Population Genetic Differentiation Research Articles

Comparing microsatellites and single nucleotide polymorphisms to evaluate genetic structure and diversity in wolverines (Gulo gulo) across Alaska and western Canada

Abstract The Wolverine (Gulo gulo) is a cold-adapted species of conservation interest because it is sensitive to human development, disturbance, exploitation, and climate warming. Wolverine populations have been studied across much of their distributional range to evaluate patterns of genetic diversity, genetic structure, and gene flow. Little population structure has been detected in northwestern North America with microsatellite loci, but low genomic diversity in wolverines may limit detection of genetic differences in this highly vagile species. Here, we genotyped a relatively large sample of wolverines from across Alaska (US) and adjacent Yukon (Canada) with 12 microsatellite loci (n = 501) and 4,222 single nucleotide polymorphisms (SNPs; n = 201) identified using restriction-site associated DNA sequencing. We compared the relative ability of our microsatellite and SNP datasets to evaluate population genetic structure, genetic diversity, differentiation, and isolation by distance (IBD). We predicted that the SNP dataset would detect a higher degree of genetic structure and provide more significant support for IBD. We found evidence for multiple genetic clusters, including genetic distinctiveness of wolverines in southeast Alaska and on the Kenai Peninsula. The SNP dataset detected additional genetic clusters that align largely with ecoregions, and the SNP dataset showed stronger evidence of IBD, while the 2 datasets were generally consistent in estimates of genetic diversity and differentiation among regional groups. Our results highlight the importance of genomic methods to assess gene flow in wolverines. Identifying population genetic structure allows an assessment of the potential impacts of conservation threats and is an important precursor for designing population monitoring programs.

Genetic Mechanism Analysis Related to Cold Tolerance of Red Swamp Crayfish, Procambarus clarkii.

In China, the red swamp crayfish (Procambarus clarkii), a notorious invasive species, has become an important economic freshwater species. In order to compare the genetic diversity and population structure of crayfish from northern and southern China, we collected 60 crayfish individuals from 4 crayfish populations in northern China and 2 populations in southern China for sequencing using the 2b-RAD technique. Additionally, the whole genome sequence information obtained by 2b-RAD of 90 individuals from 2 populations in northern China and 7 populations in southern China were downloaded from NCBI. After quality control, a total of 25,371 SNPs were detected from approximately 54.22 billion raw reads. Based on these SNPs, high genetic diversity was observed in the 15 crayfish populations in China. The pairwise FST values indicated that there was a large genetic differentiation of crayfish populations in northern and southern China. Despite common genetic backgrounds, due to geographical barriers, genetic divergence has been observed in northern and southern China crayfishes. The principal component analysis in combination with Admixture and Neighbor-Joining tree analysis showed that the crayfish fell into two clusters corresponding to geographical regions. The integrated analysis of whole genome and transcriptome data showed that two genes (CETN4 and CPEB2) might play important roles during crayfish resistance to a cold environment. This study reveals the genetic differentiation of crayfish populations in northern and southern China and provides clues to the genetic mechanism related to cold adaptation.

Genetic Structural Changes While Maintaining Effective Population Size of Bighead Catfish in Nong Han Lake: Implications of Metapopulation Dynamics or Release Activities

ABSTRACTThe Bighead Catfish (Clarias macrocephalus) plays crucial roles in the ecosystem and as a protein source for humans in Nong Han Lake, Thailand, but their ecological and population dynamics, along with their genetic diversity and structure, are poorly understood. Therefore, the dynamics of genetic diversity and differentiation of bighead catfish populations in Nong Han Lake were investigated during 2018–2023 to provide essential insights into preserving biodiversity and maintaining ecological balance. Microsatellite genotyping was used to assess the genetic diversity of one bighead catfish population in 2018, two populations in 2023, and one hatchery population. Potentially stable, effective population sizes and distinct genetic clusters of these populations were identified, which represented the resilience of populations and the complexity of their genetic dynamics. Genetic differentiation between sample dates and among populations suggested that limited recent and historical genetic exchanges could potentially influence genetic structure. The impact of ecological factors, including flooding, metapopulation dynamics, and human interventions, was indicated by unique and shared gene pools among populations and subpopulations in different years. Ongoing assessment of genetic diversity and structure of bighead populations is essential for developing conservation strategies and ensuring sustainable management.

