Timothy J. Ehlinger Associate Professor B.A., Northwestern Univ. 1980 M.Sc., Northwestern Univ. 1981 Ph.D., Michigan State Univ. 1986 Postdoctoral Fellow Kellogg Biological Station 1987- 88 University of Toronto 1989-90	Office: Lapham S493 Phone: 414-229-4358 CGLS: 414-382-1734 FAX: 414-229-3926 Email: ehlinger@csd.uwm.edu Personal Homepage Electronic Reserve Materials:
Ecology and Evolution of Fishes

Research Interests

Nesting Male Bluegill Sunfish Research in my laboratory explores the ecological and evolutionary processes involved in the adaptive differentiation of fish populations. I am particularly interested in how behavioral and morphological phenotypes reflect the joint pressures of selection on trophic and sexual performance. Current projects are examining questions on several levels, including; (1) the formation and maintenance of polymorphisms within populations, (2) the causes and consequences of phenotypic variation between populations, and (3) phylogenetic patterns in the evolution of trophic and sexual divergence. We employ a combination of field observation, laboratory behavior studies, andmorphometric and genetic analysis. My ongoing studies with sunfishes (genus Lepomis) examine how populations adapt to limnetic versus littoral lake types and how this differs among closely related species. These lake types not only differ in feeding niches but also in the intensity of sexual selection. Fish from these populations are brought into the laboratory for behavioral experiments that explore whether morphological differences translate into differences in fitness. The parameters we measure include habitat-specific feeding ability and differences in nesting success mediated either through female choice or male aggressive competition. A common theme in our research is the conservation of fish biodiversity through understanding the ecology of naturally- reproducing native populations. Examples of current graduate student research include a study of genetic and morphological divergence in populations of Walleye (Stitzostedion vitreum) that exhibit both a lake spawning and river-run spawning sub-population. Another project is examining the reproductive ecology of brook trout (Salvelinus fontinalis), comparing native populations with populations naturalized from introduced hatchery stocks. We are also actively involved in several stream and wetland projects that apply basic ecological principles to the restoration of degraded habitats and the rehabilitation of species populations.

Selected Publications

Ehlinger TJ. Ecology, Phenotype, and Character Evolution in Bluegill Sunfish: A Population Comparative Approach. In Foster SA & JA Endler (eds) Geographic Variation in Behavior; an Evolutionary Perspective. Oxford Univ Press. 1996. Phillips RB and Ehlinger TJ. Evolutionary and Ecological Considerations in the Rehabilitation of Great Lakes Coregonid Fishes. Trans. Amer. Fisheries Soc. 1995. Ehlinger TJ. Allometry and the analysis of morphometric variation in bluegill, Lepomis macrochirus. Copeia (2) 347-357, 1991 Ehlinger TJ. Phenotype-limited feeding efficiency and habitat choice in bluegill: Individual differences and trophic polymorphism. Ecology 7:886-896, 1990. Ehlinger TJ. Foraging mode shifts in the golden shiner (Notemigonus crysoleucas). Canadian Journal of Fisheries and Aquatic Sciences 46:1250-1254, 1989. Ehlinger TJ, and Wilson DS. A complex foraging polymorphism in bluegill sunfish. Proceedings of the National Academy of Sciences, USA 85:1878-82, 1988.