If you are having sex with a lot of people, you might be messing with evolution.

Researchers have found that polygamous birds do not evolve in the same way as birds with only one partner at a time, because having multiple partners reduces competition and spreads genes around more, even between separate populations of the same species. According to a study in Evolution, that reduces “diversification,” which is how the genetics of a species evolve over time, favoring certain traits over others.

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The scientists studied dozens of plover populations and found that there were fewer subspecies — a genetically unique population group of a species — in polygamous birds as compared to monogamous ones. That is in part because birds from one population may mate with birds from another, stopping one population’s gene pool from being isolated from another and evolving separately.

Based on their observations, the researchers say that having multiple partners “may act as a brake rather than an engine” when it comes to evolving new species.

“They effectively mix up the gene pool by diluting any genetic differences between geographically distant locations, so that populations are less likely to diversify into new species over time,” first author Josie D’Urban Jackson, from the University of Bath and Cardiff University, said in a statement from Bath. “In contrast, monogamous species … gradually adapt to their local environment which increases the chance that they will split off and form a new species.”

The university gave the examples of plovers in Madagascar that had multiple partners. The species was largely uniform across that island country, while monogamous plovers there had unique genetic populations.

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Screwing with evolution is not the only consequence of too much sex for animals. Scientists from the University of Sydney in Australia recently suggested that being obsessed with sex is deadly for male snakes. They were studying red-sided garter snakes and found that when the males emerged from months of hibernation to mate with the females, they are delaying eating. Between the lack of food and the physical exertion of mating, the snakes are cutting their lives short.

 

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