Forging links between population and quantitative genetics

Frankham, Richard; Nurthen, Roderick K.

doi:10.1007/bf00265506

Cited by 21 publications

(7 citation statements)

References 41 publications

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“…There are several lines of evidence that support the hypothesis that genetic variation at candidate loci causes quantitative variation in bristle number. First, alleles of candidate loci with large effects on bristle number have occasionally been found segregating in natural populations (22,64). Second, as noted previously, the positions of many QTLs map to positions very near those of candidate loci.…”

Section: Does Variation In Candidate Loci Cause Quantitative Variatiomentioning

confidence: 64%

Patterns of Genetic Variation in Mendelian and Complex Traits

Zwick

Cutler

Chakravarti

2000

Annu. Rev. Genom. Hum. Genet.

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This review discusses the prospects for understanding the genetic basis of complex traits in humans. We take the view that work done on Drosophila melanogaster can serve as a model for understanding complex traits in humans, and the literature on this model system, as well as on humans, is reviewed. The prospects for success in understanding the genetic basis of complex traits depend, in part, on the nature of the forces acting on genetic variation. We suggest that different experimental approaches should be undertaken for traits caused by common genetic variants versus those arising from rare genetic variants.

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Section: Does Variation In Candidate Loci Cause Quantitative Variatiomentioning

confidence: 64%

Patterns of Genetic Variation in Mendelian and Complex Traits

Zwick

Cutler

Chakravarti

2000

Annu. Rev. Genom. Hum. Genet.

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“…Even with directional dominance and asymmetrical gene frequencies, gene effects must be of a reasonable size for asymmetry to be detectable in short-term response. Asymmetrical responses to selection due to rare essentially recessive alleles of large effect have been observed by Costantino et al (1967) and Frankham & Nurthen (1981). Rare deleterious recessive mutations in mutation-selection balance could be contributing to the observed asymmetry.…”

Section: Discussionmentioning

confidence: 85%

Are responses to artificial selection for reproductive fitness characters consistently asymmetrical?

Frankham

1990

Genet. Res.

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Non-linear offspring-parent regressions and heritabilities are expected for characters showing genetic asymmetry due to directional dominance and/or asymmetrical gene frequencies. Since reproductive fitness characters exhibit these characteristics, they should show consistently nonlinear heritabilities, with greater heritabilities in the direction of lower fitness. As a consequence, responses to bi-directional selection on fitness traits should be asymmetrical in the same direction. This prediction has been tested by an analysis of published bi-directional selection experiments for reproductive fitness traits. Significant asymmetry (24 of 30 studies) in the predicted direction was found. For studies reporting realized heritabilities, the means were 0-173 and 0-259 for lines selected for higher and lower reproductive fitness, respectively, the high lines being 33 % less than the low lines. Asymmetry was evident for studies reporting realized heritabilities and for those with random mating controls of the same size as the selection lines. Consequently, it is argued that the asymmetry results from genetic asymmetries. This asymmetry has important implications in the improvement of reproductive fitness traits in plant and animal breeding.

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“…This measures the total genetic variation, plus a small component of between-fly common environmental effects. It has proven to be a reliable means for measuring changes in quantitative genetic variation and to be stable over long periods under controlled environmental conditions (see Reeve & Robertson, 1954 ;Latter, 1964;Frankham et al, 1968 ;Frankham & Nurthen, 1981 ;Frankham, 2000). In brief, this method is dependent on environmental correlations between repeat segments being close to zero, genetic correlations between repeat segments being nearly unity and differences between repeat bristle segments (fluctuating asymmetry) being unrelated to inbreeding.…”

Section: (Ii) Measuring Quantitative Genetic Variationmentioning

confidence: 99%

Comparative losses of quantitative and molecular genetic variation in finite populations of Drosophila melanogaster

2005

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Quantitative genetic variation, the main determinant of the ability to evolve, is expected to be lost in small populations, but there are limited data on the effect, and controversy as to whether it is similar to that for near neutral molecular variation. Genetic variation for abdominal and sternopleural bristle numbers and allozyme heterozygosity were estimated in 23 populations of Drosophila melanogaster maintained at effective population sizes of 25, 50, 100, 250 or 500 for 50 generations, as well as in 19 highly inbred populations and the wild outbred base population. Highly significant negative regressions of proportion of initial genetic variation retained on inbreeding due to finite population size were observed for both quantitative characters (b = -0.67 +/- 0.14 and -0.58 +/- 0.11) and allozyme heterozygosity (b = -0.79 +/- 0.10), and the regression coefficients did not differ significantly. Thus, quantitative genetic variation is being lost at a similar rate to molecular genetic variation. However, genetic variation for all traits was lost at rates significantly slower than predicted by neutral theory, most likely due to associative overdominance. Positive, but relatively low correlations were found among the different measures of genetic variation, but their low magnitudes were attributed to large sampling errors, rather than differences in the underlying processes of loss.

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Forging links between population and quantitative genetics

Cited by 21 publications

References 41 publications

Patterns of Genetic Variation in Mendelian and Complex Traits

Patterns of Genetic Variation in Mendelian and Complex Traits

Are responses to artificial selection for reproductive fitness characters consistently asymmetrical?

Comparative losses of quantitative and molecular genetic variation in finite populations of Drosophila melanogaster

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