Recombination rates in S. mansoni. (a) Relationship between adjusted map length and physical size of chromosomes. The positive relationship (P = 0.0008) indicates that the average recombination rates are comparable among chromosomes. (b) Comparison of female and male recombination rates. Plus signs indicate comparisons among 78 autosomal intervals. The recombination rate is 1.27-fold higher in females than in males (P = 0.019) for these intervals. For comparison, the open circles are the four pseudoautosomal intervals on the sex chromosomes and the triangle is the interval over the Z-specific region.