Effects of a change in the level of inbreeding on the genetic load

@article{Barrett1991EffectsOA,
  title={Effects of a change in the level of inbreeding on the genetic load},
  author={Spencer C. H. Barrett and Deborah Charlesworth},
  journal={Nature},
  year={1991},
  volume={352},
  pages={522-524}
}
"THE effects of inbreeding may not be as noticeable in the first generation as the invigoration immediately apparent after crossing"1. This statement, published in 1919, has received little attention, and has apparently never been tested empirically, although the reduction of the genetic load of populations by inbreeding is well known in theoretical terms2–5. Because inbreeding increases homozygosity, and hence the effectiveness of selection against recessive or partially recessive detrimental… 

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TLDR
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TLDR
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TLDR
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EFFECTIVENESS OF SELECTION IN REDUCING THE GENETIC LOAD IN POPULATIONS OF PEROMYSCUS POLIONOTUS DURING GENERATIONS OF INBREEDING

  • R. LacyJ. Ballou
  • Biology
    Evolution; international journal of organic evolution
  • 1998
TLDR
The effects of selection on inbreeding depression varied substantially among populations, perhaps due to different histories of inbreeding and selection.

Selection, load and inbreeding depression in a large metapopulation.

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

Purging inbreeding depression and the probability of extinction: full-sib mating

TLDR
The effectiveness of purging the genetic load is examined by documenting both the reduction in inbreeding depression and the increase of the probability of extinction when there is continous full-sib mating.

Inbreeding and extinction: Effects of rate of inbreeding

TLDR
It is concluded that purging may slow the rate of extinction slightly, but it cannot berelied on to eliminate the deleterious effect of inbreeding.

Genetics underlying inbreeding depression in Mimulus with contrasting mating systems

TLDR
It is shown here that deleterious recessive alleles are mainly responsible for inbreeding depression in two closely related annual plants, the primarily selfing Mimulus micranthus and the mixed-mating M. guttatus.
...

References

SHOWING 1-10 OF 19 REFERENCES

INBREEDING DEPRESSION, GENETIC LOAD, AND THE EVOLUTION OF OUTCROSSING RATES IN A MULTILOCUS SYSTEM WITH NO LINKAGE

We studied deterministic models of multilocus systems subject to mutation–selection balance with all loci unlinked, and with multiplicative interactions of the loci affecting fitness, in partially

INBREEDING DEPRESSION WITH HETEROZYGOTE ADVANTAGE AND ITS EFFECT ON SELECTION FOR MODIFIERS CHANGING THE OUTCROSSING RATE

TLDR
The equilibrium level of inbreeding depression in populations with different selfing rates is studied for models with symmetrical or asymmetrical heterozygous advantage at several loci with partial linkage, and the stability of outcrossing populations to invasion by alleles that give increased selfing is found to depend on levels of in breeding depression being greater than one‐half.

Genetic loads and estimates of mutation rates in highly inbred plant populations

TLDR
The inbreeding depression expected in completely inbred populations is derived and used to estimate mutation rates per genome for some plant species.

Inbreeding depression due to overdominance in partially self-fertilizing plant populations.

TLDR
The effect of the rate of partial self-fertilization and viability selection on the magnitude of inbreeding depression was investigated for the overdominance genetic model and Distributions of viabilities in progenies resulting from mixtures of selfing and outcrossing were shown to be bimodal when inbreeding depressed levels are high.

INBREEDING DEPRESSION AND ITS EVOLUTIONARY CONSEQUENCES

TLDR
The evidence that the evolution of breeding systems of animals and plants has been significantly influenced by the occurrence of inbreeding depression is reviewed, and the contemporary genetic theory of inmarriage depression and heterosis and the experimental data concerning the strength of in breeding depression are considered.

THE EVOLUTION OF SELF‐FERTILIZATION AND INBREEDING DEPRESSION IN PLANTS. I. GENETIC MODELS

TLDR
Genetic models are constructed which allow inbreeding depression to change with the mean selfing rate in a population by incorporating both mutation to recessive and partially dominant lethal and sublethal alleles at many loci and mutation in quantitative characters under stabilizing selection.

Fitness Rebound in Serially Bottlenecked Populations of the House Fly

TLDR
It is shown that additive genetic variation can actually increase in experimentally bottlenecked lines of the house fly, and this note reports on the changing fitness of the bottleneck lines through five successive bottleneck cycles.

Inherited biochemical variation in Drosophila melanogaster: noise or signal? I. Single-locus analysis.

TLDR
An interaction between the small population size treatment and excess heterozygosity suggests that the loci studied may be selectively neutral and linked to other loci which are under the influence of selection or either four of the seven enzymes studied are signaling the operation of selection.

Deleterious mutations as an evolutionary factor. II. Facultative apomixis and selfing.

TLDR
T truncation selection against deleterious mutations may be a factor supporting obligate or facultative sex despite the twofold advantage of apomixis or selfing.

Factors eliminating inbreeding depression in a captive herd of speke's gazelle (Gazella spekei)

TLDR
It is concluded that inbreeding depressions can be rapidly and effectively reduced by an appropriate breeding program, and hence an inbreeding depression does not constitute an insurmountable barrier to the long-term maintenance of a species in which inbreeding cannot be avoided.