Environmental perturbation can drive the evolution of behavior and associated brain structure and function. Generation of high-resolution whole-brain atlases have provided insights into neuroanatomy and neural circuit connectivity associated with behaviors in many model systems, but these approaches have yet to be applied to models of brain evolution. The Mexican tetra, A. mexicanus, comprises river-dwelling surface fish and multiple independently evolved populations of blind cavefish, providing a unique opportunity to identify evolved neurological differences associated with divergent behaviors including sleep loss and alterations in foraging behavior. We employed intact brain imaging combined with image registration to generate neuroanatomical atlases of surface fish and three different cave populations of A. mexicanus. Analyses of neuroanatomical brain regions and neural circuits associated with behavioral regulation identified convergence on hypothalamic expansion, as well as changes in transmitter systems including elevated numbers of catecholamine and hypocretin/orexin neurons in cave populations. To define changes in neural function associated with the evolution of behavior, we quantified changes in neural activity associated with sleep and feeding. Together, these analyses identified broad alterations in brain structure and function associated with differences in foraging behavior and sleep loss across independently evolved populations. These atlases represent the first comparative brain-wide study of intraspecies variation and provide a resource for studying the neural basis underlying behavioral evolution.  

Cavefish brain atlases reveal functional and anatomical convergence across independently evolved populations