Climate change appears to have driven a large-scale hybridization event in the Arctic between two subspecies of puffins. In the wake of warming temperatures in northern Norway, the habits of the two family members have merged and seemingly resulted in prolific canoodling between the pair.
The large-bodied subspecies of Atlantic puffins (Fratercula arctica naumanni) used to primarily live on the island of Spitsbergen in Svalbard, while the smaller subspecies (F. a. arctica) lived further south on the island of Røst off the coast of mainland Norway. Halfway between these two habitats is Bear Island, which was recently found to be the home to a colony of hybrids created by the two subspecies mating.
In a new study, scientists at the University of Oslo collected blood samples from the array of puffins that inhabit this part of the High Arctic and carried out a genetic deep dive. They also managed to get their hands on the genomes of 22 puffins that lived between 1868 and 1910 on Spitsbergen, Røst, and Bear Island.
The two subspecies diverged from a common ancestor at least 40,000 years ago, but their DNA indicates there has been prolific interbreeding over the past century. Before 1910, all the puffins on Bear Island belonged to the subspecies F. a. arctica. After this, however, the genetic makeup of puffins here becomes increasingly infiltrated by the other subspecies, F. a. naumanni.
The researchers argue the rate of hybridization is linked to the rising temperatures seen in the Arctic over the past century.
“While fishery-induced food shortages or pollution are harmful factors that cannot be ruled out, the estimated onset of hybridization notably coincides with the beginning of the 20th-century Arctic warming, where sea-surface temperature increased by up to 1.5°C [2.7°F],” the study authors write.
Typically, Arctic species migrate northwards in response to climate change, heading further towards the poles in search of cooler temperatures. In a break away from this general rule, the puffin hybridization was caused by the larger birds of Spitsbergen flying south to Bear Island.
Hybridization can go either way for a species. In some instances, it can prove detrimental to their survival; in others it can embolden their existence by enriching their genetic diversity. It doesn’t seem that this hybridization is hurting the High Arctic’s puffin population, although it is clear their demographics are being radically shifted by the great specter of climate change.
“Although hybridized individuals have been observed in several Arctic species (e.g., polar bear and beluga whale), we provide the first genomic evidence for the recent establishment of an entire hybrid population driven by a southward distributional shift. Our findings present a rare observation of a population-scale response to the rapid environmental changes that the Arctic ecosystem has started experiencing within the past century,” the study authors conclude.
The study is published in the journal Science Advances.