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  1. Abstract

    Sexual signals often function in species recognition and may also guide mate choice within a species. In noctuid moths, both males and females may exercise mate choice. Females of the tobacco budwormChloridea virescensprefer to mate with larger males, but the signal(s) underlying female choice remain unknown. Male hairpencil volatiles are emitted during close range courtship displays. However, previously identified male hairpencil volatiles, namely acetate esters, aldehydes, alcohols, and fatty acids, are not associated with female choice. Recently, two new hairpencil compounds were identified that elicit strong electrophysiological responses in female antennae: methyl salicylate (MeSA) and δ-decalactone. In this study, we investigated the effect of larval diet and adult feeding on MeSA and δ-decalactone content in hairpencils and determined whether these compounds are involved in female choice. We found that larval diet affected MeSA content in hairpencils, but not δ-decalactone. Conversely, adult feeding affected the level of δ-decalactone, but not MeSA: sugar-water feeding increased δ-decalactone content compared to plain water. In two-choice assays, females mated more with males that had higher amounts of δ-decalactone, and less with males with higher amounts of MeSA.

     
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  2. Abstract Background

    Ever since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we hypothesize that in polygamous species these roles change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis by assessing fitness costs and benefits of multiple matings in both males and females in a polygamous moth species, as in moths not males but females are the signalers and males are the responders.

    Results

    We found that multiple matings confer fitness costs and benefits for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but only 67% of the males and 14% of the females mated successfully in all five nights. In addition, the female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, more than 3 matings decreased her reproductive output, so that the Bateman gradient for females fit a quadratic model better than a linear model. The male’s reproductive success was positively affected by the number of matings and a linear regression line best fit the data. Simulations of the effect of sperm competition showed that increasing last-male paternity increases the steepness of the male Bateman gradient and thus the male’s relative fitness gain from additional mating. Irrespective of last-male paternity value, the female Bateman gradient is steeper than the male one for up to three matings.

    Conclusion

    Our results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.

     
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  3. Abstract

    Transcriptome quality control is an important step in RNA‐Seq experiments. However, the quality of de novo assembled transcriptomes is difficult to assess, due to the lack of reference genome to compare the assembly to. We developed a method to assess and improve the quality of de novo assembled transcriptomes by focusing on the removal of chimeric sequences. These chimeric sequences can be the result of faulty assembled contigs, merging two transcripts into one. The developed method is incorporated into a pipeline, which we named Bellerophon, that is broadly applicable and easy to use. Bellerophon first uses the quality assessment tool TransRate to indicate the quality, after which it uses a transcripts per million (TPM) filter to remove lowly expressed contigs and CD‐HIT‐EST to remove highly identical contigs. To validate the quality of this method, we performed three benchmark experiments: (1) a computational creation of chimeras, (2) identification of chimeric contigs in a transcriptome assembly, (3) a simulated RNA‐Seq experiment using a known reference transcriptome. Overall, the Bellerophon pipeline was able to remove between 40% and 91.9% of the chimeras in transcriptome assemblies and removed more chimeric than nonchimeric contigs. Thus, the Bellerophon sequence of filtration steps is a broadly applicable solution to improve transcriptome assemblies.

     
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