1Anthropology, Washington University at St. Louis, 2Anthropology and Archaeology, University of Calgary, 3Cumming School of Medicine, University of Calgary
April 14, 2016 1:45, A 602
Mammals rely heavily on smell, however this varies across and within taxa. Genomic comparisons reveal substantial variation in genes encoding main olfactory receptor proteins (OR genes) and vomeronasal proteins (VR genes). While both olfactory systems have overlapping functions, evidence supports the vomeronasal system’s role mediating innate responses to chemosignals, with the main olfactory system mediating conditioned responses. Given the importance of olfaction in intraspecific signaling, we hypothesize that the vomeronasal system and main olfactory system are partly shaped by grouping and sociality. Solitary mammals with little regular conspecific contact may rely heavily on innate olfactory responses mediated by the vomeronasal system, while group living social mammals may mediate these cues via main olfaction. We collected data on OR and V1R genes from the literature on 80 mammal species, including 55 primates. Data on home range size and social group size were collected from the PanTheria database as proxies for proximity and sociality. We ran phylogenetically corrected regressions on log-transformed values of intact OR and V1R genes against home range size and social group size. We found no statistical relationship between measures of home range or sociality and OR genes; but a significant relationship between all predictor variables and V1R genes. Particularly, mammals with larger home ranges and social groups have fewer intact V1R genes. These results support the hypothesis that solitary mammals rely more on vomeronasal-mediated olfaction. The implication for primate evolution is that increased gregariousness in haplorhines, especially anthropoids, may have contributed to relaxed selection on their vomeronasal system.