What happens when a geologist, a biochemist, an evolutionary biologist and an ichthyologist get together and decide to write a research proposal?
This may sound like the start of a bad joke, but in this instance a novel combination of researchers from Stellenbosch University and their international partners have pooled their expertise and sourced R9,7 million (640 000 Euro) from the Volkswagen Foundation in Germany for a unique three year project.
The Volkswagen Foundation established the ‘Off the Beaten Track’ funding initiative “for projects that pursue innovative, extraordinary and cross-disciplinary lines of research that do not fall under any other current funding initiative”. In order to be eligible for funding, projects in this category have to fulfil stringent requirements of scientific excellence.
Two researchers from Stellenbosch University, Prof. Dirk Bellstedt (biochemist and geneticist) and Dr Woody Cotterill (evolutionary biologist and geologist), are working with specialists in Germany and Africa to develop a novel approach to reconstruct the evolution of central Africa over the past 20 million years.
They will do this by combining next-generation DNA sequencing of fish groups, such as Africa’s famous cichlid fishes, with high precision rock dating of key landforms.
The proof-of-concept study is being conducted over a study area of 300 000 km2 in northern Zambia and the south-eastern Katanga Province of the Democratic Republic of the Congo. During the past five to 30 million years, this region has undergone major tectonic activities and break ups.
In some rivers these breaks have formed waterfalls of up to 30 metres high, called knick-points, and so prevented dispersals in ancestral fish species. This persistence of these waterfalls over geological time has therefore caused fishes to speciate upstream and downstream of the geographical barrier.
Prof. Bellstedt explains: “Freshwater fish are locked into a landscape that tightly constrains their ecology and evolution. Their existence and distributions are entirely dependent on prevailing drainage patterns, so their evolution over time has closely tracked even the slightest of wetland changes.”
These tight links between the landforms and aquatic biodiversity can be exploited by Africa’s cichlids, especially, because these fishes are famous for their ability to speciate in a very short time in order to adapt to their new environments. There are about 1500 species of cichlids in the great lakes of East Africa.
The combination of the genomic record of selected fish species with accurate rock dating of the selected waterfalls will enable the researchers to reconstruct on a much finer scale how and when the landforms evolved.
For the past six weeks Dr Cotterill has been in the study area with a team of geologists and an ichthyologist to sample fish and rocks from above and below key waterfalls. They are Mr Frederick Schedel, a PhD student in ichthyology from the Ludwig Maxmillian University of München, and Dr Samuel Niedermann and his PhD student, Mr Spiros Olivotos from the GFZ German Research Centre for Geosciences in Potsdam.
Dr Cotterill says current knowledge of the tempo and mode of landscape dynamics is surprisingly incomplete: “A detailed knowledge of landscape evolution will establish the platform to reconstruct details of palaeo-environments. Improved dating of landscape evolution will significantly improve our understanding of the palaeoecology and evolution of hominins, from the late Miocene into the Pleistocene.”
Four postgraduate students from Stellenbosch University and Lubumbashi University in the Democratic Republic of the Congo will travel to Germany in January 2016 to receive training in the latest next-generation sequencing techniques.
On the photo (left): With a drop of 35 metres and 100 metres across, the magnificent Lumangwe Falls in North Zambia is the ideal sampling point to investigate the speciation of freshwater fishes upstream and downstream of the waterfall. Photo: Woody Cotterill
Picture (middle) of cichlids in Lake Malawi. Photo credit: Creative Commons license - "Mbuna 2" by User:Haplochromis - Self-photographed. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Mbuna_2.JPG#/media/File:Mbuna_2.JPG
Picture (right),
