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The proposed paper introduces a new optimization algorithm inspired by nature called the polar fox optimization algorithm (PFA). This algorithm addresses the herd life of polar foxes and especially their hunting method. The polar fox jumping strategy for hunting, which is performed through high hearing power, is mathematically formulated and implemented to perform optimization processes in a wide range of search spaces. The performance of the polar fox algorithm is tested with 14 classic benchmark functions. To provide a comprehensive comparison, all 14 test functions are expanded, shifted, rotated and combined for this test. For further testing, the recent CEC 2021 test's complex functions are studied in the unimodal, basic, hybrid and composition modes. Finally, the rate of convergence and computational time of PFA are also evaluated by several changes with other algorithms. Comparisons show that PFA has numerous benefits over other well-known meta-heuristic algorithms and determines the solutions with fewer control parameters. So it offers competitive and promising results. In addition, this research tests PFA performance with 6 different challenging engineering problems. Compared to the well-known meta-artist methods, the superiority of the PFA is observed from the experimental results of the proposed algorithm in real-world problem-solving. The source codes of the PFA are publicly available at https://github.com/ATR616/PFA. [ABSTRACT FROM AUTHOR]

The trophic structures of tundra ecosystems are often viewed as a result of local terrestrial primary productivity. However, other resources can be brought in through long-distant migrants or be directly accessible in coastal areas. Hence, trophic structures may deviate from predictions based on local terrestrial resources. The Arctic fox (Vulpes lagopus) is a small canid that may use marine resources when available. We used stable isotope values in Arctic fox fur and literature data on potential prey to evaluate Arctic fox summer resource use in a mountain tundra without coastal access. The dietary contribution of local prey, presumably mostly rodents, declined with declining rodent abundance, with a subsequent increased contribution of migratory prey relying on marine resources. Stable isotope values did not differ between this terrestrial area and an area with direct coastal access during years of high rodent abundance, but isotope values during low rodent abundances suggested less marine input than in a coastal population feeding primarily on marine prey. Our study shows that marine resources may be used by animals in areas without any coastal access, and we highlight that such partial coupling of ecosystems must be included in the modeling and assessments of tundra environments. [ABSTRACT FROM AUTHOR]

The 'Menglina Leddy' lily cultivar was selected from the Lilium longiflorum Thunb. 'White Fox' γ-rays irradiation line. It produces much less pollen than 'White Fox' but has similar morphology traits. In order to reveal the effects of gamma irradiations on the chromosomes, mitosis, and meiosis in 'Menglina Leddy' cells were investigated by fluorescence in situ hybridization using rDNA and telomeric repeat probes. Although both 'Menglina Leddy' and 'White Fox' had 24 chromosomes, a considerable amount of chromosomal breaking and rejoining were detected in the former. A super long and two super small chromosomes appeared in all the 'Menglina Leddy' cells. Meiotic abnormalities occurred at each separation stage. Chromosomes pairing configuration showed that complex recombination had happened in 'Menglina Leddy'. The super long chromosome was a Robertsonian translocation product composed of two non-homologous long arms. The chromosome deletions and recombinations did not affect the main ornamental traits, but allowed it to acquire the characteristic of less pollen. [ABSTRACT FROM AUTHOR]

The geographic variability of the shape of the toothrow of the upper cheek was studied in Arctic foxes using the methods of geometric morphometrics. The geographical variability was studied using 288 specimens from 19 localities in North America, Eurasia, and islands of the Pacific and Arctic oceans. A significant monomorphism of the toothrow was demonstrated for all mainland Arctic foxes, as well as Arctic foxes from Greenland and St. Lawrence Island. The Arctic foxes of four Pacific island populations (two Commander and two Pribilof) differ significantly from the mainland Arctic foxes by the shape of the toothrow. At the same time, Arctic foxes of Mednyi Island, Bering Island, and the Pribilof Islands also differ from each other. The Arctic fox from Mednyi Island has the shortest and most widely spaced toothrow, as well as very large teeth. On the contrary, the Arctic fox from the Pribilof Islands has the smallest teeth. Allometry does not play a significant role in the formation of geographic variability in the toothrow in Arctic foxes. A high level of fluctuating asymmetry was detected in Arctic foxes of Mednyi Island and St. George Island as compared with its level in other Arctic fox populations. It is most likely that, for the Arctic fox from Mednyi Island, this is caused by known low genetic diversity of the population due to passage of an extreme population bottleneck in the recent past. It was suggested that the factors of fluctuating asymmetry affecting the Arctic foxes of Mednyi and St. George islands are identical. [ABSTRACT FROM AUTHOR]

