Meeting Abstract
The mammalian skull performs multiple functions, including feeding and protecting the brain and sensory organs. Dietary adaptation is considered a major driver of mammal skull diversity, but there have been few, large-scale quantitative tests of the impact of feeding versus other functions on skull morphological evolution. Bats are an ideal group to investigate this issue because they represent 20% of all mammals, are diverse in cranial morphology, and encompass nearly the full spectrum of mammal diets and sensory ecologies. We explore whether and how the macroevolution of skull shape is related to feeding strategies in bats, or if other functional demands have influenced their cranial diversity. We compiled a large dataset of 3D representations of bat skulls, spanning all major bat lineages, diets and sensory ecologies. We used this dataset in phylogenetic comparative analyses of skull shape to (1) map major evolutionary trends, (2) detect selective regime shifts without imposing a priori hypotheses, and (3) investigate the association among skull shape evolution, diet, and primary sensory modality across bats. We found that the bat skull morphospace is characterized by gradients in skull elongation, facial flexure, and zygomatic breadth. Old World fruit bats (Pteropodidae) tend to be morphologically distinct, as are lineages of specialized neotropical frugivores (Stenodermatini) and insectivores (Mormoopidae). The evolution of skull shape across bats is well explained by selective regimes that broadly match echolocation use and type. However, patterns of skull shape evolution mirror dietary evolution within the most trophically diverse bat lineage (Phyllostomidae). Altogether, these results illuminate how multiple functions have impacted skull evolution during the ecological and lineage diversification of bats.
