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!
Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz
Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences