FIGURE 4.

Implications of reversible and non-reversible developmental phenotypic plasticity. In this scenario, two organisms are tracked during their development as they experience multiple, short-term extreme environmental changes (vertical gray bars). Both Organism #1 (red) and Organism #2 (blue) respond to the first extreme environmental change by switching from their normal range of phenotypes (Ph₁) to a specialized, adaptive phenotype (Ph₂) that allows continued survival in that environment. However, Organism #1, lacking the ability to reverse (correct) its phenotype that was suitable for the extreme high environment, is now non-viable when the environment reverts back to more typical conditions as development continues. Organism #2, which similarly responded to the first environmental change with a switched phenotype (Ph₂), has the ability to reverse or correct the costly or even lethal modified phenotype back to normal ranges (Ph₁) when the environment returns to normal, aiding its survival. Organism #2 can also move to other phenotypes (Ph₃) and revert back to normal ranges (Ph₁) as subsequent environmental swings occur. Thus, in this overall scenario, reversible phenotypic switching during development heavily favors survival of the developing organism.