Random amplified polymorphic DNA (RAPD) analysis and length variations in the chloroplast trnL-trnF intergenic spacer were used to analyze the geographic structure of Juniperus thurifera L. populations in Spain and North Africa. The chloroplast DNA analysis indicated three size classes of the spacer, but was uninformative of any geographic pattern. In contrast, the RAPD data based on 127 polymorphous bands clearly showed the existence of three population groups: (a) a group comprising two populations from northeastern Spain and two from southern Spain, (b) a group comprising the rest of the Spanish populations, and (c) a group whixh consisted of the two Moroccan populations. Analysis of molecular variance (AMOVA) showed that 24% of the variation is found between groups of populations, 15% between populations within groups, and 61% within populations. The results are consistent with a hypothetical migration of J. thurifera starting from central Europe, passing through France and Spain and finally reaching North Africa
