Differences in Sex Ratio, Tail Autotomy, Body Size and Body Condition Between Suburban and Forest Populations of the Cuban Endemic Lizard Anolis Homolechis

Abstract

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 surburban 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 surburban 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.

What Causes Differences in the Age-Class Structure between Suburban and Forest Populations of Anolis homolechis?

“…On the one hand, it may result from a reduced adult survivorship in forest populations compared to suburban ones. However, the results from a capture-mark-recapture study conducted at the same sites failed to show any significant effect of habitat on adult survival rate [81]. On the other hand, the differences in age-class structure may reflect habitat-related differences in female fecundity and/or in juvenile mortality.…”

“…We excluded juveniles that were too small to be marked and those captured for the first time during the last sampling session from the analysis. We added tail autotomy rate and SVL to the model as explanatory variables, both at the first capture, as tail autotomy is supposed to affect survival [80] and SVL has a positive effect on recapture probability [81]. Secondand third-order interactions were also included in the model.…”

Do Suburban Populations of Lizards Behave Differently from Forest Ones? An Analysis of Perch Height, Time Budget, and Display Rate in the Cuban Endemic Anolis homolechis

“…On each capture, we recorded perch height and time of the day. On first capture, we marked all captured individuals with a unique combination of colored elastomers, implanted under the skin into the ventral area of the limbs [78], as part of a long-term capture-marking-recapture study [79]. We also temporarily identified 184 captured individuals (adult males and females, in equal proportions) with a numbered tag pasted with an hypoallergic substance on the dorsal posterior area [80] (Figure 2).…”