Oh, Great: Burmese Pythons In FL May Be Adapting To Cold, Speeding Up Metabolism & Feeding
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That discovery was made inadvertently after the 2010 freeze. Even as they searched for clues to human diseases, Castoe said researchers were well aware of the python’s toll on South Florida’s Everglades, where the snakes have been blamed for driving down the population of small mammals, taking over as top predator and shifting the balance in a swamp that is vast but also vulnerable to small changes. After the freeze, reports started coming in that between 40 and 90 percent of pythons were found dead. “To us, as evolutionary biologist, that was a trigger to say hmmm, that looks like extremely strong selection. I wonder if there’s something related to freeze tolerance,” Castoe said.
So the researchers started examining genes in 97 snakes. Just under 50 were collected before the freeze, between May 2003 and June 2009. Another 49 were found between October 2012 and December 2013. They also looked at five years worth of data on stomach contents between 2003 and 2008 and found that no matter when the snakes were caught, they frequently had food in their guts. “Those things looked like conveyor belts,” he said. “All year long they’re absolutely full of food.”
In sorting through the genes, researchers found that almost all remained the same in snakes captured before and after the freeze. But a small sequence of genes that determine the snakes’ metabolism and, at least in mice, influences how they respond to cold, had changed. The researchers also put their lab snakes on a fast to see if they began to atrophy without food like their Burmese cousins. In fact, the Florida snakes kept metabolizing. And generating heat, leading researchers to conclude the snakes that survived the freeze had likely been on the leading edge of a Florida python evolution.
Castoe said wildlife managers will likely need to rethink how they manage the snakes. With a higher threshold for cold weather, they may no longer be bound by South Florida’s steamy temperatures. Anecdotally, there may be some proof they’re already pushing north. The vast majority of pythons continue to be found in South Florida marshes, where Florida has hired trained hunters to catch them after confirming a breeding population in South Florida, including the Keys. But more than a few dozen have been found further north.
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https://www.miamiherald.com/news/local/environment/article220459160.html
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