3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Molecular Genetic Variation in Mozambican and Zimbabwean populations(2001) Eddy, Carey-AnneGenetic data, used in conjunction with linguistic, archaeological and anthropological data, is extremely valuable in understanding the evolutionary and demographic history of subSaharan African populations. Present-day southern African populations are represented by Khoisan and Bantu-speaking groups. The Bantu languages have their origins in the Benue- Niger area between present-day Nigeria and Cameroon, and has spread to central and southern Africa over the past 2-3000 years. The spread of Bantu-speaking peoples, referred to as the “Bantu expansion”, ought to have contributed to the spectrum of genetic variation found in sub-Saharan African populations. In this study we propose to examine the genetic structure of two southeastern Bantu-speaking population groups: the Remba (a Lemba group) from Zimbabwe and a Mozambican group sampled near Inhambane. Although the Lemba from South Africa live among the Venda and the Remba among the Shona, their intriguing oral history and unique Semitic-like cultural practices have set them apart from their Bantu-speaking neighbours. They claim descent from Jews who came to Africa from “Sena”. A previous study using Y chromosome markers suggested both a Bantu and Semitic contribution to the Lemba gene pool. More recently, the presence of a particular Y chromosome type termed the “Cohen Modal Haplotype” (CMH) in the Lemba from South Africa, led others to conclude that the Lemba have a specifically Jewish ancestry. These studies, however, have not resolved conclusively the origins of the Lemba. The Mozambican gene pool might reflect contributions from other populations particularly. The Mozambican gene pool might reflect contributions from other populations particularly due to the crucial geographic position it occupied, linking landlocked countries to coastal IV ports, during the days of slavery and trade with the East. There have only been limited genetic studies in populations from Mozambique and even the archaeological record from present-day Mozambique is especially sparse. We used the non-recombining portion of the Y chromosome and mtDNA data to examine the contribution of males and females, respectively, to the gene pools of the Remba and the Mozambicans and to investigate the prehistory of these two population groups. The Remba from Zimbabwe and the Lemba from South Africa shared common Y chromosome haplotypes that were connected via single mutational steps, suggesting that they have a common recent ancestry. The CMH was found in only one Lemba individual from South Africa and was absent in the Remba. Furthermore, there were no one-step derivatives of the CMH in the Lemba or the Remba. It is possible that the CMH was introduced into the Lemba fairly recently due to gene flow from South African Jews. Although the Remba and Lemba do have a common Semitic contribution to their Y chromosme gene pool, it is premature to use the CMH as evidence of Jewish ancestry in the Lemba. There was no evidence from the mtDNA data to suggest any non-African contribution to the mtDNA gene pool of the Remba and Lemba or the Mozambicans. There is, however strong evidence suggesting that the Remba, Lemba, Mozambicans, Venda, southeastern Bantu speaking population groups from South Africa and several other sub-Saharan African populations share a recent common maternal ancestry that most likely has its roots in the Benue-Niger region prior to the Bantu expansion. Despite the role the Mozambicans may have played during the days of slavery and trading, their Y chromosome profile shows no reflection of any contribution from non-African populations.Item Molecular Genetic Variation in the Malagasy(2001) Dorf, CindyABSTRACT The island of Madagascar has been separated from Africa for almost 70 million years and was the last of the major land masses to be colonised by humans. Several theories concerning Malagasy origins have been proposed, but the prehistory of the Malagasy is still unresolved. Historical, archaeological, linguistic and genetic data suggest two major contributors to the Malagasy, namely African and Indonesian populations, with additional contributions from Arab, Indian, Chinese and various other Asian sources. All the islanders speak a common language called Malagasy, and although there are dialectical differences, these are not sufficient to elucidate the geographic origins of the proto- Malagasy. Some studies have reported that differences in physical appearance and culture between populations occupying different regions of the island may suggest different ancestral histories. In this study, we made use of information from three different genetic systems, namely mitochondrial DNA (mtDNA), the Y chromosome and several autosomal DNA markers to trace the origins of the males and females who contributed to the gene pool of the present-day Malagasy. We found that the mtDNA 9-bp deletion was present, throughout the island, at a total frequency of 22.5%. The 1.1 kb mtDNA control region was sequenced from 228 Malagasy individuals from which one hundred and twenty four unique mtDNA types, defined by 151 nucleotide changes were derived. Studies have shown that when the 9-bp deletion is used in conjunction with mtDNA control region sequence variation, the 9-bp deletion is a useful marker to trace population affinities. We were able to demonstrate that an overall Asian to African contribution of approximately 2:1 is indicated in present-day Malagasy populations. We used the Y Ala polymorphism (YAP) in conjunction with M9 to distinguish between African and non-African Y chromosomes. Overall, an African contribution of 78.2% and a non-African contribution of 21.85% was calculated. To gain insight into the autosomal DNA found in the Malagasy, we made use of three loci with population specific alleles (Sbl9.3, AT3id and APO-4) and the human mannose binding protein. Again, we observed both African and Asian affinities in the various Malagasy ethnic groups. By jointly analysing all the marker systems that were used, we were able to demonstrate a close relationship between ethnic groups from the different geographic regions on the island, and found the Malagasy to be a relatively homogeneous population. To test the ethnic and geographical structure present on the island, we conducted an analysis of molecular variance (AMOVA). These tests showed little biological support in favour of such hierarchies. A correlation analysis showed that very weak correlations exist between the data generated by the different genetic systems. Furthermore, by vividly demonstrating the differential input from males and females to the present-day Malagasy, this study also illustrates the advantages of combining mtDNA data with Y chromosomal results from the same individuals.