Differences in sex ratio, tail autotomy, body size and body condition between suburban and forest populations of the cuban endemic lizard Anolis homolechis.
Résumé
Although growing evidence suggests that natural and sexual selection pressures may differ between natural and urban habitats, their consequences in terms of morphological differentiation, extent of sexual dimorphism and sex ratio remain poorly studied. Anolis lizards are an ideal model to study the phenotypic effects of urbanization, as they are well known for the existence of ecomorphs adapted to particular microhabitats. However, so far most studies of urban populations of anoles have considered invasive species and largely focused on males. Here, we compared morphological differentiation, sexual dimorphism and sex ratio between suburban and forest populations of the native A. homolechis, in western Cuba, based on large sample size (n > 800) and a balanced nested design. Overall, both male and female individuals from suburban populations were larger and in better body condition than individuals from forest populations. In addition, evidence of caudal autotomy was more than twice more frequent in suburban populations compared to forest ones, with no sex effect. Habitat type and season of the year had additive effects on sex ratios, with a significant excess of males in suburban habitats and during the non-reproductive season. Accordingly, the extent of sexual dimorphism in size was more pronounced in suburban populations compared to forest ones. Our results suggest that the shape and direction of natural selection may differ between urban and natural populations of anoles.