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Long-term structural habitat use of male individuals of two native and one introduced Anolis (Iguanidae) species on the north coast of Jamaica.

Article Excerpt
Abstract.--This study compares the perch heights and densities of male Anolis grahami, A. sagrei and A. lineatopus at four localities near Ocho Rios, Jamaica during the spring of 1983, 1987, 1994, 1996, 1998 and 2000. This is the first report of an Anolis perch height study sampling the same study area for a period of almost two decades. The finding of stability over the long-term in this system lends validity to numerous short-term studies. Data analyses included assessment of perch height and densities. Mean perch heights were signifi-cantly different among species during the study. However, there was still significant overlap in this niche dimension in many years of the study. Anolis sagrei is an invader that has integrated into the Anolis community at this locality. Implications of these findings are discussed regarding reasons for coexistence and potential competition between these species.

Community structure may arise by both rapid processes occurring in ecological time, as well as by more long term processes acting over evolutionary time (Roughgarden et al. 1983; Grant 1986). Communities may be structured by invaders, where to be successful as a colonist, an invading species must be pre-adapted to fit in with other members of the community (Rummel & Roughgarden 1983; 1985), or structured through mutual co-adaptation of community members (Beuttell & Losos 1999). Caribbean Anolis lizards provide good model systems for analyzing community structure because of their simplicity, ease of observation, and because anoles are likely to be relatively insensitive to unobtrusive observation (Sugerman 1990). However, the extent to which such communities are the result of coevolution among species is ambiguous (Williams 1972; Roughgarden et al. 1989; Losos 1992a; 1992b; Butler et al. 2000). Investigation of the effects of invasion by Anolis sagrei may provide insight into the evolution of Anolis communitie s in the Caribbean. This is the first long-term report in the literature studying the Anolis community structure at the same study area for nearly two decades.

This study examines perch heights and densities of three common Anolis species (Anolis grahami, A. sagrei and A. lineatopus) at four localities of a study site on the north coast of Jamaica (see Underwood & Williams 1959 for a complete description of these species). Rand (1964) originally used perch height and perch diameter to distinguish the spatial niche dimensions used by the anole species that he studied, and other authors have used these measures to quantify habitat use (Schoener 1967; Schoener & Schoener 1971; Losos et...