Death by a thousand cuts? Not for small populations

Date:

Share post:

In a paper published in Nature Communications,
Christoph Adami, professor of microbiology and molecular genetics, and
graduate student Thomas LaBar have provided a look at how certain
species survive by evolving a greater ability to weed out harmful
mutations — a new concept called “drift robustness.”

Death by a thousand cuts? Not for small populations
We’ve all heard Darwin’s theory described as favoring the fittest, but
new research from Michigan State University

shows that, at least in
small populations, it’s ok to not be the best [Credit: Shutterstock]

Drift robustness occurs when small populations normally susceptible to harmful mutations evolve to protect themselves from going extinct. The organisms rearrange their genomes so mutations either have no effect or they kill an individual organism, providing the rest of the population with a chance to stay alive.

“We found that organisms that always live in small groups adapt to such environments and survive, but organisms in originally large populations that become greatly reduced in size are the ones at risk, continually suffering mutation after mutation — in essence they suffered death from a thousand cuts,” Adami said. “Traditional thinking was that organisms from both large and small populations would have suffered equally and both gone extinct.”

This beneficial adaptation allows small populations to reach fitness peaks — evolutionary mountains that organisms climb over a span of many generations. While larger populations can climb only one mountain, organisms in small populations are able to move to other drift-robust, fitness peaks to remain alive.

“Our study shows that if a mutation kills you, this is good from an evolutionary sense,” Adami said. “If you are dead, you are removed from the gene pool. You get one cut, but you can’t get a second one because you are already dead. This allows the rest of your population to reach the top of the peak or even move to a different peak.”

Drift-robust organisms are able to stay on their high fitness peaks because the slopes of the peak are so steep they can’t just slide off. Take a step off by suffering a mutation, and the organism can no longer replicate. The sacrifice of an individual organism protects the entire population from genetic death.

“The research shows that drift robustness arises because small populations preferentially adapt to drift-robust fitness peaks,” Adami said. “In a sense, we are showing that Darwin’s theory of evolution is more complicated than previously thought. Sometimes being the fittest is not enough. When your population dwindles, it is the organism on the steepest fitness peak that survives, even if that organism may not be the fittest.”

The research was supported by the BEACON Center, a National Science Foundation center for the study of evolution in action.

Source: Michigan State University [October 19, 2017]

ADVERTISEMENT

spot_img

Related articles

New prehistoric elephant ancestor found in China

In the main Proboscidean taxon of Elephantiformes, a huge pair of developed top incisors (ivories) has become a...

Beijing's forgotten tomb

While most Beijing residents and tourists are familiar with the Imperial Tombs of the Ming and Qing Dynasties,...

Rare basement, fireplace excavated at 2,400-year-old palace in NW China

Chinese archaeologists have unearthed a rare basement and fireplace in the ruins of an ancient city that served...

Rome shows off restored Circus Maximus

Rome unveiled a restored archaeological site at the Circus Maximus on Wednesday, showing off the spruced-up ruins of...

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants...

Study into Jersey Neanderthal mammoth hunters

Archaeologists are investigating the truth behind the story that Ice Age Neanderthals in Jersey would push mammoths off...

Climate change helped kill off super-sized Ice Age animals in Australia

During the last Ice Age, Australia, Tasmania and New Guinea formed a single landmass, called Sahul. It was...

Wanted dead and alive: New concept for a better understanding of biodiversity in time and space

By now, biodiversity is a well known term even in the broader public, as it is used in...