Osmanovic, D.; Rabin, Y.; Soen, Y.

Accumulated evidence of transgenerational inheritance of epigenetic and symbiotic changes begs the question of whether (and under which conditions) the population can benefit from inheritance of changes that are acquired during the individuals\' lifetime. To address this question, we introduce a population epigenetics model of individuals undergoing stochastic and/or induced changes that are either partially or fully transmitted to the offspring. This model is equally applicable to internal changes in individuals (e.g. epigenetic and symbiotic variations) as well as niche construction changes that they make in their environment. Potentially adaptive and maladaptive responses are represented, respectively, by induced changes that reduce and increase the individuals\' rate of death (i.e. reduction and increase of selective pressure). We use this framework to investigate how inheritance of acquired changes affects the long-term dynamics of the population. Analytic solution in a simple case of a population exposed to environments that change in time shows that inheritance of changes that transiently alleviate the selective pressure is beneficial even when the offspring environment differs from that of their parents. The benefit from these changes is even more pronounced at lower fidelity of inheritance as well as for populations with age-dependent decline in fertility. We also show that this benefit is essential for preventing population extinction under a range of successive shifts in the environment. Analysis of long-term influences of various population and environmental factors reveals a non-trivial landscape of outcomes, including a surprising regime in which the population benefits from inheritance of changes that increase the selective pressure. Taken together, these findings show that inheritance of changes that are dynamically acquired within a generation can have a tremendous benefit for the evolution of the population on timescales that are much longer than the lifetime of an individual.