Evolution under the multilocus Levene model without epistasis

Evolution under the multilocus Levene model is investigated. The linkage map is arbitrary, but epistasis is absent. The geometric-mean fitness, (w) over tilde(rho), depends only on the vector of gene frequencies, rho; it is nondecreasing, and the single-generation change is zero only oil the set, Lambda, of gametic frequencies at gene-frequency equilibrium. The internal gene-frequency equilibria are the stationary points of (w) over tilde(rho). If the equilibrium points (rho) over cap of rho(t) (where t denotes time in generations) are isolated, as is generic, then rho(t) converges as t -> infinity to some (p) over cap. Generically, p(t) converges to a local maximum of (w) over tilde(rho). Write the vector of gametic frequencies, p, as (rho, d)(T), where d represents the vector of linkage disequilibria. If (rho) over cap is a local maximum of (w) over bar(rho), then the equilibrium point ((rho) over cap, 0)(T) is asymptotically stable. If either there are only two loci or there is no dominance. then d(t) -> 0 globally as t -> infinity. In the second case, (w) over tilde (p) has a unique maximum (rho) over cap and ((rho) over cap, 0)(T) is globally asymptotically stable. If under dominance and overdominance are excluded, and if at each locus, the degree of dominance is deme independent for every pair of alleles, then the following results also hold. There exists exactly one stable gene-frequency equilibrium (point or manifold), and it is globally attracting. If an internal gene-frequency equilibrium exists, it is globally asymptotically stable. On Lambda, (i) the number of denies, Gamma, is a generic upper bound on the number of alleles present per locus; and (n) if every locus is diallelic, generically at most Gamma - 1 loci can segregate Finally. if migration and selection are completely arbitrary except that the latter is uniform (i.e, deme independent), then every uniform selection equilibrium is a migration-selection equilibrium and generically has the same stability as under pure selection. (C) 2009 Elsevier Inc All rights reserved