Evolutionary genetics of maternal effects

Abstract

Maternal genetic effects (MGEs), where genes expressed by mothers affect the phenotype of their offspring, are important sources of phenotypic diversity in a myriad of organisms. We use a single-locus model to examine how MGEs contribute patterns of heritable and non-heritable variation and influence evolutionary dynamics in randomly mating and inbreeding populations. We elucidate the influence of MGEs by examining the offspring genotype-phenotype relationship, which determines how MGEs affect evolutionary dynamics in response to selection on offspring phenotypes. This approach reveals important results that are not apparent from classic quantitative genetic treatments of MGEs. We show that additive and dominance MGEs make different contributions to evolutionary dynamics and patterns of variation, which are differentially affected by inbreeding. Dominance MGEs make the offspring genotype-phenotype relationship frequency dependent, resulting in the appearance of negative frequency-dependent selection, while additive MGEs contribute a component of parent-of-origin dependent variation. Inbreeding amplifies the contribution of MGEs to the additive genetic variance and, therefore enhances their evolutionary response. Considering evolutionary dynamics of allele frequency change on an adaptive landscape, we show that this landscape differs from the mean fitness surface, and therefore, under some condition, fitness peaks can exist but not be ‘available’ to the evolving population.

Roles of maternal effects in maintaining genetic variation: Maternal storage effect

“…The parameter a can be further decreased by, for example, grand-maternal effects or the combination of maternal effects and overlapping generations. When the offspring phenotype is affected by both maternal and offspring genotypes (Wolf and Wade 2016), the parameter a will be between one-half and one (Wright 1969). We examined the mutual invasibility of rare alleles for understanding coexistence conditions (see Appendix S2 for details).…”

“…Maternal effects that have a genetic basis have been reported in various organisms in both laboratory and natural populations (Räsänen and Kruuk 2007;Mousseau et al 2009;Wolf and Wade 2016). For example, delayed inheritance has been detected in fish (Reznick 1981) and maternal genetic effects have been quantified in mammals (Wilson et al 2005), but little is known about the molecular mechanisms.…”

Decoupled Maternal and Zygotic Genetic Effects Shape the Evolution of Development

“…The simplest scenario is that co-adapted trait combinations are affected by shared alleles, either by pleiotropy (for example, ref 30 ) or tight linkage (e.g., a supergene with suppressed recombination 31,32 ). The necessity to coordinate maternal traits (larval size) with zygotic traits (larval morphology) adds additional constraints 20,33,34 . Fig 1b shows that alternative paths from planktotrophy to lecithotrophy make different predictions about the correlations among genetic effects.…”

Genetic benefits of extreme sequential polyandry in a terrestrial‐breeding frog

“…Nevertheless, we expect that environmental-maternal effects may be substantial because they are known to have strong effects on offspring performance in various amphibians (Merilä et al 2004;Eads et al 2012;Rudin-Bitterli et al 2018). Causes of environmental-maternal effects are diverse, but they are typically related to variation in the degree to which females invest in offspring (Wolf and Wade 2016). Pseudophryne bibronii has no maternal care, and females in our study had no opportunity to interact with their offspring.…”

“…). Causes of environmental‐maternal effects are diverse, but they are typically related to variation in the degree to which females invest in offspring (Wolf and Wade ). Pseudophryne bibronii has no maternal care, and females in our study had no opportunity to interact with their offspring.…”