Abstract—An analysis of changes in the role of mammals in the infection of humans with hydrophobia in Russia for the period 1534–2017 is presented. Human deaths when dealing with dogs have continually been recorded since the 16th century. The share of dogs in human hydrophobia infection reached 85% from the end of the 19th century to the middle of the 20th century. In the 1960s and 1970s, it decreased to 30–35%, but in the early 21st century, it increased again to 43%. The role of cats in infecting humans has been reliably traced since the late 19th century, and it has increased from 2 to 18% over the last 130 years. The epidemic value of foxes is cyclical. In the late 18th century, fox rabies in Russia was not known. People died from hydrophobia after fox bites in the early 19th century, but since 1825 cases of human hydrophobia due to contacts with foxes were no more recorded. Foxes again started infecting people only from the 1940s. In some years from the 1970s to the 1990s, foxes were the source of hydrophobia in 50–52% cases. In the 21st century, the role of foxes in human infection has decreased to 16%, but the value of that predator in animal infection increased to almost 50%. The wolf has infected people throughout the historical record. Before World War II, the epidemic value of the wolf reached 19%, but since the second half of the 20th century and in the 21st century, the death of people caused by wolf bites has varied within 2–7% cases. The raccoon dog started infecting people after World War II (0.4%). Its epidemic role has slowly increased and reached 11% in the 21st century. The corsak, the badger, the marten, the ferret, and the Arctic Fox rarely infect people, but they have participated in the epidemic process for at least 50 years, while the Arctic Fox has for 100 years. Over the territory of Russia, only two cases of human death have been recorded from hydrophobia after a bat bite, one in 1985 and the other in 2008. Cattle have infected humans throughout the observable past five centuries, but not too often, 0.3–2% cases. Small livestock, horses, and pigs have been extremely rare as an epidemic danger for at least the last 130 years. In Russia, people have never been infected with rabies received from insectivores, while that obtained from rodents has been recorded only three times: two from gophers and one from a squirrel. [ABSTRACT FROM AUTHOR]

Most animal ecology studies using remote sensing data have assessed how environmental characteristics shape animal abundance, distribution, or behavior. But the increasing availability of high-resolution data offers new opportunities to study how animals, in turn, shape ecosystems at diverse scales. We evaluate the efficacy of using Sentinel-2 satellite imagery to quantify the effects of Arctic fox (Vulpes lagopus) denning activity (nutrient accumulation, bioturbation) on vegetation. Using an imagery-derived metric (NDVI), we compared maximum plant productivity and plant phenology patterns on 84 Arctic fox dens vs. reference sites, i.e., points generated within preferred denning habitat areas (predicted from a habitat selection analysis). We show that high-resolution imagery can be used to measure the effects of Arctic fox denning activity on vegetation. Plant productivity and the rate of green up were both greater on fox dens compared to reference (preferred-habitat) sites. Productivity on reference sites was lower than average productivity on the tundra (i.e., random sites), indicating foxes primarily establish dens in low-productivity areas. Plant productivity on dens was also unrelated to recent occupancy patterns, indicating fox denning activity has long-term legacy effects on plants that last beyond the lifetime of foxes. Our findings support Arctic foxes being classified as ecosystem engineers in low-Arctic tundra ecosystems by converting low-productivity sites into relatively high-productivity sites through their denning activity. We demonstrate the efficacy of using remote sensing technologies to study how predators increase landscape heterogeneity and influence ecosystem dynamics through patch-scale mechanisms, and ultimately advance our understanding of animal functional roles. [ABSTRACT FROM AUTHOR]

