Conservation Genetics

ContextGenetic diversity is essential for the persistence and future adaptation of species. However, human-driven habitat fragmentation results in population isolation, often leading to rapid loss of genetic diversity and adaptive capacity. Genetic management of focal taxa may be overlooked in many threatened species conservation programs. The Endangered southeastern Australian mallee emu-wren Stipiturus mallee is a species that may benefit from genetic management. Its current range encompasses patchily distributed sub-populations, prone to bottlenecks and genetic drift. Thus, the reintroduction to areas from which the species has been locally extirpated requires careful selection of founders to maximise genetic diversity. AimsWe analyse reduced-representation genomic data from seven sampling areas across the global meta-population to design a translocation strategy that maximises heterozygosity and retention of mallee emu-wren allelic diversity. MethodsWe estimated genetic structure, genetic diversity within, and differentiation between subpopulations, thus testing previous inference based on 12 length-variable loci of low population differentiation with 10,840 genome-wide SNP loci. We also estimated effective population sizes to identify populations in need of genetic augmentation, Finally, we used metapop2 simulations to estimate the relative contributions of each population to global genetic diversity of the species and to estimate the source and number of founders that would maximise heterozygosity and allelic richness in a hypothetical newly established population. Key resultsWe found weak genetic structure across all sampling areas, supporting previous conclusions that the global mallee emu-wren population should be considered a single genetic unit for management purposes. Low but significant Weir and Cockerham pairwise FST among locations indicated differentiation between sampling areas, suggesting that contemporary gene flow is restricted. Effective population sizes for the two regions supporting the largest numbers of mallee emu-wrens were below the threshold associated with reduced adaptive potential. ConclusionsThe genetic health and adaptive potential of sampled mallee emu-wren sub-populations are at risk. Implications The global mallee emu-wren meta-population would likely benefit from genetic augmentation, including reciprocal gene flow between extant sub-populations. To maximise genetic diversity in newly established populations, managers should prioritise gene-pool mixing with founders sourced from all sampled areas.

Various species conservation paradigms are facing enormous challenges during the ongoing Anthropocene. While the widely-used reintroduction/translocation-based approaches have supported many endangered species population recoveries, they seldom use detailed genetic information during initial planning. The Indian greater one-horned rhino typifies such assisted migration-driven species recovery, but currently facing long-term survival concerns due to their mostly small, isolated populations reaching respective carrying capacities. We assessed nation-wide rhino genetic health, identified suitable source populations and provided future translocation scenarios for all extant and proposed rhino habitats. Analyses with 504 unique rhino genotypes across all seven Indian rhino-bearing parks revealed six genetically-isolated populations with overall moderately low genetic diversity. Our results showed that Kaziranga and Manas NPs (Assam) to have the best rhino genetic health, whereas Jaldapara and Gorumara NPs (West Bengal) undergoing strong genetic erosions. Forward genetic simulations suggested that annual supplementation efforts from only few Assam rhino populations (Kaziranga NP, Orang NP and Pobitora WLS) are best suited for genetic rescue of most of the extant populations. Overall, the genetic diversity and differentiation patterns mimics the complex evolutionary history and individual recovery histories. We suggest park-specific management solutions (ranging from protection measures, grassland restoration, livestock and conflict management, regular supplementation events etc.) to ensure the species long-term persistence and prevent the alarming loss of grassland habitats and its associate biodiversity. We insist on utilising such genetic health indices-driven population management solutions to identify targeted mitigative measures in other species.

Urbanization is a dominant driver of habitat fragmentation globally, creating small, isolated wildlife populations vulnerable to accelerated genetic drift, reduced genetic diversity, and increased population differentiation. We investigated how urban development affects the genetic composition and structure of caracals (Caracal caracal) in Cape Town, South Africa using microsatellites and mitochondrial DNA sequence data. Sampling across four geographically disparate urban and rural populations revealed contrasting temporal patterns: mitochondrial markers indicated historical genetic connectivity among populations, while microsatellite data demonstrated recent genetic structuring driven primarily by urbanization. An extensively isolated urban population showed reduced allelic richness and pronounced genetic differentiation, reflecting urbanization as a strong barrier to gene flow. Within the isolated urban population, GPS-collared caracals demonstrated a degree of spatial genetic organization, with related individuals maintaining significantly higher home range overlap despite inhabiting a severely fragmented urban landscape. This kin-structured space use occurred despite caracals in the system having large home ranges compressed within a relatively small, isolated environment. Our findings reveal that urbanization has rapidly disrupted gene flow in this otherwise geographically widespread and adaptable carnivore, imposing a sufficient barrier to generate detectable genetic consequences within contemporary timeframes. The contrasting signals from historical versus contemporary molecular markers highlight urbanizations role in fragmenting previously connected populations and demonstrates the value of multi-marker approaches for detecting anthropogenic impacts on wildlife populations. These results underscore urbanizations capacity to rapidly alter population genetic dynamics, even in a highly mobile and adaptable carnivore.

