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Title: Evolution of breeding plumages in birds: A multiple-step pathway to seasonal dichromatism in New World Warblers (Aves: Parulidae)
  • Ryan Terrill,
  • Glenn Seeholzer,
  • Jared Wolfe
Ryan Terrill
Occidental College
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Glenn Seeholzer
Louisiana State University
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Jared Wolfe
Michigan Tech
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Peer review status:ACCEPTED

15 Jun 2020Submitted to Ecology and Evolution
16 Jun 2020Submission Checks Completed
16 Jun 2020Assigned to Editor
17 Jun 2020Review(s) Completed, Editorial Evaluation Pending
17 Jun 2020Editorial Decision: Revise Minor
18 Jun 20201st Revision Received
19 Jun 2020Submission Checks Completed
19 Jun 2020Assigned to Editor
19 Jun 2020Review(s) Completed, Editorial Evaluation Pending
29 Jun 2020Editorial Decision: Accept

Abstract

Bird feathers serve multiple functions through their physical structure and coloration, but the evolution of functional novelty in bird feathers remains poorly understood. We investigated how selective pressures gave rise to seasonal coloration change in the feathers of the New World Warblers (Aves: Parulidae), a family with a remarkable diversity of plumage, molt, and life history strategies. Seasonal color changes in the plumages of migratory warblers are hypothesized to reflect a tradeoff between natural and sexual selection on the breeding and non-breeding distributions. We used comparative methods including phylogenetic path analysis to examine nested hypotheses relating to the evolution of seasonal dichromatism (i.e. breeding and nonbreeding plumages) and the molts that produce these plumages. We found that biannual molts likely evolved in response to increased feather wear and that changes in feather coloration evolved after the biannual molt itself. These results demonstrate that structural needs, not seasonal selection on coloration, drive the evolution of molt strategies in Parulidae. Importantly, once a biannual molt evolves, it served as a preadaptation for seasonal changes in plumage color. These results reveal how life history strategies act upon multiple and separate feather functions to drive the evolution of feather replacement patterns and bird coloration.