Genes behind the post-mating refractory period of Drosophila females
Females of many insect species remate before exhausting sperm supply from previous mates, thus sperm from different males often co-occur inside a female and have to compete for fertilization. However, after mating, females typically pass through a refractory period in which they tend to reject new mating attempts, resulting in a reduction of sperm competition risk.
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The duration of this period is highly variable among members of the Drosophila genus and determines whether the arena of sexual selection is prior to, as opposed to after, copulation. In species with a long refractory period, such as D. biarmipes, there are few mating opportunities for males and strong competition for receptive females, which favors the evolution of male characters that maximize mating success. In species with a short one, such as D. hydei, there is a high sperm competition risk, which favors sperm or ejaculate traits that enhance fertilization success.
It is clear that the duration of the refractory period has both shortened and extended several times during the evolution of the Drosophila genus. However, little is known about the genes underlying the wide phenotypic variation observed within and between species. It is uncertain, for instance, how many genes are involved; to what extent the involved genes differ from one group of species to another; or whether these genes are expressed mainly in males or females.
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In view of these open questions, using 'genomic introgression mapping' and 'evolve and resequencing' studies, we are identifying the genes underlying the duration of the refractory period within and between Drosophila species of the buzzatii cluster.
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