Meeting Abstract

P3-34    Early Evolution of Cranial Shape in Bats is Linked to Echolocation Gilley, D/T*; Santana , S/E; Arbour, J/H; Middle Tennessee State University ; University of Washington; Middle Tennessee State University delaneygilley4@gmail.com

The origin and distribution of morphological variation is of keen interest to many evolutionary biologists. The means by which this diversity originates may be adaptive or non-adaptive in nature. Chiroptera (bats) are the second most species-rich mammal order and has extraordinary diversity in cranial shape and function. This includes three echolocation modalities and several dietary specializations, which have been linked to their diversity of ecological, behavioral, and sensory adaptations. Previous analyses have suggested that the relative positioning of the rostrum and the neurocranium (upturned or downturned faces) are linked to the evolution of echolocation modes. We tested this directly by quantifying rostral flexion via 3D geometric morphometrics and using phylogenetic comparative methods to detect macroevolutionary patterns across over 200 species of bats. We determined the total skull shape variation and the timing of the diversification of bats with respect to rostral flexion, and used maximum likelihood model fitting to test for selection on rostral flexion associated with echolocation modes. We found that >30% of all skull shape variation is linked to rostral flexion. Disparity though time analysis found that the rostral angle was established early in the evolution of many clades, and that echolocator modes have different adaptive optima. Due to the early diversification of cranial morphology, each echolocator mode may have had different opportunities to adapt to diverse ecological niches.