Inter- and Intraspecific Variation in the Species Complex Demonstrates Size and Shape Partitioning Among Species

Neotropical leaf-nosed bats (family Phyllostomidae) are one of the most diverse mammalian families and spp. is one of the most speciose phyllostomid genera. In spite of their species diversity, previous work on crania using linear morphometrics has uncovered limited interspecific variation. This dearth of shape variation suggests that differences in cranial morphology are not contributing to niche partitioning across species, many of which are often found in sympatry. Using two-dimensional geometric morphometric methods on crania from eleven species from the species complex, the current study demonstrates substantial cranial interspecific variation, sexual size and shape dimorphism, and intraspecific geographic variation. The majority of species were shown to have a unique size and shape, which suggests that each species may be taking advantage of slightly different ecological resources. Further, both sexual size and shape dimorphism were significant in the species complex. Male and female are known to have sex specific foraging strategies, with males eating near their roosts and females feeding further from their roosts. The presence of cranial sexual dimorphism in the species complex, combined with previous work showing that different fruit size and hardness is correlated with different cranial shapes in phyllostomids, indicates that the males and females may be utilizing different food resources, leading to divergent cranial morphotypes. Additional field studies will be required to confirm this emergent hypothesis. Finally, significant geographical shape variation was found in a large intraspecific sample of crania However, this variation was not correlated with latitude and instead may be linked to local environmental factors. Additional work on ecology and behavior in the species complex underlying the morphological variation uncovered in this study will allow for a better understanding of how the group has reached its present diversity.