Morphologic Variation in the Raccoon, Procyon lotor, and Its Relationship to Genic and Environmental Variation

Abstract

Morphologic variation in the raccoon, Procyon lotor, from the southeastern United States was assessed with univariate and multivariate analyses. The species was found to be sexually dimorphic with skulls of males generally more massive. This may relate to intraspecific territorial defense rather than intersexual resource partitioning. A matrix of correlation among skull characters was computed, and the first three principal components were extracted. These accounted for 84.2% of the variation in the character set among males and 86.5% among females. Three-dimensional projection of localities onto principal components showed that, for both males and females, large individuals occurred in western and northern states and the smallest animals occurred in the Florida Keys. Size gradations were seen with most raccoons similar to those in nearby geographic areas. No relationship was detected between genic and morphologic variation; however, a relationship was found between patterns of morphologic and environmental variation. This relationship was stronger in males. Canonical correlation suggested that trends in size of raccoons follow Bergmann's rule, but other arguments are against this. It appears that patterns of variation in size in raccoons have developed under a complex array of environmental pressures which cannot be individually dissected. It may be that the raccoon genome, while relatively static, allows for a high degree of morphologic plasticity in the face of environmental variation.