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For many species, the ability to rapidly adapt to changes in seasonality is essential for long-term survival. In the Arctic, seasonal moulting is a key life-history event that provides year-round camouflage and thermal protection. However, increased climatic variability of seasonal events can lead to phenological mismatch. In this study, we investigated whether winter-white (white morph) and winter-brown (blue morph) Arctic foxes (Vulpes lagopus) could adjust their winter-to-summer moult to match local environmental conditions. We used camera trap images spanning an eight-year period to quantify the timing and rate of fur change in a polymorphic subpopulation in south-central Norway. Seasonal snow cover duration and temperature governed the phenology of the spring moult. We observed a later onset and longer moulting duration with decreasing temperature and longer snow season. Additionally, white foxes moulted earlier than blue in years with shorter periods of snow cover and warmer temperatures. These results suggest that phenotypic plasticity allows Arctic foxes to modulate the timing and rate of their spring moult as snow conditions and temperatures fluctuate. With the Arctic warming at an unprecedented rate, understanding the capacity of polar species to physiologically adapt to a changing environment is urgently needed in order to develop adaptive conservation efforts. Moreover, we provide the first evidence for variations in the moulting phenology of blue and white Arctic foxes. Our study underlines the different intraspecific selective pressures that can exist in populations where several morphs co-occur, and illustrates the importance of integrating morph-based differences in future management strategies of such polymorphic species. camera trapping, camouflage, climate change, colour polymorphism, phenological mismatch, phenotypic plasticity

Accelerating climate change is causing severe habitat fragmentation in the Arctic, threatening the persistence of many cold-adapted species. The Scandinavian arctic fox (Vulpes lagopus) is highly fragmented, with a once continuous, circumpolar distribution, it struggled to recover from a demographic bottleneck in the late 19th century. The future persistence of the entire Scandinavian population is highly dependent on the northernmost Fennoscandian subpopulations (Scandinavia and the Kola Peninsula), to provide a link to the viable Siberian population. By analyzing 43 arctic fox genomes, we quantified genomic variation and inbreeding in these populations. Signatures of genome erosion increased from Siberia to northern Sweden indicating a stepping-stone model of connectivity. In northern Fennoscandia, runs of homozygosity (ROH) were on average ~1.47-fold longer than ROH found in Siberia, stretching almost entire scaffolds. Moreover, consistent with recent inbreeding, northern Fennoscandia harbored more homozygous deleterious mutations, whereas Siberia had more in heterozygous state. This study underlines the value of documenting genome erosion following population fragmentation to identify areas requiring conservation priority. With the increasing fragmentation and isolation of Arctic habitats due to global warming, understanding the genomic and demographic consequences is vital for maintaining evolutionary potential and preventing local extinctions.

Accelerating climate change is causing severe habitat fragmentation in the Arctic, threatening the persistence of many cold-adapted species. The Scandinavian arctic fox (

1. Estimating the contribution of demographic parameters to changes in population growth is essential for understanding why populations fluctuate. Integrated population models (IPMs) offer a possibility to estimate the contributions of additional demographic parameters, for which no data have been explicitly collected— typically immigration. Such parameters are often subsequently highlighted as important drivers of population growth. Yet, accuracy in estimating their temporal variation, and consequently their contribution to changes in population growth rate, has not been investigated. 2. To quantify the magnitude and cause of potential biases when estimating the contribution of immigration using IPMs, we simulated data (using northern wheatear Oenanthe oenanthe population estimates) from controlled scenarios to examine potential biases and how they depend on IPM parameterization, formulation of priors, the level of temporal variation in immigration and sample size. We also used empirical data on populations with known rates of immigration: Soay sheep Ovis aries and Mauritius kestrel Falco punctatus with zero immigration and grey wolf Canis lupus in Scandinavia with near-zero immigration. 3. IPMs strongly overestimated the contribution of immigration to changes in population growth in scenarios when immigration was simulated with zero temporal variation (proportion of variance attributed to immigration = 63% for the more constrained formulation and real sample size) and in the wild populations, where the true number of immigrants was zero or near-zero (kestrel 19.1%–98.2%, sheep 4.2%– 36.1% and wolf 84.0%–99.2%). Although the estimation of the contribution of immigration in the simulation study became more accurate with increasing temporal variation and sample size, it was often not possible to distinguish between an accurate estimation from data with high temporal variation versus an overestimation from data with low temporal variation. Unrealistically, large sample sizes may be required to estimate the contribution of immigration well. 4. To minimize the risk of overestimating the contribution of immigration (or any additional parameter) in IPMs, we recommend to: (a) look for evidence of variation in immigration before investigating its contribution to population growth, (b) simulate and model data for comparison to the real data and (c) use explicit data on immigration when possible.

