Abstracts (first author)
Evolution of two multigene families involved in subspecies recognition and sexual isolation in the house mouse: insights from a transcriptomic and genomic perspective
The two subspecies of the house mouse Mus musculus musculus and M. m. domesticus have evolved in allopatry for half a million years before meeting secondarily in Europe 5000 years ago, forming a narrow hybrid zone with unfit hybrids. Previous studies have shown that these incipient species recognise each other through signals present in urine and mate assortatively in the contact zone. This suggests a reinforcement process in this zone where prezygotic isolation would evolve as a response to selection against hybridisation. Our study addresses the genetic basis of sexual isolation between these two subspecies by analyzing divergence of two large multigene families involved in chemosensory recognition. On the signaling side, we focused on the Major Urinary Proteins (MUP), a cluster of more than 21 duplicated genes known to act as pheromones in the house mouse. On the reception side, we focused on their potential receptors, the vomeronasal receptors (VR), a very large multigene family composed of more than 200 genes, expressed in the vomeronasal organ of the mouse and known to be involved in pheromone recognition. Since assortative mating is displayed in the hybrid zone, we predicted strong sign of divergence between the two subspecies at our candidate families provided that they are involved in sexual isolation. Moreover, if reinforcing selection is acting on the mate recognition system in the hybrid zone, we expected a stronger signature of selection in the genomic regions baring VR and MUP genes in individuals of the hybrid zone as compared to individuals residing in allopatric zones of the distribution range. By combining several high-throughput genomic methods such as RNA-seq and exome sequencing, we tested these predictions and explored divergence affecting the VR and MUP gene families at the sequence, expression and structural levels.