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Nature 426, 70-74 (6 November 2003) | doi:10.1038/nature02004; Received 3 June 2003; Accepted 16 August 2003

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Sophisticated sperm allocation in male fowl

Tommaso Pizzari1,4, Charles K. Cornwallis2, Hanne Løvlie3, Sven Jakobsson3 & Tim R. Birkhead2

  1. Department of Animal Environment & Health, Swedish University of Agricultural Sciences, Skara PO Box 234, SE-532 23, Sweden
  2. Department of Animal & Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
  3. Department of Zoology, Stockholm University, Stockholm SE-106 91, Sweden
  4. Present address: School of Biology, The University of Leeds, Leeds LS2 9JT, UK

Correspondence to: Tommaso Pizzari1,4 Email: t.pizzari@leeds.ac.uk

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When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs1; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs2. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity1, 3, 4, 5, (2) saving some for copulations with new females3, 6, 7, and (3) to females producing more and/or better offspring3, 8. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour.

  1. Department of Animal Environment & Health, Swedish University of Agricultural Sciences, Skara PO Box 234, SE-532 23, Sweden
  2. Department of Animal & Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
  3. Department of Zoology, Stockholm University, Stockholm SE-106 91, Sweden
  4. Present address: School of Biology, The University of Leeds, Leeds LS2 9JT, UK

Correspondence to: Tommaso Pizzari1,4 Email: t.pizzari@leeds.ac.uk