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Theses

En dehors de la norme : déviation de l'optimalité écologique et originalité fonctionnelle

Abstract : A central hypothesis in functional ecology is that certain trait combinations let individuals have a maximum growth rate in certain environmental conditions, they represent as such a functional optimum. The abundant trait values are thus supposed to reflect the best performance of species close to the optimum. However, some processes, such as neutral processes, can affect the presence of a functional optimum. Some species also harbour original trait combination compared to the functional optimum, locally among communities as well as in regional species pools. The general goals of this thesis are (i) to propose community assembly models to test the influence of different processes that can affect the presence of a functional optimum, (ii) to identify specific processus that affect functional optimum by using these models, (iii) to identify globally original species and study their determinants, (iv) to evaluate the importance of originality in a conservation context. In the first chapter we propose to community assembly models, the first couples regional and local processes, while the second is more inspired by population dynamics model. In the second chapter, we identify two processes that affect the presence of a functional optimum: species habitat saturation and traits not affected by the environment. In the third chapter, we propose a statistical tool to quantify functional originality and we evaluate the relationships betwen regional functional originality and climatic factors. In the fourth chapter, we show that functionally original species are more at threat than other species and that they face more threats than functionally common species. The thesis shows the importance of taking into account multiple spatial, temporal and taxonomic scales to characterize functional originality. The diversity of biological models studied in this thesis (herbs, trees, birds, mammals, and coral reef fishes) underline the conceptual interest of functional originality in diverse ecological contexts.
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Matthias Grenié. En dehors de la norme : déviation de l'optimalité écologique et originalité fonctionnelle. Sciences agricoles. Université Montpellier, 2020. Français. ⟨NNT : 2020MONTG027⟩. ⟨tel-03157339⟩

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