Variation in the coat-color-controlling genes, Mc1r and Asip,in the house mouse Mus musculus from Madagascar

Variability in the coat color of the house mouse, Mus musculus, provides an opportunity to study the evolution of phenotypes in this species. Here we associated genetic variations with coat color in seven mice from Madagascar that had identical M. m. gentilulus mitochondrial DNA sequences. The entire coding region of the 948-base pair (bp) coat-color-related gene, Mc1r, was shown to have no nonsynonymous changes. However, analyses of the two exon-1 promoter regions—termed 1A (317 bp) and 1B (499 bp)—from a second gene, Asip, which is also involved in the evolution of coat color, revealed two distinct haplotypes in each region. Associations between Asip promoter regions and dorsal color were ambiguous; however, two ventral color types—light and dark gray—were associated with the haplotypes of 1A, as determined by clustering analysis. Notably, the haplotype of the light gray animals was identical to the Asip Aw allele that is associated with white bellies

Whole-genome sequencing analysis of wild house mice (Mus musculus) captured in Madagascar

In Madagascar, the house mouse (Mus musculus) is widely believed to have colonized with human activities and is now one of the most abundant rodents on the island. However, its genetic background at the genomic level remains unclear, and clarifying this would help us to infer the timing of introduction and route of migration. In this study, we determined the whole-genome sequences of five Madagascar house mice captured from an inland location in Madagascar. We examined the genetic background of samples by analyzing the mitochondrial and autosomal genomes. We confirmed that the mitochondrial genome lineages of collected samples formed a single clade placed at one of the most basal positions in the Mus musculus species. Autosomal genomic sequences revealed that these samples are most closely related to the subspecies M. m. castaneus (CAS), but also contain a genetic component of the subspecies M. m. domesticus (DOM). The signature of a strong population bottleneck 1,000-3,000 years ago was observed in both mitochondrial and autosomal genomic data. In a comparison with global samples of M. musculus, the Madagascar samples showed strong genetic affinity to many CAS samples across a wide range of Indian Ocean coastal and insular regions, with divergence time estimated as around 4,000 years ago. These findings support the proposition that the ancestors of these animals started to colonize the island with human agricultural activity and experienced a complex history during their establishment