Study reveals the genetic diversity of the wild house mouse

The wild house mouse (Mus musculus) is the most common species of rodents and can be found across the entire world. Although it is most often considered a pest, this mouse has also been domesticated as a pet and laboratory mouse.

Laboratory mice have been invaluable to medical and genetic research as animal models, and their genetic structure has been comprehensively studied. However, until recently, the wild house mouse received much less scientific attention. Now, a research team led by the Hokkaido University has investigated the genetic structure and diversity, as well as the population history, of the wild house mouse in Europe and Asia. Their findings will likely facilitate future biomedical and evolutionary research.

Previous research has revealed that, genetically, wild house mice are highly diverse, consisting of three main subspecies: M. m. musculus from northern Eurasia, M. m. castaneus from southern and southeast Asia, and M. m. domesticus from western Europe. By sequencing the whole genomes of 121 wild house mice, the scientists confirmed that these animals have a greater genetic diversity than humans, with castaneus being the most diverse among the three subspecies. Moreover, samples from Japan and China showed the highest degrees of interbreeding between the musculus and castaneus subspecies.

The researchers also reconstructed the population history of these three subspecies, and found that they diverged between 187,000 and 247,000 years ago, the most recent being the evolutionary split between the musculus and the castaneus. According to the experts, the domesticus and musculus subspecies experienced major population bottlenecks and expansions in the recent past, most likely associated with the worldwide spread of agricultural practices.

These findings suggest that the extent and geographical range of interbreeding between the three subspecies is greater than previously thought, and occurred most likely after their spread alongside human populations. The genomic and evolutionary mappings the experts constructed can significantly contribute to a better understanding of mice models too.

“As the lab mouse was bred from wild house mice, our study paves the way for significantly increasing the understanding of mice models,” concluded study senior author Naoki Osada, a professor of Evolutionary Biology at Hokkaido.

The study is published in the journal Genome Biology and Evolution.  

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By Andrei Ionescu, Earth.com Staff Writer