Expressed vomeronasal type-1 receptors (V1rs) in bats uncover conserved mechanisms of social chemical signaling

Abstract

In mammals, social and reproductive behaviors are mediated by chemical cues encoded by hyperdiverse families of receptors expressed in the vomeronasal organ. Between species, the number of intact receptors can vary by orders of magnitude. However, the evolutionary processes behind variation in receptor number, and also its link to fitness-related behaviors are not well understood. From vomeronasal transcriptomes, we discovered the first evidence of intact vomeronasal type-1 receptor (V1r) genes in bats, and we tested whether putatively functional bat receptors were orthologous to those of related taxa, or whether bats have evolved novel receptors. We found that V1rs in bats and show high levels of orthology to those of their relatives, as opposed to lineage-specific duplications, and receptors are under purifying selection. Despite widespread vomeronasal organ loss in bats, V1r copies have been retained for >65 million years. The highly conserved nature of bat V1rs challenges our current understanding of mammalian V1r function and suggest roles other than conspecific recognition or mating initiation in social behavior.