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Leveraging Whole Genomes, Mitochondrial DNA and Haploblocks to Decipher Complex Demographic Histories: An Example
Xavier Dallaire1,2, Eric Normandeau3,4, Thomas Brazier5
1Institut de Biologie Intégrative et Des Systèmes, Université Laval, Québec, Canada.
Molecular Ecology
|April 28, 2025
Summary
Whole-genome sequencing of Arctic Char revealed complex hybridization histories. Atlantic lineage introgression increased genetic diversity in Canadian populations, suggesting intricate postglacial recolonization patterns.
Area of Science:
- Evolutionary biology
- Population genomics
- Phylogeography
Background:
- Phylogeographic studies have advanced from mitochondrial DNA to genome-wide analyses.
- Whole-genome sequencing enables investigation of both mitochondrial and nuclear DNA, offering high resolution for admixture studies.
Purpose of the Study:
- To characterize genetic variation and diversity in Arctic Char across Canada and Greenland.
- To understand the impact of hybridization between Arctic and Atlantic glacial lineages on genetic patterns.
Main Methods:
- Sequencing of 1120 Arctic Char genomes from 33 populations.
- Mitochondrial genome analysis.
- Admixture analyses and demographic inferences using nuclear markers.
- Local principal component analyses to identify ancestry tracts.
Main Results:
- Mitochondrial genomes were mostly Arctic, with some Atlantic descent observed in Greenland.
- Canadian populations south of the 66th parallel showed Atlantic lineage introgression, increasing genetic diversity.
- Identified large, low-recombining haploblocks representing local ancestry tracts.
Conclusions:
- Whole-genome sequencing provides a powerful tool for studying complex phylogeographic dynamics.
- Arctic Char exhibit a complex postglacial history shaped by hybridization.
- Introgression from the Atlantic lineage has influenced genetic diversity in Canadian Arctic Char populations.
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