Hitchhiking of neutral alleles is a simple example of a neutral effect for linkage disequilibrium. Hitchhiking of weakly deleterious alleles is a simple example of a deleterious effect for linkage disequilibrium. Stable mimetic polymorphism based on epistatic fitness interactions illustrates one possible advantage for linkage disequilibrium. See the next section below. If the effects of linkage disequilibrium are advantageous, then recombination may be harmful.
Recombination can break up beneficial allele combinations.
Even though recombination can also create new advantageous combinations, it will just as easily take them apart again. But if the effects of linkage disequilibrium are disadvantageous, then recombination can be beneficial. Recombination can separate beneficial alleles from linked deleterious alleles. Recombination is genetically variable, and should be subject to selection. Wright invented the influential concept of an adaptive topography.