Diversity of recombination rates. Heat map of the chromosome-wide recombination rates measured for each chromosome in the 23 genetic maps. On the x-axis, 'All' corresponds to a pooled analysis of all chromosomes. On the y-axis, 'DentAll', 'FlintAll', and 'All' correspond to pooled analyses with all Dent × Dent populations, all Flint × Flint populations, and all 23 populations together, respectively. Warmer colors indicate higher recombination rates. Dendrograms indicate hierarchical clustering of -log10(P value) based on Euclidian distances, and were used to order the populations and chromosomes.