Seascape Genomics of the Sugar Kelp Saccharina latissima Along the North Eastern Atlantic Latitudinal Gradient

Abstract

Temperature is one of the most important range-limiting factors for many seaweeds. Driven by the recent climatic changes, rapid northward shifts of species’ distribution ranges can potentially modify the phylogeographic signature of Last Glacial Maximum such as increased genetic diversity at lower latitudes. To explore this question in detail in the kelp Saccharina latissima, we used microsatellites and double digest RAD-sequencing derived SNPs on S. latissima sporophytes sampled within 11 sites spanning the entire European Atlantic latitudinal range of this species. In addition, we checked for statistical correlation between genetic marker allele frequencies and three environmental proxies (sea surface temperature, salinity, and water turbidity). Our findings revealed that genetic diversity was significantly higher for the northern localities compared to the southern ones in contrast to the expected phylogeographic pattern. This suggests that the southernmost S. latissima populations are negatively affected by the recent climatic changes but also that the recolonization of S. latissima range following the LGM may have occurred from northerly refugia. Seven SNPs and 12 microsatellite alleles were found to be significantly associated with at least one of the three environmental variables. We discuss the potential adaptive functions of the genes associated with the outlier markers and the importance of these markers for successful conservation and aquaculture strategies for S. latissima in this age of rapid global change.

Genotype–Environment mismatch of kelp forests under climate change

“…Genome‐wide association studies can unravel the genetic basis underlying local adaptation. Although genome‐wide associations with environmental variables have been shown for many taxonomic groups worldwide, this information is scant for macroalgae (but see Guzinski et al, (2020); Mao et al, (2020)) and it is not clear to what extent genomic variation is shaped by environmental variables or which molecular processes are underpinning thermal adaptation (King et al, 2017).…”

Arctic marine forest distribution models showcase potentially severe habitat losses for cryophilic species under climate change

“…Genetic diversity is expected to be high at lower latitudes where refugia are hypothesized to have occurred during the last glaciation (~21 ka). However, recent work in the North Atlantic (Bringloe et al, 2020; Guzinski et al, 2020) and North Pacific (Grant & Bringloe, 2020; Grant et al, 2020) have challenged this paradigm by suggesting genetic diversity is also high in some northern populations. Conducting genomic surveys of marine forest populations would provide definitive context for anticipating the resilience of populations in threatened areas identified here (Figure 2).…”

The Saccharina latissima microbiome: algal tissue matters more than region, season, and physiology

“…However, the regional differences might also be due, in part, to the genetic diversity of the algae. Using single nucleotide polymorphisms (SNPs) and microsatellites, Guzinski et al (2016Guzinski et al ( , 2020 determined that S. latissima individuals from Roscoff, Helgoland, and Norway are genetically distinct, and this might lead to the attraction of different bacterial species (Griffiths et al, 2019). Furthermore, S. latissima displays a unique lipidomic signature depending on its geographic origin (Monteiro et al, 2020), as the content of chemical elements (C, H, N, S), fatty acids, and lipids varies depending on the region.…”