Douglass H. Morse
Hermon Carey Bumpus Professor of Biology, Emeritus
Research Profesor
Ph.D., Louisiana State University

Our primary research interests focus on the relationship between resource exploitation and lifetime fitness, concentrating this work on the crab spider Misumena vatia, a sit-and-wait predator on flowers. The critical activity of adult female M. vatia is finding food and that of the adult males is finding females. Since the two activities require considerable time and search, it is appropriate to consider them both as measures of foraging. We have evaluated the consequences of foraging success on key life history variables throughout M. vatia's life cycle. To understand how M. vatia's attributes and limitations affect them in this quest, we have recently concentrated on the role played by cognitive factors in determining success in foraging at different stages of the life cycle. Misumena vatia is one of the most dimorphic of free-living land animals, and these studies simultaneously provide insight into the forces driving this striking condition and the degree to which they result from mutualistic and antagonistic selective pressures on the two sexes.

A second interest focuses on four-trophic-level systems and the role that indirect effects may play in structuring communities. For instance, what effect does the first trophic level, as channeled through the second and third levels, have upon the fourth level? Chemical differences between food plants may affect their quality to herbivores, but what effect may this result play in the success of parasitoids, and on the success of their own parasitoids, the hyperparasitoids? These questions have considerable importance for the success of biological control, yet the parasitoid-hyperparasitoid relationship, a potentially key aspect of parasitoid success, is but poorly studied. Our system permits realistic field experimentation of these two links.

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