The critically endangered white-thighed colobus, Colobus vellerosus, is on the brink of extinction, necessitating the implementation of effective conservation management strategies. The population in Kikele village serves as the primary remaining stronghold for this species in Benin, comprising around twenty-eight individuals in the small Kikele Sacred Forest and an additional eight individuals in the community-managed Okuta Kobunan Forest. These two populations are believed to have descended from a single founding pair introduced to the Kikele region circa 1800. Given the small population size and the possible severe genetic bottleneck at its foundation, the genetic diversity might be extremely low. In our study, we conducted a first analysis of the genetic diversity of the two populations using mitochondrial markers, the complete cytochrome b (cytb) and a segment of the hypervariable control region (D-loop, 750 bp). Our findings revealed only one cytb haplotype, along with two haplotypes that differ by just one site in the D-loop. We recommend a range-wide population genetic assessment of the species to explore the possibility of translocations as a potential genetic rescue strategy.

Island endemics exhibit low genetic diversity due to founder effects and geographical isolation, increasing their vulnerability to inbreeding depression. The Narcondam Hornbill (Rhyticeros narcondami), restricted to the 6.8 km2 Narcondam island in the Andaman archipelago, has the smallest range size among hornbills, a globally threatened group of birds. We compared the genetic diversity of the Narcondam Hornbill with the Wreathed Hornbill (Rhyticeros undulatus) distributed from the Eastern Himalaya to Bali. We generated DNA sequences for four mitochondrial markers ; Cytochrome B (Cytb), cytochrome c oxidase subunit I (COI), NADH dehydrogenase subunit 2 (ND2) and displacement loop (D-loop) regions) from 14 Narcondam Hornbill faecal samples and for three markers (Cytb, COI and ND2) from 19 Wreathed Hornbill tissue samples from north-east India. Our results suggest markedly lower genetic diversity in the island endemic Narcondam Hornbill compared to the Wreathed Hornbill. Specifically, Cytb and COI showed no genetic variation in the island endemic, compared to three to five haplotypes in the Wreathed Hornbills. In the ND2 region, Narcondam Hornbills showed seven haplotypes among 13 samples compared to the Wreathed Hornbills six haplotypes among eight samples. The observed genetic diversity in the D-loop in the Narcondam Hornbill was lower than other island-endemic hornbill species in the Philippines. The extremely low genetic diversity in the Narcondam Hornbill likely stems from a small founder population and/or past hunting pressures that reduced its numbers to approximately 30% of its current population of 1000 birds, rendering the Narcondam Hornbill susceptible to environmental and human-driven changes.

Wildlife responses to habitat loss and fragmentation are a central concern in the management and conservation of biodiversity. Small and isolated populations are vulnerable, both due to demographic and genetic mechanisms, which are often linked. Thus, understanding how (changes in) genetic diversity, effective population sizes, and levels of inbreeding relate to population size and degree of isolation is key for developing effective conservation strategies. High-density Single Nucleotide Polymorphism (SNP) arrays represent an increasingly cost-efficient tool to achieve the data needed for such analysis. Here, we present the development of a novel 625k SNP array for reindeer Rangifer tarandus and apply this array to assess conservation genetic issues across thirteen Norwegian wild reindeer populations of varying size, isolation, and genetic origin (i.e., semi-domesticated reindeer origin or a mix of wild reindeer and semi-domesticated reindeer origins). Many of these populations are currently completely isolated, with no gene flow from other populations. We genotyped n = 510 individuals sampled by hunters and found that variation in population size across the populations largely predicted their (recent loss of) genetic variation (observed heterozygosity, Ho), as well as effective population size (Ne) and (change in) level of recent inbreeding. For the smallest and most isolated populations, with total population sizes of <50-100 individuals and a high and increasing level of recent inbreeding, estimated loss of genetic variation was as high as 3-10% over the time span of a generation or less, and estimated Ne was as low as six individuals. With the current level of isolation and associated lack of gene flow, and considering their already low genetic diversity, these populations are hardly viable - neither demographically nor genetically - in the long term. These results have direct relevance for the management of Norwegian wild reindeer, recently red-listed as Near Threatened. Yet, these genetic challenges, characterizing many of the small wild reindeer populations in Norway, have been largely ignored by management thus far. Mitigation efforts such as reducing barriers would introduce substantial conservation dilemma due to the aim of avoiding further spread of chronic wasting disease (CWD), as well as potential further domestic introgression into populations with genetically wild reindeer (or mixed) origin. Nevertheless, our cost-efficient and high-density SNP array especially designed for reindeer and caribou offers a powerful genetic tool to include in future monitoring, providing important contributions to management and conservation decisions.

