highly significantp < 0.001
We found that heterozygous parents produced a highly significant excess of heterozygous genotypes for markers within the MUP cluster (χ 2 = 71.2, df = 2, p < 0.001), whereas for markers flanking the cluster, offspring genotypic frequencies did not differ from Mendelian expectations (χ 2 = 3.52, df = 2, p = 0.17, Supplemental Fig.