Fluctuating environments, sexual selection and the evolution of flexible mate choice in birds.

Carlos A Botero,Dustin R Rubenstein,Marty L Leonard

doi:10.1371/journal.pone.0032311

Carlos A Botero, Dustin R Rubenstein + Show 1 more

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https://doi.org/10.1371/journal.pone.0032311

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Abstract

Environmentally-induced fluctuation in the form and strength of natural selection can drive the evolution of morphology, physiology, and behavior. Here we test the idea that fluctuating climatic conditions may also influence the process of sexual selection by inducing unexpected reversals in the relative quality or sexual attractiveness of potential breeding partners. Although this phenomenon, known as ‘ecological cross-over’, has been documented in a variety of species, it remains unclear the extent to which it has driven the evolution of major interspecific differences in reproductive behavior. We show that after controlling for potentially influential life history and demographic variables, there are significant positive associations between the variability and predictability of annual climatic cycles and the prevalence of infidelity and divorce within populations of a taxonomically diverse array of socially monogamous birds. Our results are consistent with the hypothesis that environmental factors have shaped the evolution of reproductive flexibility and suggest that in the absence of severe time constraints, secondary mate choice behaviors can help prevent, correct, or minimize the negative consequences of ecological cross-overs. Our findings also illustrate how a basic evolutionary process like sexual selection is susceptible to the increasing variability and unpredictability of climatic conditions that is resulting from climate change.

Highlights

Local variation in precipitation and temperature, can lead to temporal fluctuation in the form and strength of natural selection [1,2,3,4,5]
After removing all non-significant terms from this model, we find that extra-pair broods are more common in species that experience higher adult mortality (b = 0.050, t = 2.056, df = 119, P = 0.042; Fig. 1A), and breed in environments with greater within-year variance in temperature (b = 0.042, t = 2.068, df = 119, P = 0.041; Fig. 1B)
Once non-significant terms are removed from this model, we find that the frequency of divorce is higher in species with more pronounced visual ornamentation (b = 0.034, t = 2.348, df = 80, P = 0.021; Fig. 2A) and higher adult mortality (b = 0.089, t = 5.182, df = 80, P,0.001; Fig. 2B)

Summary

Introduction

Local variation in precipitation and temperature (e.g., wet and dry periods, changing seasons, or El Nino events), can lead to temporal fluctuation in the form and strength of natural selection [1,2,3,4,5]. Individuals attempt to maximize future direct or indirect benefits by choosing mates with superior phenotypic characteristics and/or more attractive courtship displays [16] Because these secondary sexual characters are often plastic, sudden changes in environmental conditions can lead to unexpected reversals in the relative quality or sexual attractiveness of potential breeding options ([14,17,18] for review see [19]). Known as ecological cross-over [14], has been observed in a variety of species including mites [20], flies [21], birds [15,22], fish [23], and frogs [24], it is currently unclear the extent to which it may explain general patterns of interspecific variation in reproductive behavior

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