The experiments will replicate and extend a key citation in the study of sexual selection, Bateman (1948). This classic study of sex differences in mating success variance (MSV) in Drosophila melanogaster used inbred individuals with unique heritable mutant phenotypes to infer mating success. Mutant phenotypes might have affected Bateman's results. Thus, in this research the investigators will assign parentage using molecular DNA analyses of wild-type individuals in three species, Drosophia melanogaster, D. pseudoobscura, and D. hydei, which differ in sperm size, sperm number per ejaculate, gamete size ratios, and female remating latencies. The objectives are to verify that sex differences in MSVs in D. melanogaster are similar to those Bateman found and to test the overlapping predictions of more modern theories of the causes of sex differences in MSVs through comparisons of three species that differ in factors widely-thought to affect MSVs. The intellectual merit lies in the importance of sex differences in MSV to sexual selection. Bateman's result that MSV is greater among males than females is a central tenet of sexual selection, yet doubts about his results remain because of the potential effects of deleterious mutant phenotypes. The broader impacts include: (1) The PIs' will include undergraduate students in their research. (2) The PIs will recruit interns from nearby historically black colleges such as Spellman, Morehouse, and Clark-Atlanta. (3) The PI's will improve the quality of K-12 education through sponsoring an outreach series on biodiversity and animal behavior. (4) The PI's will recruit K-12 teachers to participate in their research through the NSF-Research Experiences for Teachers program. (5) The PIs will broadly disseminate the results of their research by writing articles for the public.
