The evolution of cavefish odor perception shifts fish response from avoidance to approach when exposed to alarm and death odors

An organism’s survival is dependent on activating the correct behavioral circuit in response to a stimulus. While stimulus perception is largely conserved, we still do not know the evolutionary mechanisms that drive changes in stimulus perception. Therefore, we wondered how odor perception has evolved in cavefish that encounter vastly different odors compared to their surface ancestors. While surface populations show attraction to social odors and avoidance of alarm and death odors, cave populations are sexually dimorphic in their responses to social odors and exhibit attraction to alarm and death odors. Finally, we find that odor perception variation is genetically encoded and plastic, while tissue clearing and brain mapping suggest odor perception is governed by thalamic and hypothalamic circuits. Taken together, we describe a unique model for investigating the environmental, genetic, and neurological mechanisms underlying olfactory evolution in vertebrates.