Significance We are experiencing the accelerated loss and reconfiguration of biological diversity. Meanwhile, those charged with natural resource management are struggling to meet the challenges of monitoring and managing wildlife populations across vast areas crisscrossed by political borders. What if, akin to weather maps, we could track and forecast the dynamics of wildlife populations across space and time? Using the world’s most extensive large carnivore monitoring program, we showcase the application of an effective tool for spatially explicit quantification of wildlife population dynamics at scales that are relevant to management and conservation., The ongoing recovery of terrestrial large carnivores in North America and Europe is accompanied by intense controversy. On the one hand, reestablishment of large carnivores entails a recovery of their most important ecological role, predation. On the other hand, societies are struggling to relearn how to live with apex predators that kill livestock, compete for game species, and occasionally injure or kill people. Those responsible for managing these species and mitigating conflict often lack fundamental information due to a long-standing challenge in ecology: How do we draw robust population-level inferences for elusive animals spread over immense areas? Here we showcase the application of an effective tool for spatially explicit tracking and forecasting of wildlife population dynamics at scales that are relevant to management and conservation. We analyzed the world’s largest dataset on carnivores comprising more than 35,000 noninvasively obtained DNA samples from over 6,000 individual brown bears (Ursus arctos), gray wolves (Canis lupus), and wolverines (Gulo gulo). Our analyses took into account that not all individuals are detected and, even if detected, their fates are not always known. We show unequivocal quantitative evidence of large carnivore recovery in northern Europe, juxtaposed with the finding that humans are the single-most important factor driving the dynamics of these apex predators. We present maps and forecasts of the spatiotemporal dynamics of large carnivore populations, transcending national boundaries and management regimes.

Translocation of captive-bred animals has become a widespread conservation practice to counteract species extinctions. We analyse and discuss the apparent success and shortcomings of Arctic fox (Vulpes lagopus) reintroductions in alpine tundra areas of Norway. We followed the fate of 915 foxes between 2007 and 2020 and estimated the apparent survival and reproductive success of captive-bred and released Arctic foxes, compared to wild-born descendants. Relationship to abundance of small rodents, population size, and age were explored. Overall, apparent survival and probability of breeding were similar between captive-bred and wild-born foxes, positively linked to rodent abundance. For wild-born foxes, both breeding propensity and litter size declined with increasing fox population size. This could be a first sign of the limited capacity of single tundra patches to house self-subsistent populations. Thus, facilitating and maintaining connectivity among remnant and re-established Arctic fox populations, creating functional metapopulations, is essential for further improvement and longterm survival. Relying on the combined measures of supplementary feeding and red-fox (Vulpes vulpes) control, the Arctic fox captive-breeding and reintroduction programme has so far been highly successful. However, anthropogenic drivers facilitating red fox invasion into the Arctic fox habitat, along with climate driven irregularities and dampened small rodent cycles, could inhibit the establishment of a self-sustained population. A more holistic ecosystem approach and conservation measures to restore alpine fauna should be considered.

Transboundary connectivity is a key component when conserving and managing animal species that require large areas to maintain viable population sizes. Wolves Canis lupus recolonized the Scandinavian Peninsula in the early 1980s. The population is geographically isolated and relies on immigration to not lose genetic diversity and to maintain long term viability. In this study we address (1) to what extent the genetic diversity among Scandinavian wolves has recovered during 30 years since its foundation in relation to the source populations in Finland and Russia, (2) if immigration has occurred from both Finland and Russia, two countries with very different wolf management and legislative obligations to ensure long term viability of wolves, and (3) if immigrants can be assumed to be unrelated. Using 26 microsatellite loci we found that although the genetic diversity increased among Scandinavian wolves (n = 143), it has not reached the same levels found in Finland (n = 25) or in Russia (n = 19). Low genetic differentiation between Finnish and Russian wolves, complicated our ability to determine the origin of immigrant wolves (n = 20) with respect to nationality. Nevertheless, based on differences in allelic richness and private allelic richness between the two countries, results supported the occurrence of immigration from both countries. A priori assumptions that immigrants are unrelated is non-advisable, since 5.8% of the pair-wise analyzed immigrants were closely related. To maintain long term viability of wolves in Northern Europe, this study highlights the potential and need for management actions that facilitate transboundary dispersal.

Swayne's hartebeest Alcelaphus buselaphus swaynei was once widely distributed in the Horn of Africa. By the early 20th century, however, it was extirpated across most of its range and is now limited to two relict populations in the Ethiopian Rift Valley and categorized as Endangered on the IUCN Red List. In this study, we estimated the size and genetic diversity of these two remaining populations, with a particular focus on competition with livestock. We used a total block count method for both Swayne's hartebeest and livestock population counts, and faecal samples for a population genetic analysis. We estimated the total population of Swayne's hartebeest to be 1,528, with 518 individuals in Senkele Swayne's Hartebeest Sanctuary and 1,010 individuals in Maze National Park. Livestock densities were 212 and 153 times those of Swayne's hartebeest in Senkele Swayne's Hartebeest Sanctuary and Maze National Park, respectively. Among 73 mitochondrial D-loop sequences (34 from Senkele Swayne's Hartebeest Sanctuary and 39 from Maze National Park), we found 22 haplotypes (Senkele 12, Maze 16, shared 6). Population genetic parameters suggest only weak sub-structuring between the two populations (FST = 0.164). Despite the positive population trends in both protected areas, the spatial overlap with livestock may lead to future population decline as a result of resource competition and disease transmission. We therefore recommend further translocation to other protected areas within the species’ former range.

Genetic drift can dramatically change allele frequencies in small populations and lead to reduced levels of genetic diversity, including loss of segregating variants. However, there is a shortage of quantitative studies of how genetic diversity changes over time in natural populations, especially on genome-wide scales. Here, we analyzed whole-genome sequences from 76 wolves of a highly inbred Scandinavian population, founded by only one female and two males, sampled over a period of 30 yr. We obtained chromosome-level haplotypes of all three founders and found that 10%-24% of their diploid genomes had become lost after about 20 yr of inbreeding (which approximately corresponds to five generations). Lost haplotypes spanned large genomic regions, as expected from the amount of recombination during this limited time period. Altogether, 160,000 SNP alleles became lost from the population, which may include adaptive variants as well as wild-type alleles masking recessively deleterious alleles. Although not sampled, we could indirectly infer that the two male founders had megabase-sized runs of homozygosity and that all three founders showed significant haplotype sharing, meaning that there were on average only 4.2 unique haplotypes in the six copies of each autosome that the founders brought into the population. This violates the assumption of unrelated founder haplotypes often made in conservation and management of endangered species. Our study provides a novel view of how whole-genome resequencing of temporally stratified samples can be used to visualize and directly quantify the consequences of genetic drift in a small inbred population.