This paper discusses the distribution of terrestrial vertebrates in the northeastern part of the Kanin Peninsula (67°50′47″ N, 46°20′40″ E) based on the results of their census conducted in July 2021. In total, 1 amphibian species, 1 reptile species, 57 bird species, and 6 mammal species have been recorded. The following bird species have been recorded in the tundra zone of the Kanin Peninsula for the first time: tufted duck (Aythya fuligula L.), common eider (Somateria mollissima L.), pallid harrier (Circus macrourus S.G. Gmelin), and common sandpiper (Actitis hypoleucos L.). A distinct feature of the vertebrate fauna inhabiting this region located in the low-growing dwarf-birch tundra belt is the presence of boreal species, including common frog (Rana temporaria L.), viviparous lizard (Zootoca vivipara Lichtenstein), tufted duck, common goldeneye (Bucephala clangula L.), Eurasian crane (Grus grus L.), common sandpiper, brown bear (Ursus arctos L.), and European elk (Alces alces L). So far, this is the northernmost known habitat of the viviparous lizard. The following factors are favorable for the presence of boreal species in this area: its location on the southern slope of the plateaulike Kanin Kamen Ridge and ruggedness of its relief, including deep river valleys with well-heated slopes protected from winds. It is established that the spatial density of the Arctic fox (Alopex lagopus L.) brood burrows has decreased ten times when compared with the 1940–1950s due to the activation of cryogenic processes in permafrost that destroy the burrows dug by this predator in loose soils. [ABSTRACT FROM AUTHOR]

Demographic consequences of rapid environmental change and extreme climatic events (ECEs) can cascade across trophic levels with evolutionary implications that have rarely been explored. Here, we show how an ECE in high Arctic Svalbard triggered a trophic chain reaction, directly or indirectly affecting the demography of both overwintering and migratory vertebrates, ultimately inducing a shift in density-dependent phenotypic selection in migratory geese. A record-breaking rain-on-snow event and ice-locked pastures led to reindeer mass starvation and a population crash, followed by a period of low mortality and population recovery. This caused lagged, long-lasting reductions in reindeer carrion numbers and resultant low abundances of Arctic foxes, a scavenger on reindeer and predator of migratory birds. The associated decrease in Arctic fox predation of goose offspring allowed for a rapid increase in barnacle goose densities. As expected according to r- and K-selection theory, the goose body condition (affecting reproduction and post-fledging survival) maximising Malthusian fitness increased with this shift in population density. Thus, the winter ECE acting on reindeer and their scavenger, the Arctic fox, indirectly selected for higher body condition in migratory geese. This high Arctic study provides rare empirical evidence of links between ECEs, community dynamics and evolution, with implications for our understanding of indirect eco-evolutionary impacts of global change. [ABSTRACT FROM AUTHOR]

Mesocestoides canislagopodis is a common parasite of the arctic fox (Vulpes lagopus) in Iceland. In the past, household dogs (Canis familiaris) and cats (Felis catus) were also reported in Iceland to be infected. Recently, scolices of a non-maturing Mesocestoides sp. were detected in the intestines of the gyrfalcon (Falco rusticolus), and tetrathyridia were isolated in the body cavity of rock ptarmigan (Lagopus muta) and subsequently described. All stages were confirmed, using both morphological and molecular methods, to belong to the same species, M. canislagopodis. In the present study, post-mortem examination of wood mice (Apodemus sylvaticus), sampled in autumn 2014 on a farm in Northeast Iceland, revealed the presence of tetrathyridia in the peritoneal cavity and in the liver. Most tetrathyridia in the peritoneal cavity were free, but some were encapsulated in a thin connective tissue stroma and loosely attached to the inner organs. They appear as whitish, heart-shaped, flattened, unsegmented bodies with a slightly pointed posterior end. In the liver, tetrathyridia were seen as pale-tanned nodules embedded in the parenchyma. Comparative molecular analysis, both at the generic level (D1 domain LSU ribosomal DNA), and at the specific level (cytochrome c oxidase subunit I (cox1) and 12S mitochondrial DNA), revealed that the tetrathyridia belonged to M. canislagopodis. A. sylvaticus represents a new second intermediate host record in Iceland, and the first description of a rodent as intermediate host for this species, thus participating in the life cycle of the parasite. [ABSTRACT FROM AUTHOR]

