Fig. 3.

Linkage disequilibrium (i.e., correlation of alleles) between pairs of polymorphic sites as a function of physical distance between the two sites. Points are average r² for all pairs within a particular distance, with 1-kb increments. The lines show the two 97.5% upper and 2.5% lower bounds calculated from 1,000 datasets generated under a neutral coalescent model, given the length of sequences, number of polymorphic sites, and the rholike estimate of ρ (from Table 2; using the ms program in ref. 49). The asymptote (i.e., the expected r² when there is no association between alleles) is 1/n, where n is the number of sequences (1/12 = 0.083 for Europe and 1/8 = 0.125 for the Far East).