Figure 2. Effect of sperm supply on mate preference in Drosophila bifurca. The bars indicate the percentages of mating by previously mated (m) or virgin (v) females (F) or males (M). Virgin males mated preferentially with virgin females (P < 0.001), whereas virgin females mated equally often with mated or virgin males (P > 0.05). The number of flies mated is indicated in the bars.