Both cell types may rely on stochastic diversification of phenotypes to improve their survival rate in the event of an encounter with the other cell type.
Intuitively, stochastic diversification of the repertoire would seem advantageous, maximizing potential immune coverage without prior bias towards certain specificities.
Some tree imbalance is expected under null models of stochastic diversification [ 59], and this needs to be taken into account in comparison of diversification rates.
Our hypothesis, that PCD can make bet-hedging strategies more effective, is both distinct from these alternatives, and may be fairly general, as stochastic phenotypic diversification is used to hedge against many different forms of risk29,39,40,41,42,43.
In our models, PCD indirectly promotes diversification via stochastic phenotype switching by increasing the number of reproductive events between disasters.
We show that when reproductive opportunities are limited by carrying capacity, PCD drives population turnover, providing increased opportunities for phenotypic diversification through stochastic phenotype switching.
As the chemical composition and physical conditions of tissue microenvironment are complex, their change with age will impact the existing mutation-generated functional diversity through an independent stochastic component, contributing to diversification of the relative fitness of different cells in a stochastic manner (Fig. 7F).
Following a disaster, the surviving types reproduce until the total population is restored to a carrying capacity, N. Phenotypic diversification occurs via stochastic phenotype switching such that each time a strain reproduces there is a probability p that the alternate phenotype will be produced.
This interpretation is similar to conceptual models that tend to abandon the classical assumption of a strict hierarchy during differentiation and understand cell differentiation as a dynamic process of "isologous diversification" or autostabilization of stochastic processes [26], [27], [28], [29].
Micro-organisms typically enact diversification bet-hedging strategies through stochastic phenotype switching, in which reproducing cells give rise to phenotypically distinct offspring with a low (typically 10−1 to 10−5) probability29,30.
G7 countries do not seem to cointegrate around one common stochastic trend, and potential long-run international diversification benefits still exist.
