The methylome of clonal seagrass shoots shows age-associated variation and differentiation of roots from other tissues.

Factors influencing variance of DNA methylation in vegetatively reproducing plants, both terrestrial plants and aquatic seagrasses, is just beginning to be understood. Improving our knowledge of these mechanisms will increase understanding of transgenerational epigenetics in plant clones, of the relationship between DNA methylation and seagrass development, and of the drivers of epigenetic variation, which may underly acclimation in clonally reproducing plants. Here, we sampled leaves, rhizomes and roots of three physically and spatially separated ramet sections from a clonally propagated field of the seagrass Zostera marina.

Evolutionary genomics of the emergence of brown algae as key components of coastal ecosystems.

Brown seaweeds are keystone species of coastal ecosystems, often forming extensive underwater forests, and are under considerable threat from climate change. In this study, analysis of multiple genomes has provided insights across the entire evolutionary history of this lineage, from initial emergence, through later diversification of the brown algal orders, down to microevolutionary events at the genus level. Emergence of the brown algal lineage was associated with a marked gain of new orthologous gene families, enhanced protein domain rearrangement, increased horizontal gene transfer events, and the acquisition of novel signaling molecules and key metabolic pathways, the latter notably related to biosynthesis of the alginate-based extracellular matrix, and halogen and phlorotannin biosynthesis.

Genome analysis reveals three distinct lineages of the cosmopolitan white shark.

The white shark (Carcharodon carcharias) (Linnaeus, 1758), an iconic apex predator occurring in all oceans, is classified as Vulnerable globally-with global abundance having dropped to 63% of 1970s estimates,-and as Critically Endangered in Europe. Identification of evolutionary significant units and their management are crucial for conservation, especially as the white shark is facing various but often region-specific anthropogenic threats. Assessing connectivity in a cosmopolitan marine species requires worldwide sampling and high-resolution genetic markers.

Unmasking microsatellite deceptiveness and debunking hybridization with SNPs in four marine copepod species of Calanus.

Interspecific hybridization events are on the rise in natural systems due to climate change disrupting species barriers. Across taxa, microsatellites have long been the molecular markers of choice to identify admixed individuals. However, with the advent of high-throughput sequencing easing the generation of genome-wide datasets, incorrect reports of hybridization resulting from microsatellite technical artefacts have been uncovered in a growing number of taxa.

Characteristics of the spiny dogfish (Squalus acanthias) nuclear genome.

Sequenced shark nuclear genomes are underrepresented, with reference genomes available for only four out of nine orders so far. Here, we present the nuclear genome, with annotations, of the spiny dogfish (Squalus acanthias), a shark of interest to biomedical and conservation efforts, and the first representative of the second largest order of sharks (Squaliformes) with nuclear genome annotations available. Using Pacific Biosciences Continuous Long Read data in combination with Illumina paired-end and Hi-C sequencing, we assembled the genome de novo, followed by RNA-Seq-supported annotation.

Evolutionary dynamics of sex-biased gene expression in a young XY system: insights from the brown alga genus Fucus.

Sex-biased gene expression is considered to be an underlying cause of sexually dimorphic traits. Although the nature and degree of sex-biased expression have been well documented in several animal and plant systems, far less is known about the evolution of sex-biased genes in more distant eukaryotic groups. Here, we investigate sex-biased gene expression in two brown algal dioecious species, Fucus serratus and Fucus vesiculosus, where male heterogamety (XX/XY) has recently emerged.

Insights into the species evolution of copepods in the northern seas revealed by transcriptome sequencing.

Copepods of the zooplankton genus play a key role in marine ecosystems in the northern seas. Although being among the most studied organisms on Earth, due to their ecological importance, genomic resources for spp. remain scarce, mostly due to their large genome size (from 6 to 12 Gbps).

Population and seascape genomics of a critically endangered benthic elasmobranch, the blue skate .

