Sexual size dimorphism and its allometry in Chinese lizards

Abstract

Rensch's rule is an allometric rule on sexual size dimorphism. It states that in small-sized species, females are larger than males, whereas in larger species, males are relatively larger than females. Several studies have explored this pattern, and its inverse in lizard species. China has a unique and high diversity of species, with a variety of ecological systems which shape diversity of phenotypes. In this study, sexual size dimorphism and Rensch’s rule were determined using a dataset of Chinese lizard species. The findings show that Chinese lizards generally exhibit female-biased sexual size dimorphism. In addition, clutch size was positively correlated with sexual size dimorphism. Agamidae species were the only taxa that followed Rensch’s rule (slope of males against females was steeper than 1). Clutch size was correlated with sexual size dimorphism in groups that do not follow Rensch's rule. This finding implies that strong fecundity selection limits application of Rensch's rule in these groups.