Tuesday, April 17, 2012

Warming Climate Sets Evolution Within Ice to High

Microbes frozen in ice for eons are evolving as they thaw. 


While they pose little threat to humans now, they could force out existing microbial populations, with unknown effects.


Don't expect to see strange, cobbled-together creatures like miniscule Frankenstein's monsters climbing out onto a shore near you.

The world's ice sheets, scientists now say, are a gigantic reservoir of microbial life – some of which are relics hundreds of thousands of years old. Most of what has melted out and been identified appears related to common soil and marine bacteria. But scientists see evidence that these bugs are evolving within the ice.

Scientists think it’s unlikely that any off-the-wall organisms will turn up. "I think whatever we've been exposed to at this point won't be terribly different from things that are melting out now," said Scott Rogers, an evolutionary biologist at Bowling Green State University in Ohio. "The chances of something really bizarre coming out now are very, very slim."

A warming climate could set the speed of evolution to high, however. University of Wisconsin, Madison, biologist Jonathan Klassen and a colleague have identified five new species of a common bacterium from Antarctica's Victoria Upper Glacier. The new strains, found in 4,000-year-old ice, are bright pink and have acquired new traits that show the organisms are exchanging DNA.

"Bacteria can be fairly promiscuous in terms of trading genes with each other," Klassen said. By moving snippets of genetic information directly from cell to cell, these ice-bound microbes are "creating a whole bunch of diversity that wasn't there before." Recombining in ice is a particularly good mechanism for microbial evolution because it involves individual cells, which can then melt out and introduce new traits into the existing population. 

"You'll get new combinations of organisms that have the ability to take advantage of modern conditions," Klassen added. In an altered climate, many existing types of microbes will be unable to adapt and will end up going extinct. The environmental niches they inhabited will be available to opportunists.

"And that's where these [new] organisms come in," he said.

By Cheryl Katz@The Daily Climate

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