A mating plug protein reduces early female remating in Drosophila melanogaster.
ABSTRACT Mating plugs are formed within the female reproductive tract during mating from male ejaculate constituents or even from male genitalia themselves. Across species, mating plugs have roles in sperm storage and the prevention of female remating. In the fruitfly Drosophila melanogaster, accessory gland proteins such as the sex peptide are known to reduce female remating, however this effect can take some time to establish, hence other ejaculate components must also be involved. We hypothesised a role for the PEBII mating plug protein in the prevention of early female remating. Using RNA interference we produced PEBII knockdown males. We found that these males were significantly less able to prevent female remating in the 4h following mating. The mating plugs produced by PEBII knockdown males also showed lower levels of autofluorescence in the first 10min after the start of mating, suggesting they differed in composition to those of control males. Reduced levels of PEBII had no effect, however, on fecundity, progeny production or egg-adult viability in the first 24 after mating, suggesting there were no short-term effects of PEB II on sperm transfer, storage or use. Our results show that PEBII has a subtle but significant role in the prevention of early female remating.
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ABSTRACT: Multiple mating by females establishes the opportunity for postcopulatory sexual selection favoring males whose sperm is preferentially employed in fertilizations. Here we use natural variation in a wild population of Drosophila melanogaster to investigate the genetic basis of sperm competitive ability. Approximately 101 chromosome 2 substitution lines were scored for components of sperm competitive ability (P1', P2', fecundity, remating rate, and refractoriness), genotyped at 70 polymorphic markers in 10 male reproductive genes, and measured for transcript abundance of those genes. Permutation tests were applied to quantify the statistical significance of associations between genotype and phenotype. Nine significant associations were identified between polymorphisms in the male reproductive genes and sperm competitive ability and 13 were identified between genotype and transcript abundance, but no significant associations were found between transcript abundance and sperm competitive ability. Pleiotropy was evident in two genes: a polymorphism in Acp33A associated with both P1' and P2' and a polymorphism in CG17331 associated with both elevated P2' and reduced refractoriness. The latter case is consistent with antagonistic pleiotropy and may serve as a mechanism maintaining genetic variation.Genetics 02/2005; 169(1):243-57. · 4.39 Impact Factor
- Biological Reviews 01/2008; 45(4):525 - 567. · 10.26 Impact Factor
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ABSTRACT: The functional significance of mating plugs and their relation to male mating behaviour in insects are obscure. InDrosophila hibisci, we describe a firm, gelatinous, mating plug that fills the entire uterus at copulation, and evaluate two nonmutually exclusive hypotheses for the plug’s function: (1) retention of sperm near the openings of the sperm storage organs and (2) inhibition of further matings. Unlike full-sized plugs, smaller plugs produced by previously mated males failed to retain sperm at the anterior end of the uterus, indicating that full-sized plugs prevent sperm backflow away from female storage organs. Sexually mature males failed to copulate with previously mated, young females, suggesting that the plug may also deter rival matings. In newly emerged females, the plug remains within the uterus for up to 4 days after copulation, but in mature females, the plug and ejaculate are expelled whenever the next mature oocyte descends into the uterus from the common oviduct, which may be soon after copulation. Males remained in copula significantly longer with mature females, perhaps to compensate for this greater likelihood of ejaculate expulsion. Males showed a mating preference for young virgins over older virgin and nonvirgin females. This unusual mating preference may confer fertility benefits made available through the effectiveness of the plug in reducing sperm competition.Animal Behaviour 02/2013; 56(4):919-926. · 3.07 Impact Factor