Inference of Selective Force on House Mouse Genomes during Secondary Contact in East Asia

Abstract

AbstractThe house mouse (Mus musculus), commensal to humans, has spread globally via human activities, leading to secondary contact between genetically divergent subspecies. This pattern of genetic admixture can provide insights into the selective forces at play in this well-studied model organism. Our analysis of 163 house mouse genomes, with a particular focus on East Asia, revealed substantial admixture between the subspeciescastaneusandmusculus, particularly in Japan and southern China. We revealed, despite the admixture, all Y chromosomes in the East Asian samples belonged to themusculus-type haplogroup, potentially explained by genomic conflict under sex ratio distortion due to varying copy numbers of ampliconic genes on sex chromosomes. We also investigated the influence of selection on the post-hybridization of the subspeciescastaneusandmusculusin Japan. Even though the genetic background of most Japanese samples closely resembles the subspeciesmusculus, certain genomic regions overrepresented thecastaneus-like genetic components, particularly in immune-related genes. Furthermore, a large genomic block containing a vomeronasal/olfactory receptor gene cluster predominantly harboredcastaneus-type haplotypes in the Japanese samples, highlighting the crucial role of olfaction-based recognition in shaping hybrid genomes.