Polymorphism in the lengths of restriction fragments of the whole cpDNA mol
ecule were studied in 15 taxa (species or subspecies) of the genus Olea. Fr
om restriction analysis using nine endonucleases, 28 site mutations and fiv
e length polymorphisms were identified, corresponding to 12 distinct chloro
types. From a phenetic analysis based on a Nei's dissimilarity matrix and a
Dollo parsimony cladistic analysis using, as an outgroup, a species of the
genus Phillyrea close to Olea, the ten taxa of section Olea were distingui
shed clearly from the five taxa of section Ligustroides which appear to pos
ses more ancestral cpDNA variants. Within the section Ligustroides, the tro
pical species from central-western Africa, Olea hochtetteri, showed a chlor
otype which differed substantially from those of the other four Olea taxa g
rowing in southern Africa, supporting a previous assessment according to wh
ich O. hochtetteri may have been subjected to a long period of geographical
isolation from the other Olea taxa. Within the Olea section, three phyla w
ere identified corresponding to South and East Africa taxa, Asiatic taxa, a
nd a group including Saharan, Macaronesian and Mediteranean taxa, respectiv
ely. On the basis of cpDNA variation, the closest Olea taxa to the single M
editerranean species, Olea europaea, represented by its very predominant ch
lorotype, observed in both wild and cultivated olive, were found to be Olea
laperrinei (from the Sahara), Olea maroccana (from Maroccan High Atlas) an
d Olea cerasiformis (from Macaronesia). These three taxa, which all share t
he same chlorotype, may have a common maternal origin.