Effects of partial selfing on the equilibrium genetic variance, mutation load, and inbreeding depression under stabilizing selection

ABSTRACTThis preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100041).The mating system of a species is expected to have important effects on its genetic diversity. In this paper, we explore the effects of partial selfing on the equilibrium genetic variance Vg, mutation load L and inbreeding depression δ under stabilizing selection acting on a arbitrary number n of quantitative traits coded by biallelic loci with additive effects. Overall, our model predicts a decrease in the equilibrium genetic variance with increasing selfing rates; however, the relationship between self-fertilization and the variables of interest depends on the strength of associations between loci, and three different regimes are observed. When the U/n ratio is low (where U is the total haploid mutation rate on selected traits) and effective recombination rates are sufficiently high, genetic associations between loci are negligible and the genetic variance, mutation load and inbreeding depression are well predicted by approximations based on single-locus models. For higher values of U/n and/or lower effective recombination, moderate genetic associations generated by epistasis tend to increase Vg, L and δ, this regime being well predicted by approximations including the effects of pairwise associations between loci. For yet higher values of U/n and/or lower effective recombination, a different regime is reached under which the maintenance of coadapted gene complexes reduces Vg, L and δ. Simulations indicate that the values of Vg, L and δ are little affected by assumptions regarding the number of possible alleles per locus.

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Selection Response in Finite Populations

Genetics ◽

10.1093/genetics/144.4.1961 ◽

1996 ◽

Vol 144 (4) ◽

pp. 1961-1974 ◽

Cited By ~ 2

Author(s):

Ming Wei ◽

Armando Caballero ◽

William G Hill

Keyword(s):

Linkage Disequilibrium ◽

Inbreeding Depression ◽

Genetic Variance ◽

Relative Rate ◽

Selection Response ◽

Rate Of Change ◽

Effective Population ◽

Short Term ◽

Model Account

Formulae were derived to predict genetic response under various selection schemes assuming an infinitesimal model. Account was taken of genetic drift, gametic (linkage) disequilibrium (Bulmer effect), inbreeding depression, common environmental variance, and both initial segregating variance within families (σAW02) and mutational (σM2) variance. The cumulative response to selection until generation t(CRt) can be approximated asCRt≈R0[t−β(1−σAW∞2σAW02)t24Ne]−Dt2Ne,where Ne is the effective population size, σAW∞2=NeσM2 is the genetic variance within families at the steady state (or one-half the genic variance, which is unaffected by selection), and D is the inbreeding depression per unit of inbreeding. R 0 is the selection response at generation 0 assuming preselection so that the linkage disequilibrium effect has stabilized. β is the derivative of the logarithm of the asymptotic response with respect to the logarithm of the within-family genetic variance, i.e., their relative rate of change. R 0 is the major determinant of the short term selection response, but σM2, Ne and β are also important for the long term. A selection method of high accuracy using family information gives a small Ne and will lead to a larger response in the short term and a smaller response in the long term, utilizing mutation less efficiently.

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The mutation load under tetrasomic inheritance and its consequences for the evolution of the selfing rate in autotetraploid species

Genetics Research ◽

10.1017/s0016672399003845 ◽

1999 ◽

Vol 74 (1) ◽

pp. 31-42 ◽

Cited By ~ 59

Author(s):

J. RONFORT

Keyword(s):

Inbreeding Depression ◽

Deleterious Mutation ◽

Stable State ◽

Approximate Solutions ◽

Balance Model ◽

Deleterious Mutations ◽

Selfing Rate ◽

Mutation Load ◽

Mean Fitness ◽

The Mean

Single-locus equilibrium frequencies of a partially recessive deleterious mutation under the mutation–selection balance model are derived for partially selfing autotetraploid populations. Assuming multiplicative fitness interactions among loci, approximate solutions for the mean fitness and inbreeding depression values are also derived for the multiple locus case and compared with expectations for the diploid model. As in diploids, purging of deleterious mutations through consanguineous matings occurs in autotetraploid populations, i.e. the equilibrium mutation load is a decreasing function of the selfing rate. However, the variation of inbreeding depression with the selfing rate depends strongly on the dominance coefficients associated with the three heterozygous genotypes. Inbreeding depression can either increase or decrease with the selfing rate, and does not always vary monotonically. Expected issues for the evolution of the selfing rate consequently differ depending on the dominance coefficients. In some cases, expectations for the evolution of the selfing rate resemble expectations in diploids; but particular sets of dominance coefficients can be found that lead to either complete selfing or intermediate selfing rates as unique evolutionary stable state.

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Selection, Load and Inbreeding Depression in a Large Metapopulation

Genetics ◽

10.1093/genetics/160.3.1191 ◽

2002 ◽

Vol 160 (3) ◽

pp. 1191-1202 ◽

Cited By ~ 1

Author(s):

Michael C Whitlock

Keyword(s):

Population Structure ◽

Inbreeding Depression ◽

Population Subdivision ◽

Response To Selection ◽

Mutation Load ◽

Deleterious Alleles ◽

Subdivided Population ◽

Soft Selection ◽

Mean Fitness ◽

The Mean

Abstract The subdivision of a species into local populations causes its response to selection to change, even if selection is uniform across space. Population structure increases the frequency of homozygotes and therefore makes selection on homozygous effects more effective. However, population subdivision can increase the probability of competition among relatives, which may reduce the efficacy of selection. As a result, the response to selection can be either increased or decreased in a subdivided population relative to an undivided one, depending on the dominance coefficient FST and whether selection is hard or soft. Realistic levels of population structure tend to reduce the mean frequency of deleterious alleles. The mutation load tends to be decreased in a subdivided population for recessive alleles, as does the expected inbreeding depression. The magnitude of the effects of population subdivision tends to be greatest in species with hard selection rather than soft selection. Population structure can play an important role in determining the mean fitness of populations at equilibrium between mutation and selection.

