|By Tyler MacDonald | 9 months ago|
A new study discovered that approximately 0.9 to 2.4 percent of living brown bears’ DNA can be traced back to the extinct cave bears species, which died out approximately 24,000 years ago.
The discovery is the second time that scientists have discovered the DNA of extinct ice-age creatures in living relatives.
“By any standard definition, [cave bears] are extinct, but it doesn’t mean that their gene pool is erased, because they continue to live on in the genomes of these living animals,” said Axel Barlow, a postdoctoral researcher at the University of Potsdam and one of the lead authors of the study.
The data also suggests that some species interbreed regularly. For example, the DNA of Tibetan cattle and yak exhibit signs of interbreeding.
“The old-fashioned idea of a species [is that] it’s reproductively isolated from other species,” said Rasmus Nielsen, a geneticist at the University of California who wasn’t involved in the study. “This paper is a part of a series of papers that have been saying that worldview really is wrong.”
And since animal genomes are so massive, there’s plenty of room for variation in some genes. Just by chance alone, similar genes located in distantly related animals can appear similar, and identical genes in closely related animals can appear different.
“If we get an overabundance of genome positions where cave bears and brown bears are showing more similarity to each other than to polar bears, then something else must have happened,” Barlow said. “And that something is hybridization between the two species.”
The findings were published in Nature Ecology and Evolution.