Polar Bears Evolutionarily Five Times Older and Genetically More Distinct: Ancestry Traced Back 600,000 Years
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Added: Fri, 20 Apr 2012 19:12:50 UTC
ScienceDaily (Apr. 20, 2012) — A study appearing in the current issue of the journal Science reveals that polar bears evolved as early as some 600,000 years ago. An international team led by researchers from the German Biodiversity and Climate Research Centre (BiK‐F) shows the largest arctic carnivore to be five times older than previously recognized. The new findings on the evolutionary history of polar bears are the result of an analysis of information from the nuclear genome of polar and brown bears, and shed new light on conservation issues regarding this endangered arctic specialist.
Polar bears are uniquely specialized for life in the arctic. This fact is undisputed, and supported by a range of morphological, physiological and behavioural evidence. However, conducting research on the evolutionary history of polar bears is difficult. The arctic giant spends most of its life on sea ice, and typically also dies there. Its remains sink to the sea floor, where they get ground up by glaciers, or remain undiscovered. Fossil remains of polar bears are therefore scarce. Because the genetic information contained in each organism carries a lot of information about the past, researchers can study the history of the species by looking at the genes of today's polar bears.
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Using a process called paleo-experimental evolution, Georgia Tech researchers have resurrected a 500-million-year-old gene from bacteria and inserted it into modern-day Escherichia coli (E. coli) bacteria. This bacterium has now been growing for more than 1,000 generations, giving the scientists a front row seat to observe evolution in action. Credit: Georgia Institute of Technology
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