Energy Constraints and Ecological Adaptation Drive Divergent Evolution of Sensory and Cognitive Brain Regions in Bats.

Brain evolution is influenced by energy constraints and ecological adaptation for bats, but the specific factors driving specialization in sensory versus cognitive brain regions remain poorly understood. By integrating morphological traits, ecological information, and neuroanatomical traits from 145 bat species, we reveal the driving mechanisms of differentiation: sensory regions (auditory nuclei and inferior colliculus) were constrained by body-size allometry, while cognitive regions (neocortex and hippocampus) were directly shaped by ecological selection. Auditory nuclei decrease in size with increasing echolocation peak frequency, suggesting functional specialization through optimized neural efficiency under energy constraints. Ground-foraging behavior drives neocortical expansion to meet the cognitive demands of complex spatial navigation. Similarly, the dietary diversity was linked to hippocampal enlargement, convergent with the adaptive evolution linking hippocampal expansion to spatial memory in birds. The total brain mass shows dual regulation-dietary diversity drives the enlargement, while the higher wing loading associated with aerial foraging suppresses expansion through metabolic constraints. These findings extend the expensive tissue hypothesis by revealing intra-brain energy trade-offs and demonstrate that ecological and behavioral selection serve as the key driver for cognitive brain region evolution. Our study has highlighted the critical need for multi-scale frameworks that integrate developmental constraints, ecological adaptation, and metabolic trade-offs to unravel brain evolution.