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Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding.

ABSTRACT: The deleterious mutation model proposes that quantitative trait variation should be dominated by rare, partially recessive, deleterious mutations. Following artificial selection on a focal trait, the ratio of the difference in inbreeding effects between control and selected populations (?B), to the difference in trait means caused by directional selection (?M), can inform the extent to which deleterious mutations cause quantitative trait variation. Here, we apply the ?B/?M ratio test to two quantitative traits (male mating success and body size) in Drosophila melanogaster. For both traits, ?B/?M ratios suggested that intermediate-frequency alleles, rather than rare, partially recessive alleles (i.e. deleterious mutations), caused quantitative trait variation. We discuss these results in relation to viability data, exploring how differences between regimens in segregating (measured through inbreeding) and fixed (measured through population crosses) mutational load could affect the ratio test. Finally, we present simulations that test the statistical power of the ratio test, providing guidelines for future research.

SUBMITTER: Dugand RJ

PROVIDER: S-EPMC6781166 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding.

Dugand Robert J RJ Kennington W Jason WJ Tomkins Joseph L JL

Heredity 20190409 3

The deleterious mutation model proposes that quantitative trait variation should be dominated by rare, partially recessive, deleterious mutations. Following artificial selection on a focal trait, the ratio of the difference in inbreeding effects between control and selected populations (ΔB), to the difference in trait means caused by directional selection (ΔM), can inform the extent to which deleterious mutations cause quantitative trait variation. Here, we apply the ΔB/ΔM ratio test to two quan ...[more]

PMID: 30967644

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Project description:BackgroundRainbow trout is a significant fish farming species under temperate climates. Female reproduction traits play an important role in the economy of breeding companies with the sale of fertilized eggs. The objectives of this study are threefold: to estimate the genetic parameters of female reproduction traits, to determine the genetic architecture of these traits by the identification of quantitative trait loci (QTL), and to assess the expected efficiency of a pedigree-based selection (BLUP) or genomic selection for these traits.ResultsA pedigreed population of 1343 trout were genotyped for 57,000 SNP markers and phenotyped for seven traits at 2 years of age: spawning date, female body weight before and after spawning, the spawn weight and the egg number of the spawn, the egg average weight and average diameter. Genetic parameters were estimated in multi-trait linear animal models. Heritability estimates were moderate, varying from 0.27 to 0.44. The female body weight was not genetically correlated to any of the reproduction traits. Spawn weight showed strong and favourable genetic correlation with the number of eggs in the spawn and individual egg size traits, but the egg number was uncorrelated to the egg size traits. The genome-wide association studies showed that all traits were very polygenic since less than 10% of the genetic variance was explained by the cumulative effects of the QTLs: for any trait, only 2 to 4 QTLs were detected that explained in-between 1 and 3% of the genetic variance. Genomic selection based on a reference population of only one thousand individuals related to candidates would improve the efficiency of BLUP selection from 16 to 37% depending on traits.ConclusionsOur genetic parameter estimates made unlikely the hypothesis that selection for growth could induce any indirect improvement for female reproduction traits. It is thus important to consider direct selection for spawn weight for improving egg production traits in rainbow trout breeding programs. Due to the low proportion of genetic variance explained by the few QTLs detected for each reproduction traits, marker assisted selection cannot be effective. However genomic selection would allow significant gains of accuracy compared to pedigree-based selection.

Dataset Information

Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding.

Publications

Evaluating the genetic architecture of quantitative traits via selection followed by inbreeding.

Similar Datasets

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