Fig. 2

Copulation duration in unselected and experimentally evolved SPR- and control flies. Copulation duration measured in flies that either did (control, C) or did not express sex peptide receptor (SPR-), for unselected flies (in which any differences between C and SPR- flies are caused by the SPR deficiency itself) and experimentally-evolved selected flies. Dotted lines demarcate different comparisons where we tested for experimentally evolved differences in males by pairing SPR- or C males with wild-type females (at generation 16 or 36), in females by pairing SPR- or C females with wild-type males (at generation 26), or in within-treatment pairings of SPR- (or C) males with SPR- (or C) females (measured at generation 26). Asterisks indicate significant differences between SPR- and C flies. Least squares means are presented with 95 % confidence intervals