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In order to test the validity of the prediction of the mating pattern of females from the sperm length distribution in males, three species of Drosophila were analysed. Males in the three species are equally polygynous but females differ in the level of polyandry. A 'low recurrence polyandry' is observed in the sperm dimorphic species D. affinis while a 'high recurrence polyandry' is observed in the sperm monomorphic species D. latifasciaeformis and D. littoralis. These results are consistent with the hypothesis proposed previously that sperm dimorphism in males can only be maintained by a selective alternative in females (i.e. facultative female polygamy), whereas a stricter mating system (e.g., 'obligatory' polyandry) should only result in sperm monomorphism irrespective of the absolute value of sperm length. [ABSTRACT FROM AUTHOR]

When Drosophila simulans females from the Seychelles are crossed with D. mauritiana males the number of hybrids produced decreases with an increase in, both density of flies and male/female proportion. The patterns are consistent in the reciprocal cross although the number of progeny is reduced. The asymmetry of mating success affects not only mating preference and the outcome of the cross, but also the progeny numbers. [ABSTRACT FROM AUTHOR]