Josh Van Buskirk Trent Garner Benedikt Schmidt Uli Steiner

supported by the Swiss National Science Foundation (SNF) ... and the frogs

Phenotypic plasticity, local adaptation, and habitat specialization in amphibians

This project addresses the conditions under which populations evolve ecological specialization and generalization. Examples of these include phenotypic plasticity (generalization) and local adaptation (specialization). Theory suggests that environmental heterogeneity can be involved in both

processes, and we are interested in how that takes place. Our empirical focus is on amphibian larvae because they are experimentally tractable, the connection between phenotypic variation and performance can be estimated, and they appear to show both ecological specialization and generalization. One feature that turns out to be critical is the scale at which variation occurs, and therefore we sample the predator composition of natural ponds at various temporal and spatial scales. The extent to which individuals move among ponds is also important, and we are screening populations at microsatellite loci to obtain indirect estimates of dispersal. To understand how environments with different predator compositions impose natural selection on tadpoles, we measure the performance consequences of phenotypic variation for living individuals and models.

The goal of all these efforts is to reach a general understanding of how different scales of environmental variation give rise to population structure, including demography and dynamics, and adaptive and neutral genetic variation. This level of understanding is necessary to acheive an integrated picture of evolutionary dynamics, and for effectively managing patchily-distributed populations.

Recent publications:

• Van Buskirk, J. 2002. A comparative test of the adaptive plasticity hypothesis: relationships between habitat and phenotype in anuran larvae. American Naturalist 159: in press.
• Van Buskirk, J., and G. Saxer. 2001. Delayed costs of an induced defense in tadpoles? Morphology, hopping, and development rate at metamorphosis. Evolution 55:821-829.
• Van Buskirk, J. 2000. The costs of an inducible defense in anuran larvae. Ecology 81:2813-2821.
• Van Buskirk, J., and B.R. Schmidt. 2000. Predator-induced plasticity in larval newts: trade-offs, selection, and variation in nature. Ecology 81:3009-3028.