Plumage diversity without differential expression of pigmentation genes in a rapid avian radiation

In Capuchino Seedeaters (Sporophila), male plumage color differences are not matched by widespread differential expression of pigmentation genes; only ASIP is downregulated in crown feathers.

• Why it matters: The work addresses how reproductive plumage traits diverge at the molecular level, especially when genetic scans point to regulatory variants.
• What they did: The authors performed outlier scans for pigmentation variants and then used RNA-seq of growing feather follicles, finding expression differences mainly by body region and sex, including BCO2 upregulation in males.
• The result: An improved genome annotation placed 9.5% of candidate variants into coding and untranslated sequence, suggesting species-diagnostic variants may act post-transcriptionally rather than by changing transcript abundance.

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