Suzanne's Mom's Blog

I love the environmental radio show Living on Earth, and I’m grateful that they post transcripts of programs even though natural speech requires a lot of editing. One thing I try to edit out is every “So” at the start of a sentence. When did we start doing that? I first noticed the verbal tic in 2005 at a new job. When did you?

From Living on Earth …

“HOST BOBBY BASCOMB: The Arctic is warming faster than any other region on earth, it actually rained on the Greenland ice sheet in August for the first time ever. And sea ice recently reached its minimum extent for 2021. It was the 12th lowest amount of ice since scientists began keeping records. And for the endangered polar bear, a warming Arctic is bad news. With their habitat melting, polar bears are having trouble finding food. At the same time grizzly bears are moving north and, in some cases, mating with polar bears, creating a hybrid animal known as a pizzly bear. Larisa DeSantis is a paleontologist and associate professor of biology who studies pizzly bears at Vanderbilt University. …

“How do these hybrids compare with the parent species of grizzly and polar bears?

“LARISA DESANTIS: A pizzly bear is essentially an intermediate between these two. It’s a hybrid species, and it’s actually fertile. … Polar bears tend to have really elongated skulls. And this is because they’re really well suited for being able to hunt seals in sea ice. [They] get into those holes and effectively hunt those seals. The grizzlies have much shorter skulls, and they’re able to exude really high bite forces to be able to eat really hard foods when needed. And so essentially, this pizzly is intermediate between those two, you can also see that their coloration is sort of intermediate. [They’re] a bit lighter in coloration than a grizzly, but darker in coloration than a polar bear. … They’re better swimmers than grizzlies, not as good as polar bears. [As] we’re dealing with a warming Arctic, we really don’t know how these pizzlies will do in the future, and they may be better suited for the warming Arctic than the polar bear.

“BASCOMB: Now, many hybrid species, like ligers, or mules, are sterile and can’t produce offspring themselves. But I think you just said that pizzly bears actually can reproduce. Does that make them their own species? …

“DESANTIS: The polar bear and the grizzly bear are really sort of a unique situation. They diverged roughly around 500,000 or 600,000 years ago. They’re pretty closely related to one another in the grand scheme of things. And they also look quite different from one another, right? These are different bears, we know they’re different species. They do completely different things in their ecosystems. They’re of different ecological niches, for example. … But you’re absolutely right, you know, they can produce these fertile hybrids, that’s really interesting. And we know that it’s actually able to persist. …

“BASCOMB: So then would you say pizzly bears are their own species?

“DESANTIS: I wouldn’t go that far. They are a hybrid. And hybrids occur pretty frequently in nature. And typically we see hybridization occurring, you know, over and over and over in particular regions where two different species are coming together. And so it’s not surprising that we see hybrids of these two bears, especially since they’re closely related. And this is because essentially, the brown bears, the grizzly bears, are moving north due to Arctic warming. The polar bears are actually having to retreat from the sea ice, the lack of sea ice, and they’re having to come further inland and often travel further south or look for other food resources. [New studies show] that they’re trying to eat [seabird] eggs. …

“This elongated skull [is] not well suited to eating just sort of any type of food source, right? It actually has biomechanical constraints that prevent it from, you know, eating really hard things. And so it’s sort of having to scavenge potentially, to find different food resources. It’ll find these bowhead whale carcass sites, that’s where the grizzly bears can also be as well. And they’re coming into increased contact and occasionally mating. …

“BASCOMB: With polar bear populations declining so dramatically with the loss of sea ice, and with climate change, as you were just saying, how likely is it that they will ultimately be replaced by pizzly bears or even grizzly bears if it gets much, much warmer? And for that matter, how would a different apex predator in the Arctic affect the whole ecosystem?

“DESANTIS: [We] really don’t know the answer to that. But what we need to do is actually monitor the polar bears, continue to monitor grizzlies, and also monitor these pizzlies, and see how they do. So as I mentioned, hybrids normally aren’t better suited than either parent species, right? But in this case, with the environment changing, they may be our hope for an Arctic bear. And what we do know about predators across the globe, and through time is that apex predators especially are really key to the functioning of ecosystems, right. This is why wolves were reintroduced to Yellowstone, because the elk populations were sort of out of control, wreaking havoc on the vegetation, things were out of balance. [The pizzly] may give us hope for an Arctic bear in a world in which we have Arctic warming.”

More at Living on Earth, here.