Interacting mutations promote diversity

June 28, 2012

Genetic diversity arises through the interplay of mutation, selection and genetic drift. In most scientific models, mutants have a fitness value which remains constant throughout. Based on this value, they compete with other types in the population and either die out or become established. However, evolutionary game theory considers constant fitness values to be a special case. It holds that the fitness of a mutation also depends on the frequency of the mutation.

Scientists from the Max Planck Institute for in Plön and the University of British Columbia in Vancouver developed a to address the scenario of being frequency-dependent but having random fitness parameters. The results demonstrate that the dynamics that arise in random increase the genetic diversity within a . Fitness, though, may even decline.

Population geneticists generally study mutations with constant fitness values. However, frequency-dependent selection is a recurrent theme in evolution: it enables the evolution of new species without geographical separation (sympatric speciation) or a relatively rapid change in the immune system of a population.

A mutation may be advantageous for low frequencies, for instance, but the fitness of the mutant decreases with rising frequency. A reverse trend in the fitness value is also conceivable. "Our computer model combines aspects of population genetics and evolutionary game theory in order to obtain a new perspective on genetic evolution," says Arne Traulsen from the Max Planck Institute for Evolutionary Biology. Whereas mutations have a random yet fixed fitness value in many mathematical models, this new model also enables a change in random fitness values with the frequency of the different types.

The results of the simulations show that frequency-dependent selection leads to higher within a population of individuals even though diversity per se is not favoured. The interaction of different mutations and the emergence of new mutants support the development of dynamic diversity in the population. One mutant does not always need to replace all other mutations or the original population. "It is possible for different mutations to exist in parallel such that a new mutant does not to completely replace the residents," says Weini Huang, lead author of the study. What is particularly interesting is the fact that diversity in this model remains naturally limited.

Fitness, on the other hand, does not necessarily rise with frequency-dependent selection in contrast to constant selection. By way of example, a mutation may arise within cells which halts the production of substances that are passed on to other cells. This can initially be advantageous; however, if it reaches fixation, the average fitness of the cell population declines. Advantageous mutations can thereby be lost and deleterious ones become established.

Explore further: Human testes may multiply mutations

More information: Huang, Haubold, Hauert & Traulsen, Emergence of stable polymorphisms driven by evolutionary games between mutants, Nature Communications, June 26, 2012, DOI:10.1038/ncomms1930

Related Stories

Human testes may multiply mutations

August 28, 2007

The testes in humans may act as mutation multipliers that raise the odds of passing improved DNA to offspring – but that can also backfire by increasing the frequency of certain diseases.

Genetic differences influence aging rates in the wild

December 12, 2007

Long-lived, wild animals harbor genetic differences that influence how quickly they begin to show their age, according to the results of a long-term study reported online on December 13th in Current Biology, a Cell Press ...

There's a speed limit to the pace of evolution, biologists say

November 2, 2009

Researchers at the University of Pennsylvania have developed a theoretical model that informs the understanding of evolution and determines how quickly an organism will evolve using a catalogue of "evolutionary speed limits." ...

Recommended for you

Genomes uncover life's early history

August 24, 2015

A University of Manchester scientist is part of a team which has carried out one of the biggest ever analyses of genomes on life of all forms.

Rare nautilus sighted for the first time in three decades

August 25, 2015

In early August, biologist Peter Ward returned from the South Pacific with news that he encountered an old friend, one he hadn't seen in over three decades. The University of Washington professor had seen what he considers ...

Study shows female frogs susceptible to 'decoy effect'

August 28, 2015

(Phys.org)—A pair of researchers has found that female túngaras, frogs that live in parts of Mexico and Central and South America, appear to be susceptible to the "decoy effect." In their paper published in the journal ...

Why a mutant rice called Big Grain1 yields such big grains

August 24, 2015

(Phys.org)—Rice is one of the most important staple crops grown by humans—very possibly the most important in history. With 4.3 billion inhabitants, Asia is home to 60 percent of the world's population, so it's unsurprising ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.