Theory and experiments to decipher the role of time and space in ecological systems, from populations to ecosystems

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Understanding the role played by time and space in ecological systems in a rapidly changing environment is essential for devising better conservation policies. The SETE (Theoretical and Experimental Ecology Station), founded by Jean Clobert and Michel Loreau of the National Centre for Scientific Research, conducts innovative theoretical and experimental research to reach this goal in a unique research station.

Understanding the function of time and space when an ecosystem is disturbed is essential for devising sustainable conservation and management policies. From the ‘micro-genetic phenotype scale’ to the ‘meso-individual population scale’ and to the ‘macro-ecosystem scale’, there has been an increased focus upon the broad roles played by time and space when studying ecological processes at every scale and their interactions.

The effects of time and space on ecological processes are further complicated by growing anthropogenic disturbances such as ecosystem fragmentation, pollution, climate change, and habitat loss. To better understand and predict the response of ecological systems to these disturbances, researchers must develop new theoretical and experimental approaches, looking at the long-term implications of anthropogenic factors and how they might be mitigated.

The variety of spatial and temporal scales that govern ecosystem processes demands large-scale monitoring efforts and vast amounts of manpower and financial investment. As a result, the subject is still understudied, and the studies that have been performed often lack replicability and scope.

“The researchers are interested in the cascade of effects from the genotype-phenotype to the individual, population, community and ecosystem.”

There is a strong need for developing new theory to generate novel predictions and experimental approaches that can be easily replicated and adapted. The research team at the Theoretical and Experimental Ecology Station (SETE) aims to provide both theory and experimental methodologies to understand and predict the responses of ecological systems to environmental changes. A distinctive feature of the Station is the fact that its experimental facilities are open to the whole international research community.

SETE

Since 2016, SETE and its research staff have developed cutting-edge knowledge on biodiversity and ecosystems with a view to ensuring greater sustainability. Recently, the station has also developed research on the relationship between biodiversity and human society.

The SETE station has a number of unique experimental platforms. These include terrestrial and aquatic metatrons (experimental meta-ecosystems in which researchers can manipulate biotic or abiotic features), aviaries, natural caves, greenhouses, and an MRI system (for phenotyping small animals). These facilities allow researchers to manipulate environmental disturbances in artificial ecosystems, mimicking natural changes in both space and time.

Theoretical models and experiments developed at SETE cover a wide range of scales, from microcosms (microbial studies) to mesocosms (terrestrial and aquatic metatrons) and up to the biosphere (theoretical models). Each scale includes interactions between different levels of complexity, from genes to individuals, and from populations to entire ecosystems. These interactions create a continuous chain of investigation, from the production of theories and models to experimentation.

On genes, individuals and populations

All of SETE research is performed in an integrative way. One of SETE’s objectives is to study the evolutionary adaptation needed at the genetic and phenotypic levels to deal with environmental changes. This research addresses the effects of changes in environmental gradients, such as temperature and humidity, on evolutionary dynamics. It assesses how phenotypic plasticity (the ability of a genotype to express itself as different phenotypes in different environments) is affected by environmental gradients and how these phenotypic changes influence eco-evolutionary dynamics. One example of this research at SETE is an experimental microcosm with the unicellular organism, Tetrahymena thermophila, which the researchers exposed to 25 different combinations of temperature and nutrient availability to assess the plasticity of five phenotypic traits.

The terrestrial metatron at SETE station

Another objective is to understand how environmental changes alter species population dynamics, and how these alterations are shaped by phenotypic and genomic changes. The researchers are interested in the cascade of effects from the genotype and phenotype to the individual and the population. An example of this research is a study of how lizard phenotypes react to a warmer climate by having a faster-paced life, higher mortality rates, and earlier ages of reproduction, which result in a younger lizard population but with higher extinction risk.

Evolutionary and population dynamical changes can then be linked to alterations in the whole ecosystem. A good example is again provided by lizards. As lizards are exposed to a warmer climate and increase their pace of life, they use more energy, which shifts their diet to more energy-rich prey such as predatory invertebrates (e.g. spiders). Over a long timescale, this shift could result in changes in the functioning of the broader ecosystem.

On communities and ecosystems

SETE also studies how global changes, such as climate change, habitat fragmentation and biodiversity changes, affect the dynamics of species interactions and ecosystem functioning. Researchers accomplish this by combining theories, experiments in metatrons, and field studies.

Aviaries experimental area

In particular, SETE has played a key role in the emergence and development of a whole new research field on the relationships between biodiversity and ecosystem functioning (BEF). SETE researchers have built the theoretical foundations of this research field, which studies how changes in biodiversity affect ecosystem functioning, stability and services. BEF theory is now recognised as a fundamental and empirically validated theory in biology, and is used in conservation policy globally. Most BEF studies, however, are conducted at very small scales, whereas SETE seeks to extend BEF theory to large temporal and spatial scales.

