How sperm from competing males are used to fertilize eggs is poorly understood, yet has important implications for postcopulatory sexual selection. Sperm may be used in direct proportion to their numerical representation within the fertilization set or with a bias toward one male over another. Previous theoretical treatments have assumed a single sperm-storage organ, but many taxa possess multiple organs or store sperm within multiple regions of the reproductive tract. In Drosophila, females store sperm in two distinct storage organ types: the seminal receptacle (SR) and the paired spermathecae. Here, we expand previous 'raffle' models to describe 'fertilization bias' independently for sperm within the SR and the spermathecae and estimate the fertilization set based on the relative contribution of sperm from the different sperm-storage organ types. We apply this model to three closely related species to reveal rapid divergence in the fertilization set and the potential for female sperm choice.
Number of progeny and sperm in storage for D. melanogaster
NA indicates no data. For methods, see Manier, M.K., J.M. Belote, S. Lüpold, K.S. Berben, O. Ala-Honkola, W.F. Collins and S. Pitnick. 2013. Rapid diversification of sperm precedence traits and processes among three sibling Drosophila species. Evolution in press.; Manier, M.K., J.M. Belote, K.S. Berben, D. Novikov, W.T. Stuart and S. Pitnick. 2010. Resolving mechanisms of competitive fertilization success in D. melanogaster. Science 328: 354-357. Variables: N1 – number of progeny sired by the first male to mate. N2 - number of progeny sired by the second male to mate. SR1 – number of first-male sperm in the SR. SR2 – number of second-male sperm in the SR. Sp1 – number of first-male sperm in both spermathecae combined. Sp2 – number of second-male sperm in both spermathecae combined.
mel.txt
Number of progeny and sperm in storage for D. simulans
NA indicates no data. For methods and analysis, see Manier, M.K., J.M. Belote, S. Lüpold, K.S. Berben, O. Ala-Honkola, W.F. Collins and S. Pitnick. 2013. Rapid diversification of sperm precedence traits and processes among three sibling Drosophila species. Evolution in press.; Manier, M.K., J.M. Belote, K.S. Berben, D. Novikov, W.T. Stuart and S. Pitnick. 2010. Resolving mechanisms of competitive fertilization success in D. melanogaster. Science 328: 354-357. Variables: N1 – number of progeny sired by the first male to mate. N2 - number of progeny sired by the second male to mate. SR1 – number of first-male sperm in the SR. SR2 – number of second-male sperm in the SR. Sp1 – number of first-male sperm in both spermathecae combined. Sp2 – number of second-male sperm in both spermathecae combined
sim.txt
Number of progeny and sperm in storage for D. mauritiana
NA indicates no data. For methods and analysis, see Manier, M.K., J.M. Belote, S. Lüpold, K.S. Berben, O. Ala-Honkola, W.F. Collins and S. Pitnick. 2013. Rapid diversification of sperm precedence traits and processes among three sibling Drosophila species. Evolution in press.; Manier, M.K., J.M. Belote, K.S. Berben, D. Novikov, W.T. Stuart and S. Pitnick. 2010. Resolving mechanisms of competitive fertilization success in D. melanogaster. Science 328: 354-357. Variables: N1 – number of progeny sired by the first male to mate. N2 - number of progeny sired by the second male to mate. SR1 – number of first-male sperm in the SR. SR2 – number of second-male sperm in the SR. Sp1 – number of first-male sperm in both spermathecae combined. Sp2 – number of second-male sperm in both spermathecae combined
maur.txt