CE02 - Terre vivante

Ecological consequences of Temperature induced Body size shifts – EcoTeBo

Ecological consequences of Temperature induced Body size shifts

A common phenotypic response to climate change is the reduction in body size of ectotherms with temperature — the hotter it is, the smaller they get—. However, the ecological consequences of these body size changes on communities remain largely unexplored.

Objectives and research hypothesis

The general objective of EcoTeBo is to assess and understand how temperature and top predator body size reduction affect trophic interactions, community dynamics, and ecosystem functioning. While the body size of the other species within the community level are also likely to be affected by temperature, we choose to focus, as a first step, on top predator body size reduction because (i) body size reductions appear to be stronger at high trophic level, (ii) top predator body size is an important determinant of food web stability, especially in aquatic food webs that are strongly size-structured and top-down regulated. Another major advantage of focusing on top predator body size reduction is that EcoTeBo can build on an ongoing experiment on thermal adaption in the medaka fish (Oryzias latipes) by using fishes from “warm” and “cold” populations for which life history and morphological traits have been monitored across generations (see below for more details). This offers a golden opportunity to test for the ecological consequences of top predator body size reduction. Manipulating the thermal history/body size of the other species could be the focus of a larger follow-up project aiming at determining the relative influence of top-down and bottom-up effects using both top predators and primary consumers that have been maintained at different temperatures over generations.

By simultaneously manipulating the temperature and size of top predators in simple and complex freshwater systems, we will provide:
(1) A unique experimental test concerning the ecological impacts of size changes induced by temperature on trophic interactions, community dynamics and ecosystem functions.
(2) An assessment of the relative effects of temperature and predator size on trophic interactions and community dynamics by combining modeling and experiments at different levels of complexity (food chain and whole community).
(3) New models of trophic networks taking into account the phenotypic responses to temperature with predictions linked to the stability of ecosystems.

The results are being analyzed.

By exploiting the synergies between new theories and experimental tests in simple and more complex systems, our objective is to disentangle the relative effects of temperature and size changes on various ecological features and to identify the mechanisms at the origin of these. effects.

Communications in international journals:
1. Sentis A., Montoya J., Lurgi M. (2021-03-31). Warming indirectly increases invasion success in food webs. Proceedings of the Royal Society B: Biological Sciences, 288 (1947), dx.doi.org/10.1098/rspb.2020.2622, hal.inrae.fr/hal-03321097
2. Sentis A., Haegeman B., Montoya J. (2020-01-28). Stoichiometric constraints modulate the effects of temperature and nutrients on biomass distribution and community stability. Peer Community in Ecology, , dx.doi.org/10.1101/589895, hal.inrae.fr/hal-02941241
3. Bideault A., Galiana N., Zelnik Y., Gravel D., Loreau M., Barbier M., Sentis A. (2021-01). Thermal mismatches in biological rates determine trophic control and biomass distribution under warming. Global Change Biology, 27 (2), 257-269, dx.doi.org/10.1111/gcb.15395, hal.inrae.fr/hal-03175973

Human activities induce rapid climate change that poses major threats to global biodiversity, ecosystem functions, and ultimately to the fate of mankind. Forecasting and mitigating these detrimental effects is thus an urgent challenge. Warming not only increases the speed of biochemical reactions but also influences the phenotype of species trough plastic or selective processes. One ubiquitous phenotypic response to climate change is the reduction of ectotherm body size with temperature—the warmer it is, the smaller they get—. This temperature-induced body size shift has been proposed as the third universal species response to global warming altogether with shifts in phenology and species geographical distribution. However, the ecological consequences of temperature-induced body size shift on communities remain largely unexplored. This is an important gap, both for fundamental and applied research, as body size determines many ecological properties such as fecundity, growth rate, trophic position and community stability. Thus, knowledge of how temperature-induced body size shift modulates species interactions is important for understanding and predicting climate change impacts on ecological systems.

The project EcoTeBo combines modelling and experimental approaches to investigate the ecological consequences of warming and body size shift on trophic interactions, community dynamics and ecosystem functions. EcoTeBo focuses on top predator body size reduction because (i) body size reductions appear to be stronger at high trophic levels and (ii) top predator body size is an important determinant of food web stability, especially in aquatic food webs that are strongly size-structured and top-down regulated. To achieve this ambitious objective, EcoTeBo brings together researchers with highly complementary expertise on trophic interactions, community ecology, ecosystem functioning, aquatic ecosystems, ecological models and management of large experimental infrastructures. By simultaneously manipulating temperature and top predator body size in simple and complex freshwater systems, we will provide:

(1) A unique experimental test of the ecological impacts of temperature-induced body size shifts on the strength of trophic interaction, community dynamics, and ecosystem functions.

(2) An unprecedented assessment of the relative effects of temperature and top predator body size on trophic interactions and community dynamics by combining modelling and experiments at different levels of complexity (i.e. food chain and whole community).

(3) Novel food web models accounting for phenotypic responses to temperature with predictions connected to the stability of freshwater ecosystems, in terms of both their temporal variability and persistence.

To our knowledge, EcoTeBo would be one of the first project to investigate the consequences of temperature-induced body size shifts on different components of trophic interactions, community dynamics and ecosystem functions. By exploiting the synergies between new theories and experimental tests in simple and more complex freshwater systems, we will disentangle the relative effects of temperature and body size shift on various ecological features and identify the mechanisms driving these effects. In addition to novel and important scientific results, EcoTeBo will facilitate the integration of trait based approach into climate change research and ease the detection and mitigation of climate change impacts by developing predictive models and using body size as a bio-indicator of ecosystem functioning.

Project coordination

Arnaud Sentis (RECOVER RISQUES ECOSYSTEMES VULNERABILITE ENVIRONNEMENT RESILIENCE)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

RECOVER RECOVER RISQUES ECOSYSTEMES VULNERABILITE ENVIRONNEMENT RESILIENCE
SETE Station d'Ecologie Théorique et Expérimentale

Help of the ANR 308,637 euros
Beginning and duration of the scientific project: February 2020 - 42 Months

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