Eastern and Western house mice took parallel evolutionary paths after colonizing US

Parallel evolution is common, but do different animal populations evolve in similar ways and alter the same genes to adapt to similar environmental conditions? Researchers tested this in two U.S. populations of house mice. They found independent evolution of a heavier body and larger nests as Eastern and Western populations invaded northern habitats after introduction from Europe. Many of the same genes changed allele frequency along with the increase in body mass.