Figure 4.—

Expected site-frequency spectra (SFS) for a recent gene duplication event. Expected SFS were estimated by 1000 simulated replicates for n = 10 and θ = 10 for a 1000-bp region. The SFS are normalized to be independent of θ. The duplicate gene fixed at time τ = 0. The mean gene conversion tract length is 100 bp. The SFS is shown separately for fixed differences between genes, for polymorphisms shared between genes, and for private polymorphisms unique to one gene. The effect of the rate of crossing over between loci (4Nr > 0) on the SFS is because crossing over will cause the two duplicated loci to have different histories, such that the most recent common ancestor of the ancestral gene does not occur at the same time as the origin of the duplicate gene (e.g., Figure 3).