Browsing by Author "Gauzens, Benoit"
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- Biodiversity of intertidal food webs in response to warming across latitudesPublication . Gauzens, Benoit; Rall, Bjoern C.; Mendonca, Vanessa; Vinagre, Catarina; Brose, UlrichGlobal warming will affect food-web structure and species persistence, and real world data is needed for better prediction. Combining species counts and temperature data from rock pools with dynamic modelling predicts biodiversity increases in arctic to temperate regions and declines in the tropics. Global warming threatens community stability and biodiversity around the globe. Knowledge of the mechanisms underlying the responses to rising temperatures depends heavily on generic food-web models that do not account for changes in network structure along latitudes and temperature gradients. Using 124 marine rock-pool food webs sampled across four continents, we show that despite substantial variation in ambient temperature (mean 11.5-28.4 degrees C), similar empirical food-web and body-mass structures emerge. We have used dynamic modelling to test whether communities from warmer regions are more sensitive to warming and found a general hump-shaped relationship between simulated biodiversity and temperature (gradient from 0-50 degrees C). This implies that an expected anthropogenic global warming of 4 degrees C should increase biodiversity in arctic to temperate regions while biodiversity in tropical regions should decrease. Interestingly, simulations of synthetic networks did not yield similar results, which stresses the importance of considering the specificities of natural food webs for predicting community responses to environmental changes.
- Consistent predator-prey biomass scaling in complex food websPublication . Perkins, Daniel M.; Hatton, Ian A.; Gauzens, Benoit; Barnes, Andrew D.; Ott, David; Rosenbaum, Benjamin; Vinagre, Catarina; Brose, UlrichThe ratio of predator-to-prey biomass is a key element in food webs. Here, the authors report a unified analysis of predator-prey biomass scaling in complex food webs, finding general patterns of sub-linear scaling across ecosystems and levels of organization. The ratio of predator-to-prey biomass is a key element of trophic structure that is typically investigated from a food chain perspective, ignoring channels of energy transfer (e.g. omnivory) that may govern community structure. Here, we address this shortcoming by characterising the biomass structure of 141 freshwater, marine and terrestrial food webs, spanning a broad gradient in community biomass. We test whether sub-linear scaling between predator and prey biomass (a potential signal of density-dependent processes) emerges within ecosystem types and across levels of biological organisation. We find a consistent, sub-linear scaling pattern whereby predator biomass scales with the total biomass of their prey with a near 3/4-power exponent within food webs - i.e. more prey biomass supports proportionally less predator biomass. Across food webs, a similar sub-linear scaling pattern emerges between total predator biomass and the combined biomass of all prey within a food web. These general patterns in trophic structure are compatible with a systematic form of density dependence that holds among complex feeding interactions across levels of organization, irrespective of ecosystem type.