Integrated genomic analysis reveals the fine‐scale population genetic structure and variety differentiation of Taihangia rupestris, a rare cliff plant

AbstractTaihangia rupestris Yu & Li, an early spring flowering plant of the Rosaceae family, is classified as a second‐level protected species in China. Endemic to the cliff faces of the Taihang Mountains in central China, this rare species requires a comprehensive understanding and conservation approach. In this study, we analyzed population‐level genetic variations in both chloroplast and nuclear genomes. Taihangia rupestris var. ciliate exhibited higher genetic diversity than T. rupestris var. rupestris in both genome types. All individuals of T. rupestris var. rupestris formed a single cluster, while individuals of T. rupestris var. ciliate were grouped into three distinct clusters. Approximately 29.82 Ma, T. rupestris diverged from its closely related species. Taihangia rupestris var. ciliate appeared first, followed by the differentiation of T. rupestris var. rupestris, which adapted to the climate of the southern Taihang Mountains, around 3.55 Ma. Additionally, our study identified several chloroplast genes potentially involved in variety adaptive differentiation. These findings enhance our understanding of environmental adaptation and differentiation in the two T. rupestris varieties, providing valuable genetic insights for the conservation and utilization of this species.

Exploring the forensic effectiveness and population genetic differentiation in Guizhou Miao and Bouyei group by the self-constructed panel of X chromosomal multi-insertion/deletions

In this research, a self-developed panel comprising 22 X chromosomal multi-InDels and one X-STR was used to explore the genetic polymorphisms and forensic characteristics of these loci in Guizhou Miao and Guizhou Bouyei populations. Besides, genetic affiliations among Guizhou Miao, Guizhou Bouyei and Guizhou Han populations were investigated using principal component analysis, STRUCTURE and machine learning methods. The findings indicated that these loci in the male and female samples had comprehensive discrimination powers greater than 0.999999999. Meanwhile, the cumulative mean exclusion chance of these 23 loci for trio and duo cases were also greater than 0.9999 in Guizhou Miao and Guizhou Bouyei populations. Population genetic analyses of three Guizhou populations revealed that there were relatively low genetic divergences among these populations based on the self-constructed panel. In conclusion, this system could be utilized as the valuable tool for forensic personal identification and parentage testing in Guizhou Miao and Guizhou Bouyei populations.

Conservation genetics of Stylophorum diphyllum (Papaveraceae): investigating the genetic diversity and differentiation of peripheral and core populations across the range

Conservation genetics of Stylophorum diphyllum (Papaveraceae): investigating the genetic diversity and differentiation of peripheral and core populations across the range

Broad thermal tolerance and high mitochondrial genetic connectivity in the pinfish (Lagodon rhomboides).

Pinfish (Lagodon rhomboides) are highly abundant in coastal ecosystems of the Gulf of Mexico and western Atlantic Ocean and serve as a crucial link in marine food webs. Despite their ecological relevance, little is known about this species' susceptibility to anthropogenic climate change. Here, we characterized patterns of mitochondrial genetic divergence and examined the upper thermal tolerance of pinfish across a large portion of the species' range. We found little evidence of population genetic differentiation among distant localities with divergent temperature regimes (e.g., Mexico and North Carolina), using two mitochondrial markers (cytochrome b [CytB] and cytochrome c oxidase I [COI]). This suggests high genetic connectivity, which implies low potential for local adaptation of populations to different thermal conditions along a latitudinal gradient. To further examine population-scale differences in thermal tolerance, we assessed the critical thermal maxima (CTmax) of pinfish from four localities: North Carolina, Florida Keys, Alabama, and Texas. We found that CTmax was similar across sites, with all localities showing an average CTmax within a 1°C temperature range (34.5-35.5°C). This suggests that southern populations of pinfish may be more susceptible to the detrimental effects of ocean warming, as individuals in lower latitudes regularly experience temperatures within a few degrees of their CTmax. Finally, we examined the influence of varying salinity on the upper thermal limit of the pinfish and found that pinfish show no variation in CTmax under salinity conditions ranging from hypo- to hypersaline (15-35 ppt). These results show that pinfish can tolerate a wide range of environmental parameters but may rely on phenotypic plasticity, rather than local adaptation, to distinct conditions to cope with different environmental regimes.

