Adaptation, Diversification, and Desert Ecology of the Most Diverse Order of Mammals (Mammalia, Rodentia)

Globally, species diversity is regulated by speciation and extinction, and regionally it is regulated by competition, niche, colonization, emigration, and extinction, and more locally, by environmental tolerance and species interactions which filter out non-adapted species based on intrinsic characteristics, or their Hutchinsonian niche. In this dissertation, I examined some of the mechanisms that govern biodiversity patterns in order to determine the main causes of uneven diversity in muroid rodent clades, the most diverse superfamily of mammals, comprising 28% of all mammal species. This extensive diversity, in addition to the remarkable eco-morphological adaptability which facilitated their colonization of all terrestrial biomes make muroids an ideal system to study this fundamental question in evolutionary ecology. In addition, the use of robust phylogenies that have recently been developed in muroids and non-muroid rodents makes the order an especially attractive model system to understand the process of mammalian adaptation to arid environments and the ecological interactions that shaped patterns of coexistence within desert communities, the second main goal of the dissertation. The use of a combination of molecular phylogenetics and geometric morphometrics allows for a robust investigation of general patterns that shape the ecological evolution of this group within and without desert habitats, warranting a reinterpretation of classical studies in evolutionary biology, desert ecology, and the traditional systematics of desert rodent clades.