Echolocation and dietary adaptations mediate brain-endocast covariation in bats.

Bats exhibit remarkable ecological diversity, reflected in different species' sensory, cognitive and behavioral ecology. Bat brain volume has been linked to powered flight, laryngeal echolocation, and dietary transitions. Given the developmental trajectories and functional demands the skull and brain share, the bat skull-brain complex represents a unique means to better understand evolutionary processes and trade-offs. We assessed the brain-endocast correspondence across bats, considering whether changes in correspondence reflect ecological adaptations. We demonstrate that estimates of brain volume from both methods showed similar allometric trajectories, apart from those for cerebral cortex. Our results reveal a significant effect of diet and echolocation on brain-endocast correspondence of the cerebral cortex and olfactory bulbs, respectively. We suggest that shifts in the brain-endocast correspondence of the olfactory bulbs indicate an evolutionary trade-off between olfaction and echolocation. Our study offers a different perspective for future comparative neuroanatomical studies involving extinct and living species in museum collections.