Beyond Darwin – Establishing a Theory of Individual-Specific Adaptation, Complementary to Natural Selection

Every individual is endlessly challenged by internal perturbations in its somatic genome, epigenome and gut microbiome. This gives rise to unimaginable number of novel combinations of changes that are unique to each individual. Overcoming these individual-specific perturbations cannot be explained solely by natural selection, because the latter only accounts for adaptation of the population as a whole. How individual-specific adaptation comes about has remained THE grand puzzle of evolution. To address this problem, we introduced a concept of individual-specific adaptation, complementary to natural selection. It explains how newly-forming adaptations can be acquired in every individual by ongoing emergence of variations (e.g. in the microbiome and epigenome) that are largely stochastic but nonetheless tend to be non-lethal. In a follow-up that was recently published in Nature Com, we demonstrated the mathematical feasibility of this adaptation. Here we propose to test the predictions of this theory by dedicated experiments and establish a modelling framework that integrates individual-specific adaptation with adaptation by natural selection. The experimental testing will be achieved using a dedicated model system that we established in the fly, D. melanogaster. We will use it test if stochastic changes in the gut microbiota can support de novo acquisition of host adaptation to metabolic challenges that cannot be alleviated by the host on its own. To investigate the theoretical repertoire of these adaptations, we will use a compatible modelling framework that we developed specifically for this purpose. This model will also allow us to generate new predictions and integrate the concept of individual-specific adaptation with traditional adaptation by natural selection. Preliminary work provide multiple lines of consistent experimental and theoretical evidence in support of our theory.