Article

Mate choice for non-additive genetic benefits: a resolution to the lek paradox.

Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario, Canada N6A 5B7.
Journal of Theoretical Biology (Impact Factor: 2.3). 06/2008; 254(1):147-55. DOI: 10.1016/j.jtbi.2008.05.019
Source: PubMed

ABSTRACT In promiscuous mating systems, females often show a consistent preference to mate with one or a few males, presumably to acquire heritable genetic benefits for their offspring. However, strong directional selection should deplete additive genetic variation in fitness and consequently any benefit to expressing the preference by females (referred to as the lek paradox). Here, we provide a novel resolution that examines non-additive genetic benefits, such as overdominance or inbreeding, as a source of genetic variation. Focusing on the inbreeding coefficient f and overdominance effects, we use dynamic models to show that (1) f can be inherited from sire to offspring, (2) populations with females that express a mating preferences for outbred males (low f) maintain higher genetic variation than populations with females that mate randomly, and (3) preference alleles for outbred males can invade populations even when the alleles are associated with a fecundity cost. We show that non-additive genetic variation due to overdominance can be converted to additive genetic variation and becomes "heritable" when the frequencies of alternative homozygous genotypes at fitness loci deviate from equality. Unlike previous models that assume an infinite population size, we now show that genetic drift in finite populations can lead to the necessary deviations in the frequencies of homozygous genotypes. We also show that the "heritability of f," and hence the benefit to a mating preference for non-additive genetic benefits, is highest in small populations and populations in which a smaller number of loci contribute to fitness via overdominance. Our model contributes to the solution of the lek paradox.

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    • "Similarly, although substantial literature exists on maternal influences on life-history traits (e.g., Bernardo 1996; Green 2008), their role in population responses to selection has received less attention (Mousseau and Fox 1998; Wilson et al. 2005; Räsänen and Kruuk 2007). For example, nonadditive genetic variance can be converted to additive genetic variance, the material that can be used by selection, during a bottleneck (Carson 1990; Neff and Pitcher 2008). Also, maternal effects (maternal additive genetic and maternal environmental) can modify the rate and direction of a change in response to selection (Mousseau and Fox 1998; Wilson et al. 2005; Räsänen and Kruuk 2007). "
    Canadian Journal of Fisheries and Aquatic Sciences 05/2015; 72(5):751-758. DOI:10.1139/cjfas-2014-0472 · 2.28 Impact Factor
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    • "However, there is an increasing evidence that non-additive genetic effects are key components of phenotypes (Crnokrak and Roff, 1995; Roff and Emerson, 2006). Furthermore, non-additive genetic effects are a cause of inbreeding depression (Crnokrak and Roff, 1999; Keller and Waller, 2002) and can be converted to additive genetic effects, for example, during a bottleneck, which can then provide genetic variation for natural selection to act on (Carson, 1990; also see Neff and Pitcher, 2008). Phenotypic variance can also be explained by maternal environmental effects (Falconer and Mackay, 1996) and these effects can also affect evolutionary trajectories (Räsänen and Kruuk, 2007). "
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    ABSTRACT: The additive genetic effects of traits can be used to predict evolutionary trajectories, such as responses to selection. Non-additive genetic and maternal environmental effects can also change evolutionary trajectories and influence phenotypes, but these effects have received less attention by researchers. We partitioned the phenotypic variance of survival and fitness-related traits into additive genetic, non-additive genetic and maternal environmental effects using a full-factorial breeding design within two allopatric populations of Atlantic salmon (Salmo salar). Maternal environmental effects were large at early life stages, but decreased during development, with non-additive genetic effects being most significant at later juvenile stages (alevin and fry). Non-additive genetic effects were also, on average, larger than additive genetic effects. The populations, generally, did not differ in the trait values or inferred genetic architecture of the traits. Any differences between the populations for trait values could be explained by maternal environmental effects. We discuss whether the similarities in architectures of these populations is the result of natural selection across a common juvenile environment.Heredity advance online publication, 14 August 2013; doi:10.1038/hdy.2013.74.
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    • "If natural selection for heterozygosity reduces the fathereoffspring heterozygosity correlation and preferences depend on this relationship, the strength of this selection can be very influential in the evolution of preferences. In the models by Fromhage et al. (2009) and Neff & Pitcher (2008), the strength of natural selection is determined by the strength of inbreeding depression for descendants, which can be measured as the degree of association between heterozygosity and offspring viability. Therefore, to understand the range of parameters of this relationship that allows for the evolution of mate choice based on heterozygosity, it is essential to test the hypothesis in real conditions. "
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    ABSTRACT: Recent theoretical approaches using dynamic models have tried to explain the so-called ‘lek paradox’ arguing that female preferences for more heterozygous males could evolve in the absence of direct fitness benefits associated with mate choice. However, these models do not specify the degree of inbreeding depression required for the evolution of these preferences, nor what kinds of benefits promote this process. To answer these questions, I analysed one of these models considering different degrees of inbreeding depression. Paradoxically, choosy females had a higher chance of mating with siblings and achieved similar or even lower reproductive success than nonchoosy ones. Nevertheless, the allele determining female preferences for heterozygous males could still spread in some populations if the presence of this allele was correlated with male ornament expression, as in a runaway process. However, preference never prevailed over nonpreference under any of the following circumstances: limited dispersal, incest avoidance (which constrained top males’ mating success), exclusive maternal transmission of female preferences (which impeded correlations between preferences and ornament), inbreeding depression or low heterozygosity–ornament correlation. In the light of these results, the hypothesis of mate choice based on heterozygosity can hardly be advocated as a general solution to the lek paradox.
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