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Devin Edmonds, USGS via Wikimedia Commons // Public Domain

Good News: One Endangered Frog Species Is Bouncing Back

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Devin Edmonds, USGS via Wikimedia Commons // Public Domain

It’s always nice to be able to deliver good amphibian news. The latest: after decades of decline, numbers of Sierra Nevada yellow-legged frogs (Rana sierrae) are on the rise in Yosemite National Park. A report on the frogs’ return was published today, October 3, in the Proceedings of the National Academy of Sciences.

One hundred years ago, California’s Sierra Nevada mountains croaked with yellow-legged frogs. R. sierrae was one of the most abundant species around. Then came the habitat destruction. People began stocking naturally fish-less local lakes with non-native fish like trout, which feed on amphibian eggs, tadpoles, and even full-grown frogs.

After that came the fungus. Batrachochytrium dendrobatidis, or Bd, is a parasitic chytrid fungus that gets into frog skin and causes it to thicken. This might sound like a good thing, but frogs are amphibians. They take in air, water, and nutrients through their porous skin. When that skin ceases to be porous, the resulting lack of oxygen and chemical imbalances can stop their hearts from beating.

Mention Bd to any herpetologist if you want to see them shudder. The teeny-tiny fungus has wreaked havoc on amphibian species the world over and is believed to be responsible for the decline or extinction of hundreds of species to date. And it only continues to spread.

But the power of Bd’s scythe depends on the species it infects. Some frogs, including the American bullfrog and the lowland leopard frog have evolved a resistance to the pathogen, and it seems R. sierrae may have done the same. In the early waves of chytrid infestation, many frogs fell to the fungus, but others were naturally resistant. In the aftermath, the survivors mated, creating a small but relatively hardy new community in the middle of Bd territory.

Still, even with this toughness, by 1996 more than 93 percent of yellow-legged frogs had vanished from their habitat [PDF]. Things were not looking so good for R. sierrae. But how bad were they, exactly?

To find out, researchers analyzed data from more than 7000 frog population surveys conducted across Yosemite National Park between 1993 and 2012. Yosemite comprises 13 percent of the frog’s total range.

To their delight, the scientists found that the frogs were, if not completely rebounding, at least hopping back from the brink a bit. Within the 20-year study period, R. sierrae populations had increased sevenfold.

What happened? The study authors aren’t completely sure, but the frogs’ resistance to Bd certainly didn’t hurt. Another big change: people finally stopped putting frog-gobbling non-native fish in the dang waterways.

In recent years, habitat loss and chytrid fungus have made the decimation of Earth’s amphibians seem inevitable. But if R. sierrae is any indication, the authors write, "some amphibians may be more resilient than is assumed, and with appropriate management, declines of such species may be reversible."

Woo! 

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Big Questions
Why Don't We Eat Turkey Tails?
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Turkey sandwiches. Turkey soup. Roasted turkey. This year, Americans will consume roughly 245 million birds, with 46 million being prepared and presented on Thanksgiving. What we don’t eat will be repurposed into leftovers.

But there’s one part of the turkey that virtually no family will have on their table: the tail.

Despite our country’s obsession with fattening, dissecting, and searing turkeys, we almost inevitably pass up the fat-infused rear portion. According to Michael Carolan, professor of sociology and associate dean for research at the College for Liberal Arts at Colorado State University, that may have something to do with how Americans have traditionally perceived turkeys. Consumption was rare prior to World War II. When the birds were readily available, there was no demand for the tail because it had never been offered in the first place.

"Tails did and do not fit into what has become our culinary fascination with white meat," Carolan tells Mental Floss. "But also from a marketing [and] processor standpoint, if the consumer was just going to throw the tail away, or will not miss it if it was omitted, [suppliers] saw an opportunity to make additional money."

Indeed, the fact that Americans didn't have a taste for tail didn't prevent the poultry industry from moving on. Tails were being routed to Pacific Island consumers in the 1950s. Rich in protein and fat—a turkey tail is really a gland that produces oil used for grooming—suppliers were able to make use of the unwanted portion. And once consumers were exposed to it, they couldn't get enough.

“By 2007,” according to Carolan, “the average Samoan was consuming more than 44 pounds of turkey tails every year.” Perhaps not coincidentally, Samoans also have alarmingly high obesity rates of 75 percent. In an effort to stave off contributing factors, importing tails to the Islands was banned from 2007 until 2013, when it was argued that doing so violated World Trade Organization rules.

With tradition going hand-in-hand with commerce, poultry suppliers don’t really have a reason to try and change domestic consumer appetites for the tails. In preparing his research into the missing treat, Carolan says he had to search high and low before finally finding a source of tails at a Whole Foods that was about to discard them. "[You] can't expect the food to be accepted if people can't even find the piece!"

Unless the meat industry mounts a major campaign to shift American tastes, Thanksgiving will once again be filled with turkeys missing one of their juicier body parts.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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