Evolutionary Experiments Show Natural Selection Opposes Sexual Selection

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Evolutionary Experiments Show Natural Selection Opposes Sexual Selection

By University of Exeter on Jun 08, 2021

Natural selection can reverse evolution that occurs through sexual selection and this can lead to better females, new research shows.


The study — led by the University of Exeter and Okayama University — examined broad-horned flour beetles, whose males have exaggerated mandibles, while females do not.

Male beetles with the largest mandibles win more fights and mate with more females — an example of “sexual selection,” where certain characteristics (like a male peacock’s tail) improve mating success.

However, having bigger mandibles requires a masculinized body (large head and neck), and a smaller abdomen — which, for females, limits the number of eggs they can carry. A masculinized body is not good for females.

Experimentally enhanced natural selection through predation, however, targets the same males favored by sexual selection and this results in the evolution of less masculinized bodies and better-quality females.

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