Mutation accumulation in inbreeding populations under evolution of the selfing rate

Abstract

Self-fertilization is common in hermaphroditic plants and also occurs in some co-sexual animals (Jarne & Charlesworth, 1993). Compared to outcrossing, self-fertilization enjoys an automatic transmission advantage, since a selfing individual not only transmits both its own male and female gametes to its offspring, but also can fertilize other individuals through pollen dispersal (Lande and Schemske, 1985;Lloyd, 1979;Nagylaki, 1976;). Selfing can also provide reproductive assurance when mates of mating opportunities are limited (Pannell & Barrett, 1998). However, macroevolutionary studies show negative diversification rates and higher extinction rates of self-compatible lineages compared to self-incompatible ones (Goldberg et al., 2010;Takebayashi & Morrell, 2001;Wright et al., 2013), which suggests self-fertilization is an evolutionary dead end. One of the most plausible explanations is that selfing leads to more rapid accumulation of deleterious mutations in the population (Bernardes, 1996;

The role of self-fertilization in plant colony establishment

“…The model captures the coevolution between the selfing rate, inbreeding depression and genetic load, but does not account for the accumulation of deleterious mutations. Therefore, the model tends to slightly overestimate fitness, since mutation accumulation is likely to occur when the population size becomes small (Charlesworth et al 1993, Xu 2022a).…”

The genetic basis of selfing rate evolution

“…Selfing is often controlled by multiple modifier loci, and a recent study shows that the genetic architecture of selfing can affect the rate of mutation accumulation (Xu 2021). It is thus critical to know whether the evolution of selfing is more likely when the selfing rate is controlled by many slight-effect modifier loci or few large-effect loci.…”

“…Using simulations incorporating both selfing modifiers and deleterious mutations, Damgaard (1996) found weak frequency-dependent selection on a selfing modifier, which he explained as a result of variation of the number of deleterious mutations among individuals. A recent study showed that under coevolution, the genetic architecture of selfing and inbreeding depression can mutually affect the temporal dynamics of selfing rate and mutation accumulation (Xu 2021). Therefore, a multilocus model that incorporates both viability and modifier loci under a finite population size is needed to better predict the coevolution of selfing and inbreeding depression in small populations.…”

How should we measure population-level inbreeding depression? Impacts of standing genetic associations between selfing rate and deleterious mutations

“…A modifier enhancing selfing can develop association with fitter alleles by promoting segregation and, thus, may invade even when ID is high ( Holsinger, 1988 ; Uyenoyama and Waller, 1991a , 1991c ). Conversely, in a highly selfing population, an outcrossing-enhancing modifier may invade under low ID ( Kamran-Disfani and Agrawal, 2014 ; Xu, 2022 ) because outcrossing promotes effective recombination between loci, thus increasing the efficacy of selection ( Uyenoyama and Waller, 1991a ). However, that genetic associations with fitness alleles may only slightly affect the invasibility of a selfing rate modifier, unless the modifier or deleterious mutations have strong effects ( Charlesworth et al., 1991 , 1992 ; Schultz and Willis, 1995 ; Damgaard, 1996 ).…”