This New Hybrid Bear is About to Take Over

In 2006, Jim Martell, a trophy hunter from Idaho, shot what he thought was a polar bear in the northern Canadian Arctic. Officials took interest in the creature after noticing that while it did have thick, creamy white fur typical of polar bears, it also had long claws, a humped back, a shallow face, and brown patches around its eyes, nose, back, and foot, which are all traits If the bear had been adjudicated to be a grizzly, the hunter would have faced a possible $1,000 Canadian dollar fine and up to a year in jail. A DNA test was conducted and the results were surprising. This was neither a grizzly bear nor a polar bear, but rather a hybrid of both. With a polar bear mother and a grizzly bear father, this marked the discovery of the first ever pisley bear, also known as the growler bear. Over the years to come, subsequent discoveries have been increasing with a 2017 study in the journal Arctic showing eight hybrids springing from a single female polar bear who mated with two grizzly bears. What's fascinating is that the polar bear and grizzly bear are two very different kinds of bears. They are two very separate species and yet they can still interbreed. The pisley's takeover coincides with the polar bear's decline. The WWF projects that global polar bear numbers are to decline by 30% by 2050. As the world has warned, temperatures in the Arctic have risen about twice as fast as they have elsewhere in a phenomenon known as Arctic amplification. The rapid changes to the Arctic environment have resulted in declining sea ice, which the polar bears depend on to hunt, but scientists also believe it is allowing grizzly bears to expand their territories further north. But their occurrence may be more common with ongoing Arctic warming. As grizzlies move north, they are more likely to come in contact with polar bears in regions where their ranges overlap. Both grizzlies and polar bears have been known to co-occur at bowhead whale carcass sites and while there engage in opportunistic mating. The result is that grizzly bear ranges are now within polar bear ranges and the two species are coming into contact with each other with greater regularity. What is particularly interesting about this new bear hybrid is that they can produce fertile offsprings. Many other hybrids including zorses and zonkeys are sterile, meaning that although they still display normal breeding behavior, they are unable to produce an offspring of their own. In 2010, scientists confirmed that a bear shot by a hunter was in fact a second generation pisley bear. How is this possible? We know that polar bears and grizzlies only diverged about 500 to 600,000 years ago. There's also evidence of times when polar bear DNA has become integrated with grizzly bear DNA. Take horses and donkeys which probably diverged about 2.4 million years ago. Horses have 64 chromosomes while donkeys have 62 and when they mate their chromosomes don't pair up properly As a result, mules are sterile. Brown bears and polder bears, by contrast, evolved from the same ancestor only about 500,000 years ago, a relatively brief period, and have not developed significant genetic differences. The pisley bear might not be the only hybrid to come out of the Arctic in upcoming years. Some scientists believe that global climate change could cause the hybridization of many arctic animals, particularly marine mammals. In 2009, a cross between a bowhead and a right whale was spotted in the Bering Sea between Alaska and Russia. In 2019, researchers confirmed the only known specimen of a beluga narwhal hybrid, also known as a narluga. While it is certainly fascinating to explore the world of hybrids, we shouldn't get lost daydreaming about our dream After all, the existence of many hybrids can be bad for the natural world. If hybrids are successful, they may be so many hybrids that they compete with their parent species for food and living space. This could lead to the extinction of the parent species. While the pisley bear certainly is a marvel, we don't want to lose either the grizzly bear or the polder bear. Hybridization is a complex process involving the mixing of two species. Hybridization is an important part of evolution due to the transfer of genes through introgression and its role in the generation of new species. The fact that there is currently more hybridization in the wild than in captivity suggests an evolutionary response to pressure imposed by humans, but at this point it is unclear whether the hybrids are more vigorous and better able to adapt to a specific environment, particularly if the environment is deviating from what it once was. This is an area that requires far more study and research. Is this mother nature giving polder bears a better chance of long-term survival? Processor of biological sciences Dr. Larissa DeSantis says, unfortunately, what we are learning about the polder bear and what we've known about other hyper-specialized apex predators in the past, such as saber-toothed cats, does give us reason to be concerned with the ability, or rather inability, of polder bears to adapt to the warming arctic. The hybrids do have certain features, such as intermediate skull forms, that may make them better suited for eating mechanically challenging food, but this comes with trade-off, such as not being as robust swimmers as polder bears. Time will tell if these hybrids are able to withstand a warming arctic.