Genome Sequencing Reveals Why Songbirds Are Larger in Colder Climates

Scientists have unlocked the genetic basis underlying the remarkable variation in body size observed in song sparrows, one of North America’s most familiar and beloved songbirds. This discovery also provides insights into this species’ capacity to adapt to the challenges of climate change. The study, published on November 7, 2023 in Nature Communications, used genomic sequencing to successfully pinpoint eight genetic variants, or DNA mutations, largely responsible for the nearly threefold difference in body size observed across the song sparrow range from Mexico to Alaska. For instance, song sparrows that live year-round in the Aleutian Islands can be up to three times larger than their counterparts in the coastal marshes of California. The open-access article is titled “Candidate Genes Under Selection in Song Sparrows Co-Vary with Climate and Body Mass in Support of Bergmann’s Rule.”