetics. Genetic differentiation within an incompletely panmictic population should theoretically be proportional to geographical distance and other factors of i s o l a t i o n (Male'cot, l^hQ; Wright, 1951). Tne high mobility of wolves would compensate for the extent of their area of distribution and tend to erase the amount of differentiation probably induced by isolation during recent glaciations. Between-group variation i s most pronounced northeastward. Sampling has perhaps much to do with the predominance of northeastward variation i n this study. But genetical differentiation may be actually greater i n that direction. The genetical interpretation of geographical variation i s not the only one available however. The marked northeastward zonation of the environment may have direct influences upon the growth processes involved i n s k u l l development. The peripheral dimensions of length and breadth of the s k u l l of Canidae reach f u l l development at a l a t e r age than the posterior central region (Huxley, 1880). This appears to be indeed a general pattern of mammalian s k u l l development (Baer, 195*0 • Particular growth processes could be especially affected i f they were i n progress during temporary physiological disturbances. Juvenile sheep with thyroid deficiencies grow skulls with normal braincase and teeth but with underdeveloped f a c i a l region (Todd and Wharton, 193*+) • Their descriptions would f i t  29  surprisingly well the skulls of northeastern wolves with large teeth cramped i n a short palate. Stockard and others ( 1 9 ^ 1 ) found p i t u i t a r y and thyroid abnormalities more frequently i n domestic dog breeds with short-broad skulls than i n those with long-narrow skulls. The f a c i a l development of a r c t i c wolves may therefore possibly be hindered by a low a c t i v i t y of the p i t u i t a r y and thyroid glands. Seasonal periodicity of the environment ( l i g h t , temperature, food, etc.) may have effects upon growth just as on other physiological a c t i v i t i e s . Molts and coat-color changes of weasels were controlled photoperiodically by Bissonnette and Bailey ( 19kh ); the pituitary gland was considered to be involved. Seasonal periodicity i s also known to act through endocrine glands and metabolic factors upon b i r d migrations, on the reproductive cycles of various vertebrates, etc. Large mammals should be especially affected by seasonal, periodicity i n prairies and tundra where climatic and ecological conditions are so homogeneous. The northward increase i n seasonal periodicity of the environment may therefore have something to do with the s k u l l dimensions reached by wolves. Studies of seasonal variations i n wolf behavior may give valuable clues on the effect of a r c t i c winters on the endocrine balance and the metabolism of young wolves. Such studies should also lead to a more integrated view of wolf and dog behavior than either Scott ( 1 9 5 0 ) or Stockard ( 1 9 4 1 ).have reached. Inasmuch as geographical variation expresses genetic differentiation, t h i s analysis may improve our knowledge of genetic a f f i n i t i e s . Manitoba wolves are quite closely similar to the ones of  30  the Northwest T e r r i t o r i e s from which Alaska wolves a l s o show l i t t l e d i f f e r e n c e . Vancouver I s l a n d wolves have features o f t h e i r own but i n other respects they resemble northern wolves more than those p r e s e n t l y i n h a b i t i n g the I n t e r i o r o f B r i t i s h Columbia. I t i s perhaps ' w i t h northern populations t h a t Vancouver I s l a n d had i t s l a s t f r e e b i o t i c contact. As f o r the High A r c t i c wolves, t h e i r b i o m e t r i c a l c h a r a c t e r i s t i c s are i n good accordance w i t h t h e i r geographical p o s i t i o n and they give no c l e a r i n d i c a t i o n s o f unsuspected genetic affinities. Taxonomical i n t e r p r e t a t i o n s o f geographical v a r i a t i o n can only be accepted when the l a t t e r i s known t o express mostly genetic d i f f e r e n t i a t i o n . More research i s necessary to evaluate d i r e c t environmental e f f e c t s i n the present problem. The wolves o f Vancouver Island and those o f the I n t e r i o r o f . B r i t i s h Columbia e x h i b i t pronounced c h a r a c t e r i s t i c s . Such c h a r a c t e r i s t i c s f i t q u i t e w e l l i n t o the general pattern o f v a r i a t i o n however and there seems t o be no p o i n t i n t h i n k i n g o f s u b s p e c i f i c u n i t s unless f u r t h e r studies show v a r i a t i o n between populations t o be somewhat abrupt. A