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Into the age of molecular biology

Students prepare samples for phylogenetic studies in the Leslie Hill Molecular Laboratory.

One of the remarkable features of the research programme at Kirstenbosch is its breadth and depth. Following the wonderful philosophy of Rene Dubos – think globally, act locally’ – the research agenda includes studies at the global scale (on climate-change modelling); at the continental scale (on plant taxonomy); at the national scale (biodiversity assessments, species conservation, vegetation mapping); and down to the molecular scale (studies on the evolution and relationships of selected plant and animal groups).

The establishment of a molecular laboratory at Kirstenbosch was a great advance in the modernisation of its facilities. By a stroke of good fortune, Leslie Hill, a longtime supporter and benefactor of Kirstenbosch, called one day to discuss the interest he had developed in molecular biology. Having read an article on molecular phylogenetics in the magazine Scientific American, Leslie, at the age of 92, expressed the view that Kirstenbosch should have the facilities to undertake such cutting-edge research. A few months later, and with his gift of R1.5 million, the Leslie Hill Molecular Laboratory was established at the KRC in 2000. The molecular biology programme has expanded from a focus on the evolution of proteas and other fynbos plants to include animal groups with special importance in South Africa, in particular reptiles and frogs. Our national obsession with the big, hairy mammals means we have tended to overlook our lizard fauna. With 267 species, of which 53 per cent are endemic, it is the third richest in the world, even richer in endemics than our terrestrial mammal fauna of 249 species, of which only 14 per cent are endemic to the country.

The use of sophisticated technologies such as those available at the Leslie Hill Molecular Laboratory allows researchers to explain often controversial phenomena. A well-documented observation in the Cape is the recent expansion of the range of the Hadeda Ibis Bostrychia hagedash, explained by the increased availability of nesting sites and feeding habitats in the expanding wooded suburbs of Western Cape towns over the past century. Hadedas were certainly unknown in Kirstenbosch during Pearson’s time, yet they are now very much part of the Garden’s avifauna. Less easily explained was the westward expansion – by 500 kilometres during the last decade – of the Painted Reed Frog Hyperolius marmoratus. To understand this, molecular techniques were needed.

Early hypotheses proposed that the expansion was due to climate change – a much over-stated cause of many recent environmental phenomena. But careful genetic studies by Krystal Tolley, leader of the molecular biology group at the KRC (see A cradle of faunal diversity’), and colleagues at the University of Stellenbosch have shown that the expansion can only be due to direct human-mediated jump dispersal’ – a fancy way of saying that frogs or their fertile eggs might have been intentionally or accidentally transferred from their natural habitats in the east of the country to streams and dams further west. Reed frogs are often found in aquatic plants, transported around the country by nurserymen, homeowners and aquarists – so this frog is expanding its range as a result of being transported by humans, without any environmental change being needed. The noisy, entertaining and occasionally aggressive Helmeted Guineafowl and Egyptian Geese were introduced to decorate both garden and table, making their presence in the Western Cape another product of human-mediated jump dispersal’.

A cradle of faunal diversity’ The beautifully decorated Cape Dwarf Chameleon Bradypodion pumilum is a rare sight in the Garden. Krystal Tolley, leader of the molecular biology group at the KRC, has been undertaking some fascinating research using the Cape’s rich diversity of Dwarf Chameleons as models of climatic, ecosystem and evolutionary change that has taken place over the past 14 million years. Using DNA sequence data for the 15 described species, plus a possible nine additional new species of Dwarf Chameleon, Tolley has established the correlation between speciation events (that is, the evolution of new species) and the changing environment of southern Africa. Her results indicate, furthermore, that southern Africa may truly be a cradle of faunal diversity’ – a characteristic well established for plants, but not widely recognised for animals. Science in service of society

South Africa’s National Biodiversity Assessment 2011 was co-ordinated by SANBI’s team at the CBC. The status of terrestrial ecosystems presented in this map guides decisionmakers on conservation priorities.

As Pearson’s prescient thinking repeatedly illustrates, moving from basic science to the application of its results has increasingly influenced the role that Kirstenbosch, and particularly the Kirstenbosch Research Centre (KRC), has played in the country. On global and regional scales, climate change and land-degradation studies have contributed to a predictive understanding of how our ecosystems work and how they might be managed sustainably. The fine-scale information gathered by field biologists and synthesised by modellers and spatial planners has guided the selection of sites deserving priority action for conservation. Research at the molecular level helps us to understand problems of invasive species. Gradually, the collective scientific studies and research practised under the auspices of Kirstenbosch have fed into determination of future policy and planning.

Fynbos Fynmense – people making biodiversity work documents the highly successful Cape Action for People and the Environment (CAPE) programme, based at the Centre for Biodiversity Conservation, Kirstenbosch.