Global warming is getting worse every year, with record breaking temperatures being recorded worldwide. The Earth, as we know it, will soon forever change the way it looks. With Arctic sea ice melting a bit more each year, a few generations from now might not even know the globe used to be white at the poles.
Polar bears have often been associated with climate change. Their numbers keep decreasing as more and more animals starve to death due to the lost of hunting ground. The sea ice is where polar bears find their food, their favourite being seals. But with the polar cap melting, each year they are pushed further south in their search for food. On the other hand, warming temperatures are pushing grizzly bears higher north. And this is how a new species appeared.
The first pizzly, or grolar, bear to be recorded was found by a hunter in the Northwest Territories of the Canadian Arctic in 2006. From a distance, it looked enough like a polar bear, but once the man got close, he realised it had peculiar characteristics. The fur was cream-white, like a polar bear’s, but the animal had brown patches. Moreover, it had long claws, a humped back and a shorter snout, characteristics of a grizzly bear. Subsequent DNA tests confirmed the specimen was indeed a hybrid.
We’ve known about pizzlies for quite some time, but their occurrence may be more common with ongoing Arctic warming.
Larisa DeSantis, associate professor of biological sciences, Tennessee Vanderbilt University
Polar bears can encounter grizzlies at common feeding rounds, for example around whale carcases, and can engage “opportunistic mating”, giving birth to the pizzlies, Larisa DeSantis, associate professor of biological sciences at Tennessee’s Vanderbilt University explained. However, unlike other hybrid species who cannot reproduce, because polar bears and grizzlies only diverged 500,000 to 600,000 years ago, the pizzlies can have offspring of their own, one study recording a specimen as a result of a pizzly mating with a grizzly.
Sightings of pizzly bears have been increasing since 2006. A study published in the Arctic journal in 2017 traced 8 pizzly hybrids to a single polar bear female that had mated with two different grizzly bear males. At the same time pizzly populations grow, polar bear ones decline, whose numbers are expected to decrease by 30% in the next 30 years, according to a study published in the Biology Letters journal in 2016.
Moreover, the pizzlies seem to have an advantage in the new environment compared to polar bears, anther unusual feature for a hybrid species. “Usually hybrids aren’t better suited to their environments than their parents, but there is a possibility that these hybrids might be able to forage for a broader range of food sources”, DeSantis told Live Science.
The polar bear’s longer skulls give them an advantage when hunting seals in the water, but because they eat mostly blubber (a thick layer of soft tissue, rich in fat, found under cetaceans’ skin), their molars are smaller than is typical for their body size. On the other hand, grizzlies have a very diverse diet. The combination of the two, resulting in an intermediate skull, could potentially offer pizzlies a biomechanical advantage.
Since the ecosystem is “deviating from what it once was”, the pizzlies could end up replacing polar bears if the latter do not manage to adapt. “Polar bears consumed soft foods even during the Medieval Warm Period, a previous period of rapid warming. Their diets haven’t changed much at all. It’s why what we’re seeing now, all of these starving polar bears trying to find alternative food sources, could really represent a tipping point”, DeSantis emphasised.
