GENE-POOL VARIATION IN CALEDONIAN AND EUROPEAN SCOTS PINE (PINUS-SYLVESTRIS L.) REVEALED BY CHLOROPLAST SIMPLE-SEQUENCE REPEATS

We have used polymorphic chloroplast simple-sequence repeats to analys e levels of genetic variation within and between seven native Scottish and eight mainland European populations of Scots pine (Pinus sylvestr is L.). Diversity levels for the Scottish populations based on haploty pe frequency were far in excess of those previously obtained using mon oterpenes and isozymes and confirmed lower levels of genetic variation within the derelict population at Glen Falloch. The diversity levels were higher than those reported in similar studies in other Pinus spec ies. An analysis of molecular variance (AMOVA) showed that small (3.24 -8.81%) but significant (P less than or equal to 0.001) portions of th e variation existed between the populations and that there was no sign ificant difference between the Scottish and the mainland European popu lations. Evidence of population substructure was found in the Rannoch population, which exhibited two subgroups. Finally, one of the loci st udied exhibited an allele distribution uncharacteristic of the stepwis e mutation model of evolution of simple-sequence repeats, and sequenci ng of the PCR products revealed that this was due to a duplication rat her than slippage in the repeat region. An examination of the distribu tion of this mutation suggests that it, may have occurred fairly recen tly in the Wester Ross region or that it may be evidence of a refugial population.