Browsing by Author "Fouqueau, Louise"
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- Development of tools to rapidly identify cryptic species and characterize their genetic diversity in different European kelp speciesPublication . Mauger, Stéphane; Fouqueau, Louise; Avia, Komlan; Reynes, Lauric; Serrao, Ester; Neiva, J.; Valero, MyriamMarine ecosystems formed by kelp forests are severely threatened by global change and local coastline disturbances in many regions. In order to take appropriate conservation, mitigation, and restoration actions, it is crucial to identify the most diverse populations which could serve as a “reservoir” of genetic diversity. This requires the development of specifc tools, such as microsatellite markers to investigate the level and spatial distribution of genetic diversity. Here, we tested new polymorphic microsatellite loci from the genome of the kelp, Laminaria digitata, and tested them for cross-amplifcation and polymorphism in four closely related congeneric species (Laminaria hyperborea, Laminaria ochroleuca, Laminaria rodriguezii, and Laminaria pallida). Adding these 20 new microsatellite loci to the ten L. digitata loci previously developed by Billot et al. (Mol Ecol 7:1778-1780, 1998) and Brenan et al. (J R Soc Interface 11:1-12, 2014) and to the ten L. ochroleuca loci previ ously developed by Coelho et al. (Conserv Genet Resource 6:949-950, 2014), we retained a total of 30 polymorphic loci for L. digitata, 21 for L. hyperborea, 16 for L ochroleuca, 18 for L. rodriguezii, and 12 for L. pallida. These markers have been tested for the frst time in the last two species. As predicted, the proportion of markers that cross-amplifed between species decreased with increasing genetic distance. In addition, as problems of species identifcation were reported in this family, mainly between L. digitata and Hedophyllum nigripes, but also between L. digitata, L. hyperborea, and L. ochroleuca in areas where their range distributions overlap, we report a rapid PCR identifcation method based on species-specifc COI mitochondrial primers that allows these four species of kelp to be rapidly distinguished.
- Genetic structure of amphi-Atlantic Laminaria digitata (Laminariales, Phaeophyceae) reveals a unique range-edge gene pool and suggests post-glacial colonization of the NW AtlanticPublication . Neiva, J.; Serrao, Ester; Paulino, Cristina; Gouveia, Licínia; Want, Andrew; Tamigneaux, Éric; Ballenghien, Marion; Mauger, Stéphane; Fouqueau, Louise; Engel-Gautier, Carolyn; Destombe, Christophe; Valero, MyriamIn the North-east (NE) Atlantic, most intertidal fucoids and warm-temperate kelps show unique low-latitude gene pools matching long-term climatic refugia. For cold-temperate kelps data are scarcer despite their unique cultural, ecological and economic significance. Here we test whether the amphi-Atlantic range of Laminaria digitata is derived from past glacial survival (and vicariance) in both NE and North-west (NW) Atlantic refugia (as suggested by niche modelling), or post-glacial (re)colonization (as suggested by low mtDNA divergence). We screened 14 populations from across the species range for 12 microsatellite loci to identify and map major gene pools and refugia. We assessed if NW Atlantic survival was supported by unique endemic variation, and if genetic diversity and structure were, as predicted from larger hindcasted glacial ranges, higher in the NE Atlantic. Microsatellite data subdivided L. digitata into three main genetic groups matching Brittany, northern Europe and the NW Atlantic, with finer-scale sub-structuring within European clusters. The relatively diverse NE Atlantic lineages probably survived the Last Glacial Maximum along unglaciated periglacial shorelines of the Armorican and Celtic Seas (Brittany cluster) and Ireland (northern European cluster), and remain well differentiated despite their relative proximity. The unique Brittany gene pool, at the contemporary European rear edge, is projected to disappear in the near future under high greenhouse gas emission scenarios. Low allelic diversity and low endemism in the NW Atlantic are consistent with recent post-glacial colonization from Europe, challenging the long-standing hypothesis of in situ glacial survival. Confusion with Hedophyllum nigripes may have led to underestimation of regional diversity of L. digitata, but also to overestimation of its presence along putative trans-Atlantic migration routes. Partial incongruence between modelling and genetic-based biogeographic inferences highlights the benefits of comparing both approaches to understand how shifting climatic conditions affect marine species distributions and explain large-scale patterns of spatial genetic structure.
- Heat stress responses and population genetics of the kelp Laminaria digitata (Phaeophyceae) across latitudes reveal differentiation among North Atlantic populationsPublication . Liesner, Daniel; Fouqueau, Louise; Valero, Myriam; Roleda, Michael Y.; Pearson, Gareth; Bischof, Kai; Valentin, Klaus; Bartsch, InkaTo understand the thermal plasticity of a coastal foundation species across its latitudinal distribution, we assess physiological responses to high temperature stress in the kelp Laminaria digitata in combination with population genetic characteristics and relate heat resilience to genetic features and phylogeography. We hypothesize that populations from Arctic and cold-temperate locations are less heat resilient than populations from warm distributional edges. Using meristems of natural L. digitata populations from six locations ranging between Kongsfjorden, Spitsbergen (79°N), and Quiberon, France (47°N), we performed a common-garden heat stress experiment applying 15°C to 23°C over eight days. We assessed growth, photosynthetic quantum yield, carbon and nitrogen storage, and xanthophyll pigment contents as response traits. Population connectivity and genetic diversity were analyzed with microsatellite markers. Results from the heat stress experiment suggest that the upper temperature limit of L. digitata is nearly identical across its distribution range, but subtle differences in growth and stress responses were revealed for three populations from the species' ecological range margins. Two populations at the species' warm distribution limit showed higher temperature tolerance compared to other populations in growth at 19°C and recovery from 21°C (Quiberon, France), and photosynthetic quantum yield and xanthophyll pigment responses at 23°C (Helgoland, Germany). In L. digitata from the northernmost population (Spitsbergen, Norway), quantum yield indicated the highest heat sensitivity. Microsatellite genotyping revealed all sampled populations to be genetically distinct, with a strong hierarchical structure between southern and northern clades. Genetic diversity was lowest in the isolated population of the North Sea island of Helgoland and highest in Roscoff in the English Channel. All together, these results support the hypothesis of moderate local differentiation across L. digitata's European distribution, whereas effects are likely too weak to ameliorate the species' capacity to withstand ocean warming and marine heatwaves at the southern range edge.