The blue skate () has a patchy distribution across the North-East Atlantic Ocean, largely restricted to occidental seas around the British Isles following fisheries-induced population declines and extirpations. The viability of remnant populations remains uncertain and could be impacted by continued fishing and by-catch pressure, and the projected impacts of climate change. We genotyped 503 samples of , obtained opportunistically from the widest available geographic range, across 6 350 single nucleotide polymorphisms (SNPs) using a reduced-representation sequencing approach.

Adaptation of Temperate Seagrass to Arctic Light Relies on Seasonal Acclimatization of Carbon Capture and Metabolism.

Due to rising global surface temperatures, Arctic habitats are becoming thermally suitable for temperate species. Whether a temperate species can immigrate into an ice-free Arctic depends on its ability to tolerate extreme seasonal fluctuations in daylength. Thus, understanding adaptations to polar light conditions can improve the realism of models predicting poleward range expansions in response to climate change.

The microbiome of the habitat-forming brown alga Fucus vesiculosus (Phaeophyceae) has similar cross-Atlantic structure that reflects past and present drivers.

Latitudinal diversity gradients have provided many insights into species differentiation and community processes. In the well-studied intertidal zone, however, little is known about latitudinal diversity in microbiomes associated with habitat-forming hosts. We investigated microbiomes of Fucus vesiculosus because of deep understanding of this model system and its latitudinally large, cross-Atlantic range.

The complete mitochondrial genome of the blue skate .

The complete mitochondrial genome of the blue skate is described from shotgun sequencing on an Illumina next-generation sequencing platform. We report a 16,911 bp long sequence similar in size to other members of the genus, containing 13 protein-coding regions, 22 genes, 2 genes, and 2 non-coding areas. Phylogenetic analysis was performed using the complete mitochondrial genomes of 17 related species, placing within the Rajini tribe of the Rajidae family, consistent with current taxonomy.

The Seagrass Methylome Is Associated With Variation in Photosynthetic Performance Among Clonal Shoots.

Evolutionary theory predicts that clonal organisms are more susceptible to extinction than sexually reproducing organisms, due to low genetic variation and slow rates of evolution. In agreement, conservation management considers genetic variation as the ultimate measure of a population's ability to survive over time. However, clonal plants are among the oldest living organisms on our planet.

Proteomic and Transcriptomic Patterns during Lipid Remodeling in .

Nutrient limited conditions are common in natural phytoplankton communities and are often used to increase the yield of lipids from industrial microalgae cultivations. Here we studied the effects of bioavailable nitrogen (N) and phosphorus (P) deprivation on the proteome and transcriptome of the oleaginous marine microalga . Turbidostat cultures were used to selectively apply either N or P deprivation, controlling for variables including the light intensity.

Novel genomic resources for shelled pteropods: a draft genome and target capture probes for Limacina bulimoides, tested for cross-species relevance.

Background: Pteropods are planktonic gastropods that are considered as bio-indicators to monitor impacts of ocean acidification on marine ecosystems. In order to gain insight into their adaptive potential to future environmental changes, it is critical to use adequate molecular tools to delimit species and population boundaries and to assess their genetic connectivity. We developed a set of target capture probes to investigate genetic variation across their large-sized genome using a population genomics approach.

Towards population genomics in non-model species with large genomes: a case study of the marine zooplankton .

Advances in next-generation sequencing technologies and the development of genome-reduced representation protocols have opened the way to genome-wide population studies in non-model species. However, species with large genomes remain challenging, hampering the development of genomic resources for a number of taxa including marine arthropods. Here, we developed a genome-reduced representation method for the ecologically important marine copepod (haploid genome size of 6.

Decadal stability in genetic variation and structure in the intertidal seaweed Fucus serratus (Heterokontophyta: Fucaceae).

Background: The spatial distribution of genetic diversity and structure has important implications for conservation as it reveals a species' strong and weak points with regard to stability and evolutionary capacity. Temporal genetic stability is rarely tested in marine species other than commercially important fishes, but is crucial for the utility of temporal snapshots in conservation management. High and stable diversity can help to mitigate the predicted northward range shift of seaweeds under the impact of climate change.