Spatial capture-recapture modelling (SCR) is a powerful tool for estimating densities, population size and space use of elusive animals. Here, we applied SCR modeling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016 - 2018) and southern Norway (2017 - 2018). Estimated densities were overall lower in the northern study area (mean = 0.04 foxes per km2 [95%CI: 0.02-0.09] in 2016, 0.09 [0.05-0.18] in 2017 and 0.07 [0.04-0.13] in 2018) compared to the southern study area (0.16 [0.09-0.26] in 2017 and 0.10 [0.07-0.16] in 2018). We found a positive effect of forest cover on density in the northern, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover, but could also be due to climatic differences (e.g., winter severity) between the two areas. Estimated mean home range size in the northern study area was 45 km2 [34-60] for females and 88 km2 [69-113] for males. Mean home range sizes were smaller in the southern study area (26 km2 [16-42] for females and 56 km2 [35-91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modeling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space-use.

Age at first reproduction constitutes a key life-history trait in animals and is evolutionarily shaped by fitness benefits and costs of delayed versus early reproduction. The understanding of how intrinsic and extrinsic changes affects age at first reproduction is crucial for conservation and management of threatened species because of its demographic effects on population growth and generation time. For a period of 40 years in the Scandinavian wolf (Canis lupus) population, including the recolonization phase, we estimated age at first successful reproduction (pup survival to at least three weeks of age) and examined how the variation among individuals was explained by sex, population size (from 1 to 74 packs), primiparous or multiparous origin, reproductive experience of the partner and inbreeding. Median age at first reproduction was 3 years for females (n = 60) and 2 years for males (n = 74), and ranged between 1 and 8–10 years of age (n = 297). Female age at first reproduction decreased with increasing population size, and increased with higher levels of inbreeding. The probability for males to reproduce later first decreased, reaching its minimum when the number of territories approached 40–60, and then increased with increasing population size. Inbreeding for males and reproductive experience of parents and partners for both sexes had overall weak effects on age at first reproduction. These results allow for more accurate parameter estimates when modelling population dynamics for management and conservation of small and vulnerable wolf populations, and show how humans through legal harvest and illegal hunting influence an important life-history trait like age at first reproduction.

1. Selection for crypsis has been recognized as an important ecological driver of animal colouration, whereas the relative importance of thermoregulation is more contentious with mixed empirical support. A potential thermal advantage of darker individuals has been observed in a wide range of animal species. Arctic animals that exhibit colour polymorphisms and undergo seasonal colour moults are interesting study subjects for testing the two alternative hypotheses: demographic performance of different colour morphs might be differentially affected by snow cover with a cryptic advantage for lighter morphs, or conversely by winter temperature with a thermal advantage for darker morphs. 2. In this study, we explored whether camouflage and thermoregulation might explain differences in reproduction and survival between the white and blue colour morphs of the Arctic fox Vulpes lagopus under natural conditions. 3. Juvenile and adult survival, breeding propensity and litter size were measured for 798 captive-bred and released or wild-born Arctic foxes monitored during an 11-year period (2007–2017) in two subpopulations in south-central Norway. We investigated the proportion of the two colour morphs and compared their demographic performance in relation to spatial variation in duration of snow cover, onset of snow season and winter temperatures. 4. After population re-establishment, a higher proportion of blue individuals was observed among wild-born Arctic foxes compared to the proportion of blue foxes released from the captive population. Our field study provides the first evidence for an effect of colour morph on the reproductive performance of Arctic foxes under natural conditions, with a higher breeding propensity of the blue morph compared to the white one. Performance of the two colour morphs was not differentially affected by the climatic variables, except for juvenile survival. Blue morph juveniles showed a tendency for higher survival under colder winter temperatures but lower survival under warmer temperatures compared to white morph juveniles. 5. Overall, our findings do not consistently support predictions of the camouflage or the thermoregulation hypotheses. The higher success of blue foxes suggests an advantage of the dark morph not directly related to disruptive selection by crypsis or thermoregulation. Our results rather point to physiological adaptations and behavioural traits not necessarily connected to thermoregulation, such as stress response, immune function, sexual behaviour and aggressiveness. Our findings highlight the need to explore the potential role of genetic linkage or pleiotropy in influencing the fitness of white and blue Arctic foxes as well as other species with colour polymorphisms. apparent survival, Arctic fox, camouflage, capture–mark– recapture models, colour polymorphism, fitness, reproductive performance, snow cover This is an open access article under the terms of the Creative Commons Attribution-NonCommercial- NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2021 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society

Spatial capture–recapture modelling (SCR) is a powerful tool for estimating density, population size, and space use of elusive animals. Here, we applied SCR modelling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016–2018) and southern Norway (2017–2018). Estimated densities were overall lower in the central study area (mean = 0.04 foxes per km2 in 2016, 0.10 in 2017, and 0.06 in 2018) compared to the southern study area (0.16 in 2017 and 0.09 in 2018). We found a positive effect of forest cover on density in the central, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover. Estimated mean home-range size in the central study area was 45 km2 [95%CI 34–60] for females and 88 km2 [69–113] for males. Mean home-range sizes were smaller in the southern study area (26 km2 [16–42] for females and 56 km2 [35–91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modelling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space use.

