Adaptive Divergence across Variable Signaling Environments Mediates Signal Diversity in the Hispaniola Bark Anole, Anolis Distichus

In an adaptive radiation, closely related individuals diverge in traits which allow them to exploit available resources in an environment, ultimately leading to rapid diversification of the initial population into multiple distinct lineages. An important aspect of adaptive radiation is the role of signal evolution in contributing to patterns of adaptive divergence and speciation, as signal diversification can have immediate consequences for recognition by conspecifics, ecological competitors and predators. In this dissertation, I investigate patterns of signal diversity among populations of a highly variable tropical lizard, the Hispaniola bark anole Anolis distichus. Using a combination of large-scale field studies, comparative estimates of signal efficacy across habitats, and examination of the underlying patterns of relatedness between phenotypically distinct groups, I test whether patterns of signal diversity are consistent with prominent theories describing the evolution of animal signals in nature. I find patterns of signal diversification among bark anoles consistent with both the Sensory Drive and Character Displacement theories of signal evolution, demonstrating the dynamic nature of evolutionary mechanisms at work in this system, and the utility of exploring alternative hypothesis when characterizing trait diversification in the wild.