Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Evolutionsbiologie und Umweltwissenschaften, Institut für » Evolutionary Biology » Prof. Dr. Paul Ward (verstorben) » Ward

Completed research project

Title / Titel The mechanism of sperm competition in the yellow dung fly Scathophaga stercoraria: integrating morphology, biochemistry and behaviour
PDF Abstract (PDF, 14 KB)
Summary / Zusammenfassung The yellow dung fly, Scathophaga stercoraria, has been an outstanding study organism for the investigation of sperm competition. Most of this work, as in other species, has concentrated on understanding the importance of sperm competition for the evolution of male mating behaviour. There is also a considerable body of work on the influences on females of the accessory substances which males transfer to them at the same time as they transfer sperm. However, there has recently been a surge of interest in the possibility that subtle female behaviour may also influence the relative contributions of competing males to paternity of offspring, especially when there is a long delay between insemination and the fertilisation of eggs. Females of many species have very complex reproductive tracts; for example, female dung flies have three separate spermathecae, where sperm are stored for many weeks, but the functional morphology of the tracts is not well-understood. This project tests hypotheses on the general theme that the complexity of the female reproductive tract has evolved to allow a female to manipulate the ejaculates of different males to increase her own fitness. We investigate how male and female behaviour during mating and the genital morphologies and accessory substances of both sexes interact to affect the fertilisation of eggs. The initial stages are the histological characterisation of the genitalic interactions during copula and identifying the effects of male accessory substances on females. The functional morphology of the female tract is examined, including patterns of muscle arrangements and innervation, and sperm from individual males followed within females. The consequences of the biochemistry and functional morphology for male and female behaviour is examined. Yellow dung flies are ideal subjects for this research because they are widespread, common, simple to breed in the lab and their natural behaviour can be easily observed in the field. We can therefore integrate the results from different levels of investigation to obtain a more complete picture of the biology of a single species. Particular importance will be placed on the female perspective on sperm competition.
Publications / Publikationen Hellriegel, B. & PI Ward, P.I. (1998) Complex female reproductive tract morphology: its possible use in postcopulatory female choice. J. theoret. Biol. 190: 179-186.

Ward, P.I. (1998) A possible explanation for cryptic female choice in the yellow dung fly, Scathophaga stercoraria (L.). Ethology 104: 97-110.

Reuter, M., Ward, P.I. & Blanckenhorn, W.U. (1998) An ESS treatment of the pattern of female arrival at the mating site in the yellow dung fly Scathophaga stercoraria (L.). J. theoret. Biol. 195:363-370.

Keywords / Suchbegriffe sexual selection, reproductive physiology, Diptera, behavioural ecology, histology, microanatomy
Project leadership and contacts /
Projektleitung und Kontakte
Prof. Dr. P.I. Ward (Project Leader)
Dr. B. Hellriegel
Dr. D.J. Hosken
Other links to external web pages
Funding source(s) /
Unterstützt durch
SNF (Personen- und Projektförderung)
In collaboration with /
In Zusammenarbeit mit
Dr. M. Ayasse, Zoologisches Institut, Univeristät Wien Austria
Duration of Project / Projektdauer Oct 1996 to Mar 2000