Figure 2.

(a) Variance in laying date and its approximate 95% confidence due to presumably non-genetic individual-specific causes (sum of permanent environmental component and I×E) estimated under model 5 (table 1) as a function of standardized (zero mean, unit standard deviation) spring temperature. (b) Narrow-sense heritabilities h² (ratio of additive genetic variance over the sum of all variance components) for all 37 years as a function of standardized spring temperature. Plotted are the heritabilities under parameters estimated by model 5 (black circles and fitted regression line with a=0.11±0.0034 (t₃₅=33.8, p<0.001) and b=−0.0086±0.0034 (t₃₅=−2.5, p=0.016)) and model 6 (grey circles and fitted regression line with a=0.14±0.004 (t₃₅=32.7, p<0.001) and b=0.042±0.0042 (t₃₅=10.1, p<0.001)), as shown in table 1.