Sylvain Billiard

Lille University

Revisiting clonal interference: from competitive interactions between individuals to population dynamics and adaptation

Sylvain Billiard & Charline Smadi

[When and where]

Clonal interference, when two or more mutations coexist in a resident population, is frequent in evolving asexual populations such as bacteria, yeasts or cancers. Several theoretical models showed that clonal interference slows down adaptation because of the competition between several beneficial mutations. However, those models assumed transitive fitness and generally do not take into account explicit ecological competitive interactions between individuals. We developped a stochastic continuous-time model with three competing clones (or species), considering all types of competitive interactions, transitive or not. We first show that, under our hypotheses, many different dynamics are possible: the classical deceleration of adaptation, but also its possible acceleration, as well as non-linear and cyclical dynamics. We especially show that the time when the second mutation occurs is crucial to determine the final state of the population. Second, we estimate the likelihood of each dynamics by assuming that the effect of mutations follow some specific distributions. We finally discuss our results in the light of dynamics observed in empirical data.

Invited talk Mini-symposium 7

Updated May 25, 2015, by Minus