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Evolution - voles

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148843.  Mon Feb 19, 2007 10:44 am Reply with quote

The water vole is the world’s “fastest-evolving mammal.” It also “harbours a number of puzzling genetic traits that challenge current scientific understanding.”

Genetics prof Dr Andrew DeWoody says voles are an “evolutionary enigma.”

He looked at 60 species within the vole genus Microtus, which have all evolved in the last 500,000 to 2 million years. This means voles are evolving 60-100 times faster than the average vertebrate in terms of creating different species.

Strangely, despite this extraordinary variation, all voles look alike. “Many species are completely indistinguishable," DeWoody said. In one particular instance, DeWoody was unable to differentiate between two species even after close examination and analysis of their cranial structure; only genetic tests could reveal the difference. Nevertheless, voles are perfectly adept at recognizing those of their own species. "I have seen absolutely no evidence of mating between different species. We don't know how they do this, but scent and behaviour probably play a role."

Morning Star, 18 Sep 06

166500.  Mon Apr 16, 2007 7:19 am Reply with quote

Voles are useful when carbon dating just won’t do.

Carbon dating “only works up to about 50,000 years ago,” so for older finds, archaeologists study pollen, beetles, snails - and best of all, voles’ teeth.

Because voles evolve so rapidly, changes noted in their fossilised teeth are a good guide to the age of a site. The teeth change shape, the thickness of the enamel changes, and voles change from having rooted to unrooted teeth.

Fossilised voles teeth are “about the size of a clipping from your little fingernail,” so to find them, archaeologists have to sieve vast amounts of sediment. Ten tonnes of clay, dried out and then repeatedly sieved through a very fine mesh, “might yield say a dozen voles’ teeth.”

S: The Museum’ by Rupert Smith (BBC Books, 2007).

More voles at
post 161146


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