Snow leopards (Panthera uncia) are a keystone species of Central Asias high mountain ecosystem. The species is listed as vulnerable and is elusive, preventing accurate population assessments that could inform conservation actions. Non-invasive genetic monitoring conducted by citizen scientists offers avenues to provide key data on this species that would otherwise be inaccessible. From 2011 to 2015, OSI-Panthera citizen science expeditions tracked signs of presence of snow leopards along transects in the main valleys and crests of the Sarychat-Ertash State Reserve (Kyrgyzstan). Scat samples were genotyped at seven autosomal microsatellite loci and at a X/Y locus for sex identification, which allowed estimating a minimum of 11 individuals present in the reserve from 2011 to 2015. The genetic recapture of 7 of these individuals enabled diachronic monitoring, providing indications of individuals movements throughout the reserve. We found putative family relationships between several individuals. Our results demonstrate the potential of this citizen science program to get a precise description of a snow leopard population through time.

In this study, samples from 33 Guatemalan Beaded Lizard (Heloderma charlesbogerti) were analyzed for genetic diversity. Twenty-three samples were obtained from wild individuals from two separate population areas, and 10 samples were obtained from captive individuals. Because the seasonally dry tropical forest habitat sampled for this study, is degraded and fragmented, it was hypothesized that beaded lizard populations were small and isolated and would be subject to genetic erosion and an elevated extinction risk. To test this hypothesis, eight microsatellite markers were employed to analyze 22 individual samples from the population of Cabanas, Zacapa, a single individual from the eastern-most population and 10 captive individuals of unknown origin. An average of three alleles per maker was reported for the Cabanas population, evidencing a low genetic diversity. In addition, a recent bottleneck event was detected and an effective population size of 19.6 was estimated. Demographic reconstruction using a Bayesian approach was inconclusive possibly due to a small dataset and shallow coalescence trees obtained with the generated data. No clear structuring pattern was detected for the Cabanas population and most samples from individuals in captivity were found to have similar alleles to the ones from Cabanas. Population designation is challenging without the genotyping of every wild population, but unique alleles were found in captive individuals of unknown origin that could suggest that different genotypes might exist within other, less studied, wild populations. Low genetic diversity, and a small effective population size represent a risk for the Cabanas population facing the threats of isolation, habitat loss and climate change. These findings suggest that genetic management of the Cabanas population might be utilized to avoid high rates of inbreeding and subsequent inbreeding depression.

Trends in wildlife crime continue to rise and contribute to the ongoing decline of our planets biodiversity. We applied a genetic approach to ascertain the geographic origin of a suspected Seychelles Magpie-robin confiscated in Singapore during international transit, and to confirm illegal trade of this species. However, mitochondrial analyses revealed this individual to be a subspecies of Oriental Magpie-robin, endemic to the island of Borneo, and bearing similar morphology to the Seychelles species. We thus consider the implications of correct species identification on captive care and repatriation in cases of wildlife confiscation, and emphasise the value of using genetics in wildlife crime investigation.

Understanding the evolutionary history of diversifying lineages and the delineation of species remain major challenges for evolutionary biology. Here we use single nucleotide polymorphisms (SNPs) and sequence fragment presence-absence (SilicoDArT) data to combine phylogenetics and population genetics to assess species boundaries with a focus on diagnosability. We challenge current and proposed taxonomies in a genus of Australian freshwater turtles (Chelidae: Emydura) from northern Australia and southern New Guinea. In a six-step process, we combine phylogeny with the concept of diagnosability based on fixed allelic differences to select diagnosable lineages as candidate species. Four taxa are supported as diagnosable lineages, two of which we elevate to species status. The nuclear and mitochondrial phylogenies differed in important respects, which we attribute to recent or contemporary lateral transfer of mitochondria during hybridization events, deeper historical hybridization or possibly incomplete lineage sorting of the mitochondrial genome. Taxonomic decisions in cases of allopatry require subjective judgement. Our six-step strategy and the necessary (but not sufficient) criterion of diagnosability adds an additional level of objectivity before that subjectivity is applied, and so reduces the risk of taxonomic inflation that can accompany lineage approaches to species delimitation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/664252v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1b89bc8org.highwire.dtl.DTLVardef@fb892dorg.highwire.dtl.DTLVardef@1eb09a8org.highwire.dtl.DTLVardef@1c7300c_HPS_FORMAT_FIGEXP M_FIG C_FIG

