Measuring the Effects of Urbanization and Hurricane Maria on the Tropical Lizard Anolis Cristatellus: Morphometrics, Ecology, and Population Genomics

The effects of hurricanes and urbanization are likely to increase under scenarios of global environmental change. Nonetheless, little is known about how populations living in anthropogenically disturbed habitats will respond to climate disturbances, including hurricanes. In my dissertation, I compare urban and forest populations of the lizard Anolis cristatellus following passage of Category 5 Hurricane Maria through the island of Puerto Rico in 2017. The major aim of this research was to measure how urban lizard populations responded to a hurricane and to contrast that respond to forest populations of the same species. First, I contrasted morphological shifts before and after the hurricane. Second, I tracked population densities of A. cristatellus in paired urban and forest sites at four, eleven, and sixteen months after the hurricane. Finally, I evaluated whether pre-hurricane populations within the densest metropolitan area in Puerto Rico showed reduced genetic connectivity due to urbanization. I found that urban and forest populations exhibited broadly similar morphological responses to the hurricane. Post-hurricane populations had smaller overall body size and showed a small size-adjusted decrease in most morphological traits at four months following the hurricane. Some aspects of toe morphology, however, did not decrease in urban populations but did decrease in forest-dwelling lizards. Population densities increased in the months following the hurricane in the pair urban and forest sites closest to geographic region to the point of landfall of the hurricane. All urban sites showed population densities that were nearly half the densities of nearby forested areas. My research also showed that following the hurricane, perches available to lizards dramatically increased in density due to post-disturbance succession. In contrast, urban sites had fewer perches available to lizards and the density of perches available remained relatively unchanged following the hurricane. Finally, I found that lizards within a densely urbanized city maintained high levels of genetic connectivity across sites. I measured important phenotypic and ecological differences in the responses to this extreme weather event between urban and forest habitats. Thus, it is imperative that we accumulate a body of literature characterizing how anthropologically disturbed species will respond to large scale weather disturbances