Mutation-selection balance in multi-locus systems. I. Duplicate gene action.

A theoretical model is presented that extends the case of selection against homozygous recessives counterbalanced by mutation to a system of n loci. This extension allows analysis of the role of gene duplication in the evolution of new function. The aspect of retention of function for sufficiently long periods of time to allow for divergence vs. silencing of nonfunctional loci is discussed in relation to examples in salmonid and catastomid fishes and in the globin-like clusters.