Colonial seabirds have adopted certain strategies to minimize breeding losses during fledging. This review focuses on the most numerous high-Arctic auks: Little Auk Alle alle and Brünnich's Guillemot Uria lomvia. Colonies of Little Auks are usually situated farther from the sea than cliff-nesting guillemots. On departing the nest, Little Auk chicks are more advanced and can fly, while guillemot chicks, lacking flight feathers, jump from the cliff ledges and glide to the sea. Little Auk chicks lose weight before departure, thus improving their flight efficiency. In both species, fledglings have strong legs and a thick layer of feathers on the underside to prevent injury from hard landings. Some chicks reach the sea on foot. The fathers care for their fledglings, with whom they are in vocal contact. On land, chicks are hunted by Arctic foxes Vulpes lagopus and gulls Larus sp. When attacked by gulls at sea, young auks dive. In the air, however, only young Little Auks perform a characteristic nose-diving manoeuvre to confuse the predator. Guillemot parents can effectively counteract gull attacks on their young, while Little Auk parents do not directly defend their chicks. Unlike Little Auks, several adult guillemots usually accompany chicks during gliding and landing at sea. Adult guillemots gather near the colony during the fledging period and call loudly, thus indicating a safe landing place. In both species, fledging is highly synchronized and condensed into a few days and night-time hours, thus causing a swamping effect that reduces total losses among fledglings. [ABSTRACT FROM AUTHOR]

Responses of one species to climate change may influence the population dynamics of others, particularly in the Arctic where food webs are strongly linked. Specifically, changes to the cryosphere may limit prey availability for predators. We examined Arctic (Vulpes lagopus) and red fox (V. vulpes) population dynamics near the southern edge of the Arctic fox distribution using fur harvest records from Churchill, Manitoba, Canada between 1955 and 2012. Arctic foxes showed a declining population trend over time (inferred from harvest records corrected for trapping effort), whereas the red fox population trend was relatively stable. The positive relationship between the annual Arctic and red fox harvests suggested interspecific competition did not promote the Arctic fox decline. To investigate alternative mechanisms, we evaluated the relative influence of sea-ice phenology, snow depth, snow duration, winter thaws, and summer temperature on the harvest dynamics of both species in the most recent 32 years (1980–2012; n = 29) of our data. Arctic fox harvests were negatively related to the length of time Hudson Bay was free of sea ice. Shorter sea ice duration may reduce access to seal carrion as an alternative winter food source when lemming densities decline. Contrary to our prediction, red fox harvest was not related to summer temperature but was positively related to snow depth, suggesting winter prey availability may limit red fox population growth. Predators have an important ecological role, so understanding the influence of changes in the cryosphere on predator–prey interactions may better illuminate the broader influence of climate change on food-web dynamics. [ABSTRACT FROM AUTHOR]

Boldness is an important trait in wild populations, and among-individual differences can link to individual fitness. The strength and direction of relationships between behavioral and life-history traits may however vary according to environmental conditions, where fluctuating selection acting on behavioral traits contributes to the maintenance of personality differences. We explored sources of variation in Arctic fox (Vulpes lagopus) boldness and investigated how temporal variation in the abundance of a main prey (lemmings) influences the relationship between fox boldness and reproductive success. We measured the behavioral reaction of individuals when escaping after handling, as an indicator of their boldness. We obtained 70 measurements from 42 individuals during two years of low lemming abundance and 2 years of high lemming abundance and assessed fox litter size as an indicator of reproductive success. First, individual characteristics (age, sex, mass) did not affect Arctic fox boldness, while individual identity generated variation in boldness. Next, we found that during years of low lemming density, individuals behaving boldly had more pups than those behaving less boldly, suggesting boldness may provide an advantage when lemmings are scarce by increasing hunting success or allowing access to alternative resources. However, all individuals tended to show high levels of boldness when lemming density was high, and all produced large litters. Temporal variation in the abundance of a main prey might therefore influence the relation between boldness and reproductive success of a predator, and if individuals consistently differ in their level of boldness, fluctuating selection could contribute to the maintenance of personality. Significance statement: Effects of boldness on Arctic fox reproductive success: lemming abundance matters! When lemmings are scarce, foxes showing bold behavior have more pups than foxes showing less bold behavior. This highlights that under low prey availability, boldness may bring short-term benefits to predators, potentially because it allows to acquire more food. When lemmings are abundant, however, all foxes produce as many pups. This shows that environmental conditions such as prey abundance can influence the relation between behavior and reproductive success in a predator. Studying the context-dependency of relationships between behavior and reproductive success is critical to better understand ecological and evolutionary consequences of environmental change. [ABSTRACT FROM AUTHOR]

