Habitat Selection and the Ecological Consequences of Life History Evolution in Daphnia

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Numerous studies document substantial genetic variation among and within populations of the same species. Research intothe nature of this variation has discovered important ecological differentiation among populations and even among genotypes within the same population. The P.I.'s propose to examine the significance of this within-species, genetic variation to the ecological interactions of competition. Their system is the plankton community of small lakes in southwestern Michigan. Two species of zooplankton (Daphnia pulicaria and D. galeata mendotae)are dominant herbivores that coexist i these lakes via vertical habitat partioning. The investigations have documented large genetic variance within populations of one of these species and have preliminary evidence that it represents ecological specialization via habitatselection. The P.I.'s 1) more broadly test this hypothesis 2) describe the ecological and genetic trade-offs that maintain intra-specific habitat specialization, and then 3) experimentally determine the ecological consequences of this variation to interspecific competition and to community response to predation. The results should be broadly applicable to many ecological communities. The proposed work will contribute to undergraduate, graduate, and postdoctoral training in aquatic ecology and evolutionary biology. The grant would fund one postdoctoral scholar to work with the P.I. on merging issues of community ecology and life history evolution. Two different Ph.D candidates will be involved in the proposed work, providing them with training in both the laboratory and field (electrophoresis, culture techniques, field manipulations, etc.). We will involve undergraduate students at three levels; REU's, field help, and formal course work. In the past the P.I. has selected students from smaller universities that have restricted research opportunities for undergraduate (1989 REU's were Jennifer Welser University of Vermont; Andrew Young - Swarthmore College). These students conduct their own, spin-off projects from the grant. In each year one undergraduate field assistant is hired (Jennelle Marceau in 1989). Finally, the P.I. teaches courses in Limnology (Summer), Ecology & Evolution (Fall), and Quantitative Methods (Spring). Undergraduate in these courses are provided an opportunity to get involved in the P.I.'s research.