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Welcome to the Bridge project




Why are there so many coexisting species of tropical trees? Niche theory predicts that in a local community, each species possesses a unique combination of traits (the species niche), that enables it to avoid competition with other species. In contrast, the recently developed neutral theory of biodiversity ascribes no role to competition and niches for local species coexistence. According to the neutral theory, dispersal limitation and demographic fluctuations overwhelm the deterministic processes of competitive exclusion. This project will (i) assemble a unique database combining ecological, physiological, and genetic information in several tropical forest tree communities of French Guiana, (ii) develop an unprecedented test of existing theories of biodiversity by combining field data and novel modelling approaches, and (iii) strengthen research in a French biodiversity hotspot. We will sample ten one-hectare old-growth forest tree plots across a range of geology and rainfall in French Guiana. Using molecular techniques, we will develop a refined phylogenetic hypothesis for the tree species found in our plots, and we will provide aids for molecular-based identification. We will measure the amount of niche conservatism across an ecologically relevant set of functional, reproductive, and defense traits, as measured in the field. We will use novel modelling methods to test whether existing species assemblages are a random sample of the regional species pool, and to assess the contribution of niche partitioning to the coexistence of tropical trees.