Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences

First Advisor

Stéphanie Doucet

Second Advisor

Daniel Mennill


Biological sciences




Several factors may drive interspecific divergence, and investigating possible mechanisms from multiple angles may be most efficient for understanding the evolutionary history of diverse groups. The main objective of my thesis was to examine mechanisms that may promote plumage divergence in Parulidae warblers. In my first study, I investigated the signalling environments of 17 sympatric species of warblers to test predictions of sensory drive. I determined sexual selection has likely influenced plumage evolution in warblers, plumage and visual environment coloration were correlated, and warblers were not most conspicuous in chosen display environments. In my second study, I tested the relationship between sympatry and plumage divergence across 77 species and found an increase in sympatry is correlated with greater plumage divergence, and that closely related species tended to be highly sympatric. My thesis demonstrates multiple selective pressures have likely shaped the evolution of plumage coloration in this diverse group of birds.