Phenomenon of vicariance in the acanthaceae family in central africa (Dr Congo, Rwanda and Burundi)

This study was aimed to analyze the cases of vicariance from Acanthaceae family using the phytogeographic systems of Robyns (1948) for Central Africa and White (1979, 1986) for tropical Africa. It covered 9181 samples (48 genus, 310 species) harvested in DR Congo, Rwanda and Burundi. A geographic information system was used to produce the potential distribution maps. The uniformity of sampling density was assessed by the Pielou evenness index. It was observed that some of the phytogeographic territories have been explored more than others. Consequently, maps reflecting the potential distribution, based on harvesting locations and environmental variables, were produced to better determine the ecological niches of the species and the cases of vicariance. Two types of vicariance have been determined at the genus and subspecies level. For the phytogeographic territories of Robyns, 27 ecological vicariance pairs and six pairs of geographic vicariance were identified at the genus level; at the level of the subspecies, six pairs of ecological vicariance and two pairs of geographic vicariance were observed. Concerning the phytogeographic territories of White, 43 pairs of ecological vicariance and seven pairs of geographic vicariance were observed at the genus level; five ecological vicariance pairs and a pair of geographic vicariance were identified at the subspecies level. This study also revealed two zones of speciation that were the refuge zones and, consequently, as areas of high biological diversity (hotspots). The observations mentioned above are not only important from a phytogeographic point of view (speciation zones), but also for conservation policies development.