Multiple paternity and hybridization in two smooth-hound sharks

Multiple paternity appears to be a common trait of elasmobranch mating systems, with its occurrence likely driven by convenience, due to females seeking to minimize the stress of male harassment. Here we use molecular markers to analyse the frequency of multiple paternity in two related viviparous sharks, Mustelus mustelus and Mustelus punctulatus. We first applied molecular methods to assign pregnant females, embryos and additional reference adults (N\u2009=\u2009792) to one of the two species. Paternity analysis was performed using a total of 9 polymorphic microsatellites on 19 females and 204 embryos of M. mustelus, and on 13 females and 303 embryos of M. punctulatus. Multiple paternity occurs in both species, with 47% of M. mustelus and 54% of M. punctulatus litters sired by at least two fathers. Female fecundity is not influenced by multiple mating and in 56% of polyandrous litters paternity is skewed, with one male siring most of the pups. Genetic analyses also revealed hybridization between the two species, with a M. punctulatus female bearing pups sired by a M. mustelus male. The frequency of polyandrous litters in these species is consistent with aspects of their reproductive biology, such as synchronous ovulation and possible occurrence of breeding aggregations

Population genomics of an endemic Mediterranean fish: differentiation by fine scale dispersal and adaptation

Este artículo contiene 12 páginas, 5 figuras, 2 tablas.The assessment of the genetic structuring of biodiversity is crucial for management and conservation. For species with large effective population sizes a low number of markers may fail to identify population structure. A solution of this shortcoming can be high-throughput sequencing that allows genotyping thousands of markers on a genome-wide approach while facilitating the detection of genetic structuring shaped by selection. We used Genotyping-by-Sequencing (GBS) on 176 individuals of the endemic East Atlantic peacock wrasse (Symphodus tinca), from 6 locations in the Adriatic and Ionian seas. We obtained a total of 4,155 polymorphic SNPs and we observed two strong barriers to gene flow. The first one differentiated Tremiti Islands, in the northwest, from all the other locations while the second one separated east and south-west localities. Outlier SNPs potentially under positive selection and neutral SNPs both showed similar patterns of structuring, although finer scale differentiation was unveiled with outlier loci. Our results reflect the complexity of population genetic structure and demonstrate that both habitat fragmentation and positive selection are on play. This complexity should be considered in biodiversity assessments of different taxa, including non-model yet ecologically relevant organisms.Acknowledgements This work was supported by project CTM2013-48163 from Ministerio de Economía y Competitividad and by the European FP7 CoCoNet project (Ocean 2011-4, grant agreement #287844). CC, EM and MP are part of the research groups 2014SGR-1364, 2014SGR-120 and 2014SGR-336 of the Generalitat de Catalunya. CC was supported by a grant of the Beatriu de Pinós program of the Generalitat de Catalunya. LZ was supported by the University of Padua grant CPDA148387/14.Peer reviewe

Changes in the gene expression profiles of the brains of male European eels (Anguilla anguilla) during sexual maturation

Background: The vertebrate brain plays a critical role in the regulation of sexual maturation and reproduction by integrating environmental information with developmental and endocrine status. The European eel Anguilla anguilla is an important species in which to better understand the neuroendocrine factors that control reproduction because it is an endangered species, has a complex life cycle that includes two extreme long distance migrations with both freshwater and seawater stages and because it occupies a key position within the teleost phylogeny. At present, mature eels have never been caught in the wild and little is known about most aspects of reproduction in A. anguilla. The goal of this study was to identify genes that may be involved in sexual maturation in experimentally matured eels. For this, we used microarrays to compare the gene expression profiles of sexually mature to immature males. Results: Using a false discovery rate of 0.05, a total of 1,497 differentially expressed genes were identified. Of this set, 991 were expressed at higher levels in brains (forebrain and midbrain) of mature males while 506 were expressed at lower levels relative to brains of immature males. The set of up-regulated genes includes genes involved in neuroendocrine processes, cell-cell signaling, neurogenesis and development. Interestingly, while genes involved in immune system function were down-regulated in the brains of mature males, changes in the expression levels of several receptors and channels were observed suggesting that some rewiring is occurring in the brain at sexual maturity. Conclusions: This study shows that the brains of eels undergo major changes at the molecular level at sexual maturity that may include re-organization at the cellular level. Here, we have defined a set of genes that help to understand the molecular mechanisms controlling reproduction in eels. Some of these genes have previously described functions while many others have roles that have yet to be characterized in a reproductive context. Since most of the genes examined here have orthologs in other vertebrates, the results of this study will contribute to the body of knowledge concerning reproduction in vertebrates as well as to an improved understanding of eel biology.Peer Reviewe

