Figure 1.

(a) Selection differentials for body size of males successfully reaching the female area. A negative value means selection against large male body size within a selection line. The y-axis indicates the lines used (selection for large or small beetles) and temperature for each trial (see electronic supplementary material for an explanation of the selection lines). Numbers between parentheses denote the number of males released and recaptured in each trial. ^***p<0.001, ^**p<0.01, ^*p<0.05, (^*) p<0.1. The bottom part shows temperature-dependent selection when beetles from all lines have been pooled in a single analysis (the p-value denotes significant differences between temperatures). (b,c) Meta-analytical selection intensities (hedges d+; with lower and upper bias 95% CIs) on body size calculated across artificial selection lines. Selection calculated defining successful males as those that (b) reached the female area or (c) successfully mated. The horizontal dashed line indicates zero selection. A negative effect indicates selection favouring small male body size. Non-overlapping CIs between treatments indicate significant differences. Numbers on top of bars indicate the number of independent selection lines used. The missing box belongs to a group in which not enough beetles were observed mating for meta-analysis.