Knowledge about the connectivity among natural populations is essential to identify management units for effective conservation actions. Conservation-minded management has led to the recovery of large carnivore populations in northern Europe, possibly restoring connectivity between the two separated, but expanding brown bear (Ursus arctos) populations on the Scandinavian peninsula to the west and Karelia, a part of the large Eurasian population, to the east. The degree of connectivity between these populations has been poorly understood, therefore we investigated the extent of connectivity between the two populations using autosomal microsatellites and Y chromosome haplotypes in 924 male bears (the dispersing sex), sampled during a period of 12 years (2005–2017) across the transborder area where these two populations meet. Our results showed that the two populations are not genetically isolated as reported in earlier studies. We detected recent asymmetrical gene flow at a rate (individuals per generation) of 4.6–5.5 (1%) from Karelia into Scandinavia, whereas the rate was approximately 27.1–34.5 (8%) in the opposite direction. We estimated historical gene flow of effective number of migrants to be between 1.7 and 2.5 between the populations. Analyses of Y chromosome markers supported these results. Successful recovery and expansion of both populations led to the restoration of connectivity, however, it is asymmetric, possibly due to different recovery histories and population densities. By aligning monitoring between neighboring countries, we were able to better understand the biological processes across the relevant spatial scale. Brown bear Genetic structure Male gene flow Microsatellites Migration Recovery Ursus arctos Wildlife monitoring Y chromosome

Genome-wide association studies provide good opportunities for studying the genetic basis of adaptive traits in wild populations. Yet, previous studies often failed to identify major effect genes. In this study, we used high-density single nucleotide polymorphism and individual fitness data from a wild non-model species. Using a whole-genome approach, we identified the MC1R gene as the sole causal gene underlying Arctic fox Vulpes lagopus fur colour. Further, we showed the adaptive importance of fur colour genotypes through measures of fitness that link ecological and evolutionary processes. We found a tendency for blue foxes that are heterozygous at the fur colour locus to have higher fitness than homozygous white foxes. The effect of genotype on fitness was independent of winter duration but varied with prey availability, with the strongest effect in years of increasing rodent populations. MC1R is located in a genomic region with high gene density, and we discuss the potential for indirect selection through linkage and pleiotropy. Our study shows that whole-genome analyses can be successfully applied to wild species and identify major effect genes underlying adaptive traits. Furthermore, we show how this approach can be used to identify knowledge gaps in our understanding of interactions between ecology and evolution.

After decades, even centuries of persecution, large carnivore populations are widely recovering in Europe. Considering the recent recovery of the wolverine (Gulo gulo) in Finland, our aim was to evaluate genetic variation using 14 microsatellites and mtDNA control region (579 bp) in order (1) to determine whether the species is represented by a single genetic population within Finland, (2) to quantify the genetic diversity, and (3) to estimate the effective population size. We found two major genetic clusters divided between eastern and northern Finland based on microsatellites (FST= 0.100) but also a significant pattern of isolation by distance. Wolverines in western Finland had a genetic signature similar to the northern cluster, which can be explained by former translocations of wolverines from northern to western Finland. For both main clusters, most estimates of the effective population sizeNewere below 50. Nevertheless, the genetic diversity was higher in the eastern cluster (HE= 0.57,AR= 4.0,AP= 0.3) than in the northern cluster (HE= 0.49,AR= 3.7,AP= 0.1). Migration between the clusters was low. Two mtDNA haplotypes were found: one common and identical to Scandinavian wolverines; the other rare and not previously detected. The rare haplotype was more prominent in the eastern genetic cluster. Combining all available data, we infer that the genetic population structure within Finland is shaped by a recent bottleneck, isolation by distance, human-aided translocations and postglacial recolonization routes.

The Arctic fox (Vulpes lagopus) population in Fennoscandia experienced a drastic bottleneck in the late 19th century as a result of high hunting pressure. In the 1990s, despite nearly 70 years of protection, the population showed no signs of recovery. In order to mitigate the population decline and facilitate re-establishment, conservation actions including supplementary feeding and red fox culling were implemented in 1998, followed by the reintroduction of foxes from a captive breeding programme, starting in 2006. A positive demographic impact of these actions is evident from a doubling of the population size over the past decade. We used genetic data collected in eight subpopulations between 2008 and 2015 to address whether the recent demographic recovery has been complemented by changes in genetic variation and connectivity between subpopulations. Our results show that genetic variation within subpopulations has increased considerably during the last decade, while genetic differentiation among subpopulations has decreased. A marked shift in metapopulation dynamics is evident during the study period, suggesting substantially increased migration across the metapopulation. This shift followed the recolonization of an extinct subpopulation through the release of foxes from the captive breeding programme and was synchronized in time with the implementation of supplementary feeding and red fox culling in stepping stone patches between core subpopulations in mid-Scandinavia. Indeed, the increase in genetic variation and connectivity in the Scandinavian arctic fox population suggests that metapopulation dynamics have been restored, which may indicate an increase in the long-term viability of the population. This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Estimating wildlife population size is fundamental for wildlife management and conservation. However, making monitoring of population size less resource demanding while still keeping a high monitoring accuracy and precision remains a recurrent challenge. One proposed alternative to count individuals is to instead focus on counting a segment of the population that is easier to monitor but at the same time well informative on total population size. We show how total population size can be estimated from group counts by using an individual-based population model in a social living species. We developed a wolf ( Canis lupus ) specific Individual Based Model and used Approximate Bayesian Computation (ABC) to fit this population model to the time series of annual number of packs, reproductions and pairs obtained from Scandinavian monitoring data. Model informative priors were obtained with data from collared individuals by the Scandinavian wolf research project. The fitted model was then used to estimate a conversion factor from number of packs to total number of individuals and to number of reproductions. There was a good fit between the retained simulations by ABC and the observed Scandinavian wolf population trajectory. The fitted simulations returned a conversion factor of 8.0 (95% CI = 6.62–10.07) from number of packs to total population size and of 1.0 (95% CI = 0.93–1.12) to number of reproductions in December. A sensitivity analysis revealed that the conversion factor from packs to total population size was positively correlated with pup survival and litter size and negatively correlated with subadult, vagrant and adult survivals. Using an individual based model allowed us to model the full complexity of demographic traits of a social-living species such as the wolf. The flexibility of the model also meant that the conversion factor could be estimated for any month during the year. Our approach to estimate total population size from counts of groups requires having a population model where both individuals and groups are explicitly described and can be applied to other wolf populations and group-living species where counting all individuals over a large area is unfeasible.

