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The computer program STRUCTURE does not reliably identify the main genetic clusters within species: simulations and
1Department of Ecology, Montana State University, Bozeman, MT, USA. skalinowski@montana.edu
Heredity
|August 5, 2010
Summary
The computer program STRUCTURE, used for population genetics, may misrepresent evolutionary history and human population structure. Simulations reveal its clusters can be inconsistent with divergence times and influenced by sample size.
Area of Science:
- Population Genetics
- Computational Biology
- Evolutionary Biology
Background:
- Population genetics aims to describe genetic relationships among populations.
- The STRUCTURE program is a widely used tool for inferring population structure.
- It models individuals into Hardy-Weinberg populations and groups them into clusters representing genetic divisions.
Purpose of the Study:
- To evaluate the effectiveness of the STRUCTURE program in grouping individuals into clusters that reflect main genetic divisions within species.
- To examine how simulation parameters, such as divergence times and sample size variation, impact STRUCTURE's cluster assignments.
- To reassess human population structure analyses in light of potential STRUCTURE limitations.
Main Methods:
- Computer simulations were employed to model populations with hierarchical fragmentation.
- Simulations varied divergence times within evolutionary lineages and sample sizes.
- A reanalysis of human population structure data was conducted using insights from the simulations.
Main Results:
- STRUCTURE-generated clusters were frequently inconsistent with the evolutionary history of simulated populations, especially with long divergence times.
- The number of clusters imposed on STRUCTURE significantly affected its ability to recover true population history.
- Variation in sample size strongly influenced cluster outcomes, with large samples sometimes dominating cluster assignments.
Conclusions:
- The STRUCTURE program's cluster assignments may not always align with the evolutionary past of populations, particularly under certain demographic scenarios.
- Limitations in STRUCTURE, including the constraint on the number of clusters and sample size effects, can obscure true population relationships.
- Potential misinterpretations of human population structure, including overlooked genetic similarities between European and some African populations, may stem from these limitations.
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