Format: ORAL

Hanna Tuomisto1,2, Lassi Suominen2, Chi-Chuan Chen2, Alfonso Alonso3, Glenda Crdenas2, Samuli Lehtonen2, Gabriel Massaine Moulatlet4, Eneas Prez5, Anders Sirn2,6, Patrick Weigelt7, Gabriela Zuquim2

1 Aarhus University, Aarhus, Denmark 2 University of Turku, Turku, Finland 3 Smithsonian National Zoo and Conservation Biology Institute, Washington, D.C., USA 4 University of Arizona, Tucson, USA 5 Universidad Nacional de la Amazonía Peruana, Iquitos, Peru 6 Universidad Amawtay Wasi, Quito, Ecuador 7 University of Göttingen, Göttingen, Germany

Knowledge about plant species niches along environmental gradients is a fundamental prerequisite for addressing many ecological and evolutionary questions. For example, to what degree are plant species distributions and community compositions dictated by species niches in relation to soil properties? And to what degree does evolutionary diversification itself reflect adaptive radiation, where lineages specialize to different edaphic niches? These are especially intriguing questions in the tropical rain forests, where the origin of the high species richness has been a long-standing puzzle, but lack of data has frustrated attempts to find answers. Thanks to long-term extensive field studies across Amazonia, we are now able to model species-soil relationships for many fern species and to place them into an evolutionary context with the help of molecular phylogenies. This makes it possible to analyze niche divergence both as an ecological phenomenon and as the result of an evolutionary process. We are carrying out such analyses using two fern genera, Adiantum and Lindsaea, as example cases. Both genera are common in the understory of Amazonian forests, and both have been suggested to be useful as indicators of forest types and soil properties, even though detailed models of their edaphic niches have not previously been available. Our results show that the species edaphic niches are both relatively narrow and divergent, and that there are clear differences between the two genera. Currently ongoing analyses of niche evolution are expected to shed light on the evolutionary processes within Amazonia.