Ontogenetic Differences in Morphology, Habitat Use, Behavior, and Sprinting Capacity in Two West Indian Anolis Lizards

Abstract

We examined morphology, habitat use, movement patterns, and sprinting capacities of ju- veniles and adult males of two distantly related, yet ecologically similar species, Anolis lineatopus and A. gundlachi. Juveniles of both species tended to perch on lower and narrower perches than adult males, a finding that is consistent with other studies of Anolis. Juveniles used jumping more often as a mode of locomotion than adult males, with jumps constituting 54.1% (A. lineatopus) and 41.6% (A. gundlachi) of the movements of juveniles for these two species. Adult males of both species also were, on average, 25.9% (A. lineatopus) and 29.7% (A. gundlachi) faster than juveniles. Differences in sprinting capacity may have influ- enced the evolution of escape behavior of adult males and juveniles: juveniles typically run shorter distances and frequently escape by jumping to the ground rather than relying only on speed to elude a threat. By contrast, adult males more frequently escape by running longer distances on branches or tree trunks. Com- parisons with other lizard taxa show that slower juveniles frequently use escape behaviors that rely less on sprinting capacities than adults. Examination of how different age or sex clas- ses within a species utilize the habitat within a community is critical to understanding how ecological communities are structured (Werner and Gillam, 1984). A number of studies of a va- riety of animal taxa have shown that juveniles often differ markedly from adults in morphol- ogy, habitat use, behavior, and performance ca- pacity (Wemer and Gillam, 1984). In many cas- es, differences between juveniles and adults in one aspect (e.g., morphology) results in corre- lated differences in other variables (e.g., behav- ior). For instance, the size of prey that a fish can eat is limited by the size of its mouth, which increases as fish become older and larger. Thus, studies on sunfish have shown that this differ- ence in prey-capturing ability results in juve- niles occupying different portions of the pond habitat than adults (Wainwright et al., 1991). Therefore, documenting both how ontogenetic classes differ from adults, and understanding relationships between morphology, habitat use, behavior, and performance may shed light on how ecological communities are structured. Caribbean Anolis lizards provide an excellent opportunity for understanding how ontogenetic classes differ in morphology, habitat use, behav- ior, and performance capacity. Caribbean Anolis lizards have been studied extensively over the past 30 years, with particular attention being fo- cused on differences in habitat use and behavior