Friskier Frogs Have Faster-Changing Genomes
Physically fit frogs have faster-changing genomes, according to a study of poison frogs from Central and South America. Stretches of DNA generally accumulate changes over time, but the rate at which this occurs varies between species. Biologists have, in the past, tried to explain why some species have faster-changing genomes than others by focusing on features such as body size, lifespan and the rate at which they reproduce. Juan Santos from the National Evolutionary Synthesis Centre in North Carolina, recognized that previous tests had based their measurements of metabolism on resting animals, rather than those hopping and frolicking in the wild, so he collected around 500 poison frogs and fond the most active frogs had aerobic capacities that were five times higher than the most sluggish species and could run much longer before they tired. In order to estimate the rate at which each species’ genome changed over time, Santos reconstructed the poison frog family tree, using DNA sequences from 15 frog genes. He then estimated the number of mutations for each species over time and found a clear pattern – athletic frogs tended to have faster-changing genomes. Santos also tested factors such as body and clutch (the number of eggs laid at the same time) sizes, but found that fitness was the only factor that consistently correlated with the pace of evolution.