For socially monogamous species, breeder bond dissolution has important consequences for population dynamics, but the extent to which extrinsic or intrinsic population factors causes pair dissolution remain poorly understood, especially among carnivores. Using an extensive life-history data set, a survival analysis and competing risks framework, we examined the fate of 153 different wolf (Canis lupus) pairs in the recolonizing Scandinavian wolf population, during 14 winters of snow tracking and DNA monitoring. Wolf pair dissolution was generally linked to a mortality event and was strongly affected by extrinsic (i.e. anthropogenic) causes. No divorce was observed, and among the pair dissolution where causes have been identified, death of one or both wolves was always involved. Median time from pair formation to pair dissolution was three consecutive winters (i.e. approximately 2 years). Pair dissolution was mostly human-related, primarily caused by legal control actions (36·7%), verified poaching (9·2%) and traffic-related causes (2·1%). Intrinsic factors, such as disease and age, accounted for only 7·7% of pair dissolutions. The remaining 44·3% of dissolution events were from unknown causes, but we argue that a large portion could be explained by an additional source of human-caused mortality, cryptic poaching. Extrinsic population factors, such as variables describing the geographical location of the pair, had a stronger effect on risk of pair dissolution compared to anthropogenic landscape characteristics. Population intrinsic factors, such as the inbreeding coefficient of the male pair member, had a negative effect on pair bond duration. The mechanism behind this result remains unknown, but might be explained by lower survival of inbred males or more complex inbreeding effects mediated by behaviour. Our study provides quantitative estimates of breeder bond duration in a social carnivore and highlights the effect of extrinsic (i.e. anthropogenic) and intrinsic factors (i.e. inbreeding) involved in wolf pair bond duration. Unlike the effects of intrinsic and extrinsic factors that are commonly reported on individual survival or population growth, here we provide quantitative estimates of their potential effect on the social unit of the population, the wolf pair.

Although abundance estimates have a strong bearing on the conservation status of a species, less than 2% of the global snow leopard distribution range has been sampled systematically, mostly in small survey areas. In order to estimate snow leopard density across a large landscape, we collected 347 putative snow leopard scats from 246 transects (490 km) in twenty-six 5 × 5km sized sampling grid cells within 4393 km2 in Annapurna-Manaslu, Nepal. From 182 confirmed snow leopard scats, 81 were identified as belonging to 34 individuals; the remaining were discarded for their low (

Spatial capture–recapture models (SCR) are used to estimate animal density and to investigate a range of problems in spatial ecology that cannot be addressed with traditional nonspatial methods. Bayesian approaches in particular offer tremendous flexibility for SCR modeling. Increasingly, SCR data are being collected over very large spatial extents making analysis computational intensive, sometimes prohibitively so. To mitigate the computational burden of large‐scale SCR models, we developed an improved formulation of the Bayesian SCR model that uses local evaluation of the individual state‐space (LESS). Based on prior knowledge about a species’ home range size, we created square evaluation windows that restrict the spatial domain in which an individual's detection probability (detector window) and activity center location (AC window) are estimated. We used simulations and empirical data analyses to assess the performance and bias of SCR with LESS. LESS produced unbiased estimates of SCR parameters when the AC window width was ≥5σ (σ: the scale parameter of the half‐normal detection function), and when the detector window extended beyond the edge of the AC window by 2σ. Importantly, LESS considerably decreased the computation time needed for fitting SCR models. In our simulations, LESS increased the computation speed of SCR models up to 57‐fold. We demonstrate the power of this new approach by mapping the density of an elusive large carnivore—the wolverine (Gulo gulo)—with an unprecedented resolution and across the species’ entire range in Norway (> 200,000 km2). Our approach helps overcome a major computational obstacle to population and landscape‐level SCR analyses. The LESS implementation in a Bayesian framework makes the customization and fitting of SCR accessible for practitioners working at scales that are relevant for conservation and management.

