Molecular Phylogeny of theCeratosolenSpecies PollinatingFicusof the SubgenusSycomorus sensu stricto:Biogeographical History and Origins of the Species-Specificity Breakdown Cases

Abstract

The 14 species ofFicusof the subgenusSycomorus(Moraceae) are invariably pollinated byCeratosolenspecies (Hym. Chalcidoidea), which in turn reproduce in the fig florets. They are distributed mostly in continental Africa, Madagascar, and the Mascarene and Comoro Islands, but 1 species extends its geographical range all over the Oriental region. Fig–pollinator relationships are usually strictly species specific, but exceptions to the ‘one-to-one’ rule occur within the group we studied. In order to understand both the biogeographical history of theCeratosolenspecies associated withFicusof the subgenusSycomorusand the origins of the specificity breakdown cases, we have used cytochromebsequences to reconstruct a phylogeny of the fig wasps. The results show that the pollinators from the Malagasy region and those from continental Africa form two distinct clades, which probably diverged after the crossing of the Mozambique Channel by an ancestral population. The Oriental wasp species show strong affinities with the African species. The two species-specificity exceptions are due to different evolutionary events. The occurrence of the two West African pollinators associated withF. surcan be explained by successive speciation events of the mutualistic partner without plant radiation. In contrast, we hypothesize thatC. galilishifted by horizontal transfer from an unknown, presumably extinct,Ficusspecies toF. sycomorusafter this native Malagasy fig species colonized Africa.