Aquatic Sciences Meeting, Albuquerque 2001

SS39 Evolution in Aquatic Environments (Spatial and Temporal Connections)

Date: Monday, February 12, 2001, Time: 3:45:00 PM

Location: Dona Ana

Tessier, A, J, Kellogg Biological Station, Michigan State University, , USA, Tessier@kbs.msu.edu

Woodruff, P, , Kellogg Biological Station, Michigan State University, , USA, Woodruff@kbs.msu.edu

TRADE-OFF IN ADAPTATION OF DAPHNIIDS TO FOOD QUALITY

Daphnia includes a diversity of taxa, which occupy a wide range of lentic habitats, from large lakes to temporary pools and from oligotrophic to eutrophic conditions. This diversity is often seen as an adaptive response to spatial and temporal variation in the type and intensity of predation. But mortality is only half the fitness equation. Are there also consistent environmental gradients in resources, and do daphniids exhibit trade-offs in ability to exploit such resource variation? We quantified seasonal and among lake differences in resources using Daphnia growth rate bioassays conducted over 6 years and in >20 lakes that differ in basin size, food web structure and productivity. We document a striking and consistent contrast in resource quality between deep and shallow lakes. Further, we measured the performance of 11 daphniid taxa fed resources from the breadth of this quality gradient, and found a trade-off among taxa in ability to use rich vs. poor quality resources. The distribution of these daphniids is consistent with an adaptive matching of resource exploitative ability to resource environment.

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Aquatic Sciences Meeting, Albuquerque 2001

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