Experiment 4: Mating responses to rivals under reciprocal variation of yeast (Y) and sucrose (S). Mating tests conducted after 6 days of exposure to all six diet treatments. (a) Boxplots of mating latency (plotted on logarithmic scale) as a function of diet and male rival presence. Final latency sample sizes for ‘no rivals’, ‘rivals’ males were 100% Y: 100% S = 59, 60; 100% Y: 0% S = 59, 56; 0% Y: 100% S = 56, 57; 20% Y: 0% S = 55, 58; 0% Y: 20% S = 46, 53; 0% Y: 0% S = 54, 58. (b) Boxplots of mating duration as a function of diet and male rival presence. Final duration sample sizes for ‘no rivals’, ‘rivals’ males were 100% Y: 100% S = 59, 60; 100% Y: 0% S = 59, 56; 0% Y: 100% S = 56, 57; 20% Y: 0% S = 55, 58; 0% Y: 20% S = 46, 53; 0% Y: 0% S = 54, 58. Boxplots as in Fig. 1. Significant planned contrasts: *P < 0.05, **P < 0.01, ***P < 0.001.