Population model of epigenetic inheritance of acquired adaptation to changing environments

Accumulated evidence of transgenerational inheritance of epigenetic and symbiotic changes begs the question of under which conditions inheritance of acquired changes can confer long-term advantage to the population. To address this question, we introduce a population epigenetics model of individuals undergoing stochastic and/or induced changes that are transmitted to the offspring. Potentially adaptive and maladaptive responses are represented, respectively, by environmentally driven changes that reduce and increase the individuals’ rate of death (i.e. reduction and increase of selective pressure). Analytic solution in a simplified case of exposure to two types of dynamic environments shows that inheritance of changes that transiently alleviate the selective pressure confers long-term advantage even when the transmitted state is maladaptive to the offspring. The benefits of inheriting environmentally driven changes that reduce the death rate within a lifetime include escape from extinction under a wide range of conditions. These advantages are even more pronounced in populations with imperfect inheritance and/or age-dependent decline in fertility. These findings show that inheritance of non-genetic changes can have tremendous benefits for the population on timescales that are much longer than the lifetime of an individual.