Phenotypic plasticity – the ability of a single genotype to produce two or more different phenotypes in the face of environmental cues – has been implicated as a mechanism by which populations may rapidly respond to the challenges posed by human-induced rapid environmental change (HIREC). Plasticity has also been implicated as a mechanism of population divergence and ultimately speciation. While phenotypic plasticity has been extensively studied in terms environmental inputs and consequences, relatively little is known about the genetic underpinnings that control plasticity. Researchers have shown that reaction norms, a common measurement of plasticity, can evolve. This evidence suggests an explicit genetic basis for developmental plasticity; while environmental cues trigger plasticity, the ability to produce a plastic response is itself genetically controlled. Knowledge of the genes that control plasticity may prove beneficial to shaping conservation efforts in the face of HIREC, if we can pinpoint populations that are likely to exhibit plastic responses. I suggest using overall body shape and fin morphology along a benthic-limnetic axis of variation in two divergent teleost clades in order to provide insight into the genetic control of phenotypic plasticity.