Genome-wide insights into introgression and its consequences for genome-wide heterozygosity in the Mytilus species complex across Europe.

The three mussel species comprising the Mytilus complex are widespread across Europe and readily hybridize when they occur in sympatry, resulting in a mosaic of populations with varying genomic backgrounds. Two of these species, M. edulis and M. galloprovincialis, are extensively cultivated across Europe, with annual production exceeding 230,000 tonnes. The third species, M. trossulus, is considered commercially damaging as hybridization with this species results in weaker shells and poor meat quality. We therefore used restriction site associated DNA sequencing to generate high-resolution insights into the structure of the Mytilus complex across Europe and to resolve patterns of introgression. Inferred species distributions were concordant with the results of previous studies based on smaller numbers of genetic markers, with M. edulis and M. galloprovincialis predominating in northern and southern Europe respectively, while introgression between these species was most pronounced in northern France and the Shetland Islands. We also detected traces of M. trossulus ancestry in several northern European populations, especially around the Baltic and in northern Scotland. Finally, genome-wide heterozygosity, whether quantified at the population or individual level, was lowest in M. edulis, intermediate in M. galloprovincialis, and highest in M. trossulus, while introgression was positively associated with heterozygosity in M. edulis but negatively associated with heterozygosity in M. galloprovincialis. Our study will help to inform mussel aquaculture by providing baseline information on the genomic backgrounds of different Mytilus populations across Europe and by elucidating the effects of introgression on genome-wide heterozygosity, which is known to influence commercially important traits such as growth, viability, and fecundity in mussels

Genome‐wide insights into introgression and its consequences for genome‐wide heterozygosity in the Mytilus species complex across Europe

The three mussel species comprising the Mytilus complex are widespread across Europe and readily hybridize when they occur in sympatry, resulting in a mosaic of populations with varying genomic backgrounds. Two of these species, M. edulis and M. galloprovincialis, are extensively cultivated across Europe, with annual production exceeding 230,000 tonnes. The third species, M. trossulus, is considered commercially damaging as hybridization with this species results in weaker shells and poor meat quality. We therefore used restriction site associated DNA sequencing to generate high‐resolution insights into the structure of the Mytilus complex across Europe and to resolve patterns of introgression. Inferred species distributions were concordant with the results of previous studies based on smaller numbers of genetic markers, with M. edulis and M. galloprovincialis predominating in northern and southern Europe respectively, while introgression between these species was most pronounced in northern France and the Shetland Islands. We also detected traces of M. trossulus ancestry in several northern European populations, especially around the Baltic and in northern Scotland. Finally, genome‐wide heterozygosity, whether quantified at the population or individual level, was lowest in M. edulis, intermediate in M. galloprovincialis, and highest in M. trossulus, while introgression was positively associated with heterozygosity in M. edulis but negatively associated with heterozygosity in M. galloprovincialis. Our study will help to inform mussel aquaculture by providing baseline information on the genomic backgrounds of different Mytilus populations across Europe and by elucidating the effects of introgression on genome‐wide heterozygosity, which is known to influence commercially important traits such as growth, viability, and fecundity in mussels

POGO-AtlantOS collaboration on ocean products

Development of methodologies and sampling protocol

OPENMODS 2.0 “Instrument Jamming Meeting” report

Major achievements The feedback provided by potential users on their needs was very much appreciated. They underlined the importance of having: ● an easy to deploy instrument (i.e.: from small fishing boats); ● multi-parameter sensors in ONE device; ● less maintenance effort and prioritized the variables to measure. Although, there are technical limitations and different solutions and there is no one tool that can do everything, which is low cost, has high resolution and low maintenance, the outcomes of the platforms/sensors/communications working group meet the main requirements that emerged. Priority was given to: ● a platform that will operate in drifter mode which is extremely easy to deploy and perfect for studies associated with search and rescue operations (another need that has emerged). It also constantly guarantees the knowledge of the instrument position. The platform can be easily converted into the moored mode. ● temperature and pressure sensors. The sensors will be low -cost with the idea to replace them rather than calibrate them; ● LoRaWAN communications preferably with Bluetooth integration for the in-situ download of the data

Energy budgets in antarctic & boreal fish

In comparison to temperate fish species, most polar fish grow more slowly and show lower relative fecundity. This might be related to specific energy requirements for cold adapted metabolic processes and low or strictly seasonal food availability. In this study we focused on the energy requiring processes.To compare the effects of temperature on metabolic energy distribution on both cellular and whole animal level, we studied high Antarctic, subantarctic and boreal fish of related species or similar ecotypes. We investigated whether the proportions of energy allocated to specific metabolic pathways in the cell underlie thermally induced changes. The energetic proportions of RNA and protein synthesis, ion regulation (Na+-K+- exchanger) and ATP synthetase were measured at temperatures ranging from 0 to 15°C. As lipids are the most important energy supply in fish the lipid class and fatty acid composition was analysed. Energy uptake and dissipation at maximum food availability as well as growth were studied at temperatures between 0 and 18 °C at the whole organism level. Results are discussed in the light of consequences for ecological preferences

Influence of temperature on energy budgets in Antarctic and boreal fish

This thesis investigates how temperature and energy allocation affect the growth of fish species. In a comparative approach two eelpout species, one temperate, Zoarces viviparus, and one Antarctic eelpout, Pachycara brachycephalum, were studied. Age, growth and fecundity in the field were investigated. The energy demands of metabolism, growth and excretion as well as body composition and lipids were measured and analysed at different temperatures in long-term acclimation experiments. In Pachycara brachycephalum the predominant lipid class in muscle and liver tissue over the whole temperature range are storage lipids. Zoarces viviparus changes the lipid composition to these storage lipids in the cold. The pronounced lipid metabolism in the Antarctic eelpout may be the result of evolutionary processes of high mitochondrial densities and low metabolic rates and the high availability of a lipid enriched diet indicated by the stable isotope analyses. The field growth patterns of Pachycara brachycephalum show in its natural habitat a lower growth rate than that of the temperate eelpout population in the Wadden Sea, whereas the experimental growth rate of the Antarctic eelpout was higher. Both the Antarctic and the temperate eelpout display optimum growth temperature close to their habitat temperature (12 degrees C for the temperate eelpout) or their evolutionary approach to the habitat (4 degrees C for the Antarctic eelpout, who most like entered Antarctic waters via Deep Sea). The food conversion efficiency of the Antarctic eelpout is high. This ability to ingest and absorb energy in short periods of local appearance and to store this energy for starving periods is crucial in an environment where food supply is unstable and pulsed. The slow field growth rates of the Antarctic eelpout are due to habitat temperatures below the thermal growth optimum and to food limitation