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Age-specific inbreeding depression and components of genetic variance in relation to the evolution of senescence.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.93.12.6140 ◽

1996 ◽

Vol 93 (12) ◽

pp. 6140-6145 ◽

Cited By ~ 139

Author(s):

B. Charlesworth ◽

K. A. Hughes

Keyword(s):

Inbreeding Depression ◽

Genetic Variance

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Lethals in subdivided populations

Genetics Research ◽

10.1017/s0016672305007676 ◽

2005 ◽

Vol 86 (1) ◽

pp. 41-51 ◽

Cited By ~ 13

Author(s):

SYLVAIN GLÉMIN

Keyword(s):

Population Structure ◽

Population Size ◽

Inbreeding Depression ◽

Deleterious Mutations ◽

Mutation Load ◽

General Picture ◽

Analytical Approximations ◽

Size Population ◽

Subdivided Populations ◽

Numerical Approaches

The fate of lethal alleles in populations is of interest in evolutionary and conservation biology for several reasons. For instance, lethals may contribute substantially to inbreeding depression. The frequency of lethal alleles depends on population size, but it is not clear how it is affected by population structure. By analysing the case of the infinite island model by numerical approaches and analytical approximations it is shown that, like population size, population structure affects the fate of lethal alleles if dominance levels are low. Inbreeding depression caused by such alleles is also affected by the population structure, whereas the mutation load is only weakly affected. Heterosis also depends on population structure, but it always remains low, of the order of the mutation rate or less. These patterns are compared with those caused by mildly deleterious mutations to give a general picture of the effect of population structure on inbreeding depression, heterosis, and the mutation load.

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Quantitative genetic variability maintained by mutation-stabilizing selection balance: sampling variation and response to subsequent directional selection

Genetics Research ◽

10.1017/s0016672300028366 ◽

1989 ◽

Vol 54 (1) ◽

pp. 45-58 ◽

Cited By ~ 17

Author(s):

Peter D. Keightley ◽

William G. Hill

Keyword(s):

Genetic Variance ◽

Directional Selection ◽

Quantitative Character ◽

Stabilizing Selection ◽

Effective Population ◽

Selection Responses ◽

Quantitative Genetic ◽

Before And After ◽

Cage Population ◽

Selection Of

SummaryA model of genetic variation of a quantitative character subject to the simultaneous effects of mutation, selection and drift is investigated. Predictions are obtained for the variance of the genetic variance among independent lines at equilibrium with stabilizing selection. These indicate that the coefficient of variation of the genetic variance among lines is relatively insensitive to the strength of stabilizing selection on the character. The effects on the genetic variance of a change of mode of selection from stabilizing to directional selection are investigated. This is intended to model directional selection of a character in a sample of individuals from a natural or long-established cage population. The pattern of change of variance from directional selection is strongly influenced by the strengths of selection at individual loci in relation to effective population size before and after the change of regime. Patterns of change of variance and selection responses from Monte Carlo simulation are compared to selection responses observed in experiments. These indicate that changes in variance with directional selection are not very different from those due to drift alone in the experiments, and do not necessarily give information on the presence of stabilizing selection or its strength.

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The evolutionary genetics of personality: Does mutation load signal relationship load?

Behavioral and Brain Sciences ◽

10.1017/s0140525x06269097 ◽

2006 ◽

Vol 29 (4) ◽

pp. 409-409 ◽

Cited By ~ 11

Author(s):

David M. Buss

Keyword(s):

Mating Success ◽

Mate Selection ◽

Genetic Variance ◽

Additive Genetic Variance ◽

Evolutionary Genetics ◽

Resource Acquisition ◽

Mutation Load ◽

Normal Personality ◽

Difference Detection ◽

Show Evidence

The mutation-selection hypothesis may extend to understanding normal personality variation. Traits such as emotional stability, agreeableness, and conscientiousness figure strongly in mate selection and show evidence of non-additive genetic variance. They are linked with reproductively relevant outcomes, including longevity, resource acquisition, and mating success. Evolved difference-detection adaptations may function to spurn individuals whose high mutation load signals a burdensome relationship load.

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Genetic constraints predict evolutionary divergence in Dalechampia blossoms

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0255 ◽

2014 ◽

Vol 369 (1649) ◽

pp. 20130255 ◽

Cited By ~ 52

Author(s):

Geir H. Bolstad ◽

Thomas F. Hansen ◽

Christophe Pélabon ◽

Mohsen Falahati-Anbaran ◽

Rocío Pérez-Barrales ◽

...

Keyword(s):

Genetic Variance ◽

Floral Morphology ◽

Additive Genetic Variance ◽

Genetic Data ◽

Stabilizing Selection ◽

Evolutionary Divergence ◽

Genetic Constraints ◽

Quantitative Genetic ◽

Rates Of Evolution ◽

Genetic Constraint

If genetic constraints are important, then rates and direction of evolution should be related to trait evolvability. Here we use recently developed measures of evolvability to test the genetic constraint hypothesis with quantitative genetic data on floral morphology from the Neotropical vine Dalechampia scandens (Euphorbiaceae). These measures were compared against rates of evolution and patterns of divergence among 24 populations in two species in the D. scandens species complex. We found clear evidence for genetic constraints, particularly among traits that were tightly phenotypically integrated. This relationship between evolvability and evolutionary divergence is puzzling, because the estimated evolvabilities seem too large to constitute real constraints. We suggest that this paradox can be explained by a combination of weak stabilizing selection around moving adaptive optima and small realized evolvabilities relative to the observed additive genetic variance.

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