More and more polar bears are breeding with grizzly bears, whose ranges extend northward, multiplying members of a hybrid species called “Grolar”, or “Pizzly”.
The pizzly, a bear like no other
The first sighting of hybridization between these two species in the wild was recorded in 2006. At the time, a hunter had just shot down what he believed to be a polar bear in the Northwest Territories of l ‘Canadian Arctic. However, on closer inspection, the animal looked unusual, displaying the typical cream fur of a polar bear, but the long claws, hunchbacked back, shallow face, and brown spots of a grizzly.
DNA tests later confirmed that the animal was a hybrid. Genetically, this “mixture” does not pose a real problem. Grizzly bears and polar bears did not divide until 500,000 to 600,000 years ago, so both species can produce viable offspring.
From then on, the observations were multiplied as polar bear populations declined.
This finding is not surprising. Indeed, as the world warms, grizzly bears move north and encroach on the territories of their polar cousins for part of the year. Here where sea ice has decreased by about 870,000 square kilometers compared to its average maximum from 1981 to 2010, grizzly bears cope with several food sources.
For their part, polar bears are highly specialized hunters mainly adapted to evolve on sea ice shelves. They can sometimes attack seabird eggs or reindeer when they are on land. firm, but those calories do not compensate those burned to hunt and find food. Thus, on the same territory, the grizzly bear outstrips the polar bear.
A better adapted hybrid species?
Generally, hybrid species are no better adapted to their environment than their parent species. For the pizzly, some have highlighted the risk of physical and behavioral disorders in these animals which, for example, could have difficulty in resisting the extreme cold as well as the polar bear. Likewise, some hybrids observed in a German zoo showed poorer swimming ability than their polar “cousins”.
However, the “Pizzly” could still get by, estimates a team of researchers.
“On the one hand, polar bears have longer skulls, which makes them experts at catching seals in water”, relief Larisa DeSantis, paleontologist and associate professor of biological sciences at the University of Tennessee. “In contrast, their molars are smaller than typical bears because all they eat is fat all day long.”.
“Grizzly bears, on the other hand, can eat whatever they want,” continues the researcher. “We don’t know yet, but this ‘intermediate pizzly skull’ could ultimately give them a biomechanical advantage”. If this is confirmed, “So it is possible that these hybrids may seek a wider range of food sources”.
In a few decades, if the trend continues, “pizzly” bears could finally completely outshine polar bears, keeping some of their genetic makeup with them. In a sense, and sadly, the pizzly could be the savior of the polar bear, threatened by global warming.