Meeting Abstract
Olfactory receptor genes are the largest family of protein-coding genes in the mammalian genome, and how natural selection has influenced these odorant detectors remains largely unknown. New World Leaf-nosed bats (Phyllostomidae) occupy an enormous range of dietary niches and have evolved a high diversity of sensory adaptations to find food. While previous research has established that the number of functional olfactory receptors is greater in plant-visiting phyllostomids than in insectivorous bats, the molecular evolution of these genes has not been analyzed. To identify and compare olfactory receptor gene sequences across phyllostomids with divergent diets, we generated transcriptomes from olfactory epithelial tissues. We characterized unique sets of receptors shared only among plant-visiting bats, which may have resulted from recent duplications generating new receptors required for identifying plant resources. Several homologous receptors detected in frugivorous and nectarivorous species were nonfunctional in insectivorous species, suggesting plant-visiting bats have undergone strong purifying selection to maintain olfactory receptor function. Concurrently, bats relying on alternative sensory adaptations (e.g. echolocation) may have experienced relaxed selection on homologs. Finally, we tested for diversifying selection in functional orthologous receptors across species and found evidence of several olfactory receptors under positive selection, consistent with the neofunctionalization of receptors for discriminating fruit and flower odors. Our study illuminates how the evolution of olfactory receptors may have opened up novel dietary niches for bats.
