Geometric morphometric study of sexual dimorphism and its associated allometry in wings of Pelopidas thrax (Lep.: Hesperiidae)

Abstract

Pelopidas thrax (Hübner) (Lep.: Hesperiidae) is a widespread species in southwest Iran. We aimed to use geometric morphometric techniques to investigate the sexual dimorphism and allometric effects associated with the wings of P. thrax. Fore- and hind wings of 40 and 39 individuals, respectively, of each sex which were collected from Ahvaz city were digitized and analyzed. Sexual dimorphism was observed in size and shape of fore- and hind wings of P. thrax and was graphically illustrated. Multivariate statistics confirmed significant differences in shape of fore- and hind wing between sexes. Centroid size of both wings showed greater values in females than males and visualized by boxplots. Various multivariate regressions of shape coordinates on centroid size were significant and visualized by the thin plate splines. Allometry explained shape variance in each case between 0.8% to 19.6%. The analysis demonstrated different allometric patterns for sexes in both fore- and hind wings. Significant shape differences between wings of males and females were still remained after removing allometric effects. The variation that is not related to size could be attributed to specific behaviors such as flight speed and performance in each sex. However, specific experiments are needed to confirm the association of the wing shape variation expressed in this study with the flight traits.