Taxonomic identity of an insular population of sac-winged bat Saccopteryx (Chiroptera: Emballonuridae)

Abstract

Insular populations can differ from their continental counterparts since they are subject to particular pressures, biotic and abiotic, that can lead to variations in morphology and behavior; thus, the use of external characters may complicate taxonomic identification of insular populations. Even though the bat assemblage of Gorgona Island is a conservation target, there has been controversy about the taxonomic identity of bats from this Colombian National Natural Park. Specifically, our goal was to determine the taxonomic identity of the population of the sac-winged bat (genus Saccopteryx) resident in Gorgona, which have the peculiarity of having diurnal activity. Thus, we assessed differences among populations using morphometrics (traditional and geometric) and echolocation calls. Additionally, since the species of Saccopteryx involved have different mating systems, we assessed roosting association of Gorgona population as a surrogate for mating system. Despite the variation in skull morphometrics and echolocation calls among populations, Gorgona population was more similar to S. leptura than to S. bilineata. Besides, evolutionary allometry was significant, but size explained a small proportion of shape differences among populations. Finally, roosting association of Gorgona population suggests a monogamous mating system such as in S. leptura. We conclude that Saccopteryx from Gorgona corresponds to S. leptura. In addition, biogeographic history and geographic isolation of the island suggest that this population may have differentiated from their mainland counterparts through founder effect, genetic drift and/or adaptation to the local biotic and abiotic environmental conditions.