Adaptive processes in cnidarians: integrative study of the response to heat stress and climate change, from genes to populations
The concept of adaptation is central in evolutionary biology and progress in the tools and concepts of genomic and transcriptomic allow to deeply investigate the underlying mechanisms of adaptation. This is especially important in the current context of climate change. Cnidarians are ecologically important species which are directly facing this adaptive challenge and a study of their adaptive abilities is then required. Our project aims at studying (i) the adaptability and adaptation mechanisms to thermal stress in sessile cnidarians, and (ii) the ecological and evolutionary consequences of variability in adaptation abilities. This complex puzzle will be envisioned through its different levels of integration and variation: interindividual, interpopulational and interspecific. We will take into account the genetic and epigenetic components of adaptation and the interactions between them. We will thus try to understand their respective parts in adaptability from the cnidarian point of view and to test if species or individuals from more variable environments present a more efficient response to thermal stress than those from stable conditions. We will compare the tropical coral Pocillopora damicornis (stenotherm, symbiotic) and the Mediterranean red coral Corallium rubrum (eurytherm, non symbiotic). Thermal stress triggers bleaching in P. damicornis and necrosis / mortality in C. rubrum. For each species we will compare populations from different temperature regimes and we will test the importance of plasticity and genetic determinism in the adaptation to spatial and temporal environmental heterogeneity. First, an experimental approach will be used to study the transcriptomic response in stress situation for different individuals, populations and species. The involvement of epigenetic processes will be studied by using recurrent stresses. Secondly, a population genetic approach based on SNP genotyping will be used to search outlier loci which could be responsible for the genetic adaptation of a species to different environments. The third part of the project will be used to verify if the markers identified in the transcriptomic and the population analyzes are indeed involved in the adaptability to stress. This validation will be done using experimental stresses and natural stresses if extreme thermal events triggering necrosis or bleaching symptoms occur in natural conditions during the time of project. For these different parts a survey of the variability of associated bacteria or Symbiodinium will be realized to take into account their role in the response to thermal stress. Finally, a modeling approach is proposed to envision the response of populations and species to climate change by integrating these different factors, evolution of plasticity itself. The obtained results will also give important information for the study of the evolution of adaptive processes in metazoans
– Vidal-Dupiol, J., E. Toulza, O. Rey, D. Roquis, C. Chaparro, C. Cosseau, A. Picart-Picolo, P. Romans, M. Pratlong, K. Brener-Raffalli, F. Bonhomme, P. Pontaroti, M. Adjeroud, G. Mitta, and C. Grunau. in prep. Genetic and epigenetic changes mediate rapid adaptation to global warming in a tropical coral
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– Brener-Raffalli, K., J. Vidal-Dupiol, M. Adjeroud, P. Romans, F. Bonhomme, M. Pratlong, A. Haguenauer, R. Pillot, L. Feuillassier, M. Claereboudt, H. Magalon, P. Gélin, P. Pontarotti, D. Aurelle, G. Mitta, and E. Toulza. 2018. Gene expression plasticity and frontloading promote thermotolerance in Pocilloporid corals. bioRxiv:
– Pratlong, M., A. Haguenauer, S. Chenesseau, K. Brener, G. Mitta, E. Toulza, M. Bonabaud, S. Rialle, D. Aurelle, and P. Pontarotti. 2017. Evidence for a genetic sex determination in Cnidaria, the Mediterranean red coral (Corallium rubrum). Royal Society open science 4:160880.
– Pratlong, M., A. Haguenauer, K. Brener, G. Mitta, E. Toulza, J. Garrabou, N. Bensoussan, P. Pontarotti, and D. Aurelle. 2018. Separate the wheat from the chaff: genomic scan for local adaptation in the red coral Corallium rubrum. bioRxiv:306456