Genetics plays huge part in animal migration - study

Reindeer, known as caribou in North America, make one of the longest seasonal migrations of land animals, but their propensity to migrate depends on genetic ancestry, according to a study in the journal PLOS Genetics.

Researchers from the University of Calgary, Princeton, Liverpool John Moores and elsewhere used GPS tracking and DNA sequencing to investigate the genetic drivers of migratory behaviour in 139 female reindeer (Rangifer tarandus) living in tundra or woodland habitats across western North America. 

They identified over 50 genetic mutations associated with migratory behaviour, of which 27 were located in genes involved in brain activity, fat and energy metabolism, body development, or hormone production.

Genes outlast millienia

The sequences clustered into northerly and southerly subpopulations, descended from ancestral reindeer that were trapped either side of the Rocky Mountains during the last glaciation. Despite generations of hybridization since the glaciation ended around 11,000 years ago, the researchers found that animals with a greater proportion of genes from northern ancestry were more likely to migrate longer distances.

Migratory individuals travelled nearly 250 kilometres on average, ten times further than sedentary reindeer.

“These results indicate an evolutionary legacy from the last glaciation, when northerly reindeer had to migrate to survive in harsh tundra environments, while southerly populations living in forests could afford a sedentary lifestyle," explained Professor Stefano Mariani of LJMU's School of Biological and Environmental Sciences.

Catastrophic effects

The study is the first to investigate the genes influencing migration in an endangered terrestrial mammal.

"Wide-ranging animals, including migratory species, are significantly threatened by the effects of habitat fragmentation and habitat loss," said lead author Maria Cavedon.

"If, as we report, migratory behaviour is influenced by genes, caribou could be further impacted by the loss of the migratory trait in some isolated populations already at low numbers."

And Prof Mariani added: “The reindeer is an emblematic case: a large land animal whose migratory behaviour has evolved for survival. But the effects of climate change and habitat loss reach farther than just reindeer: similar genetic heritage mechanisms are likely common to many other organisms. If we lose these genetic variants, we’re looking at catastrophic effects on ecosystems.”

Original paper in open access:

Maria Cavedon, Bridgett vonHoldt, Mark Hebblewhite, Troy Hegel, Elizabeth Heppenheimer, Dave Hervieux, Stefano Mariani, Helen Schwantje, Robin Steenweg, Jessica Theoret, Megan Watters, Marco Musiani. Genomic legacy of migration in endangered caribou. PLOS Genetics, 2022; 18 (2): e1009974 DOI: 10.1371/journal.pgen.1009974