s c e r t a i n i n g the r e l a t i o n s h i p s o f western wolves requires more m a t e r i a l from Vancouver Island, Alaska, A l b e r t a and the regions i n between. On the other hand, the a n a l y s i s o f v a r i a t i o n should be extended t o the species as a whole o r a t l e a s t t o a l l i t s North American r e p r e s e n t a t i v e s . There are q u i t e c e r t a i n l y too many s u b s p e c i f i c designations in. use ( M i l l e r and K e l l o g ,  1955). Goldman's (Young and Goldman, lykk) f a i l u r e t o detect the major trends of geographical v a r i a t i o n seems l a r g e l y due t o h i s  31 approach. He compared specimens i n d e t a i l only with those from neighbouring l o c a l i t i e s . Gradual variation cannot show up clearly unless a l l samples are compared simultaneously. Joint trends of variation constitute a "multidimensional f i e l d " of variation rather than just "clines" (Huxley, 1938). Multivariate analysis i s optimum for multiassociated biometrical data. I t should eventually bring out relationships of growth phenomena and geographic variation with physiology and population genetics.  32  REFERENCES ANDERSON, E. 1954 E f f i c i e n t and i n e f f i c i e n t methods of measuring specific differences. •-93-106  i n KEMPIHORNE and others, 1 9 5 4 .  BAER, M.J. 1954 Patterns of growth of the s k u l l as revealed by v i t a l staining. Human Biology 2 6 : 8 0 - 1 2 6 . BANFIELD, A.W.F. 1951 Notes on the mammals of the Mackenzie D i s t r i c t , Northwest „ "territories. Arctic  1954  4:112-121.  Preliminary investigation of the barren ground caribou. Wildl.Man.Bull. 1, 10 A and 10 B. Canadian W i l d l i f e Service, Ottawa.  BISSONNETTE, T.H. and E.E. BAILEY 1944 Experimental modification and control of molts and changes of coat-color i n weasels by controlled l i g h t i n g . Ann. N.Y. Acad. S c i . 4 5 : 2 2 1 - 2 6 0 . BUTLER, L. 1947 The genetics of the colour phases of the red fox i n the Mackenzie River l o c a l i t y . Can.Jour.Res. D 2 5 : 1 9 0 - 2 1 5 .  COWAN, I.McT. 1938 Geographic distribution of color phases of the red fox and black bear i n the P a c i f i c Northwest. Jour.Mamm. 1 9 : 2 0 2 - 2 0 6 .  1947  The timber wolf i n the Rocky Mountain National Parks of Canada.  Can.Jour.Res. D 25:139-174.  DEFRISE-GUSSENHOVEN, E. 1955 Ellipses equiprobables et taux d'eloigneraent en biometrie. Bull.Inst.Royal Sci.nat. Belgique XXXI ( 2 6 ) . Bruxelles. HILDEBRAND, M. 1952 An analysis of body proportions i n the Canidae. Amer.Jour.Anat. 9 0 : 2 1 7 - 2 5 6 . HOTELLING, H. 1954 Multivariate analysis. :67-80 i n KEMPIHORNE and others, 1954.  33  HUXLEY, J.S. 1932 Problems of relative growth. xix- 276. Methuen and Co., London. 1938  Clines : an auxiliary taxonomic principle.  Nature 11+2:219.  HUXLEY, T.H. 1880 Cranial and dental characters of the Canidae. Proc.Zool.Soc. London :238-287.  KELSALL, J.P. 1957 Continued barren-ground caribou studies. Wildl.Man.Bull. 1, 1 2 . Canadian W i l d l i f e Service, Ottawa. KEMPTHORNE, 0 . and others (editors) 195k S t a t i s t i c s and mathematics i n biology. v i i - 6 3 2 . Iowa State College Press, Ames. MALECOT, G. 19k& Les mathematiques de l'he'redite. 6 3 . Masson et Cie, Paris. MILLER, G.S. and R. KELLOG 1955 L i s t of North American Recent mammals. U.S,Nat.Mus.Bull. . 2 0 5 : 9 5 . Smithsonian Institution, Washington. 1+  MURDOCH, D.C. 1957 Linear algebra for undergraduates. x i - 2 3 9 . John Wiley and Sons, Inc. New York. QUENOUILLE, M.H. 1952 Associated measurements. X - 2 U 2 . Butterworths S c i e n t i f i c Publications, London. RAO, CR. 1952 Advanced s t a t i s t i c a l methods i n biometric research. x v i i - 3 9 0 . John Wiley and Sons, Inc. New York. SCOTT, J.P. 1950 The social behavior of dogs and wolves : an i l l u s t r a t i o n of sociobiological systematics. Ann.N.Y.Acad.Sci. 5r:1009-1021.  STOCKARD, CR. and c o l l . 19hl The genetic and endocrinic basis for differences i n form and behavior as elucidated by studies of contrasted pure-line dog breeds and their hybrids. xx- 775» Amer.Anat.Mem. 1 9 . Wistar Inst.Anat.Biol., Philadelphia.  TODD, T.W. and R.E. WHARTON 193k The effect of thyroid deficiency upon s k u l l growth and form i n the sheep. Amer.Jour.Anat. 55:97-115. WRIGHT, S. 1951 The genetical structure of populations. Ann.Eugenics 15:323-35^. YATES, F. 1950 The place of s t a t i s t i c s i n the study of growth and form. Proc.Royal Soc. B, 137:^79-^89. YOUNG, S.P. and E.A. GOLDMAN I9I4.I4. The wolves of North America. xx-636. American W i l d l i f e Institute, Washington.  


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