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Selective Sweeps across Twenty Millions Years of Primate Evolution
Kasper Munch1, Kiwoong Nam2, Mikkel Heide Schierup3
1Bioinformatics Research Centre, Aarhus University, C. F. Møllers Alle, Denmark kaspermunch@birc.au.dk.
Molecular Biology and Evolution
|September 24, 2016
Summary
Selective sweeps significantly reduce genetic diversity over evolutionary time. Analyzing incomplete lineage sorting (ILS) in ancestral species reveals these sweeps, with more impact seen in the human-chimpanzee lineage than the human-orangutan lineage.
Area of Science:
- Evolutionary genetics
- Population genetics
- Genomics
Background:
- Assessing the impact of selective sweeps on genetic diversity is challenging due to limitations of polymorphism data.
- Selective sweeps, driven by positive selection, can reduce genetic variation in linked regions.
- Incomplete lineage sorting (ILS) provides a historical genomic signal reflecting past evolutionary events.
Purpose of the Study:
- To develop a method for quantifying selective sweeps across evolutionary timescales using ILS patterns.
- To investigate the role of linked selection in shaping genetic diversity in ancestral species.
- To compare the relative impact of selective sweeps and background selection on genomic diversity.
Main Methods:
- Analyzing patterns of incomplete lineage sorting (ILS) across the genomes of closely related species (human, chimpanzee, orangutan).
- Identifying regions with depleted ILS as indicators of past selective sweeps in ancestral lineages.
- Quantifying the extent and overlap of selective sweeps in human, chimpanzee, and orangutan ancestors.
Main Results:
- Selective sweeps in human and chimpanzee ancestors were identified as significant depletions of ILS in regions >100 kb.
- Recurrent selective sweeps were predicted in both ancestral species, often overlapping with human sweeps.
- The human-chimpanzee ancestor exhibited a greater excess of ILS-depleted regions and a stronger reduction in ILS around genes compared to the human-orangutan ancestor.
Conclusions:
- Selective sweeps play a substantial role in reducing genome-wide genetic diversity.
- The impact of selective sweeps on diversity was significantly greater in the human-chimpanzee ancestor than in the human-orangutan ancestor.
- ILS patterns offer a powerful tool to study historical selective pressures across deep evolutionary time.
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