Evidence for asymmetrical intraguild predation between native and introduced Anolis lizards

Since its introduction, Anolis sagrei (Sauria: Polychrotidae) has been replacing native A. carolinensis in Florida and native A. conspersus in Grand Cayman Island as the common anole of urban environments and other open habitats. To assess the likelihood that predation of juvenile native anoles by A. sagrei adults is an important interaction in this process, the propensities for intraguild predation and cannibalism were assessed for A. sagrei and A. carolinensis in Florida and for A. sagrei and A. conspersus in Grand Cayman. Predation experiments were conducted in cages, using freshly captured lizards, in which adult males of each species were presented with conspecific and heterospecific juveniles. Adult A. sagrei were (1) significantly more likely to eat juveniles than were adult A. carolinensis or A. conspersus, and (2) significantly more likely to eat heterospecific than conspecific juveniles, whereas adult A. carolinensis and A. conspersus were not. Thus, the propensity for intraguild predation is asymmetrical in favor of introduced A. sagrei in Florida and Grand Cayman. Further study is needed, however, to determine the importance of intraguild predation under field conditions. Received: 14 July 1999 / Accepted: 6 March 2000