Polar bears and brown bears continued to mate long after the species split.

Polar bears and brown bears were still mating with each other long after they split into two distinct species, a new study has found.

The two species are known to have split between 1.3 and 1.6 million years ago, but new genomic evidence suggests they have inherited traits from each other much more recently.

Scientists from the US, Mexico and Finland analyzed the genomes of 64 modern polar and brown bears, as well as that of an ancient polar bear that lived up to 130,000 years ago.

While evidence of hybridization has been found in both grizzly and polar bear genomes, the latter carrying a particularly strong brown bear DNA signature.

As global warming continued to melt Arctic sea ice, the two bear species may meet more often, their shared evolutionary history may become more significant.

It could influence how the Arctic-adapted polar bear adapts to life in a warmer climate, to which its grizzly cousins ​​are already more inclined.

The subfossil jaw of a polar bear that lived 115,000 to 130,000 years ago in Norway’s Svalbard archipelago. A genomic study includes an analysis of DNA extracted from a tooth attached to this jawbone, which showed evidence of hybridization in polar and grizzly bears.

Researchers estimate that polar bears and brown bears began to become distinct species between 1.3 and 1.6 million years ago.

The interbreeding of polar and brown bears, along with limited fossil evidence of polar bears, has made it difficult to pinpoint how long ago the two species split.

The researchers estimate that polar bears and brown bears began to become distinct species between 1.3 and 1.6 million years ago. The interbreeding of polar and brown bears has made it difficult to pinpoint how long ago the two species split.

HOW DO WE MEET POLAR BEARS AND BROWN BEARS MADE WITH EACH OTHER?

researchers analyzed the genomes of 64 modern polar and grizzly bears, including several new genomes from Alaska – a state where both species are found

They produced a newmost complete genome for a polar bear that lived 115,000 to 130,000 years ago in Norway’s Svalbard archipelago, from a tooth attached to a subfossil jaw

Using this dataset, the researchers estimate that polar bears and brown bears began to become distinct species between 1.3 and 1.6 million years ago.

They also concluded that polar bears suffered a dramatic population decline after they became their own species.

This, in turn, reduced the variation in the gene pool and left polar bears with much less genetic diversity than brown bears.

Polar bears were eventually found to carry more evidence of brown bear DNA than the other way around, despite the hybridization of both species.

“We found evidence of crosses between polar bears and brown bears that predate an ancient polar bear that we studied,” said Charlotte Lindqvist, associate professor of biological sciences at the University of Buffalo College of Arts and Sciences.

“Furthermore, our results demonstrate a complicated and intertwined evolutionary history between brown and polar bears, with the main direction of gene flow going to polar bears from brown bears.

“This reverses a hypothesis suggested by other researchers that gene flow was unidirectional and entered brown bears around the peak of the last ice age.”

This hybridization of the two types of bears reflects complexities also seen in the evolutionary history of humans.

Scientists once thought that modern humans and Neanderthals simply split into separate species after evolving from a common ancestor.

So the researchers found Neanderthal DNA in modern Eurasian people, implying that at some point modern human populations received an influx of Neanderthal genes.

They also found evidence of modern human DNA within the Neanderthal genome, demonstrating that interbreeding can affect the genomes of both species.

Dr. Lindqvist continues: ‘Species formation and maintenance can be a confusing process,

“What happened to polar bears and brown bears is a perfect analogue of what we are learning about human evolution: that the division of species can be incomplete.

“As more and more ancient genomes were recovered from ancient human populations, including Neanderthals and Denisovans, we are seeing that there was multidirectional genetic mixing going on as different groups of archaic humans mated with ancestors of modern humans.

‘Polar bears and brown bears are another system where you see this happening.’

Genomes analyzed in a new study of bears include that of this bear, pictured here in 1995 on the northern slopes of Alaska.  Scientists have wondered if this bear could be a hybrid of a grizzly bear and a polar bear, but the new research has found that

Genomes analyzed in a new study of bears include that of this bear, pictured here in 1995 on the northern slopes of Alaska. Scientists have wondered if this bear could be a hybrid of a grizzly bear and a polar bear, but the new research has found that “this bear is not a hybrid, but simply a light-colored brown bear,” says biologist Charlotte Lindqvist, from the University at Buffalo.

The researchers analyzed the genomes of 64 modern polar and brown bears, including several new genomes from Alaska, a state where both species are found, to obtain their results.

The researchers analyzed the genomes of 64 modern polar and brown bears, including several new genomes from Alaska, a state where both species are found, to obtain their results.

Researchers at the University at Buffalo in the US, the National Genomics for Biodiversity Laboratory in Mexico and the University of Oulu in Finland analyzed the genomes of 64 modern polar and brown bears, including several new genomes from Alaska, a state where both species are found.

They also produced a newmost complete genome for a polar bear that lived 115,000 to 130,000 years ago on Norway’s Svalbard archipelago.

Ancient polar bear DNA was extracted from a tooth attached to a subfossil jaw – the skeletal remains of a bear that is not old enough to be considered a true fossil.

Using this dataset, the researchers estimate that polar bears and brown bears began to become distinct species between 1.3 and 1.6 million years ago.

The interbreeding of polar and brown bears, along with limited fossil evidence of polar bears, made this age difficult to pinpoint.

Scientists also concluded that polar bears suffered a dramatic population decline after they became their own species.

This, in turn, reduced the variation in the gene pool and left polar bears with much less genetic diversity than brown bears.

Polar bears ultimately carry more evidence of brown bear DNA than the other way around, despite the hybridization of both species.

Previous research suggested that the opposite would be the case.

Kalle Leppälä, a postdoctoral researcher at the University of Oulu, said: “It is exciting how DNA can help reveal the history of ancient life.

“The direction of gene flow is more difficult to determine than just its presence, but these patterns are vital to understanding how past adaptations were transferred between species to give modern animals their current characteristics.”

Luis Herrera-Estrella of the Texas Department of Plant and Soil Technology added: “Population genomics is an increasingly powerful toolbox for studying the evolution of plants and animals and the effects of human activity and climate change on endangered species,

‘Bears don’t provide simple speciation stories any more than human evolution. This new genomics research suggests that groups of mammalian species may hide complicated evolutionary histories.’

The findings were published today in the journal Proceedings of the National Academy of Sciences.

Humans and Neanderthals were frequent lovers: DNA tests show the two species interbred ‘many times’ over 35,000 years

Early humans had sex with Neanderthals and other early cousins ​​far more often than previously thought, according to a 2018 study

DNA tests on ancient remains show the two species interbred at ‘various points in time’ over the 35,000 years they shared the Eurasian plains.

Researchers said that interbreeding began shortly after humans came into contact with Neanderthals, after they began to leave Africa around 75,000 years ago.

Previous studies have shown that about 2% of our DNA is made up of Neanderthal genes, passed down when they mated with our ancestors.

Data from the 1,000 Genomes project – which mapped the DNA of 1,000 people from around the world – suggests a more promiscuous relationship.

It was a complex web of sexual encounters in which individuals had sex with members of their own group – and different hominids.

Recent studies have found that Denisovans, another extinct relative, also had sex with Neanderthals and humans on multiple occasions.

Using AI (artificial intelligence), the researchers found that the different patterns of DNA in modern humans are explained by various periods of interbreeding between Neanderthal, East Asian and European populations.

Evidence comes from samples such as an early human skull belonging to an individual dubbed Oase 1 that was unearthed in Romania in 2002.

Denisovans (artist's impression), another extinct relative, had sex with Neanderthals and humans on several occasions

Denisovans (artist’s impression), another extinct relative, had sex with Neanderthals and humans on several occasions

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