Sexual dimorphism (SD) is expressed as phenotypic differences between males and females of the same species, and is one of the major paradigms in Evolutionary Biology. It may result from distinct between-sex evolutionary pressures, related to their ability to fulfill their ecological role. Hence, the occurrence of DS might reflect and/or influence crucial aspects of the natural history of the species. One such aspect is the morphological variation associated to microhabitat and resource use. Lizards are model organisms in this specific context - the study of ecomorphology - and provide compelling evidence of morphological adaptation and convergence driven by ecology. Patterns of morphological diversity associated with habitat use might have functional relationships, directly affecting organismal performance exhibited in specific ecological settings, but these form-function relationships with ecology may be buffered by the behavior. The knowledge on the relationships between form, function and ecological diversity of lizards is extensive although restricted to only one of the sexes. Given that morphology and performance might still be subjected to evolutionary pressures related to mate acquisition or mate choice, to disregard the existence of SD in phenotypic traits that are ecologically relevant may underestimate the adaptive component of evolutionary radiations. This research proposal aims primarily to elucidate which types of selective pressures have produced between-sex divergence in lizards, inferring subsequently which ecological characteristics would be associated with the degree of SD. Using Tropidurinae as study system, the patterns of morphological SD will be investigated within the context of differential use of resources, such as microhabitat and diet, and functional consequences for correlated activities, such as behavior, locomotion and bite performance. Also, which phenotypic traits that present SD are evolving under natural or sexual selection will be unveiled in a species of the same lineage (Tropidurus torquatus). The three approaches proposed herein will contribute significantly to the understanding of the role played by between-sex differentiation in the phenotypic evolution in specific ecological settings. The generality of the ecological SD is still unanswered, and the impasse about which traits are direct target of selective pressures (whether functional or morphological traits) remains. Assessments of SD in performance represent, therefore, key contributions to understanding the coevolution between ecological characteristics of organisms and their phenotypes. The present research proposal will be the first interspecific examination of the relationships between form-function and the ecological settings in which they evolved that incorporates the existence of SD in lizards. Finally, this will be one of the rare studies to measure both types of selective pressures (natural and sexual) together in the field, substantially contributing to the development of knowledge in several areas within Evolutionary Biology.
News published in Agência FAPESP Newsletter about the scholarship: