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Sexual Recombination and the Power of Natural Selection
W. R. Rice and A. K. Chippindale
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Supplementary Material
Development time of red eyed (
w+) and white eyed (
w-) male flies was measured under pure (all red-eyed flies or all white-eyed flies) and mixed cultures (approximately 50% red and 50% white eyed flies developing together). All data are reported as mean ±SE and N = 2000 assayed eggs. For red-eyed flies, egg-to-adult development time was 226.17 ± 0.26 hours in monoculture and 225.03 ± 0.35 hours in mixed culture. For white-eyed flies, development time was 235.95 ± 0.5 hours in monoculture and 237.02 ± 0.69 hours in mixed culture. The difference (white-eyed - red-eyed) in development time is 9.78 hours and 11.99 hours under pure and mixed conditions, respectively.
Mating success of red (w+) and white (w-) eyed males was measured by placing equal numbers of red and white males with virgin females, allowing the flies to mate for 24 hours and then rearing mated females individually in separate vials. We then used paternity analysis to determine which type of male (red or white) had mated most recently with each female (in D. melanogaster the last male to mate with a female sires most of her offspring). The fraction of matings by red-eyed males in the dark, pooling across five independent assays, was 0.5068 ± 0.024. In the light, white-eyed males obtain approximately 10% of the matings.
Total fitness of red (w+) and white (w-) males was measured in the dark by combining equal numbers of red and white males (carrying the same genetic background as the males used in the experiments) with females (X or Y clone-generator females) for 24 hours and then measuring the proportion of red versus white male offspring emerging in the next generation. (This procedure follows the same experimental protocol as described for the synthetic-X or synthetic-Y treatments). The percent red eyed males emerging in the following generation was 48.1 ± 0.017 (N = 3096 offspring) for the synthetic X treatment and 49.0 ± 0.022 for the synthetic Y treatment (N = 7952 offspring). The close match to a value of 50% red eyed males indicates that the fitness of red and white males was identical or nearly so.