Climate warming is favoring the expansion of non-native species onto the Arctic tundra, where they may compete over resources with native species. In the harsh tundra conditions, sympatric red foxes (Vulpes vulpes) and Arctic foxes (Vulpes lagopus) may compete over denning sites, which are important for their reproduction and survival. We studied den selection by red and Arctic foxes in spring and summer and their possible competition over this resource in an ecotone near Churchill, Manitoba, on the west coast of Hudson Bay, by examining patterns of den occupancy related to den characteristics and spacing patterns between neighbors. Based on 11 years of occupancy data for 42 tundra dens, we determined that red and Arctic foxes favored dens based on shelter quality in both spring and summer, rather than proximity of specific habitats (and thus specific prey). Mechanisms of den selection differed between species, which may promote coexistence, and areas of high den density were avoided by red foxes and preferred by Arctic foxes. We did not find evidence of exclusion of Arctic foxes by red foxes: spacing patterns showed that foxes spaced themselves based on their need for space, territoriality and food availability but not interference. In the current abiotic Arctic conditions, taiga species settling on the tundra could coexist with tundra endemics, at given density thresholds of both competitors. As Arctic conditions may become milder, an increase in newcomer abundance could disrupt the current balance that favors species coexistence. [ABSTRACT FROM AUTHOR]

Empirical observations and mathematical models show that climate warming can lead to the northern (or, more generally, poleward) spread of host species ranges and their corresponding diseases. Here, we consider an unexpected possibility whereby climate warming facilitates disease spread in the opposite direction to the directional shift in the host species range. To explore this possibility, we consider two host species, both susceptible to a disease, but spatially isolated due to distinct thermal niches, and where prior to climate warming the disease is endemic in the northern species only. Previous theoretical results show that species distributions can lag behind species thermal niches when climate warming occurs. As such, we hypothesize that climate warming may increase the overlap between northern and southern host species ranges, due to the northern species lagging behind its thermal tolerance limit. To test our hypothesis, we simulate climate warming as a reaction-diffusion equation model with a Susceptible-Infected (SI) epidemiological structure, for two competing species with distinct temperature-dependent niches. We show that climate warming, by shifting both species niches northwards, can facilitate the southward spread of disease, due to increased range overlap between the two populations. As our model is general, our findings may apply to viral, bacterial, and prion diseases that do not have thermal tolerance limits and are inextricably linked to their hosts distributions, such as the spread of rabies from arctic to red foxes. [ABSTRACT FROM AUTHOR]

