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. As an example of this metaphor, Box 7.3, p. 182, applies the adaptive landscape idea to explain Fisher's model of adaptive evolution. On the adaptive landscape, peaks correspond to genotypes with high fitness. Selection is expected to move populations uphill, to find local high points.