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How Species Form: The Complex History of Polar Bears and Brown Bears

How Species Form: The Complex History of Polar Bears and Brown Bears

The team also created a new, more complete genome of a polar bear that lived 115,000 to 130,000 years ago in the Norwegian archipelago of Spitsbergen. The DNA of this ancient polar bear was extracted from a tooth attached to the jawbone beneath the fossil.

Using this data set, the researchers estimated that polar bears and brown bears began turning into different species about 1.3 to 1.6 million years ago. However, the moment of the split has been and will remain a matter of debate. Previous interbreeding and the limited fossil remains of ancient polar bears are factors that make timing difficult, Lindqvist said.

In any case, the study concluded that after becoming a separate species, polar bears experienced a dramatic decline in their numbers and experienced long-term genetic suffocation. As a result, these bears have much smaller genetic diversity than brown bears. These results confirm previous research that pointed in the same direction and provide more evidence to support this hypothesis.

In addition to analyzing gene transfer and gene flow, this study provides new insights into the chaotic and intertwined evolutionary history of polar bears and brown bears, the researchers said.

The international team’s study was published in Proceedings of the National Academy of Sciences (PNAS)† The team included scientists from the University of Buffalo (UB), Langebiu in Mexico, Texas Tech University, the University of Oulu, Far Northwestern Institute of Arts and Sciences, Alaska Department of Fish and Game, and the university’s Museum of Natural History. Oslo, Nanyang Technological University in Singapore, University of Helsinki, and Aarhus University in Denmark. Tianying Lan, a former postdoctoral researcher at the University at Buffalo, was the study’s lead author along with Kali Lipala. This article is based on a press release from the University Library.

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