Circumpolar variations in the size and shape of the skull in the Arctic fox Vulpes lagopus L. 1758 was studied based on 31 linear measurements of 326 specimens. The specimens were collected from the mainland parts of North America and Eurasia, as well as from several islands within the native range of the Arctic fox, namely, Greenland, Iceland, Svalbard, St. Lawrence Island, St. Matthew Island, Pribilof Islands (St. Paul Island and St. George Island), and Commander Islands (Bering Island and Mednyi Island). A specimen from the Arctic fox populations introduced to the Atka Island and Aleutian Islands was also included in the analysis. Morphological circumpolar variations in the skull of Arctic foxes observed in the present study were compared to the genetic variations reported in earlier studies. No significant differences were observed in cranial size and shape between Arctic foxes from the mainland (both North American and Eurasian populations) and those from St. Lawrence Island, St. Matthew Island, Svalbard, and Iceland. Although the Greenland foxes were significantly smaller than the mainland ones, their cranial shape was comparable. Based on the skull shape, the Commander Islands' Arctic foxes were the most distinct among all populations. An unsupervised model-based cluster analysis implemented in MCLUST showed that, based on cranial morphology, the Commander Islands' Arctic foxes could be differentiated from the other Arctic foxes with a high level of probability (p ≥ 0.95). The morphological specificity of the Commander Islands' Arctic foxes is congruous with their genetic isolation. The morphological specificity of Greenland and Pribilof Island Arctic foxes was greater than their genetic distinctiveness. A taxonomic revision of the study species was performed based on the data presented. The Arctic foxes from the mainland parts of North America and Eurasia, St. Lawrence Island, St. Matthew Island, Svalbard, and Iceland were classified under a single nominotypical subspecies, V. l. lagopus L. 1758, while the Greenland Arctic foxes belong to a separate small subspecies of the mainland Arctic fox, namely, V. l. groenlandicus Bechstein 1799. Similarly, the Pribilof Arctic foxes V. l. pribilofensis Merriam 1903 are subspecies of the mainland animal and further should be divided into two separate subspecies, one from St. Paul Island and another from St. George Island, taking into account the level of their morphological differences, Based on marked morphological and genetic differences, the Commander Islands' Arctic foxes were reclassified as a distinct species, V. beringensis Merriam 1902, as proposed by Ognev (1931), with two subspecies, namely, V. b. beringensis Merriam 1902 from Bering Island and V. b. semenovi Ognev 1931 from the Mednyi Island. The specimen from Atka Island was identified to the species from the Commander Islands, suggesting that the Arctic fox population on Atka Island must have been introduced from the Commander Islands. Given the declining population of the Arctic foxes on the Commander Islands, this data is important for the environmental and genetic conservation of the Commander Islands' Arctic fox [ABSTRACT FROM AUTHOR]

Anthropogenic debris, including plastic pollution, is a growing concern in the Arctic and negatively impacts both marine and coastal organisms. The aim of this study was to investigate the potential for using Arctic fox (Vulpes lagopus) faeces as a monitoring tool for plastic pollution in the Arctic environment. Arctic fox faeces were collected in different regions of Iceland and analysed for anthropogenic debris presence larger than 300 µm, and diet composition. In total, 235 faecal samples from 1999, 2017, 2018 and 2020 were analysed. The overall frequency of occurrence of plastic and other anthropogenic material was 5.11% and was found in samples across all regions and years. There were no statistical differences in anthropogenic debris ingested, depending on year or region. There were no obvious differences in diet composition between samples that contained anthropogenic debris and samples without. The suitability of Arctic fox faeces as a method to monitor plastic and anthropogenic debris levels in the Arctic environment remains debatable: Whilst the vast distribution range of the Arctic fox and the non-invasive collection methodology of faecal samples could be utilised as a good monitoring tool, the overall low uptake and unclear source of plastic and anthropogenic debris (marine or terrestrial) makes the interpretation of the data difficult. Nevertheless, debris ingestion by Arctic foxes remains a concern and warrants further studies. [ABSTRACT FROM AUTHOR]

A statistical analysis of the secondary (at birth) sex ratio in the farming population of the American mink (Neovison vison Schr.) of the standard dark brown breed was carried out. The study was done on the materials of the Pushkin breeding farm in Moscow oblast according to the pedigree books. A total of 1550 litters of 999 mink females were analyzed. The total sample size for 5 years was 10 372 kits. On the basis of the results of the analysis in the expected population, the birth rate of males is estimated to be 0.492 ± 0.0067 with a 95% confidence interval of 0.473 ≤ P(A) ≤ 0.511. Unlike other main species of farming fur-bearing animals, namely, arctic foxes, foxes, and sables, in the American mink, the secondary sex ratio is characterized by inconstancy and heterogeneity with a variable predominance of females or males in the offspring, depending on paratypic factors (mother's age and litter size). At the same time, as mothers age, the deviation of the sex ratio shifts toward the predominance of males in the offspring and, with an increase in the size of the litter, toward an increase in the number of females. [ABSTRACT FROM AUTHOR]

