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Stronger evidence for relaxed selection than adaptive evolution in high-elevation animal mtDNA
Erik N K Iverson1, Abby Criswell1, Justin C Havird1
1Department of Integrative Biology, the University of Texas at Austin, Austin, TX, United States.
Biorxiv : the Preprint Server for Biology
|February 8, 2024
Summary
High-elevation species show faster mitochondrial DNA evolution, but this is likely due to relaxed selection from smaller ranges, not adaptation. Rigorous testing of non-adaptive hypotheses is crucial for mitochondrial genomes.
Area of Science:
- Evolutionary Biology
- Molecular Evolution
- Genomics
Background:
- Mitochondrial (mt) genes are central to adaptive hypotheses due to their role in energy metabolism.
- High-elevation environments are often hypothesized to drive rapid mitochondrial DNA (mtDNA) evolution via positive selection.
- The role of relaxed purifying selection versus positive selection in high-elevation mtDNA evolution remains largely untested.
Conclusions:
- Elevated mitochondrial dN/dS in high-elevation species is more likely due to relaxed selection (linked to smaller ranges and effective population size) than environmental adaptation.
- The study underscores the necessity of testing non-adaptive hypotheses against adaptive explanations for mitochondrial genome evolution.
- Results emphasize the importance of considering factors like population size and range dynamics in evolutionary studies of mitochondrial DNA.
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