Brain evolution in bats (Mammalia, Chiroptera): auditory, Olfactory and Sensorimotor systems

Data for brain structure volumes was analysed using multiple regression to test for correlated volumetric evolution in bats (Mammalia, Chiroptera). Significant partial correlations were found between major brain subdivisions, and between structures within the Auditory, Olfactory and Sensonmotor Systems that were predicted to have evolved together on the basis of anatomical connectivity and known functional relationships. Results were clearest in the auditory and sensorimotor systems and weakest for the olfactory system which included many limbic structures. Megachiroptera and microchiroptera were analysed separately; there was good general agreement between the patterns of correlated evolution in both of these clades. When compared to previous studies of con elated volumetric evolution in Insectivores and Primates, it was found that the pattern of correlations found in bats showed features that are unique to the order. These results strongly suggest that brain evolution in bats has proceeded in a mosaic fashion with individual functional systems being the targets of selection.