In wide ranging species, portions of the same population often fall within different administrative jurisdictions; where different regulations apply. The same species can be fully protected or heavily harvested on different sides of a border. This can generate a source–sink dynamic from the areas with lower to those with higher mortality, a process known as compensatory immigration. We tested this hypothesis on the wolverine (Gulo gulo) population of southern Scandinavia, which is shared between two countries: Sweden and Norway. Wolverines are fully protected in Sweden, but subject to intensive population regulation in Norway. Using non-invasive genetic sampling and capture–recapture modeling, we analyzed the dynamics of wolverine survival and emigration patterns between 2002 and 2013. Wolverines in Norway experienced a lower survival than in Sweden. Migration across the national border was directed towards movements from Sweden to Norway. There was a functional relationship between harvest rate in Norway and emigration rates across the national border, both at the individual and population level, thus confirming the compensatory immigration hypothesis. Contrasting management regimes within the same population can generate undesired demographic and spatial dynamics, jeopardize conservation goals on the two sides of a border, and reduce the efficiency of management actions. This calls for the adoption of a coordinate population approach in large carnivore conservation and management. Failing to do so can cause a waste of the already limited resources allocated for large carnivore conservation, and it might hinder effective conflict mitigation.

Population expansions of boreal species are among the most substantial ecological consequences of climate change, potentially transforming both structure and processes of northern ecosystems. Despite their importance, little is known about expansion dynamics of boreal species. Red foxes (Vulpes vulpes) are forecasted to become a keystone species in northern Europe, a process stemming from population expansions that began in the 19th century. To identify the relative roles of geographic and demographic factors and the sources of northern European red fox population expansion, we genotyped 21 microsatellite loci in modern and historical (1835-1941) Fennoscandian red foxes. Using Bayesian clustering and Bayesian inference of migration rates, we identified high connectivity and asymmetric migration rates across the region, consistent with source-sink dynamics, whereby more recently colonized sampling regions received immigrants from multiple sources. There were no clear clines in allele frequency or genetic diversity as would be expected from a unidirectional range expansion from south to north. Instead, migration inferences, demographic models and comparison to historical red fox genotypes suggested that the population expansion of the red fox is a consequence of dispersal from multiple sources, as well as in situ demographic growth. Together, these findings provide a rare glimpse into the anatomy of a boreal range expansion and enable informed predictions about future changes in boreal communities.

Understanding the response of boreal species to past climate warming can help to predict future responses to climate change. In the Northern Hemisphere, the distribution and abundance of northern populations have been influenced by previous glaciations. In this study, we investigated the population history of the Fennoscandian red fox (Vulpes vulpes), which is a generalist carnivore currently undergoing range expansion in the tundra ecosystem. By analysing a 696 bp sequence of the mitochondrial DNA (N = 259) and two Y chromosome-specific microsatellite loci (N = 120), we specifically investigated where the red fox survived the Last Glacial Maximum and how Fennoscandia was recolonized. There was high genetic continuity across most of Fennoscandia, and we identified at least two recolonization pathways: one from continental Europe and one from the northeast (Siberia). Mitochondrial haplotype diversity displayed a significant decline with increasing latitude, consistent with expectations of unidirectional colonization. Each region displayed signatures of recent demographic and/or range expansions. For Finland, an additional recolonization route was suggested from the mismatch distribution analysis and identification of novel haplotypes. We concluded that, as with many boreal generalist species, the Fennoscandian red fox originates from multiple refugia, suggesting that it has benefited from diverse evolutionary histories, potentially enhancing its tolerance to different habitat conditions.

Genetic approaches have proved valuable to the study and conservation of endangered populations, especially for monitoring programs, and there is potential for further developments in this direction by extending analyses to the genomic level. We assembled the genome of the wolverine (Gulo gulo), a mustelid that in Scandinavia has recently recovered from a significant population decline, and obtained a 2.42 Gb draft sequence representing85% of the genome and including21,000 protein-coding genes. We then performed whole-genome resequencing of 10 Scandinavian wolverines for population genomic and demographic analyses. Genetic diversity was among the lowest detected in a red-listed population (mean genome-wide nucleotide diversity of 0.05%). Results of the demographic analyses indicated a long-term decline of the effective population size (N

Source at http://dx.doi.org/10.1080/17518369.2017.1319602 The biodiversity working group of the Arctic Council has developed pan-Arctic biodiversity monitoring plans to improve our ability to detect, understand and report on long-term change in Arctic biodiversity. The Arctic fox (Vulpes lagopus) was identified as a target of future monitoring because of its circumpolar distribution, ecological importance and reliance on Arctic ecosystems. We provide the first exhaustive survey of contemporary Arctic fox monitoring programmes, describing 34 projects located in eight countries. Monitored populations covered equally the four climate zones of the species’ distribution, and there were large differences between populations in long-term trends, multi-annual fluctuations, diet composition, degree of competition with red fox and human interferences. Den density, number of active dens, number of breeding dens and litter size were assessed in almost all populations, while projects varied greatly with respect to monitoring of other variables indicative of population status, ecosystem state or ecosystem function. We review the benefits, opportunities and challenges to increased integration of monitoring projects. We argue that better harmonizing protocols of data collection and data management would allow new questions to be addressed while adding tremendous value to individual projects. However, despite many opportunities, challenges remain. We offer six recommendations that represent decisive progress toward a better integration of Arctic fox monitoring projects. Further, our work serves as a template that can be used to integrate monitoring efforts of other species, thereby providing a key step for future assessments of global biodiversity.

