Iridescent Color Signals in Context: Interactions among Behavior, Perception, Function, and Light Environment

Arizona State University, Scottsdale AZ

Investigators

Abstract

The visual signals of many animals include iridescent colors which have the unique property of changing dramatically in brightness and hue when the viewer position changes relative to the reflecting surface. Understanding the production and perception of these directional color signals in nature is a more complex problem than for non-directional colors. This study will explore a beautifully iridescent and common butterfly, the Pipevine Swallowtail. This butterfly has large iridescent areas on the lower wing surface that signal this species distastefulness to potential predators, and also on the upper wing surfaces (males only) which is used by females in mate choice. Experiments and observations in the field, lab and a large butterfly enclosure at a botanical garden will evaluate the relative positions and movements of sender and intended receivers, the perceptual capabilities of intended receivers, and the available illumination in nature. This will be done separately for each wing surface with careful attention to the function of each signal and the context in which it is viewed by intended receivers - females for the upper wing surface and predators for the lower wing surface. Behavioral experiments will explore the implications for the directionality of iridescence for signal detection and effectiveness. Overall this study has the potential to transform our views of how iridescent color signals in animals in various contexts are actually viewed and used in nature. In addition to the intellectual merits, the broader impacts of the proposed research include providing research training experiences for undergraduate and graduate students, especially for groups underrepresented in the sciences, stimulating the interest of a broad audience through publication in technical journals and popular literature, and outreach activities using established web sites (http://rutowski.lab.asu.edu and http://askabiologist.asu.edu/) and local public natural history organizations.