Linkage disequilibrium of the B. napus diversity set. Plot of linkage disequilibrium measured by squared allele frequency correlations (r
2, dots) versus physical map distance (Mb) between linked single nucleotide polymorphism (SNP) marker loci in the B. napus diversity set. The solid line represents the nonlinear regression trend line of r
2 versus the physical map distance, whereas the dashed line indicates the threshold of the 95% quantile of r
2 between unlinked loci pairs. The inset gives an enhanced view of the r
2 decay over smaller physical map distances (kb).