While communicating animals can use multiple signals simultaneously and these signals can interact during use. For example, during hummingbird courtship a male’s iridescent throat plumage is oriented and positioned towards females and the sun in specific ways through their courtship dances. The color-behavior-environment interactions shape the appearance of a male’s colorful plumage to the female, a unique signal property created by the signal interactions. Using six North American hummingbird species as my study system, my research in this theme focuses on understanding the mechanics of these signal interactions, how signal interactions vary among species, and how signal interactions co-evolved with the interacting signals themselves.
Through a novel display re-creation method, I developed, where I mapped the orientation-and-positional movements of video-recorded hummingbird courtship dances combined with full-spectrum photography, I quantified male color appearance, thus directly measuring properties of signal interactions. I discovered that male color appearance is not solely tied to the color of his ornaments (i.e. brighter feathers does not mean brighter appearance), due to behavioral alterations of appearance (Simpson & McGraw 2018), which demonstrates the need to break with traditional, static-snapshot color measurements and instead study animal coloration as a dynamic trait or behavior. Among species, I found that color appearance evolved through two divergent evolutionary pathways alongside exaggeration in plumage or behavioral displays (Simpson & McGraw 2019).
I am continuing my work on signal interactions by evaluating signal interactions in spiders, peafowl, and Peruvian hummingbird species.
My other research themes:
1. Sensory and evolutionary ecology of animal signals and their diversity
2. Evolution of signal production mechanisms