Phylogeography and Signal Evolution in a Widespread Central American Anole

Abstract

Anolis lizards are an excellent model system in which to study countless evolutionary and ecological questions. I have found great satisfaction in following my many biological interests, from disease dynamics to taxonomy to female color polymorphism, within this fascinating group. One might think that, given the broad interest and rich history of research in anoles, outstanding unknowns would be hard to come by. I have found quite the opposite. In the following chapters, I explore areas of anole biology that have plenty of room for exploration and discovery, with a focus on mainland anole phylogeography and signal evolution. In Chapter 1, I conduct phylogenetic and population genetic analyses of a widespread mainland anole clade, Anolis lemurinus and its relatives. I describe significant previously unreported population structure and discuss the implications of these findings in regard to anole taxonomy. In Chapter 2, my colleagues and I discover a novel pattern of dewlap coloration in anoles. In our study species, female anoles both within and across species show significant variation in dewlap color, while males hardly vary at all. Such a pattern is unique among anoles, and brings up many questions about signal function and evolution in females, an oft-overlooked field of study. In Chapter 3, I conduct a review and synthesis of the literature pertaining to anole dewlap evolution and diversification. I examine the evidence for three evolutionary processes as the primary factors driving anole dewlap evolution and diversification: species recognition, sensory drive, and sexual selection. I then discuss open questions in the field and promising avenues and approaches for future work. In Chapter 4, I investigate another under-researched anole trait, the tail crest in Anolis cristatellus. I find that tail crests are larger in urban populations than in forest populations. As urban areas are hotter, drier, and sparser than forests, these results suggest that tail crests may be under differential natural selection for signaling or thermoregulation in these two starkly different habitat types. In Chapter 5, I explore disease dynamics in Anolis sagrei, a widespread anole species, using opportunistic sampling of a captive colony. I identified several different adenovirus clades infecting the sampled A. sagrei, several of which were deeply divergent. Two of the four adenovirus clades identified were more closely related to adenoviruses infecting mammals and other squamates than to those infecting other A. sagrei, suggesting frequent host switching by adenoviruses.