I've begun this blog to document our second field season in Namaqualand, South Africa, working on the Gorteria diffusa species complex (research led by Beverley Glover and Alan Ellis). Gorteria diffusa is also called the 'Beetle Daisy' due to its unusual raised dark spots in the centre of the 'flower', which look not unlike beetles. It turns out that these spots actually look like female bee flies (Megapalpus capensis) - so much so that the male bee flies attempt to mate with the imitation females, and, in doing so, greatly increase the uptake and transfer of pollen, pollination efficiency, and presumably seed set. This is in fact the only example of sexual deceit pollination known outside of the orchids (famous for their insect mimicry). But of course its complicated - variation within Gorteria diffusa is immense, with at least 14 different floral types, only three of which are sexually deceptive. We are interested in the evolution of sexual deception - the floral spot morphology and the fly behaviour that the spot elicits. The current goal is to describe the relationships between the many floral types, and to do this we need DNA. Hence the field trip. We will be collecting tissue from hundreds of individuals from all over the Northern Cape and extracting their DNA. By comparing the DNA will we work out relationships between different flower types and begin to understand the context and heritage underlying the evolution of the sexually deceptive flower spots.