Gone with the currents: lack of genetic differentiation at the circum-continental scale in the Antarctic krill Euphausia superba

<p>Abstract</p> <p>Background</p> <p>Southern Ocean fauna represent a significant amount of global biodiversity, whose origin may be linked to glacial cycles determining local extinction/eradication with ice advance, survival of refugee populations and post-glacial re-colonization. This pattern implies high potential for differentiation in benthic shelf species with limited dispersal, yet consequences for pelagic organisms are less clear. The present study investigates levels of genetic variation and population structure of the Antarctic krill <it>Euphausia superba </it>using mitochondrial DNA and EST-linked microsatellite markers for an unprecedentedly comprehensive sampling of its populations over a circum-Antarctic range.</p> <p>Results</p> <p>MtDNA (ND1) sequences and EST-linked microsatellite markers indicated no clear sign of genetic structure among populations over large geographic scales, despite considerable power to detect differences inferred from forward-time simulations. Based on ND1, few instances of genetic heterogeneity, not significant after correction for multiple tests, were detected between geographic or temporal samples. Neutrality tests and mismatch distribution based on mtDNA sequences revealed strong evidence of past population expansion. Significant positive values of the parameter <it>g </it>(a measure of population growth) were obtained from microsatellite markers using a coalescent-based genealogical method and suggested a recent start (60 000 - 40 000 years ago) for the expansion.</p> <p>Conclusions</p> <p>The results provide evidence of lack of genetic heterogeneity of Antarctic krill at large geographic scales and unequivocal support for recent population expansion. Lack of genetic structuring likely reflects the tight link between krill and circum-Antarctic ocean currents and is consistent with the hypothesis that differentiation processes in Antarctic species are largely influenced by dispersal potential, whereas small-scale spatial and temporal differentiation might be due to local conditions leading to genetic patchiness. The signal of recent population growth suggests differential impact of glacial cycles on pelagic Antarctic species, which experienced population expansion during glaciations with increased available habitat, <it>versus </it>sedentary benthic shelf species.</p> <p>EST-linked microsatellites provide new perspectives to complement the results based on mtDNA and suggest that data-mining of EST libraries will be a useful approach to facilitate use of microsatellites for additional species.</p

Population genomics and phylogeography of a benthic coastal shark (Scyliorhinus canicula) using 2b-RAD single nucleotide polymorphisms

The existence of strong genetic structure is expected in species with limited ability to disperse and philopatric behaviour. These life-history traits are found in many small benthic elasmobranchs, such as in the small-spotted catshark (Scyliorhinus canicula). However, no evidence of genetic structure was found across its northeastern Atlantic (NEA) range using traditional molecular markers. Here, fine-scale genetic differentiation was detected between the British Isles and southern Iberia using 2674 single nucleotide polymorphism loci generated using 2b-restriction site-associated DNA (2b-RAD). Geographical distance and historical demography were two major drivers shaping the distribution of genetic diversity of S. canicula along the NEA. Significant positive spatial autocorrelation of allelic frequencies was detected, with genetic differentiation generally increasing with geographical distance. However, marked genetic divergence of the Celtic Sea and South Portugal collections from their closest neighbours resulted in geographically constrained genetic breaks south of the British Isles and off southwestern Iberia. Historical demographic reconstruction of population pairs across these genetic breaks suggested a scenario of historical isolation before secondary contact, probably related to distinct northern and southern glacial refugia. These results provide new insights into the population structure of S. canicula along the NEA and serve as a reference for benthic elasmobranchs with similar distribution ranges

First Evidence of Inbreeding, Relatedness and Chaotic Genetic Patchiness in the Holoplanktonic Jellyfish Pelagia noctiluca (Scyphozoa, Cnidaria).

none6Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatio-temporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environments.Aglieri G; Papetti C; Zane L; Milisenda G; Boero F; Piraino SAglieri, Giorgio; Papetti, C; Zane, L; Milisenda, Giacomo; Boero, Ferdinando; Piraino, Stefan

Spatial Structuring and Life History Connectivity of Antarctic Silverfish Along the Southern Continental Shelf of the Weddell Sea

