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 genetic variance in fitness do $n$ loci explain.
In nature, globally speaking,
- 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? … or if you prefer…
- How many loci explain 50%, 80%, 99% of the total genetic variance in fitness?
It is obvious that the answer depends on the population under consideration. Factors that might influence the answers are for example
- population size
- environment stability
I am seeking for answers based on empirical work that provide such insights in populations of any lineage (bacteria, yeast, animals, plants, whatever…).
Beside this question, I also welcome some insights concerning how different factors are likely to influence the answer.