Meeting Abstract
Urbanization alters natural habitat in drastic ways, changing the structural habitat from forests to buildings and roads, which also increases local temperature, known as the urban heat island effect. Some species persist under these conditions, but few mechanistic studies exist that assess how organisms adjust to the novel conditions in cities. Anolis lizards are an ideal system to test the effects of urbanization on locomotor performance because they are particularly sensitive to changes in the structural habitat, a key axis of diversification for anoles, and changes in environmental temperature because they are ectotherms. But, such disruptions may not necessarily reduce fitness or influence persistence. Field studies in Miami show that urban areas have an increased proportion of smooth, vertical structures and that they tend to be warmer than nearby natural forested sites. In performance trials on tracks that vary in incline and substrate roughness, we predict that two species of anoles, Anolis cristatellus and Anolis sagrei, will perform worse when running on smooth, vertical substrates, and will change limb postures to increase stability. We found that both species sprint slower and slip and pause more often on smooth, vertical substrates compared to an inclined bark substrate. Because operative temperatures, the body temperature of a lizard not actively thermoregulating, are higher in urban areas, we expected, but did not find, that urban lizard populations have higher optimal performance temperatures. However, the greater availability of warm microclimates in urban habitats may allow lizards to utilize a greater portion of their optimal performance capabilities. We demonstrate that different components of urbanization may influence persistence in opposing directions; performance decreases due to moving on smooth structures in urban areas, yet increases from a thermal perspective due to warmer microclimates available in cities.
