The author is a postdoctoral fellow in the Genetics Department of North Carolina State University, where he is currently working in the laboratory of M. Purugganan with funding from the National Science Foundation (Integrated Research Challenges in Environmental Biology). This paper represents one component of the author’s PhD dissertation completed at Washington University in St Louis (Program in Evolutionary and Population Biology) under the direction of B. Schaal.
Population history of Manihot esculenta (Euphorbiaceae) inferred from nuclear DNA sequences
Article first published online: 29 APR 2002
Volume 11, Issue 5, pages 901–911, May 2002
How to Cite
Olsen, K. M. (2002), Population history of Manihot esculenta (Euphorbiaceae) inferred from nuclear DNA sequences. Molecular Ecology, 11: 901–911. doi: 10.1046/j.1365-294X.2002.01493.x
- Issue published online: 29 APR 2002
- Article first published online: 29 APR 2002
- Received 20 December 2001; revision received 21 January 2002; accepted 21 January 2002
- Manihot esculenta ssp. flabellifolia;
- Manihot pruinosa;
- nested clade analysis;
- South America
The nature of gene flow in plants — including the propensity for interspecific introgression — makes them interesting candidates for phylogeographical analysis. Plant phylogeography studies have been limited, however, by the availability of suitable intraspecific variation. In this study, DNA sequence variation from a nuclear gene [Glyceraldehyde 3-phosphate dehydrogenase; (G3pdh)] was used to examine the population history of Manihot esculenta ssp. flabellifolia and a potentially hybridizing species, M. pruinosa. These species occur in the rainforest–savanna ecotone adjoining the Amazon basin, a region believed to have undergone major habitat shifts since the Pleistocene. Geographical distributions of the G3pdh haplotypes indicate genetic isolation-by-distance across the range of M. esculenta ssp. flabellifolia. However, there is greater genetic similarity between northeastern and western populations than would be expected given the present species distribution. A nested clade analysis suggests that northeastern and western populations were connected by gene flow until relatively recently, when they became fragmented. This inferred fragmentation event is consistent with post-Pleistocene habitat shifts proposed for the Amazon basin. At the interspecific level, haplotype sharing with M. pruinosa may reflect either recent interspecific introgression or incomplete lineage sorting between these closely related species.