Sexual size dimorphism and sexual selection in artiodactyls

Sexual size dimorphism is biased towards males in most mammalian species. The most common explanation is precopulatory intra-male sexual selection. Large males win fights and mate more frequently. In artiodactyls, previous tests of this hypothesis consisted on inter-specific correlations of sexual dimorphism with group size as a surrogate for the intensity of sexual selection (Is). However, group size is not a proper measure of sexual selection for several reasons, as is largely recognised in other mammalian taxa. I conducted an inter-specific test on the role of sexual selection in the evolution of sexual dimorphism using variance in genetic paternity as a proxy for the Is. I reviewed the literature and found 17 studies that allowed estimating Is=V/(W2), where V and W are the variance and mean number of offspring per male, respectively. A phylogenetic generalised least squares analysis indicated that dimorphism (Wm/Wf) showed a significant positive regression with the intensity of sexu...