Fitter frogs

In a paper in the journal Molecular Biology and Evolution, Juan Santos from the National Evolutionary Synthesis Centre in the US describes how fitter poisonous frogs have faster-changing genomes. The idea that animals with faster metabolic rates might have faster evolution was first put forward in the 1990s, but nobody could come up with good evidence to support it - but Santos thinks this is because researchers only studied animals at rest, rather than during physical activity. To test his idea, he put 500 frogs from 50 different species through a froggy fitness test, and discovered that the genomes of the fitter species were changing faster than their more sluggish relatives. While the reason for this isn't clear, it may be related to the production of free-radicals during exercise - damaging oxygen molecules that can cause changes in DNA.