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Gene Expression Plasticity Evolution in Threespine Stickleback Fish

Paper Reviewed
Morris, M.R.J., Richard, R., Leder, E.H., Rowan, D.H., Barrett, N. A.-H. and Robers S.M. 2014. Gene expression plasticity evolves in response to colonization of freshwater lakes in threespine stickleback. Molecular Ecology 23: 3226-3240.

Introducing their latest work on the subject, Morris et al. (2014) write that "phenotypic plasticity is predicted to facilitate individual survival and/or evolve in response to novel environments," and they say that "plasticity that facilitates survival should both permit colonization and act as a buffer against further evolution, with contemporary and derived forms predicted to be similarly plastic for a suite of traits." In addition, as they continue, "given the importance of plasticity in maintaining internal homeostasis, derived populations that encounter greater environmental heterogeneity should evolve greater plasticity."

In exploring these concepts, Morris et al. set out to test "the evolutionary significance of phenotypic plasticity in coastal British Columbian postglacial populations of threespine stickleback (Gasterosteus aculeatus) that evolved under greater seasonal extremes in temperature after invading freshwater lakes from the sea." This they did for two ancestral (contemporary marine) and two derived (contemporary freshwater) populations of stickleback that they raised near their thermal tolerance extremes, 7 and 22°C, where gene expression plasticity was estimated for more than 14,000 genes.

In describing their findings the six scientists report that "over five thousand genes were similarly plastic in marine and freshwater stickleback, but freshwater populations exhibited significantly more genes with plastic expression than marine populations." In addition, they found that "several of the loci shown to exhibit gene expression plasticity have been previously implicated in the adaptive evolution of freshwater populations, including a gene involved in mitochondrial regulation." Given such findings, Morris et al. write in the concluding sentence of their paper's abstract, that "collectively, these data provide molecular evidence that highlights the importance of plasticity in colonization and adaptation to new environments." And in the conclusion section of the body of their paper, they say that "these results are consistent with the hypothesis that gene expression plasticity can evolve to meet the challenges of a novel environment." Such findings represent encouraging news for those concerned about animal range expansions or shifts caused by climate change.

Posted 21 October 2014