DISSERTATION RESEARCH: Shedding Light onto Butterfly Signaling: Light Environment, Signals and Visual Systems

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Animals vary both in the visual signals they produce and in the eyes they use to perceive these signals. However, in most animals the production and perception of visual signals depend on the light available in the environment. This proposed research will examine how even subtle differences in light environment (e.g. forest vs. field) has driven the evolution of diversity in visual signals, in the eyes used to perceive these diverse signals, and in the behavior of signalers and receivers. Researchers will gather information on coloration, vision, and behavior for twenty species of tropical rainforest butterflies. Species that live near the shady rainforest floor are predicted to actively seek darker environments when given a choice, have eyes that enhance visual sensitivity, and have coloration that is more conspicuous in the shade compared to species that live in the bright edge or top of the rainforest. This work will expand the knowledge of the biology of animals that live in tropical rainforests species and will provide a venue for training students in tropical biology and for international collaborations among institutions and scientists in the US, Panama, Peru, and other Latin American countries. This research will examine the potential for even subtle differences in light environment (e.g. shady forest vs. bright open areas) to drive the evolution of diversity in visual signaling, perception, and behavior. This work will address general questions in visual ecology including: 1) Do animals differ in their preferences for light environments? 2) Do animals use different visual signals depending on the habitat and environment in which they occur? 3) Does vision, both eye morphology and visual physiology, correspond to the light environment in which an animal lives? The approach is comparative, with twenty species of tropical rainforest butterflies as the focal taxa and appropriate controls for phylogeny. Species differ not only in coloration but also how deep in the rainforest they are typically found. Data collected will quantify their coloration, their light environment preferences, and their eye structure and physiology. This work will contribute to a general understanding of the causes and consequences of the enormous diversity of coloration and eyes in animals, a perennial puzzle in biology. Furthermore, this work will expand knowledge of the visual ecology of tropical rainforest animals, and foster international scientific collaborations. Data will be documented in field notebooks initially and then uploaded to secure cloud storage provided by Dropbox (dropbox.com), which will then be backed up on an external hard drive kept at Arizona State University. Data will be available to all participants through Dropbox and to the public via journal data repositories. Mature protocols of the behavioral and visual methods are posted online in an open-access mode through websites of the researchers' labs.