High Crimean-Congo hemorrhagic fever incidence linked to greater genetic diversity and differentiation in Hyalomma marginatum populations in Türkiye

BackgroundTicks are crucial vectors of a wide range of pathogens, posing significant threats to human and animal health globally. Understanding the genetic basis of tick biology and host–parasite interactions is essential for developing effective control programs. This study investigates the fine-scale genetic structure of Hyalomma marginatum Koch, 1844, the primary vector of Crimean-Congo hemorrhagic fever (CCHF) in Türkiye. Despite its significant public health importance, information regarding its population structure and genetic diversity is quite limited.MethodsWe used restriction site-associated DNA sequencing (RAD-Seq) to obtain genome-wide sequence data from 10 tick populations in Türkiye, collected from regions with low, moderate, and high incidence rates of CCHF. Based on these data, we determined population structure and diversity of populations using principal component analysis (PCA) and admixture analysis. Furthermore, we calculated pairwise FST and utilized discriminant analysis of principal components (DAPC) to understand genetic differentiation between populations.ResultsPCA and admixture analysis indicated minimal genetic structure between populations, but we detected notable genetic differentiation and high genetic diversity from regions with high CCHF rates. Furthermore, our DAPC identified 31 significant single-nucleotide polymorphisms (SNPs) associated with regions with high CCHF incidence, with 25 SNPs located near genes involved in critical biological functions such as nucleic acid binding, transmembrane transport, and proteolysis. These findings suggest that genetic variations in these regions may confer adaptive advantages in environments with high pathogen loads.ConclusionsThis study provides the first comprehensive analysis of H. marginatum genetic diversity in Türkiye, revealing significant differentiation in populations from CCHF-endemic regions. These results underscore the importance of considering fine-scale genetic diversity to fully understand the drivers of genetic variation in ticks and their implications for vectorial capacity.Graphical

Assessment of diversity and genetic differentiation in polycross-derived populations of Thymus daenensis using ISSR and SCoT markers

Assessment of diversity and genetic differentiation in polycross-derived populations of Thymus daenensis using ISSR and SCoT markers

The Evolution of Wisteria Vein Mosaic Virus: A Case Study Approach to Track the Emergence of New Potyvirus Threats.

Wisteria vein mosaic virus (WVMV, Potyvirus wisteriae), a virus belonging to the genus Potyvirus, is responsible for Wisteria vein mosaic disease (WMD), a severe disease that affects Wisteria, a genus of garden plants acclaimed worldwide. Although probably originating in the Far East, WVMV infection was first reported in the US, and subsequently in numerous countries. Following the first molecular detection of an Italian isolate, WVMV Bari, its full-length genome was achieved using NGS barcoding technology. A PhyML phylogenetic analysis, supported by clustering algorithm validation, identified a clear separation between two phylogroups. One major clade comprised WVMV strains isolated from Wisteria spp. A second clade grouped three highly divergent strains, at the borderline species threshold, all found in non-wisteria hosts. Relying on a Relative Time Dated Tips (RTDT) molecular clock, the first emergence of WVMV clades has been traced back to around the 17th century. A network inference analysis confirmed the sharp separation between the two host-related phylogroups, also highlighting the presence of potential intermediate variants. Inter-population genetic parameters revealed a very high genetic differentiation in both populations, which was made reliable by statistically significant permutation tests. The migrant number (Nm) and fixation index (FST) evidenced a restricted gene flow and strong population structures. According to the dN/dS ratio and negative neutrality tests, it was derived that purifying selection at the expense of non-silent variants is underway within WVMV populations. Targeting WVMV evolutionary traits, the present effort raised interesting questions about the underestimated potential of this culpably neglected species to spread in economically relevant crops. The main intention of our study is, therefore, to propose an evolution-based analysis approach that serves as a case study to investigate how other potyviruses or newly emerging viruses may spread.

