The accumulation of deleterious genes in a population—Muller's Ratchet

A quantitative study of the operation of Muller's Ratchet for the accumulation of deleterious genes in an asexually reproducing population is made. For a population of size N, in which deleterious mutations occur at rate λ/genome/ generation, and the relative fitness of an individual with k mutants is (1 − s) k , the most important parameter is n 0 = Ne −θ, where θ = λ s . If n 0 is large (⩾25), deleterious mutations will accumulate very slowly, and independently of each other; if n 0 is small (