The allele-frequency spectrum in a decoupled Moran model with mutation, drift, and directional selection, assuming small mutation rates.

摘要: We analyze a decoupled Moran model with haploid population size N, biallelic locus under mutation and drift scaled forward backward rates θ1=μ1N θ0=μ0N, directional selection strength γ=sN. With small θ0 θ1, which is appropriate for single nucleotide polymorphism data in highly recombining regions, we derive simple approximate equilibrium distribution polymorphic alleles constant of proportionality. also put forth an even simpler model, where all mutations originate from monomorphic states. Using this the sojourn times, conditional on ancestral fixed allele, distributions fixation rates. Furthermore, samples diffusion limit provide convenient recurrence relations calculating distribution. This enables us to give formulas analogous Ewens–Watterson estimator θ biased selection. apply theory dataset fourfold degenerate sites Drosophila melanogaster.