Genomic datasets of Laminaria digitata: Paired-end reads from dd-RADseq, reference genome assembly and filtered VCF

The impact of ongoing climate change on populations will be contingent
upon their contemporary adaptive evolution. In this study, we investigated
the contemporary evolution of four populations of the cold-water kelp
Laminaria digitata by analysing their spatial and temporal genomic
variation using ddRAD-sequencing. These populations were sampled from the
center to the southern margin of its north-eastern Atlantic distribution
at two-time points, spanning at least two generations. Through genome
scans for local adaptation at a single time point, we identified candidate
loci that showed clinal variation correlated with changes in sea surface
temperature (SST) along latitudinal gradients. This finding suggests that
SST may drive the adaptive response of these kelp populations, although
factors such as species' demographic history should also be
considered. Additionally, we performed a simulation approach to
distinguish the effect of selection from genetic drift in allele frequency
changes over time. This enabled the detection of loci in the southernmost
population that exhibited temporal differentiation beyond what would be
expected from genetic drift alone: these are candidate loci which could
have evolved under selection over time. In contrast, we did not detect any
outlier locus based on temporal differentiation in the population from the
North Sea, which also displayed low and decreasing levels of genetic
diversity. The diverse evolutionary scenarios observed among populations
can be attributed to variations in the prevalence of selection relative to
genetic drift across different environments. Therefore, our study
highlights the potential of temporal genomics to offer valuable insights
into the contemporary evolution of marine foundation species facing
climate change.