For the conservation and management of the Arctic regions vulnerable to climate change, it is important to elucidate the trophic relations and food sources for consumers in the ecosystems. We analyzed DNA extracted from feces to understand the summer diets of the major terrestrial animals and their trophic relations in tundra ecosystems near Kongsfjorden, Svalbard. Feces of Svalbard reindeer (Rangifer tarandus platyrhynchus), Barnacle Goose (Branta leucopsis), Arctic fox (Vulpes lagopus), and Rock Ptarmigan (Lagopus muta) were collected during the summer seasons of 2014, 2015, 2018, and 2019. Plant DNA was detected in the feces of herbivores (reindeer, goose, and ptarmigan) and vertebrate DNA was detected in the feces of carnivore (Arctic fox) by amplifying, cloning, and Sanger sequencing. In case of Arctic fox, VulpesB, the blocking primer preventing from amplifying Arctic fox DNA, was used to improve the detection of their prey DNA. Salix was the most detected genus in feces of Svalbard reindeer and Barnacle Goose, which were described as feeding on graminoids, forbs, and prostrate as well as bryophyte. Bryophyte was added as an important food source for all herbivores. Arctic fox preferred birds such as geese (Anatidae) and gulls (Laridae), showing that interpretation between Arctic foxes and gulls may have occurred at the same predator level. Our results suggest that cloning-based DNA analysis using fecal sample contributes to understanding the tundra terrestrial food web near Kongsfjorden. [ABSTRACT FROM AUTHOR]

We evaluated patterns of herbivory and predation/scavenging by a small mammal, the arctic ground squirrel (Urocitellus parryii), as an indicator of biological diversity, vegetation structure, and ecological integrity on two contrasting islands in the vast and remote Alaska Maritime National Wildlife Refuge. Using DNA metabarcoding techniques, we assessed the taxonomic composition of vertebrates, vascular plants, and bryophytes at family and growth form levels in arctic ground squirrel fecal samples collected on the ecologically intact island of Chowiet, which supports diverse seabird and vegetation communities, and the degraded island of Chirikof, which has incurred centuries of disturbance from introduced arctic fox (Vulpes lagopus) and cattle (Bos taurus taurus). We also evaluated whether fecal samples collected across the growing season (May—August) could act as indicators of herbivore-plant phenology. We did not detect any vertebrate taxa, however, observed herbivory patterns closely matched known differences in island plant diversity based on independent surveys. Diets from the ecologically intact island exhibited higher taxonomic richness, greater evenness, and higher shrub content than the ecologically degraded island, which is a grass- and forb-dominated ecosystem. On Chowiet Island, diets changed seasonally, likely in response to changing availability, nutritional quality, and toxin content associated with primary production. Small mammal diet served as an effective indicator of plant diversity, vegetation structure, and ecological integrity when compared against known composition and status of these remote island ecosystems. Non-invasive fecal sampling and dietary analyses using genetic techniques may provide a useful strategy for monitoring biological diversity, particularly in remote areas where widespread intensive sampling is unfeasible. [ABSTRACT FROM AUTHOR]

In socially flexible species, the tendency to live in groups is expected to vary through a trade-off between costs and benefits, determined by ecological conditions. The Resource Dispersion Hypothesis predicts that group size changes in response to patterns in resource availability. An additional dimension is described in Hersteinsson's model positing that sociality is further affected by a cost–benefit trade-off related to predation pressure. In the arctic fox (Vulpes lagopus), group-living follows a regional trade-off in resources' availability and intra-guild predation pressure. However, the effect of local fluctuations is poorly known, but offers an unusual opportunity to test predictions that differ between the two hypotheses in systems where prey availability is linked to intra-guild predation. Based on 17-year monitoring of arctic fox and cyclic rodent prey populations, we addressed the Resource Dispersion Hypothesis and discuss the results in relation to the impact of predation in Hersteinsson's model. Group-living increased with prey density, from 7.7% (low density) to 28% (high density). However, it remained high (44%) despite a rodent crash and this could be explained by increased benefits from cooperative defence against prey switching by top predators. We conclude that both resource abundance and predation pressure are factors underpinning the formation of social groups in fluctuating ecosystems. [ABSTRACT FROM AUTHOR]

