Whole-genome sequencing analysis reveals the population history of Mus musculus in Madagascar

Abstract

In Madagascar, the house mouse (Mus musculus) is thought to have colonized along with humans and is now one of the most successfully colonized rodents on the island. In this study, we determined the whole-genome sequences of the Madagascar house mouse captured from the wild. We examined the evolutionary history of its population regarding the mitochondrial and autosomal genomes. We confirmed that in the mitochondrial genomes of Madagascar house mice, a monophyletic clade forms a basal origin within the species. An analysis of autosomal genomic sequences indicates that the Madagascar house mouse population is genetically a member of M. m. castaneus (CAS). It also contains genetic elements of M. m. domesticus (DOM) resulting from ancient hybridization. The signature of a strong population bottleneck 1000-3000 years ago was observed in the mitochondrial and autosomal genomic data. We also show that the divergence of the Madagascar population from the CAS population occurred approximately 50,000-99,000 years ago. Madagascar house mice show strong genetic affinity to many CAS samples across a wide range of Indian Ocean coastal regions. However, our results suggest that they would not have originated directly from the Indonesian islands, where Austronesian-speaking people in Madagascar originated. Because the ancient hybridization signature with DOM did not appear in the Indonesian and other CAS samples, we propose that Madagascar house mice were not directly brought by Austronesian-speaking people but came from somewhere around the Middle East or South Asia soon after the colonization of initial farmers.

Inference of selective forces on house mouse genomes during secondary contact in East Asia

“…The Y-chromosomal locus formed three distinct haplogroups corresponding to the three major subspecies, whereas the mitochondrial locus showed five major haplogroups. In addition to the three mitochondrial haplogroups representing the subspecies castaneus, domesticus, and musculus, samples from Madagascar and Nepal formed distinct mitochondrial haplogroups, as previously shown (Fujiwara et al 2022a;Fujiwara et al 2022b).…”