ABOVE: A North American caribou (Rangifer tarandus) in Jasper National Park in Canada Mark Bradley, Parks Canada


Each spring and fall, groups of caribou (Rangifer tarandus) undertake marathon migrations of up to 400 kilometers, the longest of any land animal. “It’s a phenomenal behavior,” says University of Calgary wildlife ecologist Marco Musiani. Recently, he and other scientists started teasing apart the environmental and genetic contributions to these long-distance journeys, yielding findings that might explain why some subpopulations of caribou travel less far or frequently than others.

Musiani and his colleagues tracked the movements of 139 female caribou wearing GPS collars and classified the animals either as more sedentary or more migratory. Sequencing parts of their genomes, the team identified 57 single-nucleotide polymorphisms (SNPs) associated with migration, 27 of which were found in or linked to genes thought to influence migratory behavior in other species as well. These genes spur changes in energy metabolism, hormone production, body development, and brain activity. Ancestry seemed to play a role in migratory behavior, too. Caribou of the barren-ground subspecies, which live in harsh, variable conditions, made significantly longer hauls than their woodland counterparts, including caribou of the Northern mountain and boreal ecotypes, even when controlling for location.

Francisco Pulido Delgado, a zoologist at the Complutense University of Madrid who was not involved in the research, calls the use of GPS tracking “the biggest strength of the study,” but adds that without knowing how the SNPs affect surrounding genes, future research will be necessary to determine the specific mechanisms driving migratory behavior.

Tying migration to particular genes in caribou could have conservation implications, Musiani says. “With the expansion of human populations and with the increase in human infrastructure, these animals that migrate are having additional difficulties” and declining in numbers. Future selective breeding programs may want to matchmake caribou, he explains, with the goal of maintaining variation in these migration-associated genes.

M. Cavedon et al. “Genomic legacy of migration in endangered caribou,” PLOS Genet, 18:e1009974, 2022.