The influence of spatial inhomogeneities on neutral models of geographical variation: II. The semi-infinite linear habitat

摘要: Abstract The equilibrium structure of the semi-infinite, one-dimensional stepping-stone model is investigated in diffusion approximation. monoecious, diploid population subdivided into a semi-infinite linear array equally large, panmictic colonies that exchange gametes uniformly and symmetrically. Generations are discrete nonoverlapping; analysis restricted to single locus absence selection; every allele mutates new alleles at same rate. Boundaries corresponding an impenetrable geographical barrier contact with region extremely high density or dispersal rate (a “density-mobility boundary”) both treated. Relative homogeneous infinite habitat, raises, density-mobility boundary lowers, probability identity. For fixed average position two points observation, identity decreases increasing separation. separation, (increases) as recedes from (density-mobility boundary). sole dimensionless parameter theory β = 4ρo √2uVo, where ρo, u, Vo represent density, mutation rate, variance gametic dispersion per generation, respectively. characteristic length √ V o (2u) . Lower upper bounds on established; these yield simple approximation for ⪢ 1. obtained integral; this solution, approximations close far derived exact mean homozygosity evaluated.