Population Genomics and Lagrangian Modeling Shed Light on Dispersal Events in the Mediterranean Endemic Ericaria zosteroides (=Cystoseira zosteroides) (Fucales)

Type Article
Date 2021-06
Language English
Author(s) Reynes Lauric1, Aurelle Didier1, 2, Chevalier Cristele1, Pinazo Christel1, Valero Myriam3, Mauger Stéphane3, Sartoretto Stephane4, Blanfuné Aurélie1, Ruitton Sandrine1, Boudouresque Charles-François1, Verlaque Marc1, Thibaut Thierry1
Affiliation(s) 1 : Aix Marseille Univ, Université de Toulon, Centre National de la Recherche Scientifique, Institut de Recherche pour le Développement, Institut Méditerranéen d’Océanologie, Marseille, France
2 : Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, École Pratique des Hautes Études, Paris, France
3 : IRL 3614, Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Université Catholique, Université Australe du Chili, Roscoff, France
4 : Institut Français de Recherche pour l’Exploitation de la Mer, Zone Portuaire de Brégaillon, La Seyne-sur-mer, France
Source Frontiers In Marine Science (2296-7745) (Frontiers Media SA), 2021-06 , Vol. 8 , P. 683528 (18p.)
DOI 10.3389/fmars.2021.683528
Keyword(s) connectivity, Fucales, Mediterranean, marine forest, population genomics, Lagrangian modelling, dispersal, gene flow
Abstract

Dispersal is a central process that affects population growth, gene flow, and ultimately species persistence. Here we investigate the extent to which gene flow occurs between fragmented populations of the deep-water brown algae Ericaria zosteroides (Turner) Greville (Sargassaceae, Fucales). These investigations were performed at different spatial scales from the bay of Marseille (western Provence) to Corsica. As dispersal of zygotes is shown to be limited over distances beyond a few meters, we used a multidisciplinary approach, based on Lagrangian modeling and population genomics to test the hypothesis that drifting of fertile parts of thallus (eggs on fertile branches), mediated by ocean currents, enable occasional gene flow between populations. Therefore we assessed the respective contribution of oceanographic connectivity, geographical isolation, and seawater temperatures to the genetic structure of this species. The genetic structure was assessed using 10,755 neutral SNPs and 12 outlier SNPs genotyped by dd-RAD sequencing in 261 individuals of E. zosteroides. We find that oceanographic connectivity is the best predictor of genetic structure, while differentiation in outlier SNPs can be explained by the depth of populations, as emphasized by the minimum seawater temperature predictor. However, further investigations will be necessary for clarifying how depth drives adaptive genetic differentiation in E. zosteroides. Our analyses revealed that local hydrodynamic conditions are correlated with the very high divergence of one population in the Bay of Marseille. Overall, the levels of gene flow mediated by drifting were certainly not sufficient to counteract differentiation by local genetic drift, but enough to allow colonization several kilometers away. This study stresses the need to consider secondary dispersal mechanisms of presumed low dispersal marine species to improve inference of population connectivity.

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Reynes Lauric, Aurelle Didier, Chevalier Cristele, Pinazo Christel, Valero Myriam, Mauger Stéphane, Sartoretto Stephane, Blanfuné Aurélie, Ruitton Sandrine, Boudouresque Charles-François, Verlaque Marc, Thibaut Thierry (2021). Population Genomics and Lagrangian Modeling Shed Light on Dispersal Events in the Mediterranean Endemic Ericaria zosteroides (=Cystoseira zosteroides) (Fucales). Frontiers In Marine Science, 8, 683528 (18p.). Publisher's official version : https://doi.org/10.3389/fmars.2021.683528 , Open Access version : https://archimer.ifremer.fr/doc/00699/81094/