Mate Location Tactics, Vision, and Thermoregulatory Behaviorin Insects

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9723160 Rutowski In the course of their lives, animals are often faced with conflicting demands on their behavior and how these conflicts are resolved within an individual's life and over evolutionary time are important questions in the study of behavior. For example, when active, many insects use a variety of behavioral mechanisms to regulate their body temperature within a preferred range. However, thermoregulatory adjustments occur while animals are engaged in other activities, such as searching for mates. The interaction between these adjustments and the simultaneous performance of other activities are not well understood. This study addresses how thermoregulatory behavior patterns interact with visual mate-location efforts in a butterfly of the Sonoran desert. Males in this species of butterfly occupy and defend perching sites in the morning where they perch and wait for females to appear. During the morning perch preferences change as temperatures rise to maintain body temperature in their preferred range. When cool, males perch on the ground; however, as the morning progresses and temperature rises, males switch to cooler perches about 1 m off the ground. This study examines the impact of this thermally-driven change in perch preference on males' abilities to detect passing females and competing males. If perch preference leads to changes in how the butterfly's visual system is positioned in space relative to the flight paths of conspecifics, this may effect the likelihood that passing conspecifics will be detected. To address this question, several research approaches will be taken. Information will be gathered on the flight paths of females and intruding males, variation in visual acuity across the field of vision, and changes in male body position and orientation. Studies of visual system acuity involve a complex pseudopupil analysis procedure, which will be done in collaboration with a researcher at the University of Lund in Sweden, one of few places in the world where such analysis can be done. Another experimental approach will be to use a model flying device (a motorized dummy butterfly with wings attached) at field sites in Arizona to assess directly how and why the probability of detecting conspecifics changes with perch preference. Ecological variables such as background contrast will be of special interest. The end results should be a better understanding of how insects see their world, and a novel integration of behavior, physiology, and ecology that will permit a more comprehensive understanding of the immediate and evolutionary resolution of conflicting behavioral demands in animals.