Survive and thrive: nothing in plant biology makes sense except in the light of polyploid evolution


 Olivier Troccaz    31/03/2021 : 10:36

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02/04/21 - Séminaire (en ligne) de Malika AINOUCHE

Polyploidy (resulting from whole genome duplication, WGD) leads to the presence of more than two homologous chromosome sets in the nucleus, and has long been known as a common speciation mechanism in plants. Since the analyses of the first Angiosperm genome sequences twenty years ago, accumulating plant genome data have documented the recurrence of polyploidy across all plant lineages, with older events dating back to seed plant ancestry. The history of all modern plant genomes (including “diploids”) appears punctuated by superimposed rounds of polyploidization, fractionation and diploidization. How plant organisms respond to challenges such as WGD and genome merger (following hybridization in the context of allopolyploidy), what are early and long term processes involved in the adaptive success of polyploids, represent major questions in evolutionary biology. The polyploid grass genus Spartina which includes several species considered as ecosystem engineers on salt marshes, represents an excellent model system to explore such questions at various evolutionary time scales (i.e. neopolyloidy, mesopolyploidy and paleopolyploidy).  Challenges in documenting the deep history of superimposed WGD events, deciphering the molecular mechanisms involved in phenotypic novelties and species expansion (e.g. in invasive species) will be presented.


The role plays by freshwater insects in terrestrial ecosystems: a review of our current works and future challenges



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19/03/21 - Séminaire (en ligne) de Christophe PISCART et Benjamin BERGEROT

Le vendredi 19 mars 2021 à 13h00, séminaire en ligne

The role plays by freshwater insects in terrestrial ecosystems: a review of our current works and future challenges

The amount of available energy is mainly supported by autochthonous primary production in most ecosystems. However, recent studies brought out the crucial role played by reciprocal subsidies (allochtonous inputs) between ecosystems and their interface (ecotone). In freshwater ecosystems, the ratio between autochthonous and allochtonous productions is hence depending on the landscape structure (River Continuum Concept). Conversely, the highly productive and diversified freshwater ecosystems provide a large amount of organisms to adjacent terrestrial ecosystems representing until several hundreds of kg biomass per hectare per year. Exchanges between terrestrial and aquatic ecosystems are mainly controlled by landscape connectivity (e.g. presence of corridors, barriers, etc…) but also by dispersal capabilities of species. However, the research topic is still poorly investigated and both dispersal mechanisms of aquatic insects in terrestrial ecosystems and the effects of landscape characteristics remain largely unknown. That is why, we started few years ago to develop studies at the interface between freshwater and terrestrial boundary to understand the role play by aquatic insects (with aquatic larvae and terrestrial adults) in the biodiversity patterns and associated fluxes observed at the Land-Stream interface and their consequences on the ecosystem functionning. This talk aim to present i) a summary of our research questions, ii) the preliminary results already obtained and iii) our future challenges.


Caring for the life below-ground: an interdisciplinary inquiry on the values of soil biota and biodiversity among European farmers



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12/03/21 - Soutenance de thèse de Morgane HERVE

Le vendredi 12 mars 2021 à 14h00, par visioconférence

Caring for the life below-ground: an interdisciplinary inquiry on the values of soil biota and biodiversity among European farmers

Jury :

Dr. Tobias PLIENINGER, Professeur, Georg-August-Universität Göttingen ; Rapporteur

Dr. Luca MONTANARELLA, Scientific Project Manager, European Commission ; Rapporteur

Adélie POMMADE, Maître de conférences HDR, Université de Bretagne Occidentale ; Rapporteure

Dr. Julie INGRAM, Professeure, University of Gloucestershire; Examinatrice

Isabelle FEIX, Ingénieure, ADEME; Invitée

Dr. Annegret NICOLAI, Chercheuse indépendante HDR ; Directrice de thèse

Michel RENAULT, Maître de conférences HDR, Université de Rennes 1 ; Co-directeur de thèse

PD Dr. Martin POTTHOFF, scientific coordinator and project leader, Georg-August-Universität Göttingen; Co-directeur de thèse.

