Inbreeding Depression, Genetic Load, and the Evolution of Outcrossing Rates in a Multilocus System with No Linkage

Evolution ◽  
1990 ◽  
Vol 44 (6) ◽  
pp. 1469 ◽  
Author(s):  
D. Charlesworth ◽  
M. T. Morgan ◽  
B. Charlesworth
Keyword(s):  
Inbreeding Depression ◽  
Genetic Load ◽  
Outcrossing Rates

scholarly journals Inbreeding depression due to mildly deleterious mutations in finite populations: size does matter

2000 ◽  
Vol 75 (1) ◽  
pp. 75-81 ◽  
Author(s):  
THOMAS BATAILLON ◽  
MARK KIRKPATRICK
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Deleterious Mutation ◽  
Large Population ◽  
Genetic Load ◽  
Breeding Systems ◽  
Deleterious Mutations ◽  
Single Locus Analysis ◽  
Population Sizes ◽  
Inbreeding Rate

We studied the effects of population size on the inbreeding depression and genetic load caused by deleterious mutations at a single locus. Analysis shows how the inbreeding depression decreases as population size becomes smaller and/or the rate of inbreeding increases. This pattern contrasts with that for the load, which increases as population size becomes smaller but decreases as inbreeding rate goes up. The depression and load both approach asymptotic limits when the population size becomes very large or very small. Numerical results show that the transition between the small and the large population regimes is quite rapid, and occurs largely over a range of population sizes that vary by a factor of 10. The effects of drift on inbreeding depression may bias some estimates of the genomic rate of deleterious mutation. These effects could also be important in the evolution of breeding systems in hermaphroditic organisms and in the conservation of endangered populations.

scholarly journals INBREEDING DEPRESSION AND GENETIC LOAD IN LABORATORY METAPOPULATIONS OF THE BUTTERFLYBICYCLUS ANYNANA

Evolution ◽  
2000 ◽  
Vol 54 (1) ◽  
pp. 218-225 ◽  
Author(s):  
Cock van Oosterhout ◽  
Wilte G. Zulstra ◽  
Marianne K. van Heuven ◽  
Paul M. Brakefield
Keyword(s):  
Inbreeding Depression ◽  
Genetic Load

scholarly journals How much gene flow is needed to avoid inbreeding depression in wild tiger populations?

2014 ◽  
Vol 281 (1789) ◽  
pp. 20133337 ◽  
Author(s):  
John Kenney ◽  
Fred W. Allendorf ◽  
Charles McDougal ◽  
James L. D. Smith
Keyword(s):  
Gene Flow ◽  
Inbreeding Depression ◽  
Negative Impact ◽  
Genetic Load ◽  
Habitat Connectivity ◽  
Medium Size ◽  
Infrastructure Development ◽  
Population Isolation ◽  
Source Populations ◽  
Seven Generations

The number and size of tiger populations continue to decline owing to habitat loss, habitat fragmentation and poaching of tigers and their prey. As a result, tiger populations have become small and highly structured. Current populations have been isolated since the early 1970s or for approximately seven generations. The objective of this study is to explore how inbreeding may be affecting the persistence of remaining tiger populations and how dispersal, either natural or artificial, may reduce the potentially detrimental effect of inbreeding depression. We developed a tiger simulation model and used published levels of genetic load in mammals to simulate inbreeding depression. Following a 50 year period of population isolation, we introduced one to four dispersing male tigers per generation to explore how gene flow from nearby populations may reduce the negative impact of inbreeding depression. For the smallest populations, even four dispersing male tigers per generation did not increase population viability, and the likelihood of extinction is more than 90% within 30 years. Unless habitat connectivity is restored or animals are artificially introduced in the next 70 years, medium size wild populations are also likely to go extinct, with only four to five of the largest wild tiger populations likely to remain extant in this same period without intervention. To reduce the risk of local extinction, habitat connectivity must be pursued concurrently with efforts to increase population size (e.g. enhance habitat quality, increase habitat availability). It is critical that infrastructure development, dam construction and other similar projects are planned appropriately so that they do not erode the extent or quality of habitat for these populations so that they can truly serve as future source populations.

