The Tas2r cluster is a single haplotype in BXD/Ty RI mice. The coding exon of each of 21 Tas2rs in the distal chromosome 6 cluster was amplified genomic DNA from 29 BXD/Ty RI strains. Each Tas2r within an individual BXD strain originated from the same parental strain (B6 allele = gray, D2 allele = white). The 17 BXD strains that were behaviorally tested in this study are indicated (*).