 

Mots-clés : Valuation ; Pragmatisme ; Gestion du sol ; Agriculture ; John Dewey ; Milieu Valuateur

Comprendre la façon dont les agriculteurs prennent en compte les organismes des sols semble nécessaire si l’on souhaite développer des politiques préservant la biodiversité des sols dans les activités agricoles. L'épistémologie pragmatiste conçoit les valeurs comme ce qui compte en pratique pour les individus et les collectifs. Cette thèse vise ainsi à caractériser les valeurs associées aux sols et à leurs organismes par les agriculteurs européens, à déterminer les conditions de leur formation, et à étudier la publicisation des enjeux de préservation de la biodiversité du sol en agriculture. Des entretiens et une analyse de littérature ont démontré la pluralité de valeurs en jeu dans les décisions de gestion des sols des agriculteurs européens. Les situations d’évaluations, liées aux caractéristiques territoriales locales rendent ces valeurs dynamiques dans le temps et l’espace. La mobilisation du concept de « Milieu Valuateur » a permis de souligner l'importance des dispositifs de partage d’expérimentations et de débats dans la formation de valeurs, participant à légitimer les pratiques. De multiples sources peuvent transférer des connaissances sur la biodiversité du sol, bien que souvent le sujet reste marginal et ne lie que peu biodiversité des sols et pratiques de gestion. Envisager les processus de valuation comme dynamiques offre la possibilité d’interroger et de remettre en question la façon dont la vie souterraine est considérée. La formation de valeurs associées à la vie des sols nécessite des espaces où un public peut se constituer pour débattre collectivement de ce qui est attendu du et pour le sol et la diversité des organismes qui s’y trouvent.

 

Keywords: Valuation; Pragmatism; Soil management; Agriculture; John Dewey; Valuating Milieu

If politics wish agriculture to more broadly build on soil biota and biodiversity, and seek to put forward its crucial role for farming activities, it is necessary to know how farmers themselves come to value soil organisms. Pragmatism conceives values as what matters, practically, to people. This thesis seeks to characterize values associated with soils and their biota by European farmers, to determine the conditions for such valuations and to investigate publicization processes about soil biodiversity in agriculture. Interviews and literature analysis stressed the plurality of values at stake in farmers’ soil management decisions. Values appeared to be dynamic across space and time since they rely on situations of valuations that depend themselves upon various local territorial characteristics. The “Valuating Milieu” concept allowed to emphasize the importance of experimentation sharing and debates on the formation of values and on the legitimation of management practices. Multiples sources may transfer knowledge about soil biodiversity to farmers but the topic remains often marginal and unlinked to management practices. Conceiving valuations as dynamic opens offers the opportunity to investigate and to challenge the way below-ground life is considered in our societies. The formation of values associated with soil biota requires to develop spaces where a real public can form and collectively debate on what is sought from and for European soils and the huge biodiversity they host.


Values of biodiversity - from physiological responses to climate change to a collective stewardship of biodiversity



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15/12/20 - Soutenance d'HDR d'Annegret NICOLAI

Le mardi 15 décembre 2020 à 14h00, par visioconférence

Values of biodiversity - from physiological responses to climate change to a collective stewardship of biodiversity

Jury :

  • Aude Vialatte, DR INRA, Toulouse (Rapporteure)
  • Jean-Michel Salles, DR CNRS, INRA-SupAgro, Montpellier (Rapporteur)
  • Paulina Kramarz, Dr. hab., Jagiellonian University, Poland (Rapporteure)
  • Nathalie Beenarts, PR, University Hasselt, Belgium (Examinatrice)
  • Alexandra Langlais, CR CNRS, Université Rennes 1 (Examinatrice)
  • Joan van Baaren, PR, Université Rennes 1 (Examinatrice et Présidente)

Contributions des citizen sciences pour la recherche en écologie



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11/12/20 - Soutenance d'HDR de Benjamin BERGEROT

Le vendredi 11 décembre 2020 à 9h00, par visioconférence

Contributions des citizen sciences pour la recherche en écologie

Jury :

• Marianne Elias, DR CNRS Muséum national d’Histoire naturelle (rapporteur)
• Thierry Hance, PR à l’Université Catholique de Louvain (rapporteur)
• Thierry Tatoni, PR à l’Université de d’Aix-Marseille (rapporteur)
• Nathalie Machon, PR au Muséum national d’Histoire naturelle (examinateur)
• Olivier Ragueneau, DR CNRS à l’Université de Bretagne Occidentale (examinateur)
• Julien Pétillon, MCF à l’Université de Rennes 1 (examinateur et président)

Contact : Benjamin BERGEROT