Antarctic Ice Sheet Collapse Recorded In Octopus DNA

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http://blogs.scientificamerican.com/octopus-chronicles/2012/05/14/antarctic-ice-sheet-collapse-recorded-in-octopus-dna/


Map of current land and ice separating the Weddell and Ross seas, courtesy of Wikimedia Commons/Wutsje/CIA

Octopuses have made themselves at home in most of the world’s oceans—from the warmest of tropical seas to the deep, dark reaches around hydrothermal vents. Antarctic species, such as Turquet’s octopuses (Pareledone turqueti), even live slow, quiet lives near the South Pole. But these retiring creatures offer a rare opportunity to help understand how this extreme part of the Earth has changed in recent geologic times—and what climate change might bring there in the near future.


Turquet's octopus preserved specimens from 1914 courtesy if Wikimedia Commons/Charcot/Joubin

Researchers can compare genetic patterns of current animal populations to look back in evolutionary time to estimate when populations of animals might have split off. These fissures are often forced by changing climatic or geographical features, such as giant sheets of ice that come and go with different glacial patterns. The West Antarctic Ice Sheet and some low Antarctic land currently separates the Weddell Sea from the Ross Sea in the Southern Ocean.

Research has suggested that this ice shelf has collapsed a number of times in the past—likely during the Pleistocene interglacial periods, most likely starting some 1.25 million years ago. This melting, along with rising sea levels, would have opened up a seawater thruway between the Weddell and Ross seas for marine life. So scientists have been turning their attention to contemporary species in the two seas to see if they could track their evolutionary history back to a time when these disparate populations might have been connected.

“We wanted to investigate whether there was any genetic information that could tell us what the past environment could have been like,” Louise Allcock, of the National University of Ireland Galway’s zoology department, said in a prepared statement. And for that, she and her colleagues turned to the benthic Turquet’s octopus, which lives as deep as 1,000 meters on the seafloor in the Southern Ocean.