Figure 11.

Nongenetic inheritance of starvation responses. Multigenerational effects of environmental conditions are classified by the number of generations they are inherited. Phenotypic effects that persist for only one or two generations (F₁ or F₂ progeny) are “intergenerational.” In contrast, effects that persist for three or more generations (F₃ and beyond) indicate “transgenerational epigenetic inheritance.” This distinction is made since direct effects on germ cells can theoretically persist for two generations, whereas epigenetic inheritance requires germline mechanisms that actively maintain a regulatory state. Worm images were borrowed with permission from WormAtlas (Altun and Hall 2009).