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DNA Methylation Reflects Cis-Genetic Differentiation Across the European Crow Hybrid Zone
Justin Merondun1,2,3, Jochen B W Wolf1,2
1Division of Evolutionary Biology, LMU Munich, Martinsried, Germany.
Molecular Ecology
|July 10, 2025
Summary
Epigenetic DNA methylation variation in crows is linked to genome properties, not an independent evolutionary force. Methylation differences primarily follow genetic changes, particularly in regions affecting traits like plumage color.
Area of Science:
- Evolutionary biology
- Genomics
- Epigenetics
Background:
- Chromatin modifications, including DNA methylation, are crucial for epigenetic variation and evolutionary potential.
- Speciation involves understanding the interplay between genetic and epigenetic factors driving divergence.
Purpose of the Study:
- To quantify the role of epigenetic variation in crow speciation.
- To investigate the relationship between DNA methylation, genome properties, and genetic divergence in incipient crow species.
Main Methods:
- Genome and methylome sequencing of carrion crows, hooded crows, and their hybrids.
- Controlled common garden experiments and natural hybrid zone sampling.
- Analysis of 5-methylcytosine (5mC) methylation patterns and their correlation with genetic variation.
Main Results:
- 5mC methylation variation is largely explained by genome properties and organismal development (ontogeny).
- Epigenetic divergence is concentrated in intergenic regions.
- The primary region of significant genetic differentiation corresponds to genes influencing the distinct plumage color between crow taxa.
Conclusions:
- Epigenetic variation relevant to crow speciation is predominantly driven by underlying cis-genetic polymorphism.
- DNA methylation does not appear to act as an independent evolutionary mechanism in this system.
- Genetic factors are the primary drivers of divergence in this incipient speciation event.
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