Mean pairwise p-distance between IGS sequences from representatives of four species in the Daphnia pulex complex. (a) The complete IGS. (b) Nonrepetitive regions, N1 and N2. Values are plotted for segments defined by recombination analysis of multiple sequence alignments using the program, GARD . Segment 2 in the IGS corresponds to the R region, which contains the repeat arrays. Vertical black lines are standard errors of the overall mean p-distance (intraspecific and interspecific).