The proposed project studies the fundamental biological factors that determine the biodiversity and the evolution in this diversity in protistological and vegetal communities. The project aims to place the biodiversity in a temporal fi-amework: {I) do the dispersion and colonisation ofprotists influence the diversity in the communities, {II) how do the communities respond to changes in their physical environment {manipulation of temperature) and {III) what evolution is present in the subfossil material?
{I) The unicellular organisms are easily transported by wind and animals. Therefor, their -dispersion determines the diversity of the present communities. What is the density, the quality and diversity of protists in the air on the subantarctic islands? Moreover, the colonisation is linked with the dispersion. What is the colonisation speed of protists on the new substrates? What is the colonisation sequence?
{II) If we manipulate the microclimatic parameters on the vegetational stratum, how will the communities be affected? By heating small areas with infi-ared radiation systems, a future temperature increase is simulated in order to evaluate the responses of the protists and plants.
{III) Even in the past, the climatic events had their influence. Using peat cores {already collected on previous summer campaigns), we will reveal the climatic history of lIe de la Possession and we will discuss the evolution in the diversity of protist communities during the Holocene.