Testing the “Big Mother” Hypothesis in New World Bats: Do Wing Structures Show Evidence of Sexual Dimorphism?

The “Big Mother” hypothesis proposes that selection may favor larger females because increased body size can enhance reproductive success, although the aerodynamic consequences of greater size may involve trade‐offs between flight speed, maneuverability, and energetic efficiency. In this study, I examined secondary sexual size dimorphism in 11 wing structures, including metacarpals and phalanges, in 941 individuals from 13 Neotropical species of the family Phyllostomidae. To do so, significant differences in wing structures between males and females were evaluated for each species using PERMANOVA, Mann–Whitney U tests, 95% confidence intervals for the corresponding effect size (rank‐biserial correlation), and principal component analyses (PCAs). Overall, no significant differences in wing structures were found between males and females for 11 of the species. However, Artibeus lituratus (Olfers, 1818) and Desmodus rotundus (É. Geoffroy Saint‐Hilaire, 1810) supported the “Big Mother” hypothesis, as females exhibited greater absolute lengths of nearly all metacarpals and phalanges than males. This pattern may be linked to enhanced aerodynamic performance in females, particularly in relation to weight gain during reproduction. The PCAs indicate that, beyond overall size, variation among individuals is also explained by differences in wing proportions, especially in the skeletal elements of the third digit. Taken together, these findings enhance our understanding of sexual size dimorphism in New World bats, highlighting species‐specific responses shaped by their natural history. Future research should examine a broader range of Neotropical species and assess dimorphism patterns across their geographic distribution to better understand the ecological factors driving wing size variation.