The profiles of the likelihood ratio test statistics across linkage group 8A in bivalent tetraploid alfalfa. Two horizonal lines indicate the thresholds at the significance level 5% calculated from 200 permutation tests (Churchill and Doerge 1994). QTL for freezing injuries (A) measured in 1995 (blue) and 1996 (pink); QTL for winter injuries (B) measured in 1996 (blue) and 1996 (pink).