Abstract
The islands in the southwest of the Indian Ocean have been listed as hotspots for global biodiversity. We propose to explore the ecological and historical mechanisms responsible for the specific richness, by focusing on a group that has not been the subject of many studies: the Bryophytes. The ecologic study of the diversity and dispersal of this group on three islands alongside four altitudinal gradients will make it possible to identify the ecological factors underlying the diversity and structure of communities and acting on local and regional scales. The phylogeographic study of the latitudinal gradient, including the islands of the Reunion, Madagascar, Comoro and the African continent will enable the identification of regional evolutional and historical factors that affect the turnover of species between the communities. Bryophytes are ideal candidates to answer these ecological and evolutional questions because of their ubiquity, their dispersal facilities (comparative studies within one single geographical zone), their sensibility to climate change (reflection of passed changes) and their dominant haplophase (use of neutral molecular markers). The flora of Madagascar has been subject to a unique evolution due to the natural geological history of the island and the important changes of the geological map in the southwest of the Indian Ocean. The geological forming of the volcanic islands of the ocean, such as the Reunion and the Comoro Islands, has contributed at first to the development of flora composed of colonizing species (quantitatively sparse richness), and later, due to the geographic isolation, a flora rich in endemic species. Taking into account geographic and geologic variables will make it possible to understand the rules of assembling of bryophyte species at different spatial and temporal scales. This altitudinal study of the Reunion (Ah-Peng and al 2007), the Comoro Islands (February 2008) and the African continent (Kenyan and South African bibliographic data) will be completed with the altitudinal gradient of the Marojejy reserve in Madagascar. This collaboration with local Madagascan and international teams (France, Kenya, South Africa) will reinforce research cooperation in the Indian Ocean zone. It will enable an increase in taxonomy knowledge on this biological group, which until now has been a minor study topic. The teaching of bryophytic studies among Madagascan students as well as student exchanges (post-graduate and PhD students) among different partners will make these relationships perpetual.
France