Résumé : Understanding the adaptation and evolution of populations is a huge challenge, in particular for microorganisms since it plays a main role in the virulence evolution or in bacterial antibiotics resistances. We propose a general stochastic model of population dynamics with clonal reproduction and mutations. Moreover the individuals compete for resources and exchange genes. We show that the horizontal gene transfer can have a major impact on the distribution of the successive mutational fixations, leading to dramatically different behaviors, from expected evolution scenarios to evolutionary suicide, including cyclic behaviours. We present different approaches to capture mathematically these scenarii.

Keywords : horizontal gene transfer; bacterial conjugation; stochastic individual-based models; long time behavior; large population approximation; eco-evolutionary behavior