Figure 4.

Efficiency of sperm use by the (a) first and (b) second male, against remating interval and female SPR status. Shown is the number of offspring (‘offspr’) produced per sperm (in arbitrary (‘arb’) units of fluorescence). The second male's sperm was used at a higher efficiency in SPR⁺ than in SPR⁰ females. At each interval, pairs were given 2 h in which to remate, starting at the times indicated (i.e. 3–5 h, 5–7 h, 24–26 h, and 48–50 h).