Meeting Abstract
Phenotypic plasticity, the capacity of a genotype to produce more than one phenotype in response to differences in environment, has the potential to influence subsequent evolution. One way in which this can occur is that a shift from a variable to a stable environment, can cause some genetically-based aspects of the phenotype, ordinarily expressed in response to alternative environments, to be unexpressed for extended periods. Under these circumstances, mutations can accumulate in conditionally-expressed genes that are not expressed in the new environment. This can have several outcomes including degradation of gene function, greater individual variation in expression and the expression of novel phenotypes. Here we evaluate these alternatives in a population of threespine stickleback fish, Gasterosteus aculeatus, which is undergoing rapid plastic re-emergence of an ancestral foraging mode as a consequence of anthropogenic productivity increase in Lynne Lake, Alaska. As productivity increases, the limnetic, plankton-feeding stickleback native to the lake are living longer, growing faster and shifting to the benthic, ancestral foraging. Large body sizes and benthic foraging have likely been absent from this population since post-glacial colonization. We present data from this population spanning 20 years (1992-2012), the earliest data from the period before this phenotypic transition was initiated. We further present data from two historically benthic populations and ask whether the trophic structures and head shape of benthic adults in Lynne Lake are more variable than are those from historically benthic populations as might be expected under the mutation accumulation hypothesis.
