Growth trajectories and yolk-to-body mass conversion efficiencies. Mean (± 95% confidence intervals) dry weights of total embryo, yolk sac and hatchlings at 3, 20 and 31 days post fertilisation (DPF) A. rate of yolk absorption, B. rate of embryo and hatchling growth. Similar letters indicate demes that have non-significant differences in conversion efficiencies (Tukey-Kramer HSD pairwise contrast tests). C. Mean (± 95% confidence intervals) yolk-to-body mass conversion efficiency of grayling embryos from warm and cold demes raised under similar conditions (8°C). The conversion efficiency was estimated as the ratio of embryo dry weight at 20 DPF on egg dry weight at 3 DPF. Similar letters indicate demes that have non-significant differences in conversion efficiencies (pair-wise t-tests). D. Notochord length-at-age for warm and cold deme post-hatch grayling larvae raised under similar conditions (8°C). Lines correspond to the GAM-predicted growth trajectories for each deme (see Additional file 2). Dashed lines correspond to 95% confidence bounds. The GAM explained 77% of the variation (group effect: F1,144 = 803, P << 0.0001).