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Archaeogenomics of maize evolution in the South American Andes
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Zhang, Shuya (2023) Archaeogenomics of maize evolution in the South American Andes. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3960995
Abstract
Maize used as a staple crop evolved from a wild plant called teosinte due to human activities in Mexico approximately 9000 years ago. It then was brought through Central America by humans around 7500 years ago, and later, around 6500 years ago, it was spread into South America. While it is widely known when maize spread to various regions, there is still debate regarding whether maize had undergone complete domestication prior to its arrival in South America. In this thesis, the evolution and spread of maize through the Andes was examined directly over several millennia with the application of next generation sequencing and analysis technologies using archaeological maize specimens. Screening for the best-preserved representative samples across the collection of Andean maize specimens established 9 samples to take forward for genome analysis. Structure analysis placed the ancient genomes of the Andes, all pre-Inca, to a single group to the exclusion of modern Andean landraces. Genetic distances between ancient genomes established links between maize samples from distinct cultural groups and the occurrence of network hubs. Analysis of selection signatures showed two possible episodes of selection involved in the adaptation to altitude, the first in pre-Inca times and the second more recently. The relationships revealed between ancient genomes provides evidence for cultural interaction through maize in the Andes spreading from a hub in the Southeast, and later spreading across the continent to Brazil. The evidence also suggests the hypothesis of a second wave of maize into the Andes, possibly as late as the Inca period, which may have brought secondary adaptations to altitude. This project will form the foundation of a larger project to sample many more of the archaeological Andean genomes and bring greater resolution to this period of maize history.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QH Natural history > QH426 Genetics Q Science > QK Botany S Agriculture > SB Plant culture |
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Library of Congress Subject Headings (LCSH): | Corn -- Andes Region, Corn -- Adaptation, Corn -- Evolution, Corn -- History, Domestication, Genomics | ||||
Official Date: | March 2023 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Life Sciences | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Allaby, Robin G. | ||||
Format of File: | |||||
Extent: | 185 unnumbered pages : illustrations | ||||
Language: | eng |
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