S9-2.3 Jan. 6 The evolution of feeding mechanisms in bats: Balancing the costs of morphology and flight DUMONT, E.R.; UMass Amherst email@example.com
By any standard, bats (Order Chiroptera) are a successful group of mammals. Roughly 25% of all mammal species are bats and they occupy all but the coldest and most remote regions of the earth. The evolution of flight and echolocation were certainly key innovations behind their success but that is only part of the story. Bats have diversified into trophic niches that range from insectivory, through carnivory, frugivory and nectar-feeding. While flight places fundamental constraints on the shape of the postcranial skeleton, the shape of the skull in bats is remarkably varied. Morphological studies of individual clades and sympatric assemblages demonstrate that variation in skull shape is clearly associated with trophic specialization. This is best illustrated by the New World leaf-nosed bats, which exhibit the broadest range of dietary adaptations and cranial morphologies within any mammalian family. Studies of feeding performance and feeding behavior coupled with biomechanical analyses of skull shape are beginning to hint at the processes linking skull shape and dietary adaptation within these bats. Field experiments demonstrate that species-specific biting behaviors during feeding are common. Modeling experiments further suggest that these feeding (loading) behaviors and skull shape are functionally linked. This structure-function association may be stronger among bats than other mammals because the energetic cost of flight increases with excess weight. If the skull of bats is under selective pressure for minimal mass, then it may be more “streamlined” to meet mechanical demands than the skulls of other mammals; even relatively minor differences in skull shape among species may represent significant functional divergence. These qualities make bats a unique model system for studying the evolution of diversity in skull morphology and its functional implications for the evolution of feeding strategies in mammals.