These genomic changes led to high mutation rates in both tumor types. (genome.gov)
However, we do encounter negative and positive selection, in addition to genetic drift, at the level of the mutation, usually at high mutation loads. (sciencemediacentre.org)
«Short generation times and high mutation rates associated with short lifespan and fast growth enable new species to appear at a faster rate in the tropics,» he says. (sciencedaily.com)