Inbreeding (mating between relatives) is a major concern for conservation as it decreases the fitness of offspring and can increase the extinction risk of populations. While pedigrees have traditionally been used to measure individual inbreeding, molecular markers have opened up new avenues to characterize inbreeding. However, a limitation has been that small numbers of markers can only roughly measure the proportion of an individual’s genome that is identical-by-descent (IBD) due to inbreeding. We used whole-genome resequencing of 97 grey wolves (Canis lupus) from the highly inbred Scandinavian wolf population, originally founded by only two individuals, to identify IBD chromosome segments as runs of homozygosity (ROH). This gave the very high resolution required to precisely measure the realized IBD fraction of the genome as FROH. We found a striking pattern of complete or near-complete homozygosity of entire chromosomes in many individuals. The majority of individual IBD was contributed by long IBD segments (>5cM) originating from common ancestors of parents within the last ~10 generations. However, although most IBD segments were very short (

Introgression and admixture from domestic or foreign conspecifics into wild populations are of great concern in wildlife conservation. The issue is of particular interest in ungulates where translocations and re-introductions have been common practice. In Europe, the only large remaining wild populations of reindeer (Rangifer tarandus L.) are found in the mountainous habitats of southern Norway. These populations have during the last centuries been exposed to extensive habitat modifications and periods of contact with domestic reindeer. Through analyses of ancient and extant mitochondrial DNA (mtDNA) we document extensive intra- and inter-population genetic changes during the last millennium. Our data indicate population reduction within a short time interval during the 11th–12th century during a period when mass trapping of reindeer was common. Significant differentiation between the ancient herds suggests an ancient genetic structuring of the reindeer herds in southern Norway, although not as strong as between modern herds. Two different mtDNA lineages characterized the ancient herds. A Bayesian approach to reconstruct the recent evolutionary history suggests that the reindeer herds in southern Norway originate from two populations separated in different refugia during the last glacial period. The presence of two additional extant lineages, characteristic of domestic herds, suggests substantial introgression into the native wild reindeer. The putatively different refugial origins of the lineages represented by the extant herds in Rondane/Dovre, Hardangervidda and those with a mainly domestic origin may well reflect different adaptations to environmental conditions, including degree of human interference. Further research on this issue would provide important insights for conservation priorities and a sustainable and flexible management strategy for the remaining wild reindeer herds in the Scandinavian mountains.

Source at http://doi.org/10.1080/17518369.2017.1323621 The distribution of traditional breeding dens on the Varanger Peninsula (70–71°N) in northernmost Fennoscandia indicates that this area once harboured a large Arctic fox population. Early 20th century naturalists regarded the coastal tundra of the Fennoscandian Low Arctic to be a stronghold for the species. At the start of our research in 2004, however, the local Arctic fox population was critically small and most neighbouring populations had been extirpated. Here, we synthesize the results of 11 years of research to highlight ecosystem drivers behind the critical state of the Arctic fox in Low-Arctic Fennoscandia. We identify two fundamental drivers: (1) an increasingly climate-driven irregularity of the lemming cycle and (2) a management- and climate-driven increase in the abundance of red fox that is subsidized by more ungulate carrion. Arctic fox reproductive success is low when lemmings are scarce (despite high vole abundance), while red foxes exclude Arctic foxes from high-quality breeding territories in summer and from marine and terrestrial carrion in winter. Red fox culling on Varanger Peninsula may have prevented the extirpation of the Arctic fox population. However, one decade after the onset of this management action the Arctic fox population has failed to increase either because the action has been insufficient or because demographic and environmental stochasticity has precluded a positive response. We discuss options for future research and management of the Arctic fox in the Fennoscandian Low Arctic.

The Arctic fox (Vulpes lagopus L.) is listed as extinct in Finland, endangered in Sweden and critically endangered in Norway. Around 2000 there were only 40–60 adult individuals left, prompting the implementation of conservation actions, including a captive breeding programme founded from wild-caught pups. The initial breeding trials failed, probably because of stress among captive animals, and the programme was radically changed in 2005. Eight large enclosures within the species’ historical natural habitat were established, which had the positive effect of all pairs breeding in 2007. As of 2015, 385 pups (yearly average 37) were produced. In this ongoing programme, pups are released the winter (January–February) following their birth and have had an average first-year survival of 0.44. The release sites are prepared with artificial dens and a network of supplementary food dispensers, designed to work exclusively for the Arctic fox. After just four to seven years of releases, populations have been effectively re-established in three mountain areas where the species had been locally extinct. One of the newly re-established populations has become the largest population in Norway. Several other populations, including Swedish ones, have benefited considerably from successful immigration of released foxes. The number of wild-born pups that are descendants of released foxes has likely exceeded 600, and in 2014 50% of all free-living breeding pairs in mainland Norway included released foxes or their descendants. The Norwegian Arctic fox captive breeding programme has proven to be an important conservation action for the recovery of the Scandinavian Arctic fox population.

The Terai is one of the world's most spectacular landscapes, encompassing parts of Nepal and northern India. This area used to harbour large and continuous populations of charismatic species like elephants, tigers and rhinoceros. However, recent habitat fragmentation reduced these populations into small, partially or completely isolated remnants. The largest of these fragments in Nepal is the Bardia National Park. Here, the elephant population was functionally extinct in the early 1970s and -80s, but was rescued by a considerable number of immigrants in 1994. In order to assess population size, sex ratio, age structure, and levels of genetic variation, we carried out non-invasive genetic sampling, using elephant dung as the source of DNA. A capture-mark-recapture estimate of population size suggested that there were 57 individuals in the study area, which agrees well with field observations. Notably, a strongly male-biased sex ratio was evident among sub-adult individuals. This observation suggests the presence of sub-adult immigrants in the population, which was supported by formal migrant detection analysis. Genetic variation was quite high and the evidence for male immigrants suggests that there are good prospects for maintenance of genetic diversity. A decade ago a large-scale project was initiated in the Terai region to link remaining populations of large mammals through dispersal corridors. The program is basically founded on the assumption that habitat fragments are isolated with little or no migration between them. Our results indicate that this may not be the case, at least not for the Asian elephant in western Nepal, which therefore reduces the alleged extinction risk from genetic erosion and stochastic demographic events.

