Eighteen spontaneous populations of cork oak (Quercus suber) from Spain (14
), Portugal (1), Morocco (1) and Italy (2), were surveyed at 14 loci from 1
2 enzyme systems. Percentage of polymorphic loci (64%), mean number of alle
les (2.07), and mean expected heterozygosity (0.158) values were within the
ranges described for the genus. Populations from the central range of the
species and from peripheral areas were evaluated, and differences between t
hese two kinds were assessed. Significant lower diversity (number of allele
s and expected heterozygosity) was found for the most isolated and small si
ze populations in contrast to central forests, showing the existence of mec
hanisms maintaining the levels of diversity even in some ;isolated stands.
Interpopulation diversity (F-st) is 3.3%, indicating extensive gene flows o
r recent postglacial expansion. A possible recent bottleneck is detected in
two populations by comparing actual with expected heterozygosity from the
number of detected alleles.