Evolution Caught in the Act: Scientists Measure How Quickly Genomes Change

[Liffrea]

Mutations are the raw material of evolution. Charles Darwin already recognized that evolution depends on heritable differences between individuals: those who are better adapted to the environment have better chances to pass on their genes to the next generation. A species can only evolve if the genome changes through new mutations, with the best new variants surviving the sieve of selection.

http://www.sciencedaily.com/releases/2009/12/091231164743.htm