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Bioregions get a redistricting: basis for evolutionary theory updated for 21st century.

With a new planetwide analysis of vertebrate life, an international team has used 21st century science to update an iconic 1876 map of Earth's zoological regions.

By incorporating data on 21,037 species of mammals, birds and amphibians, Jean-Philippe Lessard of McGill University in Montreal and his colleagues have revised a zoological map created by Alfred Russel Wallace, an oft-overlooked cofounder of the theory of evolution. Wallace's map divided Earth's landmasses into six major regions, each with its own distinctive blend of vertebrates.

Scientists have redistricted Wallace's wildlife precincts several times, mostly to fit new information on what species live where. Lessard and his colleagues, however, use not just species distributions but family tree relationships. Incorporating degrees of kinship revives the evolutionary spirit of Wallace's original map, the researchers say in the Jan. 4 Science.

To reevaluate Wallace's boundaries, Lessard and his colleagues used computers to divide the planet's land into squares on a grid and compared how many species from three vertebrate groups each square shared with other squares. Using massive family trees developed at the University of Copenhagen and other places, the researchers gave more weight to differences between squares if the species within were only distantly related.

The biggest change from older maps, Lessard says, stretches the old Palearctic realm of northern Eurasia into the Western Hemisphere.

The new evolutionary approach also highlights just how unusual Australian animals are, Lessard says. People think of kangaroos and other Australian mammals as odd, but it was the amphibians that launched the realm's distinctness scores to extremes.

The revision is "really the closest we've got to mapping life on Earth while considering the way it evolved," says Serban Proches of the University of KwaZulu-Natal in South Africa.


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Title Annotation:Life; revision of a zoological map
Author:Milius, Susan
Publication:Science News
Article Type:Brief article
Geographic Code:1CANA
Date:Jan 26, 2013
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