The population genetics of the self-incompatibility polymorphism in Papaver rhoeas. III. The number and frequency of S-alleles in two further natural populations (R102 and R104)

Abstract

A sample of 36 plants drawn at random from each of two further natural populations (R102 and R104) contained between them 30 and 26 different S-alleles respectively. In both samples, the frequencies of these alleles were significantly unequal. These results are compared with those presented in a previous paper (the R106 sample; Campbell and Lawrence, 1981b) and with those obtained by Emerson (1939) from the Oenothera population. Unequal S- allele frequencies appear to be characteristic of natural populations of P. rhoeas in the West Midlands and probably also elsewhere in the British Isles. The number of S-alleles found in these samples suggest that the number of alleles in the natural populations from which they were obtained is unlikely to be less than the number that Emerson eventually found in the Oenothera population, namely, 45. However, if this is indeed the case, it is no longer possible to regard P. rhoeas as a colonising species; on the contrary, on the evidence obtained from these three populations, it appears to be a permanent member of the flora of wayside places.