Rates of coalescence and gene genealogy under a multiple-mergers coalescent. (a) The probability distribution of the different types of coalescence events, given by (2 ≤ x ≤ n) in which [δ2(x) = 1 if x = 2 and zero otherwise] in units of 2N generations (i.e., α = β = 1) when the number of ancestral lines n = 10 and φ = 1000. Solid bars, ω = 0.5; shaded bars, ω = 0.99. (b) A gene genealogy of a sample of two completely linked loci given a multiple-mergers ancestral process similar to the one described by solid bars in a. One mutation event is assumed at each locus, and the ancestral gametic type is AB.