Context-Dependent Ecological Effects of Trophic Trait Evolution Reinforce Cultural Eutrophication

The study of eco-evolutionary dynamics explores potential reciprocal interactions between ongoing evolutionary and ecological processes in nature.  Hence, it considers not just contemporary trait change in response to changing ecological conditions but also how such trait changes might themselves reshape population, community or ecosystem conditions in a dynamic feedback.  A number of studies have provided support for this framework in the form of evidence for large ecological effects of alternate fish phenotypes.  However, it is unclear the degree such effects are context-dependent.  We propose that context-dependence could be important in not only understanding generality across study systems, but also as part of the actual eco-evolutionary dynamic that unfolds within some systems.  We demonstrate this latter concept using introduced white perch (Morone americana) populations that show contemporary trophic adaptations to alternate lake productivity conditions.  Our experiments suggest that perch trophic type does not influence primary productivity under oligotrophic background conditions, but that perch from a eutrophic-adapted source exacerbate gross primary productivity under eutrophic conditions.  As a result, cultural eutrophication not only promotes the origins of alternate trophic phenotypes, but creates an environmental context where perch phenotype matters and is predicted to reinforce the alternate ecosystem and evolutionary state.