by Staff Writers
New Haven CT (SPX) Feb 16, 2012
A Yale-led study of the evolutionary history of Antarctic fish and their "anti-freeze" proteins illustrates how tens of millions of years ago a lineage of fish adapted to newly formed polar conditions - and how today they are endangered by a rapid rise in ocean temperatures.
"A rise of 2 degrees centigrade of water temperature will likely have a devastating impact on this Antarctic fish lineage, which is so well adapted to water at freezing temperatures," said Thomas Near, associate professor of ecology and evolutionary biology and lead author of the study published online the week of Feb. 13 in the Proceedings of the National Academy of Sciences.
The successful origin and diversification into 100 species of fish, collectively called notothenioids, is a textbook case of how evolution operates. A period of rapid cooling led to mass extinction of fish acclimated to a warmer Southern Ocean.
The acquisition of so-called antifreeze glycoproteins enabled notothenioids to survive in seas with frigid temperatures. As they adapted to vacant ecological niches, new species of notothenioids arose and contributed to the rich biodiversity of marine life found today in the waters of Antarctica.
Notothenioids account for the bulk of the fish diversity and are a major food source for larger predators, including penguins, toothed whales, and seals. Yale's Peabody Museum of Natural History has one of the most important collections of these specimens in the world.
However, the new study suggests the acquisition of the antifreeze glycoproteins 22 to 42 million years ago was not the only reason for the successful adaptation of the Antarctic notothenioids. The largest radiation of notothenioid fish species into new habitats occurred at least 10 million years after the first appearance of glycoproteins, the study found.
"The evolution of antifreeze was often thought of as a 'smoking gun,' triggering the diversification of these fishes, but we found evidence that this adaptive radiation is not linked to a single trait, but to a combination of factors," Near said.
This evolutionary success story is threatened by climate change that has made the Southern Ocean around Antarctica one of the fastest-warming regions on Earth. The same traits that enabled the fish to survive and thrive on a cooling earth make them particularly susceptible to a warming one, notes Near.
"Given their strong polar adaptations and their inability to acclimate to warmer water temperatures, climate change could devastate this most interesting lineage of fish with a unique evolutionary history," Near said.
Beyond the Ice Age
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
Putin receives 'prehistoric' water from Antarctic lake
Moscow (AFP) Feb 10, 2012
Prime Minister Vladimir Putin was given a water sample Friday taken from a pristine lake hidden under Antarctic ice for over a million years, after Russian scientists drilled down to its surface. The Russian strongman, who enjoys venturing into the wilderness and has accompanied an expedition to track polar bears in the Arctic, was the first recipient of a symbolic water sample. "The hea ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|