Wednesday, August 4, 2010 - 2:30 PM

COS 72-4: Phylogenetic patterns of phenotypic plasticity in larval anurans

John I. Hammond, University of Pittsburgh, Patrick R. Stephens, University of Georgia, and Rick A. Relyea, University of Pittsburgh.

Background/Question/Methods Phenotypic plasticity is widespread in nature and serves as a way of improving individual performance when faced with variable environmental conditions. During the past decade, there has been a tremendous research surge to understand the evolution and ecology of phenotypic plasticity. In several systems, there has been intensive research in a few species and this has rapidly improved our understanding of the biological mechanisms that favor and maintain this phenomenon. However, this intensive approach precludes analyses of large-scale evolutionary patterns of plasticity. By using a phylogenetic approach, we can examine how environmental factors have shaped the plastic response across multiple species and ask whether phylogenetic relatedness, environmental conditions, or interactions between the two drive the evolution of plasticty.  Results/Conclusions Using common-garden experiments, we examined the activity, growth rate, and morphology of tadpoles from over 18 North American species of anurans from three families: Ranidae, Hylidae, and Bufonidae; clades for which molecular phylogenies and extensive environmental data are available. For each species, we conducted an experiment that manipulated predator and competitor stress. Preliminary results show species vary greatly in their behavior, growth rate, and morphology with both environmental and phylogenetic signals present. For example, both closely and distantly related species restricted to either permanent or ephemeral environments show higher levels of behavioral plasticity than species that use both environments. Furthermore, closely related species regardless of environment show both similar and divergent behavioral and growth rate responses. These experimental data, combined with data from dozens of additional species still to be tested, will be overlaid on existing phylogenies and combined with environmental data to develop insights into the evolution of phenotypically plastic traits.