Absolute and relative secondary-sexual dimorphism in wing morphology: A multivariate test of the 'Big Mother' hypothesis

In many bat species, average body size of females is larger than males. One common explanation is that larger females exhibit greater reproductive success. One avenue whereby increased size could positively affect fitness is by improving aerodynamic performance. We examined secondary sexual size dimorphism in wing elements of Artibeus lituratus. In particular we examined absolute differences, relative differences after controlling for disparities in body size, and differences in the degree of morphological integration of wing elements. Females were absolutely and relatively larger than males in many wing elements and exhibited no difference in morphological integration. Absolute and relative differences in size of wing elements are likely related to enhanced aerodynamic performance in females, especially related to weight gain during reproduction. Future studies should examine patterns of dimorphism across the geographic distribution of this species to better understand the particular ecological and environmental context in which such size differences manifest.