Press release
Sexual pheromones and evolution… in drosophila flies
Paris, 2nd August , 1999
Insects carry substances on their cuticles that enable them to communicate with fellow members of the same species. These substances, or pheromones, are signals that very often help them to be recognised by their sexual partner during courtship. Sexual pheromones have generally been identified as the majority compounds in a mixture combining several dozen other substances produced in lesser quantities. Several scientists had already put forward the hypothesis of the involvement of the majority pheromones in males and females in triggering courtship behaviour in male flies of the Drosophila melanogaster species. More recent studies conducted by French scientists from associate laboratories of the CNRS* have led to a new concept being developed with respect to the roles of the various substances in courtship and evolution.
These scientists, directed by Jean-François Ferveur (Development and chemical communication laboratory, CNRS, University of Burgundy) carried out a simple genetic manipulation, completely eliminating all the majority pheromones from the cuticles of female flies. Surprisingly, these "manipulated" females continue to trigger vigorous courtship behaviour on the part of the males of their own species, as well as on the part of males from related species. Various experiments show that the excitation of the males is dependent on substances that are still present in tiny quantities on the cuticles of the "manipulated" females. Small amounts of these same substances are also found in flies of related species.
It is therefore not the majority pheromones carried by the females that stimulate courtship by males but, in fact, these trace substances, which are shared by different species of drosophila. These substances may have a common origin and could thus be the primitive pheromones of ancestral drosophila.
During a second experiment, the "manipulated" females were coated with the majority pheromones normally secreted by the females of different species. The males then refused to court these "scented" females, demonstrating that the majority pheromones of females are, above all, effective in preventing courtship by males of other species. The high production of majority substances in females is probably a recently developed characteristic.
These experiments better explain the evolution of the different species of drosophila. They also show that chemical recognition of a specific partner occurs at two different levels at least: stimulation is very effectively induced by non-specific ancestral pheromones, the action of which is modulated by substances that are more abundantly present on the cuticle. This study shows that the efficiency of chemical signals, which is not dependent on their abundance, must not only be evaluated between fellow creatures of the same species, but also been individuals of different species.
* Fabrice Savarit and Gilles Sureau, Neurobiology laboratory of learning, memory and communication, UMR 8620 CNRS, University of Paris XI, Orsay; Matthew Cohn, Laboratory of Function and evolution of ecological systems, UMR 7625 CNRS, University of Paris VI, Paris; Jean-François Ferveur, Development and chemical communication laboratory, UMR 5548 CNRS, University of Burgundy, Dijon.
Reference
Savarit F., Sureau G., Cobb M and J-F. Ferveur. 1999. Genetic elimination of known pheromones reveals the fundamental chemical bases of mating and isolation in Drosophila. Proceedings of the National Academy of Sciences, 3rd August 1999.
Research scientist
contact
Jean-François Ferveur
Development and chemical communication
UMR CNRS, University of Burgundy,
Dijon
Tel.: 03 80 39 62 19
Email: jean-francois.ferveur@u-bourgogne.fr
Life Sciences Department
contact, CNRS
Thierry Pilorge
Tel: 01 44 96 40 26
Email: thierry.pilorge@cnrs-dir.fr
Previous Page
