Sexual promiscuity may slow down a species' evolution, study finds

Ben Upton
Plovers with lots of lovers had less genetic diversity than their monogamous cousins, researchers found: ALAMY

Tinder fans beware: a new study suggests promiscuity may be slowing down the evolution of species.

Sexual reproduction, in which organisms choose a mate based on desirable traits, is a key driver of evolution as offspring are a genetic mix of two parents, rather than the clones produced by asexual reproduction.

But a paper in the journal Evolution about a study of wading birds reported that a lot of sleeping around mixes up the gene pool to the point where genetic differences between individuals are diluted.

Researchers compared populations of plovers, shorebirds that can be found all over the world, which have markedly different mating habits.

While some species always settle down with a single partner, others prefer to try someone new every time they have sex.

By taking DNA samples from 79 different plover populations, some monogamous and others polygamous, a team of scientists from the UK, US, Germany, Sweden and Madagascar was able to show that promiscuity slowed down the genetic divergence within species.

“Our findings suggest that because of the pressure to find more than one mate, polygamous shorebirds may search large areas and therefore spread their genes as they go,” said Josie D’Urban Jackson, one of the authors of the study.

Professor Tamás Székely, who like Ms D’Urban Jackson works at Bath University, added: “We’re very excited about these findings as this theory completely overturns conventional wisdom.”

Genetic diversity can help a species survive in a changing environment.

For example, genetic diversity is believed to be the main reason the Atlantic killifish was able to evolve incredibly quickly so they could survive a mix of toxic chemicals that would normally kill them in polluted waters off the US east coast.

Professor Székely stressed the promiscuous plovers would not simply have sex with anyone.

“You might think that birds choose mates arbitrarily if they are promiscuous,” he said. “But most individuals prefer a certain type, just as some humans might prefer blonde or dark hair in a partner.”

However it seems that if you really want to dedicate your sex life to the creation of a new species, it may be better to stick to more old-fashioned methods of dating.

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