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Abstract :
[en] Mammals have well-developed olfactory systems and altering the reception of chemosignals can lea d to marked modifications of behavior. Yet we still know little about the molecular logic by which biological information is extracted, how this logic evolves, and if it contributes to differences in natural behavior. North American deer mice (genus Peromyscus) occupy a wide range of habitats, each with distinct interspecific competitors and predators, as well as highly divergent mating systems, from highly promiscuous to both socially and genetically monogamous. Therefore, deer mice represent an exciting system for studying the genetic mechanisms underpinning complex behaviors and social recognition. Here, using a reference-quality chromosome-level de novo genome assembly for Peromyscus maniculatus bairdii, we first show contrasting evolutionary trajectories between the olfactory and vomeronasal (VNO) subsystems in rodents. While the complements of receptor families expressed in the MOE are largely shared, we found that the receptor repertoire of the VNO differ noticeably. Our comparative genomic analyses reveal that a small set of vomeronasal receptor genes have been preserved in the Mus and Peromyscus genomes during evolution. These include several receptors for sulfated steroids and bile acids. Next, by focusing on the evolutionary dynamic VNO, we identify genes with high divergence levels in gene expression as candidates for adaptation. Using the activation of these receptors as readouts, we identify pheromone receptors for which differential regulation correlates with the transition between promiscuity and monogamy. Together, our results provide new insights into the evolution of the mammalian olfactory system and identify differences in the olfactory repertoire that likely contribute to adaptation and the transition in the social behaviors of deer mice, opening new avenues for further investigation into the neural mechanisms underlying behavioral evolution.