Dispersal patterns dictate genetic population structure, and ultimately population resilience, through maintaining critical ecological processes and genetic diversity. Direct observation of dispersal events is not often possible, but genetic methods offer an alternative method of indirectly measuring dispersal. Here, we use 7 652 genome-wide single-nucleotide polymorphisms (SNPs) to evaluate genetic population structure and infer dispersal capabilities of the Western Grasswren (Amytornis textilis textilis; WGW) in Western Australia (n = 118), utilising a sister species, the Thick-billed Grasswren (Amytornis modestus; TBGW) as a comparison dataset (n = 80). We found genetic divergence and low genetic diversity between two populations (Hamelin and Peron) in the WGW, despite evidence of long dispersal distances within populations by females. In addition, the two WGW populations were found to be more genetically divergent than two described subspecies of TBGW, despite the WGW occurring over a smaller spatial scale. By comparing these two grasswren species, our data suggest a narrow strip of land may be acting as a geographic barrier in the WGW, limiting dispersal between a peninsula population to the mainland. We investigate if morphology aligns with genetic divergence, with some estimates of divergence between WGW populations greater than those between subspecies of TBGW. However, confidence intervals were large, preventing definitive conclusions. Our results support the hypothesis that peninsula populations of small, ground-dwelling birds are genetically isolated from adjacent mainland populations. Furthermore, there is evidence to suggest that the limited gene flow is asymmetrical, with directional dispersal occurring from the bounded peninsula population to the mainland. Our study also highlights how substantial genetic divergence does not necessarily coincide with phenotypic differences.

Otaria flavescens has been one of the most heavily exploited pinnipeds during the last 200 years with depletions of about 90% in some colonies. After the prohibition on sealing in South America, populations became stabilized except for the Uruguayan population, which showed a constant decrease. The underlying causes of its decline have remained unknown. This study used the RAD-seq approach to assess the variability and connectivity of some of the most overexploited sea lion colonies in the Atlantic Ocean. Our results revealed low allelic richness, nucleotide diversity and heterozygosity in the Uruguayan population and evidence of complete isolation from the Argentinean populations under study. In contrast, the Patagonian populations showed a high degree of connectivity, which could explain their recovery and high levels of current diversity. Our research emphasizes the precarious genetic status of the Uruguayan sea lion population, calling for the immediate implementation of conservation measures.

The European flat oyster (Ostrea edulis), like numerous other oyster species, has been exploited for millennia and cultivated and translocated for centuries. Following a severe population decline, and in the context of ongoing conservation and restoration programs, genetic considerations must now be addressed to avoid mistakes. The objective of our study was to complement population genetic studies conducted at various scales along European coasts. Our sampling primarily targeted the French Atlantic, English Channel, and Mediterranean coasts, aiming to provide a fine-scale genetic characterization of populations in these regions. By integrating SNP array and low-coverage sequencing datasets, we obtained a comprehensive overview of the population genetic structure of Ostrea edulis across western Europe. Most previously identified clusters in Western Europe were confirmed. In France, populations assigned to these clusters exhibited notable within-patch homogeneity. However, two key findings emerged: (1) an extensive overlap zone between the Atlantic and western Mediterranean clusters, spanning at least from southern Portugal to southern France, and (2) the detection of a novel, clearly distinct cryptic cluster east of the English Channel, whose geographic range remains to be better delineated. These insights are critical for informing management decisions, particularly as restoration and conservation plans are currently being implemented across the species range.

