Cichlid Fish Diversity Threatened by Eutrophication That Curbs Sexual Selection

TLDR

Cichlid fish species of Lake Victoria can interbreed without loss of fertility but are sexually isolated by mate choice, which is determined by coloration, and strong assortative mating can quickly lead to sexual isolation of color morphs. By constraining color vision, turbidity interferes with mate choice, relaxes sexual selection, and blocks the mechanism of reproductive isolation. Dull fish coloration, few color morphs, and low species diversity are found in areas that have become turbid as a result of recent eutrophication, and in this way, human activities that increase turbidity destroy both the mechanism of diversification and that which maintains diversity.

Abstract

Cichlid fish species of Lake Victoria can interbreed without loss of fertility but are sexually isolated by mate choice. Mate choice is determined on the basis of coloration, and strong assortative mating can quickly lead to sexual isolation of color morphs. Dull fish coloration, few color morphs, and low species diversity are found in areas that have become turbid as a result of recent eutrophication. By constraining color vision, turbidity interferes with mate choice, relaxes sexual selection, and blocks the mechanism of reproductive isolation. In this way, human activities that increase turbidity destroy both the mechanism of diversification and that which maintains diversity.