Genetic Polymorphism and Differentiation of Populations of Sterlet Acipenser ruthenus (Acipenseridae) in the Lower Irtysh and Middle Ob Basins

The article presents data on polymorphism of intermicrosatellite sequences in the sterlet Acipenser ruthenus of the lower reaches of the Irtysh River and the middle reaches of the Ob River. We assessed intra- and interpopulation variability and genetic differentiation of A. ruthenus and revealed a high ISSR polymorphism in the species from the central part of the Ob-Irtysh basin. The proportion of polymorphic amplicons was 0.966, genetic diversity was 0.355, and the average number of alleles per locus was 1.97. The highest polymorphism was typical for the sterlet from the Tobol River at the confluence with the Irtysh River. Genetic differentiation between the sterlet groups of the Irtysh and Ob rivers is well pronounced, the interpopulation component accounts for 42% of variability (Gst = 0.42), gene flow is limited (Nm = 0.67). The sterlet groups inhabiting the Lower Irtysh from the mouth of the Tobol River to the mouth of the Konda River do not differ genetically and form one population (Gst = 0.08–0.12, Nm = 3.76–5.55). The sterlet from the Irtysh River within the Vagay region is genetically different from the other Irtysh samples (Gst = 0.22, Nm = 1.68) and belongs to a different population group. The differentiation between samples of sterlet from the Ob basin is higher than between samples from the Irtysh basin. Groups of sterlet from the Ob River and the Yuganskaya Ob canal are genetically different (Gst = 0.30, Nm = 1.19) and form various subpopulations. Spawning migrations, as well as confinement to wintering pits, play a decisive role in the formation of the sterlet population structure in the studied part of the distribution area. The identified sterlet population groups should be considered as separate units of environmental and economic management.

Genetic and Haplotype Diversity of Clarias gariepinus (Burchell 1822) Based on Cytochrome c Oxidase I (COI) Gene

The evaluation of mitochondrial DNA and genetic analysis is helpful for economically significant species. Clarias gariepinus is a critical species in aquaculture. This study investigates the genetic diversity and population differentiation of C. gariepinus from 19 countries using 164 sequences of the mitochondrial DNA’s Cytochrome c oxidase I (COI) gene. The haplotype analysis revealed a total of 17 haplotypes, with a nucleotide diversity (π) of 0.012 and a haplotype diversity (Hd) of 0.87. The results of an AMOVA and fixation index indicated significant genetic variation and structure among the populations. Additionally, neutrality tests and mismatch distribution analysis supported the hypothesis of under-purifying selection in C. gariepinus. The findings suggested that the population did not experience expansion. In conclusion, the genetic analysis highlighted substantial variation among C. gariepinus populations from different locations, providing valuable insights for the global management of this species.

Sympatric diversity pattern driven by the secondary contact of two deeply divergent lineages of the soybean pod borer Leguminivora glycinivorella.