Population genetic analysis of species of conservation concern provides information to devise management plans to effectively conserve the genetic variation of endangered species. One such endangered plant, Physaria globosa is a federally endangered species in the mustard family with a geographically restricted range that occurs in four disjunct locations in Indiana, Kentucky, and Tennessee (i.e., Highland Rim and Nashville Basin regions) and along the Wabash, Kentucky, and Cumberland Rivers. In this study, we sampled populations from throughout the range of P. globosa, genotyped them using 20 microsatellite loci, and assessed genetic diversity and structure within and among populations. The goals of the study were to understand: 1) levels of genetic diversity in P. globosa and whether populations show evidence of having experienced reductions in genetic diversity as the result of genetic bottlenecks, genetic drift, or inbreeding, 2) rangewide genetic diversity and structure in P. globosa and how genetic structure is affected by the disjunctions in the species range, and 3) implications for prioritization of in-situ and ex-situ conservation efforts. On average, P. globosa showed comparable levels of genetic diversity to other species of Physaria. However, some populations showed evidence of inbreeding, genetic bottlenecks, or decreases in genetic diversity, possibly due to anthropogenic or climate-related pressures and decreases in population size due to competition with invasive bush honeysuckle. Genetic variation was strongly structured into two main geographic groups, one in the northern part of the species range (KY and IN), and the other in the southern part of the species range (TN), but some populations likely originated via long-distance dispersal. We also found significant isolation by distance, likely due to both life history characteristics and physical barriers associated with the complex topological structure of the landscape occupied by P. globosa, limiting population connectivity. Given the strong genetic structure found in P. globosa, several populations should be protected and managed within each geographic region to conserve genetic variation. Ex situ conservation will also be important to protect genetic diversity, particularly for populations that are difficult to access and manage.

AbstractObtaining genetic information from rare species is challenging for scientists, but it is crucial for understanding animal evolutionary history and informing conservation management initiatives. We present the first example of a collaborative local network that includes zoos and natural history collections to investigate the evolution, systematics, and conservation concerns of olingos (genus Bassaricyon, Procyonidae, Carnivora, Mammalia). We sequenced the entire (1,146 base pairs) cytochrome b gene to phylogenetically identify individuals that have been victims of wildlife trafficking. Unexpectedly, we detected an individual specimen belonging to Bassaricyon medius orinomus (western lowland olingo), which may represent a new geographical record for this taxon in Ecuador. Through our practical experiences, we describe how local collaboration is possible and crucial for promoting wildlife genetic research in the Global South and contributing to protecting the last populations of rare mammals. We also discuss the significance of wild animals under human care as a valuable genetic resource for scientific research, conservation strategies, and informed wildlife management decisions.

Ex-situ conservation is crucial for preserving endangered species by breeding to preserve genetic diversity and provide surplus for translocation, thereby supporting in-situ conservation and enhancing wild populations. Genomic tools can assist breeding strategies and ensure long-term success of ex-situ conservation efforts by assessing genetic introgression, determining genetic origin and status, and inferring genetic relatedness of potential founders. This study aims to develop a comprehensive genomic approach for assessing the genetic profiles of candidate founders for ex-situ breeding, with the goal of releasing surplus individuals while using the endangered Saker Falcons (Falco cherrug) as a study model. Genetic clustering of 31 captive sakers revealed both diverse origins, some matching wild Asian individuals (Mongolia), and a lineage (Group III) divergent from wild populations. Comparative analyses detected hybridisation signals in 61.3% of individuals, including three with gyrfalcon (F. rusticolus) introgression and Group IIIs pronounced divergence indicating past interbreeding with an unknown falcon species. All captive birds exhibited severe inbreeding (FROH = 0.352), far exceeding wild population levels (FROH = 0.131). Using the partial pedigree data of the captive sakers, we established a genetic relatedness threshold of 0.154 (95% CI: 0.096-0.211) to identify cases of related dyads (both full and half-siblings). At this threshold, 18.3% of captive dyads showed relatedness, with asymmetric genetic contributions between pairs, reflecting a functionally small breeding flock. To avoid risks from releasing admixed or inbred individuals, we recommend excluding introgressed birds, strategically pairing purebreds, and sourcing new founders from genetically validated wild sources, especially underrepresented Central Asian lineages. Applying this genomic framework, we demonstrate its role in safeguarding genetic integrity and preventing genetic erosion in conservation breeding programmes, thereby establishing a standard for genomic-led ex-situ conservation.

