Ecology, sexual dimorphism, and jumping evolution in anurans

Sexual dimorphism is a common feature of animals, and selection for
sexually dimorphic traits may affect both functional morphological traits
and organismal performance. Trait evolution through natural selection can
also vary across environments. However, whether the evolution of
organismal performance is distinct between the sexes is rarely tested in a
phylogenetic comparative context. Anurans commonly exhibit sexual size
dimorphism, which may affect jumping performance given the effects of body
size on locomotion. They also live in a wide variety of microhabitats. Yet
the relationships among dimorphism, performance, and ecology remain
underexamined in anurans. Here, we explore relationships between
microhabitat use, body size, and jumping performance in males and females
to determine the drivers of dimorphic patterns in jumping performance.
Using methods for predicting jumping performance through anatomical
measurements, we describe how fecundity selection and natural selection
associated with body size and microhabitat have likely shaped female
jumping performance. We found that the magnitude of sexual size dimorphism
(where females are about 14% larger than males) was much lower than
dimorphism in muscle volume, where females had 42% more muscle than males
(after accounting for body size). Despite these sometimes-large averages,
phylogenetic t-tests failed to show statistical significance of sexual
dimorphism for any variable, indicating sexually dimorphic species tend to
be closely related. While sexual dimorphism of jumping performance did not
vary among microhabitats, we found female jumping velocity and energy
differed across microhabitats. Overall, our findings indicate that
differences in sex-specific reproductive roles, size, jumping-related
morphology, and performance are all important determinants in how
selection has led to the incredible ecophenotypic diversity in anurans.