The soybean pod borer, Leguminivora glycinivorella (Matsumura), is an important tortricid pest species widely distributed in most parts of China and its adjacent regions. Here, we analyzed the genetic diversity and population differentiation of L. glycinivorella using diverse genetic information including the standard cox1 barcode sequences, mitochondrial genomes (mitogenomes), and single-nucleotide polymorphisms (SNPs) from genotyping-by-sequencing. Based on a comprehensive sampling (including adults or larvae of L. glycinivorella newly collected at 22 of the total 30 localities examined) that covers most of the known distribution range of this pest, analyses of 543 cox1 barcode sequences and 60 mitogenomes revealed that the traditionally recognized and widely distributed L. glycinivorella contains two sympatric and widely distributed genetic lineages (A and B) that were estimated to have diverged ∼1.14 million years ago during the middle Pleistocene. Moreover, low but statistically significant correlations were recognized between genetic differentiation and geographic or environmental distances, indicating the existence of local adaptation to some extent. Based on SNPs, phylogenetic inference, principal component analysis, fixation index, and admixture analysis all confirm the two divergent sympatric lineages. Compared with the stable demographic history of Lineage B, the expansion of Lineage A had possibly made the secondary contact of the two lineages probable, and this process may be driven by the climate fluctuation during the late Pleistocene as revealed by ecological niche modeling.

Temporal and inter-specific population genetics analyses of Sebastiscus marmoratus and S. tertius provide novel implications for fishery management

ABSTRACT Understanding population genetic diversity and evolutionary dynamics of marine fish species can provide theoretical bases for fishery management and germplasm conservation, especially facing a changing environment. The rockfish species in genus Sebastiscus are economically important species for farming and sport fisheries in China, Japan and Korea. In this study, inter-annual and inter-specific comparisons on genetic diversity, population differentiation and historical demography of S. marmoratus and S. tertius collected from coastal waters of Zhangzhou, China were conducted using mitochondrial control region sequences. High levels of genetic diversity were observed in both species, indicating high adaptive potential to environmental changes. Demographic analyses detected recent population expansion in population S. tertius (Ste-2020) and population S. marmoratus collected in 2020 (Sma-2020), yet failed in population collected in 2016 (Sma-2016). Moreover, in population Sma-2020, novel haplotypes were detected and grouped into a separate sub-branch, revealed by neighbour-joining topology. Detected recent population expansion and novel haplotypes might be considered as a response to environmental changes. Besides, results of genetic differentiation analysis suggested high intra-specific genetic variation in both species. These genetic data and information will provide novel implications for strengthening the management of S. marmoratus and S. tertius fisheries in climate change scenarios.

Population genetic differentiation and structure of rare plant Anemone shikokiana based on genotyping-by-sequencing (GBS)

BackgroundAnemone shikokiana (Makino) Makino is a perennial herb of the genus Anemone in the family Ranunculaceae. Endemic to the Shandong Peninsula in China and Shikoku Island in Japan, it is a rare and endangered plant with a narrow, disjunct distribution. It is threatened with extinction and is in urgent need of conservation. Evaluating the genetic diversity of species, revealing the population genetic structure and gene flow, and inferring the population history are of great importance for species conservation, especially for rare and endangered plants.ResultsIn our study, 73 samples from eight wild populations in China were sequenced by Super-GBS, yielding a total of 40.59 G clean reads and 52,231 SNPs. Based on the obtained SNP data set, we evaluated the population genetic diversity, genetic structure, and gene flow of A. shikokiana. A low level of genetic diversity was found (He = 0.1925, Ho = 0.1422). The neighbor-joining (NJ) tree, principal component analysis and ADMIXTURE analysis suggested that these 73 A. shikokiana could be considered as two groups. Pairwise genetic differentiation coefficients (Fst) indicated that genetic differentiation was lower between adjacent populations and higher between geographically separated populations. The gene flow between Kunyu Mountain and Lao Mountain was very low. However, neither of the two regions showed evidence of Isolation by Distance.ConclusionsHere, we revealed the population genetic structure and gene flow of A. shikokiana from the Shandong Peninsula, China. This research provides valuable genetic resources for A. shikokiana and contributes to the scientific and effective conservation of the species.

