Fig. 5. Branchial hsc70 (A), hsp70-1 (B) and hsp70-2 (C) mRNA levels in northern (NH, hatched bars) and southern (GA, grey bars) killifish in response to heat shock. Control (C) samples were taken prior to experimentation, and handling controls (CH) were treated the same as the experimental temperature groups but were transferred back to the acclimation temperature of 20°C. All mRNA data is normalized to the control gene EF-1 (values are mean ± s.e.m.; N=6). Different letters indicate significant differences between treatments but within a population, and an asterisk indicates a significant difference between northern and southern fish within a treatment.