Genetics redraws pelagic biogeography of .

Planktonic copepods of the genus play a central role in North Atlantic/Arctic marine food webs. Here, using molecular markers, we redrew the distributional ranges of species inhabiting the North Atlantic and Arctic Oceans and revealed much wider and more broadly overlapping distributions than previously described. The Arctic shelf species, , dominated the zooplankton assemblage of many Norwegian fjords, where only has been reported previously.

The complete mitochondrial genome of the copepod .

, a marine planktonic copepod, is a keystone species in the Arctic Ocean. In this study, we shotgun sequenced the total DNA of one individual, using the NextSeq Illumina platform, in order to determine its mitochondrial genome sequence. We successfully assembled and annotated this 20,674 bp long sequence, which included 13 protein-coding genes, 2 rRNA genes and 22 tRNA genes.

Dispersal similarly shapes both population genetics and community patterns in the marine realm.

Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits.

The fate of the Arctic seaweed Fucus distichus under climate change: an ecological niche modeling approach.

Rising temperatures are predicted to melt all perennial ice cover in the Arctic by the end of this century, thus opening up suitable habitat for temperate and subarctic species. Canopy-forming seaweeds provide an ideal system to predict the potential impact of climate-change on rocky-shore ecosystems, given their direct dependence on temperature and their key role in the ecological system. Our primary objective was to predict the climate-change induced range-shift of Fucus distichus, the dominant canopy-forming macroalga in the Arctic and subarctic rocky intertidal.

Variation in thermal stress response in two populations of the brown seaweed, Fucus distichus, from the Arctic and subarctic intertidal.

It is unclear whether intertidal organisms are 'preadapted' to cope with the increase of temperature and temperature variability or if they are currently at their thermal tolerance limits. To address the dichotomy, we focused on an important ecosystem engineer of the Arctic intertidal rocky shores, the seaweed Fucus distichus and investigated thermal stress responses of two populations from different temperature regimes (Svalbard and Kirkenes, Norway). Thermal stress responses at 20°C, 24°C and 28°C were assessed by measuring photosynthetic performance and expression of heat shock protein (HSP) genes (shsp, hsp90 and hsp70).

Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach.

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing.

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences.

Manta and devil rays are an iconic group of globally distributed pelagic filter feeders, yet their evolutionary history remains enigmatic. We employed next generation sequencing of mitogenomes for nine of the 11 recognized species and two outgroups; as well as additional Sanger sequencing of two mitochondrial and two nuclear genes in an extended taxon sampling set. Analysis of the mitogenome coding regions in a Maximum Likelihood and Bayesian framework provided a well-resolved phylogeny.

Thermal stress resistance of the brown alga Fucus serratus along the North-Atlantic coast: acclimatization potential to climate change.

Seaweed-dominated communities are predicted to disappear south of 45° latitude on North-Atlantic rocky shores by 2200 because of climate change. The extent of predicted habitat loss, however, could be mitigated if the seaweeds' physiology is sufficiently plastic to rapidly acclimatize to the warmer temperatures. The main objectives of this study were to identify whether the thermal tolerance of the canopy-forming seaweed Fucus serratus is population-specific and where temperatures are likely to exceed its tolerance limits in the next 200 years.

Genomic divergence between the migratory and stationary ecotypes of Atlantic cod.

Atlantic cod displays a range of phenotypic and genotypic variations, which includes the differentiation into coastal stationary and offshore migratory types of cod that co-occur in several parts of its distribution range and are often sympatric on the spawning grounds. Differentiation of these ecotypes may involve both historical separation and adaptation to ecologically distinct environments, the genetic basis of which is now beginning to be unravelled. Genomic analyses based on recent sequencing advances are able to document genomic divergence in more detail and may facilitate the exploration of causes and consequences of genome-wide patterns.