Résumé
A coalescence-based maximum-likelihood method is presented that aims to (i) detect diversity-reducing events in the recent history of a population and (ii) distinguish between demographic (e.g., bottlenecks) and selective causes (selective sweep) of a recent reduction of genetic variability. The former goal is achieved by taking account of the distortion in the shape of gene genealogies generated by diversity-reducing events: gene trees tend to be more star-like than under the standard coalescent.