Genomic epidemiology and evolutionary dynamics of the Omicron variant of SARS-CoV-2 during the fifth wave of COVID-19 in Pakistan.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed extraordinary challenges to global health systems and economies. The virus's rapid evolution has resulted in several variants of concern (VOCs), including the highly transmissible Omicron variant, characterized by extensive mutations. In this study, we investigated the genetic diversity, population differentiation, and evolutionary dynamics of the Omicron VOC during the fifth wave of COVID-19 in Pakistan. A total of 954 Omicron genomes sequenced during the fifth wave of COVID-19 in Pakistan were analyzed. A Bayesian framework was employed for phylogenetic reconstructions, molecular dating, and population dynamics analysis. Using a population genomics approach, we analyzed Pakistani Omicron samples, revealing low within-population genetic diversity and significant structural variation in the spike (S) protein. Phylogenetic analysis showed that the Omicron variant in Pakistan originated from two distinct lineages, BA.1 and BA.2, which were introduced from South Africa, Thailand, Spain, and Belgium. Omicron-specific mutations, including those in the receptor-binding domain, were identified. The estimated molecular evolutionary rate was 2.562E-3 mutations per site per year (95% HPD interval: 8.8067E-4 to 4.1462E-3). Bayesian skyline plot analysis indicated a significant population expansion at the end of 2021, coinciding with the global Omicron outbreak. Comparative analysis with other VOCs showed Omicron as a highly divergent, monophyletic group, suggesting a unique evolutionary pathway. This study provides a comprehensive overview of Omicron's genetic diversity, genomic epidemiology, and evolutionary dynamics in Pakistan, emphasizing the need for global collaboration in monitoring variants and enhancing pandemic preparedness.

Analysing the pedigree to identify undesirable losses of genetic diversity and to prioritize management decisions in captive breeding: a case study

When prevention of species extinction is the priority, captive breeding is a key component in conservation programmes, allowing the recording of pedigree information in studbooks. The genealogical information registered in Cuvier’s gazelle studbook between 1975 and 2023 was analysed to (a) assess if the implemented mating policy was successful in preserving the genetic background of the founders (1 male:3 females) in the present population, and b) improve future management and breeding decisions. Although the maternal contribution of one founder female was lost and the mean inbreeding of the total live population was high (0.305 ± 0.095), the breeding policy applied produced better results than expected from a population starting from four founders. It was successful in keeping the individual increase in inbreeding low (0.047 ± 0.021), and, notably, the inbreeding tended to decrease during the last three decades of the breeding programme, ensuring the viability of this highly inbred population. Historical dissemination of individuals among the zoos of Europe and North America caused population structuring and genetic differentiation of the live North American population. However, it did not risk the viability of the captive population. The average relatedness coefficients allowed the identification of individuals with underrepresented genotypes, which is relevant to plan future mating guidelines to keep the founders’ representation balanced in the next generations. This study highlights the importance of keeping long-term pedigree information to monitor changes in the genetic diversity of captive populations, which is crucial to implement optimal mating decisions and assuring their long-term viability within an ex situ conservation programme.

Genetic homogeneity and weak signatures of local adaptation in the marine mussel Mytilus chilensis

The natural populations of the marine mussel Mytilus chilensis and the associated aquaculture industry forms a sensitive social-ecological system that relies on the released propagules for cultivation in the highly heterogeneous environment (temperature, productivity, and salinity) of northern Patagonia (42–44 °S). We assessed spatial genetic structure, signals of local adaptation, and population assignment of M. chilensis analyzing 5963 SNPs from 125 individuals across six natural populations sampled over two consecutive years along the southeast Pacific coast (39° 25′ to 43° 07′ S, ~ 430 km). Neutral and putatively adaptive loci revealed high genetic diversity and low genetic differentiation among populations. Of the whole dataset, less than 1% (50) of loci were identified as putatively adaptive through multiple approaches, with only 0.1% detected in by all of them, and only two loci of them were correlated with environmental variables. No evidence of Isolation by Environment (IBE) was found, albeit a slight differentiation in the southern sampling location (Yaldad). These results suggest that the genetic structure observed is primarily shaped by neutral processes with weak signals of local adaptation. Gene-flow appears to be the main evolutionary force influencing the species’ population genetic structure. Because of the importance for the industry, the probability of correct assignment of individuals to their population of origin using allelic frequencies was evaluated. Analyses exhibited relatively low probabilities (< 50% for four out of six sites) of accurately assigning individuals to their geographic origin, with a limited success of SNP markers the for such purposes. Likely, species' high dispersal capacity, seed translocation, and the spill-over effect of mussel aquaculture prevents population genetic differentiation through high effective gene flow, hindering local genetic adaptation.

