Fig. 2. Histograms of T_KD for the newly established LN, CN and HN lines in generations 1 (top) and 12 (bottom). At generation 12, the flies had undergone 9 generations of knockdown selection. The error bars show s.e.m. values for groups of flies fractionated at 0.5°C intervals. Each LN, CN and HN group comprises four replicate populations. During knockdown, 1000 flies from each line are assayed for T_KD; thus, each graph represents T_KD frequency distribution for 4000 flies. The fitted line on each graph shows the maximum likelihood fit for a bimodal distribution. The fitted parameters for the distributions are listed in Table 1.