NUCLEAR-DNA POLYMORPHISMS AMONG STRAINS OF MICROSERIS-BIGELOVII (ASTERACEAE, LACTUCEAE) AMPLIFIED FROM ARBITRARY PRIMERS

The autogamous annual Microseris bigelovii occurs in isolated populations along a narrow strip of land along the Pacific Coast from Southern California to Victoria, B. C. - Thirteen inbred strains were derived from 11 representative populations. Nuclear DNA from these strains was amplified using single arbitrary 10-base-pair primers. 194 amplification products were obtained with 22 primers. Of these, 44 were shared by all strains, 32 were present or absent in only one of the strains. The remaining 118 amplification products were shared by 2 to 11 strains. Attempts to construct a cladogram of the 13 inbred genotypes revealed 5 monophyletic groups. Two of these consist of duplicate isolates from two populations each, two comprise two strains each derived from neighboring populations, and one comprises the three populations from Victoria, B. C., which are postulated to be the result of local differentiation after a single founder event. The Victoria populations share the only known chloroplast mutation in M. bigelovii with a strain from the San Mateo County south of San Francisco. Beyond the local groups of strains we found more or less random allele associations rather than cladistic groupings, with overall genetic distances (UPGMA) more or less related to geographic distance. Achene transport, too rare for direct observation, must be effective to allow gene flow among populations in M. bigelovii.