Inter-sexual phenotypic divergence is correlated with habitat structure in an invasive lizard

Abstract The success of invasive species is largely dependent on their ability to adapt to new environmental contexts. In dioecious species, adaptive responses can differ between males and females because of variation in the influence of sexual selection and/or the potential for inter-sexual niche differentiation. In invasive species, these effects may be augmented by ecological release, under which the constraints imposed by inter-specific competition on intra-specific niche divergence are shed. Differences in invaded environments, or between invaded and native environments, could therefore lead to different degrees of sexual dimorphism, which could influence intra-specific competition and invasive success. In this study, we investigate the potential for sexual divergence in adaptive change in invasive populations of the Green Anole, Anolis carolinensis, in the Ogasawara Islands, an oceanic archipelago in Japan. We find that limb length is correlated with variation in habitat structure across the islands in male lizards, but not in female lizards. We suggest that the resulting variation in sexual dimorphism is driven by exploitation of the available niche space, with male habitat use diverging further from that of females where local conditions allow. These findings represent evidence that community-level patterns observed among other anole species are mirrored by local, intra-specific patterns in this population, and add to growing evidence of the importance of ecological drivers of sexual dimorphism.