Sexual dimorphism - defined by secondary differences between males and females of a given species - is a widespread phenomenon in the animal kingdom that is fascinating. Most studies on sexual dimorphism either focus on a single species to address complex morphological differences, or rely on measures of a single trait, as body size, to infer sexual dimorphism. This proposal aims to combine such approaches and use a comparative framework with broad taxonomic sampling to evaluate selective mechanisms related to the evolution of sexual dimorphism in body shape, in addition to body size. We will focus on true toads (Anura, family Bufonidae), a family comprising approximately 600 species globally distributed that differ in size and reproductive modes. We will test two main hypotheses, using an extensive database compiled from museum specimens and collected individuals: (1) limbs are target of selection in males, but not in females, in species that compete while mating (i.e., when males dislocate pairs that are already amplectant), leading to a male-biased sexual dimorphism; and (2) the trunk region is a target of selection in females, but not males, due to a selective pressure for increasing fecundity, leading to female-biased sexual dimorphism. Our study may show that refined measurements, other than body size, must be incorporated in the study of evolutionary processes shaping differences between males and females, which will strongly contribute for the fields of functional morphology and ecomorphology.
News published in Agência FAPESP Newsletter about the scholarship: