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CYP2J19 mediates carotenoid colour introgression across a natural avian hybrid zone
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  • Alexander Kirschel,
  • Emmanuel Nwankwo,
  • Daniel Pierce,
  • Michaella Moysi,
  • Bridget Ogolowa,
  • Ara Monadjem,
  • Alan Brelsford
Alexander Kirschel
University of Cyprus
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Emmanuel Nwankwo
University of Cyprus
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Daniel Pierce
University of California Riverside
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Michaella Moysi
University of Cyprus
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Bridget Ogolowa
University of Cyprus
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Ara Monadjem
University of Eswatini
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Alan Brelsford
University of California Riverside
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Abstract

It has long been of interest to identify the phenotypic traits that mediate reproductive isolation between related species, and more recently, the genes that underpin them. Much work has focused on identifying genes associated with animal colour, with the candidate gene CYP2J19 identified in laboratory studies as the ketolase converting yellow dietary carotenoids to red ketocarotenoids in birds with red pigments. But evidence that CYP2J19 explains variation between red and yellow feather coloration in wild populations of birds is lacking. Hybrid zones between related species provide the opportunity to identify genes associated with specific traits. Here we investigate genomic regions associated with forecrown colour in red-fronted and yellow-fronted tinkerbirds across a hybrid zone in southern Africa. We sampled 79 individuals, measuring spectral reflectance of forecrown feathers as well as scoring colours from photographs. We performed a genome-wide association study to identify associations with carotenoid-based coloration, using double-digest RAD sequencing aligned to a short-read whole genome of a Pogoniulus tinkerbird that we assembled. Admixture mapping using 104,933 SNPs identified a region of chromosome 8 that includes CYP2J19 as the only locus with more than two SNPs significantly associated with both crown hue and crown score. The hybrid zone was bimodal with asymmetric backcrossing, consistent with the hypothesis that yellow-fronted females mate more often with red-fronted males than vice versa. Female red-fronted tinkerbirds mating assortatively with red-crowned males may reinforce species divergence and is consistent with the hypothesis that converted carotenoids are an honest signal of quality.

Peer review status:Published

03 May 2020Submitted to Molecular Ecology
04 May 2020Submission Checks Completed
04 May 2020Assigned to Editor
20 May 2020Reviewer(s) Assigned
15 Jun 2020Review(s) Completed, Editorial Evaluation Pending
22 Jun 2020Editorial Decision: Revise Minor
14 Aug 2020Review(s) Completed, Editorial Evaluation Pending
14 Aug 20201st Revision Received
15 Aug 2020Reviewer(s) Assigned
04 Sep 2020Editorial Decision: Revise Minor
02 Oct 2020Review(s) Completed, Editorial Evaluation Pending
02 Oct 20202nd Revision Received
05 Oct 2020Editorial Decision: Accept
15 Oct 2020Published in Molecular Ecology. 10.1111/mec.15691