Hybrid Mammoth DNA Found
mercredi 1er juin 2011
Woolly and Columbian mammoths, two species of elephant that once lived in North America, may have interbred.
Mitochondrial DNA analysis of a Columbian mammoth (Mammuthus columbi) found in Utah suggests that its mitochondrial DNA was nearly identical to that of the woolly mammoth (Mammuthus primigenius). "We think this individual may have been a woolly-Columbian hybrid," said Jacob Enk of the McMaster Ancient DNA Centre, the group that led the research, which was recently published in Genome Biology.
"Living African elephant species interbreed where their ranges adjoin, with males of the bigger species out-competing the smaller for mates," he explained in a press release. The mitochondrial genomes in the smaller females then show up in populations of the larger species.
"Since woolly and Columbian ranges periodically overlapped in time and space, it’s likely that they engaged in similar behaviour and left a similar genetic signal," Enk said.
Modern examples of this can be seen where two varieties of elephant in Africa encounter each other. The larger savanna elephant (Loxodonta africana africana) and the smaller forest elephant (Loxodonta africana cyclotis) are capable of interbreeding. Genetic evidence has fueled a debate that these two modern elephants are indeed separate species.
The hybridization of mammoths may explain other fossils that look like intermediates between the two species. These fossils were sometimes assigned to the species Mammathus jeffersonii, but further research may show them to be hybrids of the woolly and Columbian mammoths. The woolly mammoth was a smaller furrier beast, that lived in the north closer to the glaciers of the Ice Ages, from Alaska through Canada, and east to the Great Lakes and New England. The larger Columbian mammoth lived further south. It inhabited the western and southern portion of the U.S. as far south as Florida, and nearly to Chiapas in Mexico.
The mammoths should not be confused with the American mastodon (Mammut americanum), another ancient elephant from North and Central America.
Tim Wall, Discovery news June 1, 2011
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