Effects of invasions on the structure, stability and evolution of complex food webs
- Publication : 26 mars 2019
Institute of Evolution and Ecology, University of Tübingen, Germany.
Le vendredi 5 avril 2019 - 11h30 Campus Triolet Univ Montpellier: amphi 23.01 - Bât. 23
A critically important challenge in theoretical ecology is to better predict responses of ecological networks to global change, especially responses to increasing rates of species invasions. Invaders have been widely observed to trigger changes in species’ interactions and abundances and even cause catastrophic extinction cascades of native species. Classical food web models have focused on explaining and predicting such ecological responses on relatively short time scales. However, these models typically neglect changes in selection pressure on native species caused by the invaders and their subsequent effects on the structure and stability of food webs on longer time scales. Iaddress these issues using an eco-evolutionary model containing both invasion and mutation events. It integrates classical assembly models, which describe the emergence of a food web via sequential invasions, with so-called evolutionary food web models or large community evolution models, which describe food web emergence via speciation due to small mutation steps. Themodel uses body masses and diets as the key traits that determine metabolic rates and species interactions. Ivary the frequency of invasion events in relation to speciation events and the relatedness between native species and invaders. Ithen analyze the size of the emerging network (in terms total biomass and number of morphs or ‘species’), its ecological and evolutionary stability, and its species turnover pattern. Theresults show that food webs evolve most diverse and accumulate the most biomass when being exposed to frequent invasions of species similar to natives. The system is also most stable in such invasion context, both evolutionary (i.e., lower variability in the number of morphs/species over time) and ecologically (i.e., lower variability in total biomass over time).
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