Genetic variance components and heritability of multiallelic heterozygosity under inbreeding

Abstract

The maintenance of genetic diversity in fitness-related traits remains a central topic in evolutionary biology, for example, in the context of sexual selection for genetic benefits. Among the solutions that have been proposed is directional sexual selection for heterozygosity. The importance of such selection is highly debated. However, a critical evaluation requires knowledge of the heritability of heterozygosity, a quantity that is rarely estimated in this context, and often assumed to be zero. This is at least partly the result of the lack of a general framework that allows for its quantitative prediction in small and inbred populations, which are the focus of most empirical studies. Moreover, while current predictors are applicable only to biallelic loci, fitnessrelevant loci are often multiallelic, as are the neutral markers typically used to estimate genome-wide heterozygosity. To this end, we first review previous, but little-known, work showing that under most circumstances, heterozygosity at biallelic loci and in the absence of inbreeding is heritable. We then derive the heritability of heterozygosity and the underlying variances for multiple alleles and any inbreeding level. We also show that heterozygosity at multiallelic loci can be highly heritable when allele frequencies are unequal, and that this heritability is reduced by inbreeding. Our quantitative genetic framework can provide new insights into the evolutionary dynamics of heterozygosity in inbred and outbred populations.

Single nucleotide polymorphism of the growth hormone (GH) encoding gene in inbred and outbred domestic rabbits

“…According to most researchers, inbreeding leads to reduced heterozygosity and respectively, lower genetic diversity of populations (Falconer and Mackay, 1996;Кeller, 2002;Charlesworth and Willis, 2009;Nietlisbach et al, 2016;Tanchev, 2016). Some studies and analyses however provide evidence that the process of inbreeding-induced reduction of heterozygous genotypes within a population is multifactorial, although the most influential factors are its size, heterogeneity and the rate of achieving a specific inbreeding level (Maiwashe and Blackburn, 2004;Frankham, 2002;Charlesworth and Charlesworth, 1999;Demontis et al, 2009;Liao and Reed, 2009).…”

A father effect explains sex-ratio bias

“…see [17]). Inbreeding is heritable in some systems [18,19] (see electronic supplementary material S2)-with parental levels correlating with offspring inbreeding under non-random mating-allowing for paternal sex ratio bias driven by inbreeding to be adaptive. In addition, even in cases where inbreeding is not heritable, if males assess their quality and adjust offspring sex ratio accordingly, and if inbreeding depresses phenotypic quality [14], then more inbred fathers would be expected to shift the offspring sex ratio towards the less costly sex.…”

Be-Breeder - Learning: a new tool for teaching and learning plant breeding principles

“…However, this does not indicate that the number of heterozygotes in the population will increase indefinitely; that is, retention of heterozygosity (RH) reaches a plateau with a determined number of alleles. Although this value increases toward 1.00, the number of heterozygotes in the population will remain constant, just as indicated Nietlisbach et al 2016). It is known that the objective is to maintain heterozygosity at high levels in an allogamous population, so as to exploit heterosis and avoid inbreeding depression (Falconer et al 1996).…”