An international team of scientists has identified an evolutionary mechanism that counteracts the accumulation of deleterious mutations in the genome.

The team included scientists from Skoltech, the Russian Academy of Sciences’ Institute for Information Transmission Problems and Moscow State University in Russia, as well as Harvard Medical School and Michigan University in the United States. Researchers from the Netherlands also participated in the study.

Mutations, or changes in DNA, constantly occur in the cells of humans and other organisms. Some of the newly arising mutations are deleterious; that is, they have negative effects for the organism, and from an evolutionary perspective they reduce an individual’s probability of reproduction.

Natural selection acts to eliminate deleterious mutations from the populations of organisms. One of the key questions that evolutionary biologists grapple with is how effective natural selection is in purging deleterious mutations, and what mechanisms lay behind this process.

In their recent study, the international team of scientists explored the means by which natural selection acts to purge the genome of deleterious mutations. The team focused on human and drosophila (D. melanogaster or fruit fly) populations.

They found that the effects of deleterious mutations depend on the presence of other mutations in the genome. The larger the deleterious effects of the mutations already present in the genome, the larger would be the effects of newly arising mutations.

Due to such interactions between mutations, individuals carrying large numbers of deleterious mutations have a reduced probability of reproduction.

As a result harmful genetic changes are removed from the population at a higher rate than would be expected in the absence of interactions between the mutations.

This pattern enables natural selection to effectively eliminate harmful mutations from populations of organisms.

The team’s findings helped elucidate how populations of living organisms, including our own species, counteract the accumulation of harmful genetic changes that occur in the genome every generation.

The results of the study have been published in the prestigious journal Science.

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