Does Bergmann’s rule apply in bats? Evidence from two neotropical species

Abstract

Bergmann’s rule is one of the most vigorously debated ecogeographic patterns but has rarely been examined in Neotropical bats. Herein, I examined Bergmann’s rule in Carollia perspicillata and Artibeus lituratus along an elevation gradient of 2500 m at both inter- and intraspecific level. I measured 384 specimens from collections belonged to C. perspicillata (89 ♀, 102 ♂) and A. lituratus (89 ♀, 104 ♂). The size of C. perspicillata increased with increasing elevation and decreasing temperature, whereas A. lituratus showed the converse pattern. For both species, females did not differ between elevation categories, contrary to males that were larger above 1000 m in C. perspicillata, but smaller in A. lituratus. Conformity to Bergmann’s rule depends on bat size and sex. Despite C. perspicillata follows the pattern, the explanatory mechanisms still need to be understood. By contrast, A. lituratus follows the converse of Bergmann’s rule due to naked and highly vascularized wings that aid thermoregulation in warmer environments. Male size is more sensitive to changes in temperature for both species which may be partially explained by sexual selection. Elevation and temperature are not the only factors related to bat morphology and other mechanisms may explain size in bats.

Keywords

• biogeography
• body size
• chiroptera
• Colombia
• environmental gradient