Anne Leonard

Department of Ecology and Evolutionary Biology
leonard9@email.arizona.edu
Ph: 520-621-8988
Fax: (520) 621 9190
Mailing address: P.O. Box 210088, University of Arizona, Tucson, Arizona 85721-0088

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RESEARCH INTERESTS

A wide diversity of organisms produce signals that span sensory modalities, despite the costs and risks of producing a complex and conspicuous display. For example male mating displays often combine elaborate visual and acoustic signals, and warning signals directed at predators often consist of both chemical and visual components. I am interested in understanding how receivers benefit from assessing multimodal signals and investigating the decision rules they use to compare alternatives that differ in several attributes. I also explore sources of variation in how receivers make decisions using complex signals, an often-overlooked area of inquiry.

I completed my dissertation at the University of California, Davis with Dr. Ann Hedrick. My research explored how female and male field crickets, Gryllus integer, make mating decisions using both acoustic and chemical signals. In this species, the sexes use different decision rules when responding to the long-distance acoustic advertisement signals of competitors (male receivers) versus potential mates (female receivers). Males and females also differ in their use and prioritization of chemical signals in species recognition. Unlike females, males show species discrimination in response to isolated chemical cues, but not in courtship trials. For males, information at close range during courtship appears to override species-specific chemical cues. In contrast, females appear to obtain information about species from a combination of close-range signals.

A second area of my dissertation research addressed why females sequentially assess both males' acoustic and chemical signals (a long-distance calling song, followed by close-range chemical cues, then a close-range courtship song). My work shows that acoustic signals and chemical cues do not convey redundant information about male quality, but do interact in a complex manner. For example, manipulating the attractiveness of a male's long-distance calling song influences females' responses to his close-range courtship display.

As a PERT fellow, I am continuing to explore how receivers use and potentially benefit from multimodal signaling. The current project is inspired by the finding of Kulahci et al. (2008) that bumble bees trained to discriminate flowers that had both visual and olfactory differences learned more quickly and made more accurate decisions than did bees trained on flowers that only had either visual or olfactory differences. Flowers' production of both visual and olfactory signals may enhance pollinators' ability to recognize and visit similar flower types (flower constancy), thus increasing the transmission of conspecific pollen. Multimodal flower signals enhance pollinator learning, but is this why they have evolved? A clear first step towards answering this question is to determine whether increasing the number of signals within one modality benefits receivers to the same extent as adding signals in a different modality. If the benefit only occurs when signals span modalities, this could provide some of the first evidence that the way receivers process sensory information directs the evolution of multimodal signaling (i.e. the "sensory constraints" hypothesis of Hebets and Papaj, 2005). From a proximate perspective, understanding the benefits of multimodal signaling requires an exploration of how pollinators both process and prioritize visual versus olfactory information, as well as how foraging experience may affect signal prioritization.