Table 3.

Effect size (±s.d.) of ECE effects on the directional selection gradients for laying date and clutch size. The coefficients are those of interaction terms of ECEs with the life-history trait, and can be interpreted as the absolute change in selection gradients for every 10% of the population experiencing an extremely hot day during the nestling (NES) or the fledgling (FLE) stage. See §2 for meanings of abbreviations. The significant interaction term between laying date and the percentage of broods experiencing at least one extremely hot day during the nestling stage within each year is shown in italics.

ECE in interaction with the trait	laying date	p-value	clutch size	p-value
NES HOT T°C	−0.130 ± 0.037	<0.001	0.060 ± 0.038	0.113
FLE HOT T°C	−0.070 ± 0.044	0.117	0.026 ± 0.044	0.556