American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“Assortative mating in animals and its role for speciation”

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Tim Janicke, Lucas Marie-Orleach, Thomas G. Aubier, Charles Perrier, and Edward H. Morrow (Dec 2019)

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Meta-analysis finds no relationship between assortative mating and species richness across animals


Evolutionary theory predicts that positive assortative mating – the tendency of similar individuals to mate with each other – plays a key role for speciation by generating reproductive isolation between diverging populations. However, comprehensive tests for an effect of assortative mating on species richness at the macro-evolutionary scale are lacking. We used a meta-analytic approach to test the hypothesis that the strength of assortative mating within populations is positively related to species richness across a broad range of animal taxa. Specifically, we ran a phylogenetically independent meta-analysis using an extensive database of 1447 effect sizes for the strength of assortative mating, encompassing 307 species from 130 families and 14 classes. Our results suggest that there is no relationship between the strength of assortative mating and species richness across and within major taxonomic groups and trait categories. Moreover, our analysis confirms an earlier finding that animals typically mate assortatively (global Pearson correlation coefficient: r = 0.36; 95% confidence limits: 0.19−0.52) when accounting for phylogenetic non-independence. We argue that future advances will rely on a better understanding of the evolutionary causes and consequences of the observed intra- and interspecific variation in the strength of assortative mating.