For each polymorphism, pairs of TSE oligonucleotide primers were designed by use of Primer 3 and Hyther (see Table 3 in the online Data Supplement). Pairs were designed to have balanced melting temperatures ranging from 63 to 67°C. Each TSE oligonucleotide was composed of three components: a 5Ј sequence tag complementary to one of the EraCodes; a three-carbon spacer; and a 3Ј target-specific sequence fully complementary to the allele of interest. The polymorphic sequence for each pair of TSE oligonucleotides was the 3Ј base.