House mice in New York and Alberta independently evolved to have large bodies and build bigger nests to cope with the cold, according to a study publishing April 29th in the open-access journal PLOS Genetics by Kathleen Ferris and colleagues at the University of California, Berkeley.
As house mice began to colonize North America 200 - 300 years ago, populations encountered radically different temperatures to their native range in Europe. To understand how they adapted genetically, physically, and behaviorally, the researchers captured wild house mice (Mus musculus domesticus) from five populations along the west coast of North America, from Arizona to Alberta. They sequenced the genomes of 50 mice and returned 41 mice to the lab to establish breeding populations. Lab-reared descendants of mice from Alberta were significantly heavier than those of mice from Arizona and built nests twice the size, both adaptations to colder climates. A genome-wide survey identified eight mutations in five genes associated with increased body size in the Albertan mice.
Comparing the data to the results from a previous study of house mice in New York and Florida, they found 16 genes that showed parallel evolution along the north-south gradient on both coasts, many of which are involved in regulating body temperature. For example, Trpm2 - a gene that causes mice to avoid very high temperatures - showed genetic changes in southerly populations. Mice on the east and west coasts exhibited evidence of independent evolution in many of the same genes, but each coast also harbored unique genetic adaptations, which the authors suggest may be a result of distinct regional features such as rainfall and soil color.
Nachman and Ferris add, "Since their initial colonization of the Americas a few hundred years ago, house mice have independently adapted to cold environments in eastern and western North America by becoming larger and building bigger nests. By looking across the genome, we found that adaptation to latitudinal gradients in the east and west has involved a mixture of parallel and unique genetic changes."
Peer-reviewed; Experimental study; Animals
In your coverage please use this URL to provide access to the freely available article in PLOS Genetics: http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1009495
Citation: Ferris KG, Chavez AS, Suzuki TA, Beckman EJ, Phifer-Rixey M, Bi K, et al. (2021) The genomics of rapid climatic adaptation and parallel evolution in North American house mice. PLoS Genet 17(4): e1009495. https://doi.org/10.1371/journal.pgen.1009495
Funding: ASC was supported by an NSF postdoctoral Fellowship (PRFB-1402539). This work was supported by NIH grants to MWN (RO1 GM074245 and R01 GM127468). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.