Studies in this field have also led to exciting new empirical discoveries. For instance, SETE produced a groundbreaking study focused on the effect of intraspecific diversity on ecosystem functioning using a mesocosm experiment. Researchers showed for the first time that losing the diversity of genes in a single population can have powerful effects on communities and the broader ecosystem, thus extending the scope of BEF research to include intraspecific diversity. They also studied the effects of climate fluctuations on the BEF relationship, and found that biodiversity loss mostly affects ecosystem functioning at intermediate timescales.

“Researchers showed for the first time that losing the diversity of genes in a single population can have powerful effects on communities and the broader ecosystem.”

Lastly, SETE researchers are performing innovative research on the combined effects of climate warming and habitat fragmentation on community dynamics and ecosystem functioning. Although climate warming and habitat fragmentation are well studied in isolation, very little is known about their combined effects. SETE researchers use multiple species of phytoplankton and zooplankton that coexist in the aquatic metatron to conduct this research. Although the study has yet to reach its three-year duration, early publications from this study have already provided novel findings that will be essential for future research and for shaping new conservation strategies.

Observation of a zooplankton culture
A daphnae culture

Vital ecosystem conservation research

As the global human population increases, human activities further exacerbate disastrous effects on ecosystems. Understanding the part played by time and space in response to these disturbances will be essential in ensuring biodiversity conservation and responsible use of ecosystem services.

There remain enormous difficulties and limitations in performing studies of ecosystems across time and space. The complexity of species interacting across multiple trophic levels and temporal and spatial scales make this an ever-changing subject, which is constantly challenging researchers. Moreover, the way the SETE team works, with constant back and forth iterations between building models and conducting experiments, is a time-consuming and challenging process.

Nevertheless, with their crucial research, the SETE team assist in designing practical conservation strategies. Their work is integral in shaping policy and inspiring further research for deeper understanding. Their work will help ensure the relationship between humanity and biodiversity and the environment is mutually sustainable in the long term. This generates for the SETE the constant obligation of transfer of this new knowledge to conservation and nature-monitoring agencies.


To what extent do you believe the research performed at SETE is being correctly used by international governments to mitigate biodiversity loss and ecosystem collapse?

This is indeed an important question. First, the quality of the research and its robustness is key for our work to be taken seriously by policy makers. This is sadly not enough. We also need to have more time devoted to making our research accessible and to communicate on social networks, as well as participate at all social events that have the human-nature coexistence on their agenda. Finally, we have to increase our participation with nature societies and environmental agencies to build large-scale following up and/or experiments to speed up our knowledge on biodiversity and ecosystem as well as to transfer the acquired know-how.

 

References

  • Bestion, E. and Cote, J. (2018). Species Responses to Climate Change: Integrating Individual-Based Ecology Into Community and Ecosystem Studies. The Encyclopedia of the Anthropocene, 2.
  • Clobert, J. et al. (2018). How to Integrate Experimental Research Approaches in Ecological and Environmental Studies: AnaEE Franceas an Example. Frontiers in Ecology and Evolution, 6 (43).
  • Faillace, C. and Montoya, J. (2019). Eco-evolutionary consequences of habitat warming in communities from fragmented landscapes. [Preprint]
  • Legrand Delphine, et al. (2017). Eco-evolutionary dynamics in fragmented landscapes. Ecography, 40.
  • Loreau, M., Mouquet, N., and Holt, R.D. (2003). Meta-ecosystems: A theoretical framework for a spatial ecosystem ecology. Ecology Letters, 6 (8).
DOI
10.26904/RF-136-1476966800

Research Objectives

SETE conducts research to assess the broad roles played by time and space in changing ecosystems.

Funding

  • CNRS
  • Occitanie region
  • Ariege department
  • ERC
  • European funds
  • ANR

Collaborators

José Montoya, Julien Cote, Simon Blanchet, Delphine Legrand, Olivier Guillaume, Catherine Clerc, Alexis Chaine, Michelle Huet

Bio

Jean Clobert is research director (emeritus) at the CNRS and founded the SETE research station. His research moved from statistical modelling to the study of life history strategies and lately to the design and organisation of facilities for experimental approaches in ecology. His main field of expertise is evolutionary ecology.

Michel Loreau is a CNRS research director and the current director of SETE. He is founder of the Centre for Biodiversity Theory and Modelling at SETE and a renowned theoretical ecologist with broad interests. His main research themes are the relationship between biodiversity and ecosystem functioning and the ecological/societal consequences of biodiversity loss.

Contact
Rue station biologique de Moulis
09200 Moulis, France

Jean Clobert
E: jean.clobert@sete.cnrs.fr
T: +33 561040369

Michel Loreau
E: jmichel.loreau@sete.cnrs.fr

T: +33 561040578

W: https://sete-moulis-cnrs.fr/

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