Phenotypic engineering of spermproductionrate confirms evolutionarypredictions of sperm competition theory

Kiyono Sekii, Dita B. Vizoso, Georg Kuales, Katrien De Mulder, Peter Ladurner, Lukas Schärer

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


Sperm production is a key male reproductive trait and an important parameter in sperm competition theory. Under sperm competition, paternity success is predicted to depend strongly on male allocation to sperm production. Furthermore, because sperm production is inherently costly, individuals should economize in sperm expenditure, and conditional adjustment of the copulation frequency according to their sperm availability may be expected. However, experimental studies showing effects of sperm production on mating behaviour and paternity success have so far been scarce, mainly because sperm production is difficult to manipulate directly in animals. Here, we used phenotypic engineering to manipulate spermproduction rate, by employing dose-dependent RNA interference (RNAi) of a spermatogenesis-specific gene, macbol1, in the free-living flatworm Macrostomum lignano. We demonstrate (i) that our novel dose-dependent RNAi approach allows us to induce high variability in sperm-production rate; (ii) that a reduced sperm-production rate is associated with a decreased copulation frequency, suggesting conditional adjustment of mating behaviour; and (iii) that both sperm production and copulation frequency are important determinants of paternity success in a competitive situation, as predicted by sperm competition theory. Our study clearly documents the potential of phenotypic engineering via dose-dependent RNAi to test quantitative predictions of evolutionary theory.

Original languageEnglish
Article number20122563
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1757
Publication statusPublished - 2013


  • Copulation frequency
  • Phenotypic engineering
  • RNA interference
  • Simultaneous hermaphrodite
  • Sperm competition
  • Sperm production

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)


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