Wednesday, March 24, 2010

Phenotypic plasticity and adaptation

I am interested in the role of phenotypic plasticity in adaptation to different environments. Divergent selection can result in adaptive genetic divergence among populations. However, individuals can also adapt through a plastic response; i.e. the environment might have a direct impact on the phenotype without influencing genetic change. The relative contribution of each (genetic vs. plastic adaptation) should be related to the level of dispersal and gene flow among selective environments. Gene flow can constrain adaptive genetic divergence, and therefore plasticity might be favoured under high gene flow scenarios. If heritable variation for plasticity occurs in a meta-population, I predict that plasticity might evolve in response to gene flow. At the same time, plasticity might permit increased dispersal and gene flow among environments.

During my doctoral studies at McGill, I developed a conceptual framework for understanding the above pathways. I then tested some of the framework's predictions in an empirical system: an African cichlid fish from high-oxygen rivers and adjacent low-oxygen swamps. I found that morphological plasticity, in response to dissolved oxygen concentration, was high overall in this species, but that plasticity was higher at locations where dispersal between environments should also be higher. I infer that plasticity might have evolved in response to gene flow between oxygen environments, but more studies are needed to determine causality.

The conceptual framework is published in the following article. The empirical studies are currently in review.
Crispo, E. (2008) Modifying effects of phenotypic plasticity on interactions among natural selection, adaptation and gene flow. Journal of Evolutionary Biology 21:1460-1469

Latest news: I successfully defended my PhD dissertation yesterday!

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