Genetic load, inbreeding depression, and hybrid vigor covary with population size: An empirical evaluation of theoretical predictions

Evolution ◽  
2015 ◽  
Vol 69 (12) ◽  
pp. 3109-3122 ◽  
Author(s):  
Jennifer N. Lohr ◽  
Christoph R. Haag
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Empirical Evaluation ◽  
Genetic Load ◽  
Hybrid Vigor ◽  
Theoretical Predictions

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.

High Genetic Load in the Pacific Oyster Crassostrea gigas

Genetics ◽  
2001 ◽  
Vol 159 (1) ◽  
pp. 255-265 ◽  
Author(s):  
Sophie Launey ◽  
Dennis Hedgecock
Keyword(s):  
Inbreeding Depression ◽  
Genetic Load ◽  
Inbred Lines ◽  
Hybrid Vigor ◽  
Bivalve Molluscs ◽  
Recessive Mutations ◽  
Pacific Oysters ◽  
The Pacific ◽  
Microsatellite Dna Markers ◽  
Segregation Ratios

Abstract The causes of inbreeding depression and the converse phenomenon of heterosis or hybrid vigor remain poorly understood despite their scientific and agricultural importance. In bivalve molluscs, related phenomena, marker-associated heterosis and distortion of marker segregation ratios, have been widely reported over the past 25 years. A large load of deleterious recessive mutations could explain both phenomena, according to the dominance hypothesis of heterosis. Using inbred lines derived from a natural population of Pacific oysters and classical crossbreeding experiments, we compare the segregation ratios of microsatellite DNA markers at 6 hr and 2–3 months postfertilization in F2 or F3 hybrid families. We find evidence for strong and widespread selection against identical-by-descent marker homozygotes. The marker segregation data, when fit to models of selection against linked deleterious recessive mutations and extrapolated to the whole genome, suggest that the wild founders of inbred lines carried a minimum of 8–14 highly deleterious recessive mutations. This evidence for a high genetic load strongly supports the dominance theory of heterosis and inbreeding depression and establishes the oyster as an animal model for understanding the genetic and physiological causes of these economically important phenomena.

scholarly journals Mutational load, inbreeding depression and heterosis in subdivided populations

2018 ◽  
Author(s):  
Brian Charlesworth
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Population Genomics ◽  
Local Population ◽  
Genetic Load ◽  
Mutation Rates ◽  
Weak Selection ◽  
Empirical Estimates ◽  
Numerical Predictions ◽  
Subdivided Populations

AbstractThis paper examines the extent to which empirical estimates of inbreeding depression and inter-population heterosis in subdivided populations, as well as the effects of local population size on mean fitness, can be explained in terms of estimates of mutation rates, and the distribution of selection coefficients against deleterious mutations provided by population genomics data. Using results from population genetics models, numerical predictions of the genetic load, inbreeding depression and heterosis were obtained for a broad range of selection coefficients and mutation rates. The models allowed for the possibility of very high mutation rates per nucleotide site, as is sometimes observed for epiallelic mutations. There was fairly good quantitative agreement between the theoretical predictions and empirical estimates of heterosis and the effects of population size on genetic load, on the assumption that the deleterious mutation rate per individual per generation is approximately one, but there was less good agreement for inbreeding depression. Weak selection, of the order of magnitude suggested by population genomic analyses, is required to explain the observed patterns. Possible caveats concerning the applicability of the models are discussed.

scholarly journals POPULATION SIZE AND THE NATURE OF GENETIC LOAD IN GENTIANELLA GERMANICA

Evolution ◽  
2003 ◽  
Vol 57 (10) ◽  
pp. 2242-2251 ◽  
Author(s):  
Susanne Paland ◽  
Bernhard Schmid
Keyword(s):  
Population Size ◽  
Genetic Load ◽  
Gentianella Germanica

scholarly journals Lethals in subdivided populations

2005 ◽  
Vol 86 (1) ◽  
pp. 41-51 ◽  
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.

Reduced population size can induce quick evolution of inbreeding depression in the invasive ladybird Harmonia axyridis

2016 ◽  
Vol 18 (10) ◽  
pp. 2871-2881 ◽  
Author(s):  
Guillaume J. M. Laugier ◽  
Gilles Le Moguédec ◽  
Wang Su ◽  
Ashraf Tayeh ◽  
Laurent Soldati ◽  
...  
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Harmonia Axyridis

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
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