Apport de la génétique pour la délimitation des espèces et la phylogéographie au sein du genre Milicia (MORACEAE)

In order to understand the structuring of diversity in African forests and to test the validity of
the proposed forest refuges based on palynological studies, species delimitation was undertaken
within the endemic genus Milicia (Moraceae) in Africa. To this end, molecular phylogeny and
phylogeography were undertaken using choloroplast (trnC-ycf6 and psbA-trnH) and nuclear
markers (At103). Data are based on 172 specimens (33 individuals from M. regia and 139
individuals from M. excelsa), distributed in 33 populations from 11 countries of Central and
West Africa. Sequences resulting from the concatenation of both chloroplastic markers
contained 16 polymorphic sites forming 15 haplotypes while 16 haplotypes resulted from the
15 polymorphic sites detected in the nuclear gene. On the basis of choloroplastic markers, M.
excelsa from West Africa was closer to M. regia than M. excelsa from Central Africa. But
using nuclear gene, both species were distinct. M. regia and M. excelsa belong each other to
distinct haplotypes regardless all type of marker. Differentiation between populations of M.
regia is less important than the one between those of M. excela. This is an indication of a strong
genetic structure of M. excelsa between West and Central Africa. Important and endemic
haplotypes were identified in different locations. These endemism centres seem to be related to
forest refuges suggested by palynologic and phytogeographic studies except haplotypes of M.
excelsa originated from Dahomey-Gap and Nigeria (of which origin seems uncertain)