| 1. |
- Kuijper, Bram, et al.
(författare)
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Direct observation of female mating frequency using time-lapse photography
- 2009
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Ingår i: Fly. - 1933-6934. ; 3:2, s. 118-120
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Tidskriftsartikel (refereegranskat)abstract
- One basic condition of postmating sexual selection is that females mate more than once before fertilizing their ova. Knowledge of the frequency and extent of multiple mating in a given population or species is therefore important in order to fully understand the potential for sexual selection, in the form of sperm competition, sexual conflict and cryptic female choice. Surprisingly, there are only a handful of studies that have attempted to estimate the frequency of multiple mating in insects (including Drosophila) and none have made direct observations over extended periods of time. Here we use time-lapse photography to directly score matings in isolated pairs of D. melanogaster and show that multiple mating in the laboratory occurs at a high frequency but at comparable rates with wild caught females. We also find that the interval to remating rises approximately additively with each mating, indicating either an increase in female resistance or male reluctance to remate. These results suggest that the opportunity for postmating sexual selection in laboratory and natural environments are not dramatically different and that there may be a causal link between the rise in female mating resistance and the concomitant rise in the cost of mating. The method is easily executed and could be adapted to other insect models.
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| 2. |
- Rode, Nicolas O., et al.
(författare)
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An examination of genetic variation and selection on condition in Drosophila melanogaster males
- 2009
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 131:2, s. 167-177
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Tidskriftsartikel (refereegranskat)abstract
- According to the genic capture hypothesis, the maintenance of additive genetic variation in fitness-related traits is due to both condition-dependence of these traits and high genetic variation for condition. Evidence supporting this latter assumption is scarce. In this study, we investigated, using hemiclonal analysis, standing genetic variation for condition and relative adult fitness in male Drosophila melanogaster (Meigen) (Diptera: Drosophilidae). The absolute fat and the relative fat content were used as indices of body condition and were measured along with adult relative fitness from males reared in high or low larval densities. The results did not demonstrate genetic variation for condition or adult relative fitness. However, the larval density encountered during development had a strong and significant effect on all traits. Surprisingly, although not significant, negative selection gradients acting on absolute fat and relative fat content were also found in both treatments. These findings challenge one of the main assumptions of the genic capture hypothesis and the use of fat content as an ideal index of condition.
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