THE ROLE OF GENES OF LARGE EFFECT ON INBREEDING DEPRESSION INMIMULUS GUTTATUS

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreeding depression in the offspring. Inbreeding depression is a reduction in the fitness of inbred offspring relative to outbred offspring. Here, we tested whether maternal effects due to body size alter the magnitude of inbreeding depression in the burying beetle Nicrophorus vespilloides . We found that inbreeding depression in larval survival was more severe for offspring of large females than offspring of small females. This might be due to differences in how small and large females invest in an inbred brood because of their different prospects for future breeding opportunities. To our knowledge, this is the first evidence for a causal effect of the maternal phenotype on the severity of inbreeding depression in the offspring. In natural populations that are subject to inbreeding, maternal effects may drive variation in inbreeding depression and therefore contribute to variation in the strength and direction of selection for inbreeding avoidance.

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Point estimation and graphical inference of marginal dominance for two viability loci controlling inbreeding depression

Genetics Research ◽

10.1017/s0016672397002966 ◽

1997 ◽

Vol 70 (2) ◽

pp. 143-153 ◽

Cited By ~ 4

Author(s):

YONG-BI FU ◽

DEBORAH CHARLESWORTH ◽

GENE NAMKOONG

Keyword(s):

Inbreeding Depression ◽

Gene Action ◽

Marker Locus ◽

Point Estimation ◽

Relative Role ◽

Selfed Progeny ◽

Deterministic Analysis ◽

Partial Dominance ◽

Segregation Ratios

A deterministic analysis is conducted to examine marginal dominance for two linked viability loci influencing inbreeding depression and its graphical inferences. Four estimators of marginal dominance are derived, assuming a biallelic marker locus completely linked to one of the viability loci, and the biases in expected estimates due to the other deleterious locus are discussed. Three conditions under which apparent partial dominance or underdominance could occur are found, i.e. when two multiplicative, partially recessive loci are linked in coupling phase and when two synergistic, highly overdominant loci are linked in coupling or repulsion phases. Expected frequencies of the three marker genotypes in selfed progeny are derived, considering two linkage phases, two types of marker locus position with respect to the viability loci, and the multiplicative and synergistic fitness models. Segregation ratios are generated for the marker locus linked to either two overdominant or partially recessive loci and plotted in gene action graphs to examine the robustness of the graphical inferences of gene action due to the presence of an additional linked viability locus. Under a multiplicative fitness model, the presence of an additional partially recessive or overdominant locus in the vicinity of the marker locus does not greatly affect the graphical inferences of the relative role of partially recessive or overdominant genes in expression of inbreeding depression. A marker linked to two synergistic, highly overdominant loci can behave as though linked to a partially recessive, partially dominant or underdominant locus, even with relatively weak synergism.

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THE ROLE OF INBREEDING DEPRESSION IN MAINTAINING THE MIXED MATING SYSTEM OF THE COMMON MORNING GLORY,IPOMOEA PURPUREA

Evolution ◽

10.1111/j.1558-5646.1999.tb05401.x ◽

1999 ◽

Vol 53 (5) ◽

pp. 1366-1376 ◽

Cited By ~ 24

Author(s):

Shu-Mei Chang ◽

Mark D. Rausher

Keyword(s):

Mating System ◽

Inbreeding Depression ◽

Morning Glory ◽

Mixed Mating ◽

Mixed Mating System ◽

Ipomoea Purpurea ◽

The Common

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Population-level consequences of inheritable somatic mutations and the evolution of mutation rates in plants

10.1101/2020.09.29.318402 ◽

2020 ◽

Author(s):

Thomas Lesaffre

Keyword(s):

Life Expectancy ◽

Inbreeding Depression ◽

Life Histories ◽

Somatic Mutations ◽

Population Level ◽

Mutation Rates ◽

Deleterious Mutations

ABSTRACTInbreeding depression, that is the decrease in fitness of inbred relative to outbred individuals, was shown to increase strongly as life expectancy increases in plants. Because plants are thought to not have a separated germline, it was proposed that this pattern could be generated by somatic mutations accumulating during growth, since larger and more long-lived species have more opportunities for mutations to accumulate. A key determinant of the role of somatic mutations is the rate at which they occur, which likely differs between species because mutation rates may evolve differently in species with constrasting life-histories. In this paper, we study the evolution of the mutation rates in plants, and consider the population-level consequences of inheritable somatic mutations given this evolution. We show that despite substantially lower per year mutation rates, more long-lived species still tend to accumulate larger amounts of deleterious mutations because of higher per generation, leading to higher levels of inbreeding depression in these species. However, the magnitude of this increase depends strongly on how mutagenic meiosis is relative to growth.

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