Genetic resources for species monitoring should ideally be relevant for the species full distribution range, feasible economically and logistically, and validated for the range of sample types collected from the field. This is particularly important for large carnivores that are elusive and wide-ranging, where individual and population processes often traverse administrative borders, and where obtaining high-quality samples can be challenging. Here we present a small species-specific SNP panel for leopards. We used whole genome data from across the global range and RAD sequence data from Zambian leopards to select markers for assay development. These were ascertained for 590 individual leopards from eight African countries and final selection was based on marker variation and performance on non-invasive samples. The final 96 marker panel holds 5 mitochondrial markers for species recognition, 3 Y-markers for determination of individual sex, 3 X-markers and 85 somatic markers, with an associated genetic baseline holding nearly 900 individuals. The selected autosomal markers hold variation across the global range with high power to identify individuals (PID=2,45x10-35) and in most cases their provenance with high assignment probability (>95%). Markers were also selected based on their performance on samples with low target DNA content, with distinct genotype separation in the output marker plots. The genotypes from this panel are thus straightforward to analyze and do not require computationally challenging bioinformatic resources, making this a low cost and accessible resource for leopard monitoring and research.

Animal translocations are becoming increasingly popular as a tool for conservationists. Demographic factors can be crucial determinants dictating translocation viability in the short term. Translocated populations pass through artificial bottlenecks and can suffer from founder effects. Reduction in genetic variation relative to their source populations is likely, limiting their adaptive potential. Founder events can increase frequencies of deleterious alleles due to elevated rates of inbreeding and inbreeding depression. Here, we describe the effects of human-driven, serial population translocations on the genetic diversity of critically endangered Anegada iguanas (Cyclura pinguis) in the British Virgin Islands. Though founding populations were extremely small (N=8, N=4), the census sizes of translocated iguana populations increased dramatically over the first twenty years. This implies that these translocations were successful from a demographic perspective despite the small number of animals used, indicating a genetic paradox. To quantify genetic signatures in these bottlenecked populations, blood samples were collected from the source population and two translocated populations and genotyped at 21 microsatellite loci. We found that allele frequencies in translocated populations differed significantly from those of the source, with the translocated populations having less genetic diversity. However, common methods for estimating presence of genetic bottlenecks were non-significant. Estimates of internal relatedness by age class suggest that inbreeding depression may be elevated after translocation, likely reflecting the small initial population sizes associated with these translocation events. Anecdotally, our work shows that translocations may result in subtle genetic erosion that has long-term population viability impacts, even when census size indicates success.

Madagascar is home to seven unique baobab species in the genus Adansonia, all threatened by climate change, habitat destruction, and deforestation. Previous studies have highlighted the vulnerability of baobabs, particularly A. suarezensis, without delving into the specific genetic structure of its populations. In this paper we examine the genetic structure, diversity, and connectivity of seven populations of A. suarezensis, using genome-wide Single Nucleotide Polymorphism (SNP) data. The results revealed significant genetic differentiation between inland and coastal populations, with the Mahory population forming a distinct genetic cluster characterized by high heterozygosity but low polymorphism, indicative of historical bottlenecks. In contrast, northern populations showed greater admixture and gene flow but higher inbreeding coefficients in coastal regions, such as Ambilo and Cap dAmbre, suggesting localized inbreeding depression. Additionally, historical climatic shifts and potential anthropogenic dispersal are explored as contributing factors to the current genetic patterns. This study highlights the importance of understanding genetic dynamics for conservation, emphasizing habitat restoration and targeted management strategies to preserve the evolutionary potential of A. suarezensis and ensure its long-term survival.

Aquatic species throughout the world are threatened by extinction in many parts of their range, particularly in their most southerly distributions. Arctic charr (Salvelinus alpinus) is a Holarctic species with a distribution that includes the glacial lakes of North Wales, towards it southern limit. To date, no genetic studies have been conducted to determine the genetic health of the three remaining native Arctic charr populations in North Wales, despite exposure to stocking and adverse environmental and ecological conditions. We used seven microsatellite loci to determine whether: 1) genetic differentiation existed between native populations; 2) translocated populations from Llyn Peris were genetically similar to the historically connected Llyn Padarn population; and 3) hatchery supplementation negatively impacted genetic diversity in Llyn Padarn. All three native populations retained their genetic integrity, with Llyn Bodlyn showing high levels of divergence (FST = 0.26 {+/-} 0.02SD) as well as low genetic diversity (HO 0.30) compared to remaining populations (HO 0.64 {+/-} 0.14SD). Although evidence suggests that stocking increased the effective population size of Llyn Padarn in the short term without impacting genetic diversity, the long term effects of such practices are yet to be seen. Results provide baseline data for conservation management, and highlight the need for protection of small isolated populations that are being negatively impacted by the processes of genetic drift due to escalating anthropogenic pressures. Continual monitoring of both Arctic charr and their habitats using a combination of methods will increase the likelihood that these threatened and iconic populations will persist in the future.