Population Genomics of the Blue Shark, Prionace glauca, Reveals Different Populations in the Mediterranean Sea and the Northeast Atlantic.

Populations of marine top predators have been sharply declining during the past decades, and one-third of chondrichthyans are currently threatened with extinction. Sustainable management measures and conservation plans of large pelagic sharks require knowledge on population genetic differentiation and demographic connectivity. Here, we present the case of the Mediterranean blue shark (Prionace glauca, L. 1758), commonly found as bycatch in longline fisheries and classified by the IUCN as critically endangered. The management of this species suffers from a scarcity of data about population structure and connectivity within the Mediterranean Sea and between this basin and the adjacent Northeast Atlantic. Here, we assessed the genetic diversity and spatial structure of blue shark from different areas of the Mediterranean Sea and the Northeast Atlantic through genome scan analyses. Pairwise genetic differentiation estimates (F ST) on 203 specimens genotyped at 14,713 ddRAD-derived SNPs revealed subtle, yet significant, genetic differences within the Mediterranean sampling locations, and between the Mediterranean Sea and the Northeast Atlantic Ocean. Genetic differentiation suggests some degree of demographic independence between the Western and Eastern Mediterranean blue shark populations. Furthermore, results show limited genetic connectivity between the Mediterranean and the Atlantic basins, supporting the hypothesis of two distinct populations of blue shark separated by the Strait of Gibraltar. Although reproductive interactions may be limited, the faint genetic signal of differentiation suggests a recent common history between these units. Therefore, Mediterranean blue sharks may function akin to a metapopulation relying upon local demographic processes and connectivity dynamics, whereby the limited contemporary gene flow replenishment from the Atlantic may interplay with currently poorly regulated commercial catches and large-scale ecosystem changes. Altogether, these results emphasise the need for revising management delineations applied to these critically endangered sharks.

Reduced representation sequencing reveals weak genetic differentiation between Canadian and European Larus hyperboreus (Glaucous Gull)

ABSTRACT Climate change poses a significant threat to Arctic ecosystems. Evaluation of genetic diversity within and differentiation among populations is needed to effectively conserve Arctic species and ensure genetic variation is appropriately managed. This research examined the population genetic structure in Larus hyperboreus (Glaucous Gull), a circumpolar Arctic species that is declining in parts of its range. Population genetic information is needed to help delineate management units, including information on genetic differences among related species, among subspecies (currently distinguished by subtle morphometric and plumage differences), and among colonies in North America. We conducted double-digest restriction site-associated DNA sequencing for 62 L. hyperboreus, 18 L. argentatus smithsonianus (American Herring Gull), 6 L. a. argentatus (European Herring Gull), and 15 L. glaucescens (Glaucous-winged Gull) sampled across the Canadian and European Arctic. Interspecific analyses using 2,145 loci were unable to distinguish between all members of this species complex. Despite the geographic distance among sampling locations, molecular assignments and principal coordinates analyses based on 621 loci uncovered only weak population genetic differentiation among sampled European and Canadian colonies of L. hyperboreus. As L. hyperboreus occupying the eastern Canadian Arctic appears to be acting as a single panmictic population, conservation plans that protect Arctic habitat may help slow or reverse population declines. Proactive conservation strategies will benefit both L. hyperboreus and associated coastal Arctic ecosystems.