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Temperature-size responses alter food chain persistence across environmental gradients

Temperature-size responses alter food chain persistence across environmental gradients
© Chenille (Lepidoptera sp.) © Arnaud Sentis
One of the main effects of global warming is to reduce the size of cold-blooded organisms such as insects, fish and bacteria. The ecological consequences of these size changes are still poorly understood. Researchers from the EDB Laboratory (member of the TULIP LabEx), the University of South Bohemia (Czech Republic) and Linköping University (Sweden) analyzed the long-term consequences of decreasing the size of cold blooded organisms on the survival of their populations and on the functioning of food chains. In an article published in May 2017 in Ecology Letters, they demonstrate that shrinking organisms can increase their populations survival and thus mitigate the ecological consequences of global warming on ecosystems.

Body-size reduction is a ubiquitous response to global warming alongside changes in species phenology and distributions. However, ecological consequences of temperature-size (TS) responses for community persistence under environmental change remain largely unexplored. Here, we investigated the interactive effects of warming, enrichment, community size structure and TS responses on a three-species food chain using a temperature-dependent model with empirical parameterisation. We found that TS responses often increase community persistence, mainly by modifying consumer-resource size ratios and thereby altering interaction strengths and energetic efficiencies. However, the sign and magnitude of these effects vary with warming and enrichment levels, TS responses of constituent species, and community size structure. We predict that the consequences of TS responses are stronger in aquatic than in terrestrial ecosystems, especially when species show different TS responses. We conclude that considering the links between phenotypic plasticity, environmental drivers and species interactions is crucial to better predict global change impacts on ecosystem diversity and stability.

Figure Fait Marquant Sentis 2017

[Figure 1] Example of the effect of temperature on the size of organisms in a food chain composed of the dragonfly larva Libellula quadrimaculata (photo: © Arnaud Sentis) consuming the crustacean Daphnia magnia (photo: © Hajime Watanabe) - even feeds on the green alga Chlorella vulgaris (photo: © natesis.com). The higher the temperature, the smaller the individuals.

See also

Arnaud Sentis, Amrei Binzer & David S. Boukal (2017) Temperature-size responses alter food chain persistence across environmental gradients.Ecology Letters.