Figure 1

Hypothesized ontogenetic patterns of plasticity and genetic variation in plasticity of size across a thermal gradient, illustrating how ontogenetic changes in variance may increase over ontogeny due to variance compounding (a–c), or decreased over ontogeny due to selection (d–f). Three different reaction norms per genotype are shown in each panel, representing different age classes: early (black), intermediate (light gray) and late (medium gray) ontogeny. In a and d there is genetic variation in height (intercept); in b and e there is genetic variation in slope; and in c and f there is genetic variation in both height and slope. In a–c, no selection has acted on age-dependent plasticity and genetic variances increase over ontogeny due to variance compounding. In d–f, selection has favoured an increase in plasticity over ontogeny, leading to a reduction in additive genetic variances over ontogeny.