Résumé
A canon of population genetics concerns the properties of F-ST, a descriptor of spatial genetic structure. Interest for F-ST arose from Wright's early insights linking F-ST to dispersal parameters as well as to his concept of effective population size (e.g., Wright 1938, 1951). Although there is continued interest in this topic, F-ST also serves in other applications, such as detecting selected markers in natural populations (Beaumont and Nichols 1996) and more often in routine descriptive works. Remarkably, it is the latter use that seems to attract most discussion. Alternative descriptors have been proposed. Conversely, attempts have been made to draw biological inferences from F-ST properties that do not depend on biological processes. A reconsideration of its properties under biological scenarios underlines the weaknesses of such approaches.