The decay of linkage disequilibrium (r2) is more rapid in C. briggsae than C. elegans along every chromosome. The sex chromosome is not distinctive relative to autosomes in terms of linkage disequilibrium (LD) decay in either species (A), although C. elegans Chromosomes I and IV have elevated LD, and C. briggsae Chromosome II shows reduced LD compared to other chromosomes. The interchromosomal LD for C. briggsae (B) spans a narrower range of mean values among chromosome pairs than C. elegans (C), although both species have more LD between chromosomes than expected (horizontal lines). Horizontal lines indicate the background LD expected given the sample size (Weir and Hill 1980). C. briggsae strains include 25 Tropical strains (excluding reference strain AF16); C. elegans includes 39 strains (excluding Hawaiian CB4846). LD calculations exclude singleton polymorphisms.
