Poster presentation 12th International Mammalogical Congress

Evolution of sexual dimorphism in musteloid crania (#657)

Chris J Law 1 , Rita S Mehta 1
  1. University of California, Santa Cruz, Santa Cruz, California, United States of America

The remarkable uneven diversity in both species richness and phenotypes represent one of the more perplexing evolutionary patterns across the Tree of Life. Although an increasing number of researchers have begun to understand what drives uneven diversity between species, few researchers have examined how differences within single species can affect these broad scale evolutionary patterns. One source of variation lies in the difference between the sexes. The primary goal of this research is to build upon evolutionary theory by examining how sex differences contribute to species and phenotypic diversity. Here, we use musteloids (badgers, otters, raccoons, skunks and weasels) as a model to examine the effects of sexual dimorphism (SD) on cranial disparity at the macroevolutionary scale. Musteloids are a taxonomically rich and phenotypically disparate clade whose lineages exhibit uneven patterns of diversity. We used 3D geometric morphometrics to quantify cranial size and shape. We then quantified the rates of cranial disparity through time in males and females separately and pooled together (species means) to test the hypothesis that incorporating sex enhances the pattern of adaptive radiation. A rate shift in cranial evolution is predicted to occur just after the onset of the Mid-Miocene Climate Transition when using the pooled male and female dataset. Second, we examined an ecological basis for sexual dimorphism by testing the hypothesis that the degree of carnivory corresponds with the evolution of sexual dimorphism in cranial shape and size across Musteloidea. Hypercarnivorous musteloids are predicted to exhibit the highest degree of cranial SD.