A multi-disciplinary approach was employed to examine a physical-biological population hypothesis for a critical forage species, the Antarctic silverfish Pleuragramma antarctica. Caccavo et al. (2018; Sci Rep 8:17856) had shown strong gene flow along the westward Antarctic Slope Current, in addition to spatially recurring length modes that provided evidence for episodic connectivity. In this paper, otolith nucleus chemistry from a subset of fish collected in the southern Weddell Sea as part of a hydrographic survey of the Filchner Trough system was used to test between connectivity scenarios. Nucleus chemistry, which reflects environmental exposure during early life, showed significant spatial structuring despite homogeneity in microsatellite allele frequencies. Mg:Ca and Sr:Ca differentiated length modes, and Mg:Ca showed significant contrasts between Atka Bay, Halley Bay, and Filchner Trough. Physical-biological mechanisms may help reconcile structuring shown by otolith chemistry, length, and abundance data with prior evidence of gene flow. Such mechanisms include self-recruitment shaped by circulation associated with the Filchner Trough, fluctuations in mixing between immigrant and locally recruited fish, and feeding opportunities between inflowing Modified Warm Deep Water and outflowing Ice Shelf Water. The results illustrate how comparisons between multi-disciplinary techniques based on integrated sampling designs that incorporate hydrography can enhance understanding of population structure and connectivity around the Southern Ocean

eDNA Metabarcoding Applications Across Italian Marine Coastal Ecosystems: An Overview

Climate emergency and other anthropogenic pressures urgently call for technological and methodological advances to enhance our ability to protect marine habitats and their ecosystem services. In recent years, environmental DNA (eDNA) metabarcoding has emerged as a powerful tool to achieve an integrative assessment of the environmental health status, through a broad, relatively rapid, and cost-effective taxonomic monitoring of biodiversity at different spatial scales. Here we provide a time-based overview of the applications of the eDNA metabarcoding methodology carried out across diverse Italian marine and coastal habitats, with an in-depth scrutiny of the commonly adopted operative procedures, from sampling to sequencing. The lack of standardization and low replicability in space/time arose as major issues of several monitoring campaigns, preventing appropriate cross-comparability of previous studies. Given the wide potential of eDNA metabarcoding surveys along the Italian coastline, this review aims to boost a wider application of eDNA metabarcoding for biodiversity inventories and to avoid major methodological weaknesses that could compromise the long-term value and broad spatial scope of future monitoring plans

Contemporary management of traumatic cardiac arrest and peri-arrest states:a narrative review

Trauma is a leading cause of death and disability worldwide across all age groups, with traumatic cardiac arrest (TCA) presenting a significant economic and societal burden due to the loss of productive life years. Despite TCA's high mortality rate, recent evidence indicates that survival with good and moderate neurological recovery is possible. Successful resuscitation in TCA depends on the immediate and simultaneous treatment of reversible causes according to pre-established algorithms. The HOTT protocol, addressing hypovolaemia, oxygenation (hypoxia), tension pneumothorax, and cardiac tamponade, forms the foundation of TCA management. Advanced interventions, such as resuscitative thoracotomy and resuscitative endovascular balloon occlusion of the aorta (REBOA), further enhance treatment. Contemporary approaches also consider metabolic factors (e.g. hyperkalaemia, calcium imbalances) and hemostatic resuscitation. This narrative review explores the advanced management of TCA and peri-arrest states, discussing the epidemiology and pathophysiology of peri-arrest and TCA. It integrates classic TCA management strategies with the latest evidence and practical applications.</p

Connectivity Among Populations of the Top Shell Gibbula divaricata in the Adriatic Sea

Genetic connectivity studies are essential to understand species diversity and genetic structure and to assess the role of potential factors affecting connectivity, thus enabling sound management and conservation strategies. Here, we analyzed the patterns of genetic variability in the marine snail Gibbula divaricata from five coastal locations in the central-south Adriatic Sea (central Mediterranean) and one in the adjacent northern Ionian Sea, using 21 described polymorphic microsatellite loci. Observed and expected heterozygosity varied from 0.582 to 0.635 and 0.684 to 0.780, respectively. AMOVA analyses showed that 97% of genetic variation was observed within populations. Nevertheless, significant, although small, genetic differentiation was found among nearly all of the pairwise FST comparisons. Over a general pattern of panmixia, three groups of populations were identified: eastern Adriatic populations, western Adriatic populations, and a third group represented by the single northern Ionian Sea population. Nonetheless, migration and gene flow were significant between these groups. Gibbula divaricata is thought to have a limited dispersal capacity related to its lecithotrophic trochophore larval stage. Our results indicated high levels of self-recruitment and gene flow that is mainly driven through coastline dispersion, with populations separated by the lack of suitable habitats or deep waters. This stepping-stone mode of dispersion together with the high levels of self-recruitment could lead to higher levels of population structuring and differentiation along the Adriatic Sea. Large effective population sizes and episodic events of long-distance dispersal might be responsible for the weak differentiation observed in the analyzed populations. In summary, the circulation system operating in this region creates natural barriers for dispersion that, together with life-history traits and habitat requirements, certainly affect connectivity in G. divaricata. However, this scenario of potential differentiation seems to be overridden by sporadic events of long-distance dispersal across barriers and large effective population sizes