The contributions of admixture and genetic drift to diversity among post-contact populations in the Americas
| Autor: | Anthony J Koehl, Jeffrey C. Long |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Population Genetic admixture Biology 03 medical and health sciences Genetic drift Gene Frequency Humans 0601 history and archaeology Computer Simulation education Genetic diversity education.field_of_study 060101 anthropology Genetic Drift Genetic Variation 06 humanities and the arts Hispanic or Latino Black or African American Fixation (population genetics) 030104 developmental biology Genetics Population Genetic distance Evolutionary biology Anthropology Genetic structure Anatomy Founder effect Microsatellite Repeats |
| Zdroj: | American journal of physical anthropology. 165(2) |
| ISSN: | 1096-8644 |
| Popis: | Objective We present a model that partitions Nei's minimum genetic distance between admixed populations into components of admixture and genetic drift. We applied this model to 17 admixed populations in the Americas to examine how admixture and drift have contributed to the patterns of genetic diversity. Materials and Methods We analyzed 618 short tandem repeat loci in 949 individuals from 49 population samples. Thirty-two samples serve as proxies for continental ancestors. Seventeen samples represent admixed populations: (4) African-American and (13) Latin American. We partition genetic distance, and then calculate fixation indices and principal coordinates to interpret our results. A computer simulation confirms that our method correctly estimates drift and admixture components of genetic distance when the assumptions of the model are met. Results The partition of genetic distance shows that both admixture and genetic drift contribute to patterns of genetic diversity. The admixture component of genetic distance provides evidence for two distinct axes of continental ancestry. However, the genetic distances show that ancestry contributes to only one axis of genetic differentiation. The genetic distances among the 13 Latin American populations in this analysis show contributions from both differences in ancestry and differences in genetic drift. By contrast, the genetic distances among the four African American populations in this analysis owe mostly to genetic drift because these groups have similar fractions of European and African ancestry. Conclusion The genetic structure of admixed populations in the Americas reflects more than admixture. We show that the history of serial founder effects constrains the impact of admixture on allele frequencies to a single dimension. Genetic drift in the admixed populations imposed a new level of genetic structure onto that created by admixture. |
| Databáze: | OpenAIRE |
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