Taxas evolutivas, disparidade e ecomorfologia da mandíbula de marsupiais americanos

Abstract

The American marsupials chosen a diverse group of mammals that are distributed throughout the entire continent. Currently its more than ~120 species are classified into 3 main orders (Paucituberculata, Microbiotheria and Didelphimorphia). Due to its great diversity, the group is the focus of numerous evolutionary studies, among which it can be seen that these species have a high degree of morphological integration in their cranial structures. However, the adaptive patterns of the group are still unclear. As the vast majority of marsupials have nocturnal and solitary habits, the study of their foraging behavior in a natural environment is challenging. Researchers have searched for hypothetical diet descriptors based on different methodologies. However, a morphofunctional relationship of the American marsupial mandible with the main diet hypotheses, especially the more recent ones, has not yet been widely studied. In this study, the high effect of eating habits on the mandible size of American marsupials was observed, but not on their shape. Previous studies have found that variability in marsupial variety is associated with variation in size (= allometry) both intra and interspecifically. This allometric morphological variability can help in morphofunctional explanations of blood in this group. We found that allometry is an important factor in the morphological diversity of the group, affecting the rates of evolution and morphological disparity in some clades, possibly influencing the morphological heterogeneity found among the clades. Furthermore, the biogeographic history of the different clades of American marsupials is another important factor discussed here, which potentially explains the heterogeneity of the values of evolutionary rates and disparities found in the shape and size of the mandible of these animals. We emphasize the importance of improving the quality of the pending hypotheses in evolutionary studies in the group, taking into account the properties of the food items (hardness and size) consumed by these animals.