Last year I had posted about the Norwegian lemming, (Lemmus lemmus) an iconic small mammal that is unique to the Fennoscandian mountain tundra. Known for its dramatic fluctuations in population size, it is a keystone species in the mountain tundra ecosystem. As lemmings function as the main trophic link between vegetation and predators in most tundra ecosystems, their high amplitude population density cycles often have a major impact on tundra food webs.
However the origin of the Norwegian lemming has until now remained somewhat of a mystery but a new ancient DNA study shows that it has quite a unique history.
Twenty thousand years ago, Fennoscandia was covered by a thick ice sheet. Animals and plants in the region are therefore thought to originate from populations that lived to the south or east of the ice sheet, and colonized the region as the ice retreated. With this in mind, and international team of scientists, led by researchers at the Swedish Museum of Natural History, set out to investigate from where the Norwegian lemming originated at the end of the last Ice Age. To do this, the researchers analysed ancient DNA from lemming populations that surrounded the ice sheet during the last Ice Age. The study used DNA from 54 Late Pleistocene Lemming jaw bones 12 000 to 48 000 years old and collected from 11 paleontological sites across the genus' glacial range in mid-latitude Europe. The researchers used a combined data set of fragments of the mitochondrial control region and cytochrome b.
While populations surrounding the ice sheet were closely related to modern day lemmings, none of them were similar enough to be the direct ancestor of the Norwegian lemming. After eliminating these populations as potential sources, the colleagues concluded that the only remaining explanation was that the Norwegian lemming originates from a population that may have survived the last Ice Age in the far north, sealed off from the rest of the world by gigantic ice sheets. The exact location where the Norwegian lemming could have survived is not clear, but likely places include coastal areas or mountain plateaus sticking out from the ice sheet.
A fascinating new story about this adorable and quite resilient creatures.