Most evolutionary models implicitly assume that genetic variation has a uniform rate at all times. In contrast, we explore an alternative hypothesis: that the generation of variation is plastic, its rate depending on the state of the organism, so that stressed individuals have a higher tendency for variation. From the perspective of a gene regulating the generation of variation (e.g., the rate of mutation), stress responses may indicate that it is maladapted to the current environment. By increasing the rate of variation when stressed the allele can increase its own chances of having a different genetic background in the next generation. Vice versa, by decreasing the rate of variation when the individual is feeling perfectly well it can increase its chances of staying linked to a good genetic background.
See: Hadany and Beker, 2003b; Hadany et al., 2004; Hadany and Otto, 2009; Ram and Hadany, 2012; Gueijman et al., 2013;