Female preference for specific sexual partners can evolve even in species where the male reproductive contribution is minimal (only the ejaculate). Although indirect benefits such as "good genes", "sexy sons" and genetic compatibility are tipically invoked to explain such a phenomenon, a simple alternative is that male reproductive quality (for example, ejaculate quality), is associated with its ornamentation, so that by choosing males based on ornaments, females can obtain better quality ejaculate. Such explanation constitutes the phenotype-linked fertility hypothesis. It has been tested in birds, fishes, mammals and some insects. Social hymenopterans (wasps, bees and ants) are good models for testing this hypothesis, as males provide females with only the ejaculate. However, only in the last few years we discovered that visual signals (ornaments) can mediate the choice of sexual partner by females of some social wasps. Considering the recent advances in the research about sexual selection in this group, this proposal aims to test, for the first time, the phenotype-linked fertility hypothesis in a social insect - the paper wasp Polistes dominula. In this species, the male reproductive effort is exclusively represented by mating effort (no parental effort). Specifically, males defend small territories (arenas) visited by females (lekking mating system). During the reproduction, males provide females only with the ejaculate. Still, females are choosy, picking males based on the morphology of a pair of abdominal yellow spots (ornaments). Three questions are formulated: Is male ornamentation associated with appropriate aspects of ejaculate quality? Is the ejaculate present in female spermatheca similar to that of males with prefered ornamentation? Is the similarity between the ejaculate of males with prefered ornamentation and the ejaculate present in female spermatheca a result of female mate choice? These questions will be answered by using experimental, behavioral and celular approaches. We hope that the results obtained from this research will be of interest for a great audience, specially those interested in how sexual selection shapes the morphology and behavior of organisms.
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