Sexual Selection And Competitiveness Might Lead To Some Species Extinction, According To New Studies

Sexual Selection And Competitiveness Might Lead To Some Species Extinction, According To New Studies
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Sexual selection is one of the great wonders of nature. In an environment in which females can choose with whom to have offspring and males are not guaranteed to pass their genes to the next generation, specific behaviors are needed to draw the attention of the females or scare off potential competitors. But a strong sexual selection can even lead to some species extinction, according to a new study.

Sexual selection is considered beneficial for species survival

In general, however, this selective behavior when it comes to sex in the animal world would ultimately favor the survival of the species as a whole, reducing malignant mutations and facilitating adaptation, particularly when the environment is changing.

To try to better understand the effects of differences between sexes on the success of a group of animals, a team of researchers led by Gene Hunt, of the Smithsonian Institution, in Washington, examined ostracods, small crustaceans that have appeared 450 million years ago.

Big differences between genders lead to the species extinction in ostracods

The ostracods males, which are from 20% smaller to 30% bigger than the females, usually have longer elongated shells, necessary to accommodate large sexual organs. The authors of this study analyzed the fossils of 93 species of ostracods that lived about 66 to 84 million years ago.

Those species that presented pronounced sexual differences between genders had an extinction rate up to ten times higher than the species with more similarities between genders.

A too strong sexual selection also lead to extinction

Besides ostracods, a more complex sexual selection system is observed in flies, where males’ sperm contains chemicals to eliminate the receptivity of the female once they have copulated or to annihilate the sperm from a previous sexual act. As a consequence, the copulation might be too toxic for the females to survive it.

This is the first study to show these effects and it seems to go against the conventional view that strong sexual selection could, on average, reduce the chances of species extinction.


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