Meeting Abstract

43.2  Sunday, Jan. 5 10:30  Ecological Determinants of Clinal Morphological Variation in the Cranium of the North American Gray Wolf O’KEEFE, F. R. ; Marshall University okeefef@marshall.edu

The gray wolf, Canis lupus, exhibits both genetic and morphologic clinal variation across North America. While shape variation in wolf populations has been documented, no study has been made to exhaustively quantify it, or attempted to formally correlate morphology with environmental variables. This study utilizes a large historical database of gray wolf skulls to analyze shape, and attempts to correlate it with wolf ecology. The data set comprised 15 linear measurements from 289 gray wolf crania, distributed from Alaska to Mexico. Also, associated locality data was used to compile temperature and precipitation information for each occurrence. A variety of statistical tests were employed; size and shape were examined through a principal component analysis and a calculation of allometry vectors. Multiple regression analysis (both global and stepwise) was then used to test the resulting principal components against various biotic and abiotic factors. In addition, the effects of sexual dimorphism and sub-species taxonomy on morphology were explored through one-way ANOVA and canonical variates analysis, respectively. Several patterns were revealed, including size increase with latitude in accord with Bergmann’s rule. Static allometry is significant, the fundamental pattern being a decrease in the robusticity of the basicranium relative to the viscerocranium. Sexual dimorphism, allometry, and a correlation with precipitation are other key elements showing connections to morphology. Examination of these patterns allows conclusions about the direct and indirect ways that temperature and precipitation drive clinal variation in gray wolves.