Andrew Clarke BSc(Hons)
Doctoral Student, Plant Biology
Allan Wilson Centre for Molecular Ecology and Evolution, and
Institute of Molecular BioSciences
My PhD is focussed on genetic fingerprinting of the sweet potato ('kumara' in Maori) and bottle gourd ('hue' in Maori) to determine if these two species were introduced into the Pacific from South America by Polynesian voyagers ~1500 years ago.
The sweet potato (Ipomoea batatas) is a crop originally from South America and has been utilised as a starchy food source there for at least 10 000 years. Before Columbus, it is thought the only place sweet potato existed outside the Americas was the Pacific, where it was grown throughout the Polynesian triangle. Although controversial, it has been suggested Polynesian voyagers introduced the sweet potato from South America into the Pacific between A.D. 400 and 700.
The gourd (Lagenaria siceraria) does not occur naturally in the Pacific but was widely grown by Polynesian settlers of the Pacific about 1500 years ago. Because the Polynesian ancestors came from South East Asia, where the gourd has been grown for thousands of years, it has been suggested that the Pacific gourd is of Asian origin. We are currently examining an alternative hypothesis: that the Pacific gourd came from South America at the same time as the sweet potato.
Using high resolution fingerprinting techniques we have identified variable regions of the sweet potato and gourd genomes. These are currently being developed into DNA sequencing markers which will allow us to obtain DNA sequence information from Asian, Pacific and South American sweet potato and gourd cultivars. These DNA data will be used to construct phylogenies, from which we will determine the spatial and temporal patterns of sweet potato and gourd dispersal in the Pacific. This molecular phylogeny will allow us to answer the question: Did Polynesian voyagers make landfall in South America and return to Polynesia with the sweet potato and bottle gourd?
Professor David Penny, Assoc. Prof. Peter Lockhart
Allan Wilson Centre for Molecular Ecology and Evolution,
Dr John McCallum
New Zealand Institute for Crop & Food Research, Ltd