Inbreeding depression in a rare deceptive orchid

2001 ◽  
Vol 79 (10) ◽  
pp. 1181-1188 ◽  
Author(s):  
Jean-Baptiste Ferdy ◽  
Sandrine Loriot ◽  
Michel Sandmeier ◽  
Madeleine Lefranc ◽  
Christian Raquin
Keyword(s):  
Inbreeding Depression ◽  
Conservation Biology ◽  
Resource Availability ◽  
Genetic Load ◽  
Outcrossing Rate ◽  
Deleterious Mutations ◽  
Geographic Scale ◽  
Deceptive Pollination ◽  
Inbreeding Level ◽  
Small Geographic Scale

We quantified inbreeding depression for seed maturation and germination in a deceptively pollinated orchid (Dactylorhiza praetermissa (Druce) Soó). Deceptive species do not provide any reward to their pollinators, which thus visit few flowers per plant. Therefore, deceptive species are predicted to experience high outcrossing. In agreement with the prediction that species with high outcrossing rate should possess a heavy genetic load, we demonstrated inbreeding depression in one of the populations we studied. More surprisingly, we found some evidence of inbreeding depression at a small geographic scale. This was not expected, as deceptive orchids generally disperse their pollen and their seeds over long distances. We also demonstrated that the position of a flower within an inflorescence interacts with the type of cross. This indicates that resource availability might modify how severely deleterious mutations affect reproductive success. This could also explain why the intensity of inbreeding depression seems, in the populations we studied, to be determined more by environmental factors than by inbreeding level, as estimated from molecular markers. Inferences in terms of conservation biology are drawn from these results.Key words: inbreeding depression, deceptive pollination, orchid, Dactylorhiza praetermissa.

scholarly journals Domestication reshaped the genetic basis of inbreeding depression in a maize landrace compared to its wild relative, teosinte

PLoS Genetics ◽  
2021 ◽  
Vol 17 (12) ◽  
pp. e1009797
Author(s):  
Luis Fernando Samayoa ◽  
Bode A. Olukolu ◽  
Chin Jian Yang ◽  
Qiuyue Chen ◽  
Markus G. Stetter ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Rare Variants ◽  
Sequence Data ◽  
Genetic Load ◽  
Population History ◽  
Additional Contribution ◽  
Wild Relative ◽  
Small Individual ◽  
Maize Population ◽  
Close Relatives

Inbreeding depression is the reduction in fitness and vigor resulting from mating of close relatives observed in many plant and animal species. The extent to which the genetic load of mutations contributing to inbreeding depression is due to large-effect mutations versus variants with very small individual effects is unknown and may be affected by population history. We compared the effects of outcrossing and self-fertilization on 18 traits in a landrace population of maize, which underwent a population bottleneck during domestication, and a neighboring population of its wild relative teosinte. Inbreeding depression was greater in maize than teosinte for 15 of 18 traits, congruent with the greater segregating genetic load in the maize population that we predicted from sequence data. Parental breeding values were highly consistent between outcross and selfed offspring, indicating that additive effects determine most of the genetic value even in the presence of strong inbreeding depression. We developed a novel linkage scan to identify quantitative trait loci (QTL) representing large-effect rare variants carried by only a single parent, which were more important in teosinte than maize. Teosinte also carried more putative juvenile-acting lethal variants identified by segregation distortion. These results suggest a mixture of mostly polygenic, small-effect partially recessive effects in linkage disequilibrium underlying inbreeding depression, with an additional contribution from rare larger-effect variants that was more important in teosinte but depleted in maize following the domestication bottleneck. Purging associated with the maize domestication bottleneck may have selected against some large effect variants, but polygenic load is harder to purge and overall segregating mutational burden increased in maize compared to teosinte.

scholarly journals Effects of inbreeding depression on seed production in Scots pine (Pinus sylvestris)

2019 ◽  
Vol 49 (7) ◽  
pp. 854-860 ◽  
Author(s):  
Tim J. Mullin ◽  
Torgny Persson ◽  
Sara Abrahamsson ◽  
Bengt Andersson Gull
Keyword(s):  
Pinus Sylvestris ◽  
Inbreeding Depression ◽  
Scots Pine ◽  
Genetic Load ◽  
Pollen Competition ◽  
Growth And Survival ◽  
Study Materials ◽  
Inbreeding Coefficients ◽  
Future Assessment ◽  
The Impact

Like other outcrossing species, Scots pine (Pinus sylvestris L.) is thought to carry a “genetic load” of deleterious recessive alleles. When these alleles occur as homozygotes in inbred progeny, their expression can give rise to “inbreeding depression”. Although this phenomenon has been studied in several conifer species through selfing, few studies have quantified inbreeding depression in crosses with lower levels of relatedness between parents. We report here on the generation of a set of F3 study materials in Scots pine in which 142 families arose from a mating design among 49 F2 parents, representing nine levels of expected inbreeding coefficients between 0.0 and 0.5, and repeated over two consecutive seasons. Whereas the numbers of extractable seeds were unaffected by inbreeding, the proportion with fully developed embryos was strongly affected. This was expressed as inbreeding depression in the yield of full seeds per cone but not in their mean mass. Levels of germination of these full seeds were affected by inbreeding, but the depression was rather small and only weakly significant. The roles of pollen competition and polyembryony in mitigating the impact of inbreeding depression are discussed. The materials have been outplanted for future assessment of inbreeding depression on growth and survival.

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