THE POPULATION-GENETICS OF THE SELF-INCOMPATIBILITY POLYMORPHISM IN PAPAVER RHOEAS .6. ESTIMATION OF THE OVERLAP BETWEEN THE ALLELELIC COMPLEMENTS OF A PAIR OF POPULATIONS

The data obtained by cross-classifying the self-incompatibility (S-) alleles of samples taken at random from three natural populations of Papaver rhoeas, presented in the previous paper (Lawrence et al., 1993), are used here to estimate the extent of the overlap between the complements of alleles that pairs of these populations contain. These estimates indicate that this overlap is very great, so that these populations appear to contain essentially the same set of S-alleles. Three possible explanations of these results, which are not expected on the theory of the self-incompatibility polymorphism possessed by this species, are proposed and discussed. It is argued that the most likely of these alternative explanations is that the number of S-alleles in the species is not very much greater than-the number of S-alleles that these natural populations contain, a hypothesis which is put to the test in the following paper.