Assortative Mating in Animals and Its Role for Speciation

Abstract

Evolutionary theory predicts that positive assortative mating-the tendency of similar individuals to mate with each otherplays 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 macroevolutionary 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 1,447 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 p 0:36; 95% confidence interval: 0.19-0.52) when accounting for phylogenetic nonindependence. 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.

Assortative mating, sexual selection, and their consequences for gene flow inLittorina

“…Assortative mating is widespread across animal taxa (Janicke et al 2019). In most marine gastropods studied, females and males mate assortatively in relation to size (Ng et al 2019).…”

When do opposites attract? A model uncovering the evolution of disassortative mating

“…The number of mating cues within the population is an important parameter in the evolution of mate preference (Otto et al, 2008), because it modulates the opportunity costs Present model studying the Otto et al (2008) When the mating cue is a quantitative trait (e.g. size-related preferences, (Janicke et al, 2019;Jiang et al, 2013)), variations within populations may be considered as multiple cues, depending on the discrimination rules of the choosy partners. If quantitative variations are perceived as multiple differentiated phenotypes, it would probably promote the evolution of disassortative mating, in a similar manner as high level of discrete polymorphism.…”

“…Moreover, here we only consider a single choosy sex. However, when both sexes are choosy (Servedio and Lande, 2006), the positive selection on the evolution of mate preference in one sex may be relaxed when strong mate preferences are fixed in the other sex (Aubier et al, 2019). Drift then leads to periodic cycles where male and female alternatively become the most choosy sex (Aubier et al, 2019).…”

“…The evolution of mate preferences is puzzling because preferences increase the risk of missing mating opportunities, which may incur significant fitness costs. While the evolution of assortative mating has been reported in many species, disassortative mating is more scarcely observed (Janicke et al, 2019;Jiang et al, 2013), suggesting that the ecological conditions enabling its evolution could be more restrictive. Here we build a general approach aiming at investigating the selection regimes allowing the evolution of disassortative mating using a mathematical model.…”

Coevolution of male and female mate choice can destabilize reproductive isolation

“…Assortative mating -the tendency of individuals of similar phenotype to mate together more often than expected by chance -is widespread in animals 7 and plays a key role in generating premating reproductive isolation 8 . Assortative mating can arise as a by-product of adaptive divergence via temporal or spatial isolation 9 , or can be driven by various behavioural processes 10 .…”