Speciation in sexually deceptive orchids

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Ophrys orchids mimic the sex pheromone of female insects and thereby attract males for pollination. The scent of the flowers is selectively influenced by the pollinators and speciation is probably driven by changes in floral odour. The objective of this study is to investigate the role of hybridisation and introgression in processes of speciation and radiation in sexually deceptive orchids of the genus Ophrys. In a comparative approach, we will investigate hybrid swarms and sympatrically occurring Ophrys taxa of the O. fusca group on Majorca and Sardinia. We will perform molecular analyses using 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, introression). Second, we will perform combined gas chromatography and electroantennogram recording of insect olfactory responses (GC-EAD) with labella extracts of hybrids and parental species. Third, the GC-EAD active compounds will be identified by gas chromatography - mass spectrometry (GC-MS) and the bouquets of hybrids compared with the odour bouquets produced by the parental species. Fourth, behavioural experiments will show attractiveness of single flowers for pollinators of both parent species. We will be able to use from individual plants flowers for chemical analyses and morphometric measurement and plant tissue for molecular analyses. A final comparison of genotype and phenotype variation (odour, morphology) will give us insight in processes of hybridisation, introgression and speciation within the investigated taxa of the O. fusca group.