The Cape region boasts one of the world’s most diverse floras, with more than 9,000 different types of plant identified, almost 70 per cent of which are found nowhere else. In order to explain this hyperdiversity, an international team of scientists led by Jan Schnitzler of the Biodiversity and Climate Research Centre in Frankfurt am Main, Germany, conducted the most comprehensive genetic analysis of plant species in the region, looking at about 470 native plant species, representing three of the seven largest plant families present in the Cape region. The resulting family trees were then correlated with information on the ecology and geography of their habitats, with a particular emphasis on comparisons with sister species.

The results demonstrated the overwhelming influence of the underlying geology. ‘The Cape region comprises many different soil types on a relatively small space, which turns out to be very important in the development of plant diversity,’ Schnitzler said. ‘The reason is probably that it forced closely related species to develop adaptations to varied circumstances.’

The researchers also concluded that the plant diversity wasn’t the result of a rapid radiation triggered by climatic changes but rather a continuous process that took place over a long period. Indeed, the Cape’s relative climatic stability may have resulted in lower extinction rates than have been observed in regions such as northern Europe, which experienced several ice ages.

August 2011