Sex is best – whichever way you look at it

Animals that attract a mate for sexual reproduction are rewarded for their efforts by eliminating potentially harmful DNA in the future, according to Scottish scientists.

A new study shows that animals and plants that reproduce sexually are at a considerable advantage to those species, such as some insects and reptiles, that reproduce without a partner.

Researchers at the University of Edinburgh studied sexual reproduction in tiny fruit flies to learn more about how DNA is randomly shuffled when the genes of two parents combine to create a new individual.

They found that this recombination of genetic material allows for damaging elements of DNA, which might cause disease or other potential drawbacks, to be weeded out within a few generations.

The study suggests individuals that inherit healthy genes tend to flourish and pass on their DNA to the next generation, while weaker individuals are more likely to die without reproducing.

The team said the findings, made possible by genome sequencing technology, provided strong evidence to back up a long-standing theory that sexual reproduction, rather than asexual cloning of an individual, had long-term benefits for a species.They studied how the DNA of fruit flies is affected when the recombination of DNA does not occur and found that harmful DNA quickly accumulates, making the species weaker overall in the long term.

Dr Penny Haddrill, of the university’s school of biological sciences, said: “This is strong evidence to show that sexual reproduction enables a species to continually adapt.”

Researchers say the findings, published in Genome Biology and Evolution, may help develop crop species with high yields.