Variation and constraints in hybrid genome formation
Anna Runemark1, Cassandra N Trier2, Fabrice Eroukhmanoff2
1Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway. anna.runemark@ibv.uio.no.
Nature Ecology & Evolution
|January 17, 2018
Summary
Hybridization creates new species, but limits to hybrid genomes are unclear. This study shows Italian sparrow hybrid genomes vary, with some regions limiting evolution, potentially aiding reproductive isolation.
Area of Science:
- Evolutionary biology
- Genomics
- Speciation
Background:
- Hybridization is a key driver of genetic variation and speciation.
- Understanding the constraints on hybrid genome formation and evolution is crucial.
Purpose of the Study:
- To investigate the extent to which homoploid hybrid genomes can evolve.
- To identify genomic regions and genes that limit variation and potentially cause reproductive isolation in the Italian sparrow (Passer italiae).
Main Methods:
- Genome sequencing of four island populations of the Italian sparrow (Passer italiae).
- Analysis of genomic variation and introgression patterns across different populations.
Main Results:
- Novel and functional hybrid genomic combinations have arisen independently in different island populations.
- Specific genomic regions, particularly on the Z chromosome, show limited introgression and harbor candidate incompatibility genes (e.g., DNA-repair, mitonuclear genes).
- These restricted regions may contribute to reduced gene flow on sex chromosomes.
Conclusions:
- Hybrid genomes exhibit significant variation, with some regions showing constraints on evolutionary freedom.
- Candidate reproductive isolation genes have been identified, shedding light on the mechanisms limiting introgression and promoting speciation.
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