To our best knowledge this is the first study characterizing fish pathogens isolated from marine plastics from the West coast of Norway for their potential for pathogenicity using whole genome sequencing. Marine plastic polymers identified as polyethylene, polyethylene/ethylene vinyl acetate copolymer and polypropylene, yielded a total of 37 bacterial isolates dominated by Pseudomonas spp. (70%). Six isolates representing either fish pathogens or opportunistic human pathogens were selected for whole genome sequencing (WGS). These included four isolates belonging to Aeromonas spp., one Acinetobacter beijerinckii isolate and one Morganella morganii isolate. Three Aeromonas salmonicida isolates were potentially virulent and carried virulence factors involved in attachment, type II and type VI secretion systems as well as toxins such as aerA/act, ahh1, ast, hlyA, rtxA and toxA. A. salmonicida and Acinetobacter beijerinckii carried new variants of antibiotic resistance genes (ARGs) such as β-lactamases and chloramphenicol acetyltransferase (catB), whereas Morganella morganii carried several clinically relevant ARGs. Our study shows that marine plastics carry not only potentially virulent fish pathogens but also multidrug resistant opportunistic human pathogens like M. morganii and may serve as vectors for transport of these pathogens in the marine environment.

Mating systems largely affect individual reproductive strategies which further drives evolution. Monogamy, where males and females form exclusive pairs for more than one breeding season, is particularly intriguing in this context, as there are real and potential costs of genetic monogamy to both sexes. However, molecular studies in a variety of species have revealed that social monogamy does not necessarily imply genetic monogamy due to occurrence of extra-pair copulations resulting in extra-pair offspring.Although common in birds, <10% of mammals are monogamous. Here we use single nucleotide polymorphism (SNP) to investigate the genetic mating system of the Eurasian beaver (Castor fiber), a species traditionally considered to be not only socially but also genetically monogamous. We found evidence for low frequency of extra-pair paternity (EPP) and multiple paternity within litter. Only 5.4% young were produced by EPP and only 7% of litter contain at least one extra-pair young. Moreover, we found indications that only pairings of old individuals engaged in EPP. None of these pairs produced more than one litter as a result of EPP and none of the EPP events resulted in mate change. Our findings suggest that EPP in beavers might be the consequence of a lapse in mate guarding ability of old males.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.27866v1 | CC BY 4.0 Open Access | recAbstract 30 Mating systems largely affect individual reproductive strategies which further drives evolution. 31 Monogamy, where males and females form exclusive pairs for more than one breeding season, is 32 particularly intriguing in this context, as there are real and potential costs of genetic monogamy 33 to both sexes. However, molecular studies in a variety of species have revealed that social 34 monogamy does not necessarily imply genetic monogamy due to occurrence of extra-pair 35 copulations resulting in extra-pair offspring. Although common in birds, <10% of mammals are PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.27866v1 | CC BY 4.0 Open Access | rec: 17 Jul 2019, publ: 17 Jul 2019 36 monogamous. Here we use single nucleotide polymorphism (SNP) to investigate the genetic 37 mating system of the Eurasian beaver (Castor fiber), a species traditionally considered to be not 38 only socially but also genetically monogamous. We found evidence for low frequency of extra-39 pair paternity (EPP) and multiple paternity within litter. Only 5.4% young were produced by EPP 40 and only 7% of litter contain at least one extra-pair young. Moreover, we found indications that 41 only pairings of old individuals engaged in EPP. None of these pairs produced more than one 42 litter as a result of EPP and none of the EPP events resulted in mate change. Our findings suggest 43 that EPP in beavers might be the consequence of a lapse in mate guarding ability of old males.

Mating systems largely affect individual reproductive strategies which further drives evolution. Monogamy, where males and females form exclusive pairs for more than one breeding season, is particularly intriguing in this context, as there are real and potential costs of genetic monogamy to both sexes. However, molecular studies in a variety of species have revealed that social monogamy does not necessarily imply genetic monogamy due to occurrence of extra-pair copulations resulting in extra-pair offspring. Although common in birds, <10% of mammals are monogamous. Here we use single nucleotide polymorphism (SNP) to investigate the genetic mating system of the Eurasian beaver (Castor fiber), a species traditionally considered to be not only socially but also genetically monogamous. We found evidence for low frequency of extra-pair paternity (EPP) and multiple paternity within litter. Only 5.4% young were produced by EPP and only 7% of litter contain at least one extra-pair young. Moreover, we found indications that only pairings of old individuals engaged in EPP. None of these pairs produced more than one litter as a result of EPP and none of the EPP events resulted in mate change. Our findings suggest that EPP in beavers might be the consequence of a lapse in mate guarding ability of old males.

We identified two new plasmids in Shewanella baltica isolated from wild Atlantic mackerel ( Scomber scombrus ) collected from the northern North Sea, one plasmid carrying the mcr-4.3 gene for colistin resistance and the operon merRPAT for mercury resistance and the other carrying multiple heavy metal resistance genes. The marine environment has been recognized as a source of new resistance genes that are found in human pathogens.

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