Do interspecific interactions between females drive shifts in habitat use? A test using the lizards A nolis carolinensis and A . sagrei

An important goal in evolutionary ecology is to understand how and why coexisting closely related species partition habitat among themselves. Although studies of interspecific interactions typically focus on males, interactions between females may also play an important role in shaping habitat use within multi‐species communities. The green anole ( A nolis carolinensis ) exhibits a wide range of habitat use in south‐eastern L ouisiana, but its observed habitat use is restricted and altered in areas where it occurs with the introduced A nolis sagrei . We staged interactions between these two species in the laboratory to test the hypothesis that A . sagrei dominate A . carolinensis in contests over shared habitat. We examined whether species identity, bite force, dewlap size, and body size affected the outcome of interspecific interactions between both males and females, and tested the prediction that bite force and size would be the most important determinants of interaction outcomes in both sexes. In male interspecific interactions, we found that individuals with relatively larger dewlaps tended to score higher on aggressive behaviours regardless of species identity, and that interactions consisted of signalling and rarely escalated to physical combat. However, we found that A . sagrei females achieved higher aggressive scores than A . carolinensis females in almost all cases, lending support to the notion that female interspecific behaviour is probably more important than male behaviour in driving changes in habitat use. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society , 2013, 110 , 843–851.