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Introduction

Standard models in population genetics look up at the evolution of few loci which impact fitness. The variance in fitness is determined by the genetic variance and the environmental variance (and the co-variance between environment and genetics). In this question I am interested only about genetic variance and about what percentage of the total (additive or not) genetic variance in fitness do 'n' loci explain.

Question

In general, in natural populations, what percentage of the total genetic variance is explained by the 'n'- most important loci?

Here, by "most important loci" I mean loci which variance explain much of the total genetic variance.

In other words, the subquestions are of the kind:

  • how much of the fitness variance does the most important locus explain?
  • How much of the fitness variance do the 3 most important loci explain?
  • How much of the fitness variance do the 100 most important loci explain?

Of course, the answer depends on the population under consideration. Factors that might influence the answers are for example

  • species
  • population size
  • environment stability

Beside this question, I also welcome some insights concerning how different factors are likely to influence the answer.

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    $\begingroup$ Do you have at least one example of an empirical study of the type you are looking for ? It may be a helpful starting point for us in finding other ones. $\endgroup$
    – Barbara
    Feb 10 '14 at 13:16
  • $\begingroup$ No, unfortunately I don't know any empirical study that investigates my question. $\endgroup$
    – Remi.b
    Feb 10 '14 at 14:25
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    $\begingroup$ I think its exceptionally rare for the most important loci to collectively explain more than a small percentage of the total genetic variance, it's a fundamental problem with QTL - looking for something of large effect when by definition we expect most or all effects to be tiny. I'm looking forward to seeing an answer to this one! It's going on my favorites $\endgroup$
    – rg255
    Nov 20 '14 at 16:27
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    $\begingroup$ I don't think there's a great answer to this one, partly because fitness is a tough trait to measure. I think more is known for other traits like height, but even there, if we want accurate estimates of the variance associated with 100 alleles, we're limited to humans at best. $\endgroup$ Sep 18 '16 at 17:59
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    $\begingroup$ I agree with Daniel. Maybe you should open your question to other polygenic trait. A lot of money is being invested in genomic selection and most of the time the target is yield. here we have hundred of markers with effect lower than 1%. Fitness seems to be quite integrative and therefore very polygenic and environment dependent. Do you have study showing heritability of this trait? Another factor that could influence your variance is allele frequency. See GWAS model. Are you interested in study doing that on other trait? I may answer in that case! $\endgroup$
    – Untitpoi
    Apr 14 '18 at 8:37

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