Due to the highly specialized floral odour, an Ophrys species can normally attract only one pollinator species. The selective attraction of pollinators serves as the main reproductive isolation barrier between species. However, this mechanism does not provide a complete isolation, as hybrids between Ophrys species can be often found. This type of reproductive isolation barrier may also play an important role in the evolution and radiation of Ophrys. If the floral scent of an odour mutant or a hybrid plant by chance resembles the female sex‐pheromone of a different pollinator species, it is at the same time reproductively isolated from its parental species. Subsequently, a new species could evolve. This would be a rare example of sympatric speciation.

In a present study we are investigating the role of the floral odour in processes of speciation and radiation in Ophrys. In a comparative approach, we are investigating hybrid swarms and sympatrically occurring Ophrys taxa on Majorca, Sardinia, Tunisia and Germany. We use highly variable markers in combination with morphometric measurements on hybrid swarms and of the parental species to delimit species and provide us with information on the genetic relationship of hybrid plants to their parental species (hybrid status, introgression). We perform combined gas chromatography and electroantennogram recording of insect olfactory responses (GC-EAD) and chemical analyses (GC, GC-MS) in order to identify floral compounds with a potential role in pollinator attraction that are tested in behavioural experiments with pollinator males.

Coworkers: Julia Gögler

Collaborations: Johannes Stökl (MPI Chemical Ecology Jena), Wittko Francke, Robert Twele (University of Hamburg), Hannes Paulus (University of Vienna), Salvatore Cozzolino (University of Naples) 

Funding: DFG Priority Programme 1127 “Radiationen – Genese Biologischer Vielfalt”