Fig. 4. Reaction norms of fitness across the six home-away environmental pairs used in our study.

The error bars represent SEM (N = 6). The asterisks represent significant ecological specialization with respect to the ancestor for the corresponding home-away pair; “NS” denotes that the corresponding ecological specialization was not significant (see Table S1 and the text for details). The dotted lines represent ancestral reaction norms. Significant specialization happened when the reaction norms of a treatment population intersected with the ancestral norm. a Reaction norms for populations selected in Thy (TL (large) and TS (small)). b Reaction norms for populations selected in Gal (GL (large) and GS (small)). Also see Fig. 5 for reaction norm slopes across the six environmental pairs.