Sexual dimorphism in Levant Green Frog, Pelophylax bedriagae (Camerano, 1882), in Kohgilouyeh and BoyerAhmad Province

As a widely distributed phenomenon in the Animal Kingdom, sexual dimorphism is the morphological differences between two sexes of a given species. Anuran amphibians exhibit sexual dimorphism in numerous aspects such as body size, shape and color. A total number of 84 specimens of the Levant Green Frog (33 males, 51 females) were collected by hand in paddy fields of Sarfaryab, Choram Township, Kohgilouyeh & BoyerAhmad Province in Southern Iran. 12 metric characters were measured and recorded using a digital caliper with accuracy of 0.01 mm. To investigate the presence of sexual dimorphism both uni- and multivariate analyses were done using SPSS 16. Univariate analysis (using t- test) indicated the presence of significant differences in mean values between two sexes with greater values for females in the all metric characters (P < 0.05). Principal Component Analysis (PCA) showed that more than 83% of variations are included in PC1 to 4, with more than 69% only in PC1. Despite presence of sexual dimorphism in individual characters, ordination of males and females in scatter plot showed overlapping. Several factors including sexual selection, fecundity selection, ecological and behavioral effects has been proposed to the presence of sexual dimorphism in amphibians. Females are greater than males in 90% of amphibians. Two possible causes for this female-biased difference are: a) larger females attain greater reproductive outputs and b) males undergo greater rates of mortality, preventing them from reaching larger sizes.