ISO SGDC - Relationship between taxonomic and genetic diversity of aquatic plants in lakes of the Atlantic coast

While the taxonomic diversity of these communities is well known, knowledge of their genetic diversity is currently non-existent. However, improving this knowledge seems essential for better management of these ecosystems, particularly for their heritage species.

Joint analysis of the relationships between species genetic diversity within a community and taxonomic diversity of communities (species–genetic diversity correlations) provides a better understanding of how communities function and the processes responsible for the assembly of their species. Studying these two levels of diversity also makes it possible to assess whether the taxonomic diversity commonly used in conservation practices adequately takes into account the evolutionary processes revealed by genetic diversity.

Approaches

To this end, nine species belonging to the “isoetid” communities of five water bodies on the Aquitaine coast were sampled: Lobelia dortmanna, Littorella uniflora, Baldelia ranunculoides, Myriophyllum alterniflorum, Juncus bulbosus, Schoenoplectus pungens, Eleocharis multicaulis, Phragmites australis and Chara fragifera. In total, more than 4,000 individuals were collected from all the water bodies during the spring of 2022 and 2023. Around a hundred genetic markers (microsatellites) were identified and developed for each species.

Results

An initial study of population diversity validated around ten markers and identified ways to optimise genotyping protocols. DNA extraction, marker amplification and sequencing have been ongoing since autumn 2023 on all other samples. Results on the genetic diversity of the different populations are expected in spring 2024. Data on the taxonomic diversity of the sampled communities will be collected in spring-summer 2024.

ISO-SGDC has enabled the development of genetic markers and a protocol for genotyping them very accurately using high-throughput sequencing. One of the challenges was to find experimental conditions that could be adapted to the diversity of the plant species studied (difficulty of grinding depending on the structure of the tissues sampled, minimal amount of plant material sampled for protected species, more or less complex genome structures, etc.).

This project is eagerly awaited by managers, particularly the South Atlantic National Botanical Conservatory (CBNSA), as part of the coordination and implementation of the national action plan for these species.

Participants

INRAE units involved

• UR EABX - Unité de recherche Écosystèmes aquatiques et changements globaux
• UMR BIOGECO - Biodiversité, gènes et communautés

Partners

• Conservatoire Botanique National Sud-Atlantique
• SIAEBVELG - Syndicat Intercommunal d'Aménagement des Eaux du Bassin Versant et Etangs du Littoral Girondin
• Communauté de Commune des Grands lacs
• Réserve naturelle nationale de l’Étang Noir
• Association Landes Nature