Effects on Population Divergence of Within-Generational Learning About Prospective Mates

Abstract

Although learned mate preferences are suspected to have important effects during speciation, theoretical models have largely neglected the effects on speciation and population divergence of within-generational learning, that is, learning based upon prior experience with potential mates. Here, we use population genetic models to address this deficit. Focusing on the situation of secondary contact between populations that still hybridize, we consider models of learning by females and by males under polygyny.We assess the effects of learning to prefer conspecifics from previous conspecific encounters, learning to avoid heterospecifics from previous heterospecific encounters, and learning to prefer familiar types. We examine the amount of population divergence that results from learning in these models. We also assess the effect of learning on the spread of an allele that strengthens assortative mating in both models. We find that learning can have counterintuitive, but logical and understandable effects that differ with the version of the model assessed. In general, population divergence is expected to increase most consistently when females learn to strengthen their preferences for conspecifics from previous encounters with conspecifics. Our results also suggest that within-generational learning will generally inhibit the spread of alleles strengthening assortative mating. K E Y W O R D S :Assortative mating, male mate choice, mathematical model, plasticity, population genetics, speciation.

Sex differences in developmental plasticity and canalization shape population divergence in mate preferences

“…Learned mate preferences have been predicted to enhance population divergence when females learn, whereas population divergence might be constrained when males learn [13]. Whereas male mate preferences are influenced predominantly by direct selection, female mate preferences can, at least to some degree, be driven also by sexual selection for rspb.royalsocietypublishing.org Proc.…”

“…Another consequence of sex-specific selection pressures on mate preferences could be weakened selection on female mate preferences since learning should shield these plastic preferences from selection (cf. [13]). We also hypothesize that male mate preferences have become more canalized, as selection for species recognition to avoid heterospecific matings might have an overriding effect in males compared with females, relative to the strength of selection to obtain high-quality mates among conspecifics.…”

“…Sex differences in plasticity and learning can therefore maintain substantial but sex-specific population divergence in mate preference phenotypes despite gene flow ( figure 2). An interesting evolutionary implication of this sex difference is that the plastic sex (females) might become more shielded from genetic evolution of mate preferences than the less plastic sex (males) [13], a prediction that should be investigated in future quantitative genetic and selection studies in this area. A recent study on sex-specific mate preferences in birds found evidence for an evolutionary constraint in the form of an intersexual genetic correlation and shared inheritance of mating behaviours of males and females [51].…”

Geography, assortative mating, and the effects of sexual selection on speciation with gene flow

“…Indeed, I have now recognized this phenomenon to be present in some older models of my own (e.g., the models of phenotype matching of a locally adapted trait with male and female preferences in Servedio ) and have documented it in phenotype matching reinforcement models with diverse conditions such as a learned trait (Olofsson et al. ) and with within‐generational learning about prospective mates (Servedio and Dukas ). Whether it is a notable phenomenon in natural systems that use phenotype matching will depend in part on whether preference strengths in nature are strong enough to be above the preference strength α opt that leads to the peak in trait divergence.…”

Interspecific interactions and learning variability jointly drive geographic differences in mate preferences

“…A nongenetic mechanism—learning to reject heterospecific individuals—can potentially reduce such interspecific interactions within generations (Svensson et al. ; Servedio and Dukas ; Svensson et al. ).…”