Correlation patterns in roe deer cranium: sexual dimorphism across different habitats

Abstract

Complex evolutionary interactions can cause differential responses of males and females to environmental factors which result in variations of the degree of sexual dimorphism across different habitats. Roe deer Capreolus capreolus is an excellent model species for analyzing sexual dimorphism in the context of habitat variability as the most widespread ungulate species in Europe. The impact of three different habitat types (closed, intermediate and open) on the level of cranial integration in roe deer and patterns between sexes was tested by analyzing 761 adult craniums from 11 roe deer populations in Serbia. Our results confirmed higher level of integration and more pronounced sexual dimorphism in closed habitats in comparison with open habitats. Males also showed different patterns of integration across habitats than females. The general consistency of results across different tests suggests that patterns of integration between sex and habitat groups tend to be different for males and females from different habitat types. When faced with strong selective pressures, patterns of correlations among skeletal elements can evolve even within a species as an indirect influence of social organization through habitat and sexual selection. We propose that cranial integration in roe deer evolved according to the predictions of the adaptive model of phenotypic differentiation within a taxon in closed habitats channeled by stabilizing selection. The different patterns of cranial integration between sexes after successful colonization of intermediate and open habitats can be explained by a change in overall selective pressures to disruptive/directional selection, thus breaking up observed patterns of integration, since they are treated as a constraint in changed circumstances.