Experimental reduction of intromittent organ length reduces male reproductive success in a bug

Liam R Dougherty, Imran A. Rahman, Emily R Burdfield-Steel, E V Ginny Greenway, David M Shuker

Research output: Contribution to journalArticle (Academic Journal)peer-review

31 Citations (Scopus)
316 Downloads (Pure)


It is now clear in many species that male and female genital evolution has been shaped by sexual selection. However, it has historically been difficult to confirm correlations between morphology and fitness, as genital traits are complex and manipulation tends to impair function significantly. In this study, we investigate the functional morphology of the elongate male intromittent organ (or processus) of the seed bug Lygaeus simulans, in two ways. We first use micro-computed tomography (micro-CT) and flash-freezing to reconstruct in high resolution the interaction between the male intromittent organ and the female internal reproductive anatomy during mating. We successfully trace the path of the male processus inside the female reproductive tract. We then confirm that male processus length influences sperm transfer by experimental ablation and show that males with shortened processi have significantly reduced post-copulatory reproductive success. Importantly, male insemination function is not affected by this manipulation per se. We thus present rare, direct experimental evidence that an internal genital trait functions to increase reproductive success and show that, with appropriate staining, micro-CT is an excellent tool for investigating the functional morphology of insect genitalia during copulation.
Original languageEnglish
Article number20150724
Number of pages8
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1808
Early online date13 May 2015
Publication statusPublished - 7 Jun 2015


  • genital evolution
  • genital ablation
  • micro-computed tomography
  • post-copulatory
  • cryptic female choice
  • functional morphology


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