SeMoVi will take place at Emilie Du Châtelet: Bibliothèque de l'INSA, 14h - 18h.
Diversity–stability relationships across scales and levels of organisation
Michel Loreau
Centre for Biodiversity Theory and Modelling
Station d’Ecologie Expérimentale du CNRS, 09200 Moulis, France
E-mail: michel.loreau@ecoex-moulis.cnrs.fr
The relationship between the diversity and stability of ecological systems has been a hotly debated issue in ecology over the past century. Recent theoretical and experimental work provides a completely new perspective and a potential resolution of this debate. In contrast to classical theory, which is based on stability measures that are largely divorced from empirical data, new theory based on invariability predicts different diversity–stability relationships at the population and ecosystem levels. It also provides a consistent hierarchical framework for studying ecosystem stability across multiple spatial scales. This new theory agrees with empirical and experimental data and shows that biodiversity plays an important stabilising role in ecosystems at multiple scales, thereby ensuring the steady provision of ecosystem services to human societies.
Understanding the evolution and conservatism of species niches : problems and perspectives
Sébastien Lavergne
Laboratoire d'Ecologie Alpine, CNRS – Université Grenoble Alpes
http://seb.lavergne.free.fr/
No controversy has been more persistent over the short history of evolutionary biology than the one about what accelerates or slows down the pace of evolution. It recently resurfaced through the intense debates about the supposed prevalence of niche conservatism – this process (or pattern) is defined the tendency for population, species or lineages to retain ancestral ecological characteristics. Why some species or lineages seem to have remained in the same ecological niche for long periods of time while some others rapidly diversified and adapted to a variety of environments ? How can theory reconcile the apparent ecological stasis observed in many species or clades with the evidence that abundant genetic variation exists for many ecological characters and allow rapid niche evolution ? A close examination of literature shows that, in the rapidly shifting conceptual landscape of evolutionary biology, the idea of niche conservatism has drifted and diversified in a way that makes it almost indistinguishable. But theoretical simulations and recent empirical studies help confront alternative views and resolve apparent paradoxes. They also clarify a number of issues regarding the potential drivers, rates and limits of niche evolution.
Recent papers on the topic
Münkemüller T, Boucher F, Thuiller W, Lavergne S (2015) Phylogenetic niche conservatism – common pitfalls and ways forward. Functional Ecology 29:627–639 PDF
Boucher F, Thuiller W, Davies TJ, Lavergne S (2014) Neutral biogeography and the evolution of climatic niches. The American Naturalist 183:573-584 PDF
Lavergne S, Evans MEK, Burfield IJ, Jiguet F & Thuiller W (2013) Are species’ responses to global change predicted by past niche evolution? Philosophical Transactions of the Royal Society, series B 368(1610):20120091 PDF
Lavergne S, Mouquet N, Thuiller W, Ronce O (2010) Biodiversity and climate change: Integrating evolutionary and ecological responses of species and communities. Annual Review of Ecology, Evolution and Systematics 41: 321-350 PDF
Florian Mermillod-Blondin
Title:
Hydrological exchanges and biogeochemical processes at the water-sediment interface: when does bioturbation matter?
Abstract:
In streams and rivers, hydrological exchanges at the water-sediment interface play a key role on biogeochemical processes and organic matter degradation in sediments. Bioturbation (i.e., feeding, burrowing and ventilation activities) may greatly affect those processes and associated microbial community depending on the water exchanges between surface and interstitial water. It can be expected from literature that bioturbation influence was inversely correlated with the extent of hydrological exchanges. We tested this prediction in laboratory experiments using sediment filtration columns to simulate high and low permeability systems. In these permeability-contrasted systems, we quantified the influence of a common bioturbator, Tubifex tubifex, on physico-chemistry (sediment reworking, hydraulic conductivity and water chemistry), microbial abundances and activities, and breakdown rates of buried leaf litter. My talk will present the main results of this experimental test and perspectives of this work.