The timing and origin of reindeer domestication has been highly debated. Recent molecular analyses show several mitochondrial lineages of domestic reindeer across Eurasia suggesting different origins of Fennoscandian and Siberian domestic reindeer. In order to investigate the origin of domestic Fennoscandian reindeer, we sequenced a mitochondrial control region fragment of 68 ancient reindeer remains from archaeological sites in Finnmark, the major county for extant reindeer husbandry in Norway, spanning from ca. BC 3400 to AD 1800. The majority of the Stone and Iron Age reindeer assemblages in Finnmark are from settlements in the eastern part of the county, in the Varangerfjord area. The reindeer remains from these settlements show affiliation to the large and complex Beringian haplotype cluster, found in extant reindeer from the Kola Peninsula to north-eastern Russia. A distinct haplotype shift is observed in the late medieval period, when the typical haplotype signatures of extant domestic Fennoscandian reindeer appeared in coastal regions of both eastern and western Finnmark. These haplotypes were not found among the Stone and Iron Age wild reindeer samples of Finnmark, suggesting that this population was not ancestral to extant domestic reindeer of Fennoscandia.

Despite the importance of the reindeer husbandry in the subsistence of many northern cultures the origin and spread of domestic reindeer is still highly debated. Recent analyses of mitochondrial DNA in reindeer herds across Eurasia revealed distinct geographic structures of domestic reindeer in Fennoscandia and Russia, pointing towards independent origins of domestic reindeer in these areas. A high degree of haplotype sharing between the extant wild reindeer population in the Hardangervidda mountain region in southern Norway and the domestic herds in Fennoscandia indicate that this population could have contributed in the early domestication or augmented the domestic population. However, genetic analyses of excavated reindeer remains from the early medieval period from the Hardangervidda region revealed no haplotype sharing with extant domestic reindeer, demonstrating that reindeer from Hardangervidda did not contribute in the early domestication process in Fennoscandia. The substantial temporal genetic alteration observed in this population is related to introgression of domestic reindeer into the wild gene pool in the 19th century during periods when reindeer husbandry was practiced in this mountain region.

Isolation of small populations can reduce fitness through inbreeding depression and impede population growth. Outcrossing with only a few unrelated individuals can increase demographic and genetic viability substantially, but few studies have documented such genetic rescue in natural mammal populations. We investigate the effects of immigration in a subpopulation of the endangered Scandinavian arctic fox (Vulpes lagopus), founded by six individuals and isolated for 9 years at an extremely small population size. Based on a long-term pedigree (105 litters, 543 individuals) combined with individual fitness traits, we found evidence for genetic rescue. Natural immigration and gene flow of three outbred males in 2010 resulted in a reduction in population average inbreeding coefficient (f), from 0.14 to 0.08 within 5 years. Genetic rescue was further supported by 1.9 times higher juvenile survival and 1.3 times higher breeding success in immigrant first-generation offspring compared with inbred offspring. Five years after immigration, the population had more than doubled in size and allelic richness increased by 41%. This is one of few studies that has documented genetic rescue in a natural mammal population suffering from inbreeding depression and contributes to a growing body of data demonstrating the vital connection between genetics and individual fitness.

Noninvasive genetic monitoring has the potential to estimate vital rates essential for conservation and management of many species. In a long-term genetic capture-mark-recapture study using scats we evaluated temporal variation in adult survival in a wolverine (Gulo gulo) population in southern Norway. In contrast to most previous studies of large mammals we found evidence for negative density dependence in adult survival in this large carnivore. Both sexes showed the same pattern of density dependence, with higher annual survival rates in adult females than males. In addition, we also found an additive mortality effect of harvesting in the population, resulting in the lowest adult survival rates at a combination of high population density and high harvest rate. The additive effects of density and harvest on adult survival of wolverines have relevance to the conservation and management of solitary carnivores with strong intrasexual territoriality, especially for species where combats among conspecifics can cause serious injury or even mortality.

The Norwegian red deer population (Cervus elaphus) was from the mid eighteenth to the early twentieth century drastically reduced in size and distribution but has the last century expanded both demographically and spatially. We have investigated genetic variation, differentiation and admixture in this spatially expanding ungulate population, using 14 microsatellites. The present genetic structure is moderate to strong with an average F ST = 0.08. Low M-ratios indicate loss of genetic variation in all localities and signals of a recent bottleneck was identified in 14 of 15 localities. Genetic distances between the localities indicate two main routes of dispersal during expansion, from the north–west and south–west, respectively. Bayesian assignment tests verify a break of the dataset in two, and demonstrate 99.9% probability for the existence of five sub-populations, which coincide well with five relict populations described by historic records. Computer simulations suggest that the observed genetic differentiation is recent rather than ancient, and that it may be explained by models of fragmentation or of founder events and subsequent merging rather than by models of recent bottlenecks in some particular demes within an ancient genetic structure.