Sexual dimorphism and ecomorphology of the Berthold’s bush anole (Polychrus gutturosus) in Costa Rica

Morphological variation present within a species is the result of sexual or natural selection and determines the ecological relationships (i.e., ecomorphology) and the degree of sexual dimorphism. For most lizard species, either males or females are the larger sex, suggesting that selection operates differently on each sex. Thus, differences in morphology can determine the habitat use made by males and females. Here we use the Berthold’s bush anole (Polychrus gutturosus), a rare arboreal, diurnal lizard, to examine whether morphological and ecological measures differ among sexes and whether such potential differences emerge as a result of resource partitioning. We measured the morphology of wild individuals from one population and from preserved specimens collected in Costa Rica. We collected data on nine morphological measurements, nocturnal body and air temperatures, and sleeping perch height. We measured 45 wild individuals (22 males and 23 females) and 17 preserved specimens (6 males and 11 females). We found a female-biased body size, and male-biased tail length, head dimensions, and limb lengths. We also observed differences between males and females in body color and the size and shape of femoral pores, although these differences require quantification. We did not find sex differences in sleeping perch height or nocturnal body temperature. Our results demonstrate that resource partitioning does not explain differences among sexes, and that female-biased body size in P. gutturosus might reflect selection operating on increased fecundity.