Why do immune genes keep evolving across tetrapods?
Shared positive selection in birds and mammals concentrates on immune—especially antiviral—genes, implicating pathogens as a consistent selective pressure.
Source
Immune genes are hotspots of shared positive selection across birds and mammals
What they did
Authors scanned orthologous genes across birds (and compared to mammals) for positive selection, then linked selected genes to pathogen-responsive transcriptomes.
What they found
Immune pathways are recurrent selection targets; genes selected in birds are enriched for selection in mammals, especially viral-response genes. About 14% of genes are selected in all tests.
The limits
What it doesn't show
Shared selection could reflect convergence or ancient shared pressure; finer tetrapod clades still need scanning.
Key terms
- Positive selection
- Natural selection favoring amino-acid changes.
- Orthologues
- Genes in different species descended from a common ancestor.
- Pathogen-mediated selection
- Host evolution driven by infectious agents.
- Immune hotspots
- Gene classes repeatedly targeted by selection across taxa.
- Viral response genes
- Host genes induced by or interacting with viruses.
Flashcards
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Quiz yourself
Most consistent selective pressure claimed:
Common questions
What selective pressure looks most consistent?
Pathogens, especially viruses.
Do bird-selected genes matter in mammals?
Yes—they are more likely selected and immune/viral enriched.
How often are genes selected in all tests?
About 14%.
Do transcriptomes support this?
Pathogen-upregulated genes are enriched for selection.
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