Stretches of DNA accumulate changes over time, but the rate at which those changes build up varies considerably between species, said author Juan C. Santos of the National Evolutionary Synthesis Center in Durham, North Carolina.
This is Dendrobates leucomelas, a poisonous frog from Venezuelan Guiana. Credit: Photo courtesy of Cesar Barrio-Amoros (www.andigena.org)
In the past, biologists trying to explain why some species have faster-changing genomes than others have focused on features such as body size, generation time, fecundity and lifespan. According to one theory, first proposed in the 1990s, species with higher resting metabolic rates are likely to accumulate DNA changes at a faster rate, especially among cold-blooded animals such as frogs, snakes, lizards and fishes. But subsequent studies failed to find support for the idea.
The problem with previous tests is that they based their measurements of metabolism on animals at rest, rather than during normal physical activity, Santos said.
"Animals rarely just sit there," Santos said. "If you go to the wild, you'll see animals hunting, reproducing, and running to avoid being eaten. The energetic cost of these activities is far beyond the minimum amount of energy an animal needs to function."
To test the idea, Santos scoured forests in Colombia, Ecuador, Venezuela, and Panama in search of poison frogs, subjecting nearly 500 frogs — representing more than 50 species — to a frog fitness test.
He had the frogs run in a rotating plastic tube resembling a hamster wheel, and measured their oxygen uptake after four minutes of exercise.
The friskiest frogs had aerobic capacities that were five times higher than the most sluggish species, and were able to run longer before they got tired.
"Physically fit species are more efficient at extracting oxygen from each breath and delivering it to working muscles," Santos said.
To estimate the rate at which each species' genome changed over time, he also reconstructed the poison frog family tree, using DNA sequences from fifteen frog genes.
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.
The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit www.nescent.org.
Robin Ann Smith | EurekAlert!
Bioenergy cropland expansion could be as bad for biodiversity as climate change
11.12.2018 | Senckenberg Forschungsinstitut und Naturmuseen
How glial cells develop in the brain from neural precursor cells
11.12.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.
The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
11.12.2018 | Studies and Analyses
11.12.2018 | Health and Medicine
11.12.2018 | Physics and Astronomy