We initiated this selection with a founding population (selection generation zero, S0), of 82 female and 76 male HS/Npt mice, all the offspring of 25 HS/Npt pregnant dams (see Supplement 1). All mice were tested for DID for 2 days and the BEC determined. Generations S0 through S2 were maintained and tested within the Oregon Health & Science University (OHSU) facility. When S3 offspring were about 12–17 days old, the colony was moved to the Portland VA Medical Center Veterinary Medical Unit. VA and OHSU husbandry conditions were very similar. For the first five generations, we employed within-family selection, using a method we have employed for prior selections for alcohol phenotypes (14,15). Because response to selection was slower than anticipated, when selecting the S5 breeders to produce S6, we shifted to the use of individual selection, which we have since employed. Details for numbers of mice tested each generation are given in Table 1. For methods, see the Supplement 1.
