Limitations of Darwinian selection in a finite population.

In a finite population, the rate at which favorable mutations at several loci can evolve simultaneously is limited by the reproductive capacity of the species and the effective population number. The number of such loci is given by n < - (Ne/2) ln(1-LT), in which Ne is the effective population number and LT is the "substitution load" (roughly, the reproductive excess available for positive selection). If LT = 0.1, as seems reasonable for large mammals, n < 0.05Ne.