Figure 5. Interval between first and second mating (mean ± SE) of Drosophila bifurca depending on the number of times the first male had previously mated. Virgin = males which had not previously mated; 2x-, 3x-, 4x- = the first male had previously mated two, three, or four times. The number of flies mated is indicated in the bars. * = P < 0.05, NS = Not statistically significant.