Climate niche shift in invasive species: the case of the brown anole

Anolis sagrei, a Cuba and Bahama native lizard, is a successful invader in Florida and adjacent areas. Herein, we focus on conservatism in its climate niche axes and possible congruencies with its natural history properties. The not mutually exclusive hypotheses of the present study explaining its northern range limit are: (1) climatic conditions within species' native and invasive ranges are identical; (2) the species is pre-adapted to novel conditions as a result of historical climate variations; and (3) only some niche axes limit the species' invasive distribution and the observed pattern is explained by an interplay between the potential niche within its native range and life-history. Species distribution models for native and invasive distributions were built on ten bioclimatic variables. Using Schoener's niche overlap index, the degree of niche conservatism among variables was identified. Significances of hypothesis (1) were tested using null-model approaches. Possible climatic pre-adaptations were evaluated by comparing its actual tolerance within its invasive range with that of the Last Glacial Maximum (LGM) within its native range (hypothesis 2). Results of (1) and (2) are discussed in relation to natural history, approaching hypothesis 3. We detect varying overlaps in niche axes, indicating that natural history properties are associated with conservative niche axes. Climatic comparisons with LGM of native and current conditions of invasive range suggest that pre-adaptations are unlikely. Possible shifts in the fundamental niche of the species may have been facilitated by enhanced genetic diversity in northern invasive populations. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 943-954.