Urban environments are spreading and can influence the biotic and abiotic components of an ecosystem. Brown anoles (Anolis sagrei) that live in urban environments are larger in body size than their counterparts that reside in more natural areas. Body size is important for brown anoles because larger individuals can run faster, eat larger prey, and are more competitive. But what’s driving the variation in body size across urban to natural environments? Zac Chejanovski, a PhD student at the University of Rhode Island sought to answer this question.
Chejanovski did his research in south Florida at 38 sites along an urban to natural gradient. He measured food availability, abundance of conspecifics, and abundance of a known predator of anoles, the curly-tailed lizard. He also captured 15 male and 15 female anoles and measured body size, body temperature, and the thermal environment.
Curly-tailed lizard abundance had a strong positive relationship with body size for both male and female anoles. There was a weak positive relationship between the thermal environment and body size for males, but not females. Neither food availability nor abundance of conspecifics were related to body size. The findings of this research suggest that predation pressure from curly-tailed lizards might be one factor driving selection on body size variation in brown anoles.