by The bear scientists shot in the Canadian arctic in 2016 was a biological mystery. It looked like a grizzly bear, complete with long claws and a prominent snout, but most of its fur was white.
Call it pizzly or maybe growler bear. Either way, scientists have determined that the animal was the rare offspring of a polar bear that mated with a grizzly, and as the Arctic melts and polar bears gradually move onto land, there is an increase in find the number of these hybrids seen.
Pizzly bears aren’t being born in large numbers, said Charlotte Lindqvist, a biology professor at the University at Buffalo whose lab focuses on evolutionary genetics. Accounts of the bears are largely anecdotal, and it is unclear how widespread the phenomenon is.
For example, eight of the bear hybrids were found to be the offspring of a single female polar bear that appeared to be related to male grizzlies.
But as global temperatures rise and the Arctic ice melts, polar bears will be more likely to come into contact with – and mate with – other bear species.
“This may just be the beginning,” Lindqvist told CNN. “The pressure is on, and it is clear to us that in some areas polar bears are spending more time on land and the sea ice is disappearing. Brown and black bears are disrupting more Arctic habitats. And I think that’s just going to expand.”
Gene exchange between bears and other animals and plants (and humans) has been occurring for centuries. Lindqvist’s research found evidence of gene exchange between polar bears and brown bears as far back as 150,000 years ago, suggesting that the species came into contact during natural changes in the climate in the past. Scientists are also studying possible hybridization between Arctic foxes, a cold-acclimated northern species, and the red fox.
But the biggest thing Lindqvist and other scientists are watching is how much this current period of human-caused warming – the fastest by far in millennia – will bring species into contact with each other. together.
Hybridization can be a good thing in some cases, helping species adapt to a rapidly warming planet, said Daniel Rubinoff, professor of entomology and director of the University of Hawaii’s Insect Museum.
For others it could spell the end of the line.
“That’s not to say that some hybridization isn’t natural, or even something that’s been happening forever,” Rubinoff told CNN. “But the problem is that it’s too soon. This is not good, and overall climate change will not help our planet’s biodiversity or ecosystems.”
Unusual fish
The hybrid first showed up in Vermont lakes around 2009 or 2010, state fisheries biologist Shawn Good estimates.
The long, tubular fish is the unintended offspring of two different species; there is a combination of the green-yellow patterns of northern pike and black scales that resemble chains – the signature of a chain picker.
Maith realized that the species were mating without knowing each other, and the culprit behind the genetic mix was Vermont’s winters and warming springs.
Northern pike begin spawning in early April when water temperatures hover in the high 30s and low 40s, and chain pike are usually seen a few weeks later when the water warms up . But the warmth of spring is coming earlier in the marshy areas where both species disperse their eggs and honey, leading to accidental hybridisation.
The hybrid fish have become common in Vermont lakes and are regularly caught by anglers and state scientists. Good estimates he sees dozens of them per year.
Another troubling sign for the fish: the hybrids are sterile and cannot reproduce themselves. It is well said that utopias were made of the fish whose reproductive organs are not mature.
That’s still not a spelling risk for unintended hybrid parents. There are still enough northern pike and chain picker spawning to keep those fish lines strong; currently the hybridization of the fish occurs at the tail end of the pike spawning season and at the beginning of the pickerel mating season.
But it is well understood that there may be change.
“There is a strong possibility that these types of hybrids will increase in abundance and number as our spring temperature regimes change over time,” Good said. “If it gets warmer faster, these fish that are usually separated by a few weeks and a few degrees could find themselves spawning in a much tighter timeframe.”
In many of these cases, Rubinoff said, cold-adapted animals such as polar bears, arctic foxes and northern pike outnumber warm-weather animals on their territory.
“In these cases, I think what’s going to happen is somebody’s going to lose,” Rubinoff said. “In most of these cases, I’m thinking it will be the species that was cold adapted.”
Their habitat was lost
Not all scientists agree that climate change is accelerating the hybridization of species. Some argue that the other main factor – contributing to both hybridization and species extinction – is habitat loss as human development encroaches on the natural world.
“I’m going to push back against the idea that hybridization between animals or plants or fungi or whatever might be increasing in frequency because of climate change,” said Michael Arnold, a professor of genetics at the University of Georgia. “Certain habitats will be lost due to climate change. But those habitats can be recovered if we don’t build cities on top of them.”
Arnold, like other scientists, believes that the current rate of extinction is exponentially greater than those of the past. Habitat loss is a key driver, but climate change is accelerating, Rubinoff argued.
“The idea is that this has always happened. It’s the speed that’s faster,” Rubinoff said. “It’s like when people say extinction has always happened. That’s true, but it’s never been this fast. That’s what disintegrates ecosystems; they can handle some change, but you can’t increase it.”
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