When he estimated the number of mutations, or changes in the DNA, for each species over time, a clear pattern emerged athletic frogs tended to have faster-changing genomes.
Santos tested for other factors as well, such as body and clutch sizes, but athletic prowess was the only factor that was consistently correlated with the pace of evolution.
Why fit frogs have faster-changing genomes remains a mystery. One possibility has to do with harmful molecules called free radicals, which increase in the body as a byproduct of exercise.
During exercise, the circulatory system provides blood and oxygen to the tissues that are needed most the muscles at the expense of less active tissues, Santos explained.
When physical activity has stopped, the rush of blood and oxygen when circulation is restored to those tissues produces a burst of free radicals that can cause wear and tear on DNA, eventually causing genetic changes that if they affect the DNA of cells that make eggs or sperm can be passed to future generations.
Before you ditch your exercise routine, Santos offers some words of caution. The results don't debunk the benefits of regular physical exercise, which is known to reduce the risk of cancer, heart disease, and diabetes.
"What applies to cold-blooded animals such as poison frogs doesn't necessarily apply to warm-blooded animals such as humans," Santos said.
The findings appeared in the April 10th issue of Molecular Biology and Evolution.
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)