We propose an ecogenetic model of "prey–predator" community with predator fitness determined genetically by a single autosomal diallelic pleiotropic locus in the case of diploid population. Predator genotypes with different reproductive potential are unequally adapted to food resource limitation; therefore, the fitness of a predator's genotype is determined by not only its own genotype but also the prey numbers. We use discrete-time equations for modeling, which allows considering features of the community species lifecycle. The paper extends our previous studies modeling evolution of a local population to explain existing genetic diversity by litter size in various (natural and farmed) populations of Arctic foxes (Alopex lagopus). Direct inclusion of prey population dynamics in the model of community allows analyzing polymorphism maintenance in arctic fox populations under more realistic conditions. As in simpler models, the direction of evolution of the predator population is shown to be generally determined by the relative position of its genotype fitnesses, whereas the parameter set characterizing birth rates of the prey and the predator, as well as the characteristics of interspecific interaction, determines the dynamic mode of interacting species numbers. However, even without overdominance, a predator can maintain a stable polymorphism owing to large-amplitude fluctuations in the number of prey, which change the direction of natural selection in the predator population. Different dynamics in the genetic composition of the predator can lead to a change in the dynamic mode of the prey numbers. [ABSTRACT FROM AUTHOR]

The Arctic foxes, Vulpes lagopus, from the Commander Islands are known to be well differentiated in skull morphology from the mainland population. Our study is the first to compare this differentiation with interspecies variations in the family Canidae. The level of skull variations between the Arctic foxes of the Commander Islands and the mainland Arctic fox was compared with skull variations between (1) the gray fox, Urocyon cinereoargenteus, and the island fox, U. littoralis; and (2) three closely related species of the Arctic fox: the swift fox, V. velox, and the kit fox, V. macrotis. The skull variations between the Arctic foxes of the Commander Islands and the mainland Arctic fox were shown to correspond to the interspecies level of skull variation in sister species of the genera Vulpes and Urocyon. No general trend in skull variation has been found between the species studied and isolated populations. The craniological data presented support the separation of foxes from the Commander Islands as a distinct species, V. beringensis Merriam 1902, with two subspecies: V. b. semenovi Ognev 1931 (Medny Island) and V. b. beringensis Merriam 1902 (Bering Island). The Arctic foxes of the Commander Islands are a unique part of the biological diversity and must be strictly protected. [ABSTRACT FROM AUTHOR]

Selecting the right location for a den during the breeding season is a type of habitat selection in the Arctic fox (Vulpes lagopus) that is likely to affect its reproductive success. A den's suitability likely depends on its ability to provide shelter, as well as its proximity to prey resources. Depending on the different relative risks that Arctic foxes may face across their broad circumpolar range, Arctic foxes may place different emphases on selection for shelter and prey resources in different ecosystems. Understanding the different requirements for reproduction under different ecological conditions is highly relevant to conservation efforts in areas where Arctic foxes are threatened by rapid environmental changes. Here, we investigated the relative selection for shelter and prey resources in southern Yamal Peninsula (Russia) using data from 45 dens collected over a 13-year period. Arctic foxes preferred to breed in dens with more den entrances; an indicator of shelter quality. Arctic foxes also preferred dens surrounded by more prey resources (quantified by the amount of river valley habitat), but this result was less conclusive. These results complement the findings reported from other study areas, illustrating that Arctic foxes in ecosystems with diverse predator communities may put emphasis on selection for shelter quality. In less productive ecosystems, Arctic foxes may rather put emphasis on selection for prey resources. As tundra ecosystems become more productive and generalist predators move north, the reproductive requirements and habitat selection of Arctic foxes may change accordingly, depending on the species' ability to adapt. [ABSTRACT FROM AUTHOR]

Objective. To analyze the presence of melanin and to assess the frequency of pigmented pineal glands (PG) in dogs of different age groups. Material and methods. Studies were performed on racoon dogs (Nyctereutes procyonoides Grey), foxes (Vulpes L.), and Arctic foxes (V. lagopus L.). PG pigmentation was assessed visually in immature or juvenile (6–8 months) and mature (1.5–3.5 years) female animals of each species and the proportions (%) of pigmented and nonpigmented glands were determined. The numbers of immature and adult animals of each species were as follows: racoon dogs (n = 4, n = 15), foxes (n = 15, n = 28), and Arctic foxes (n = 4, n = 14, respectively). The morphological characteristics of the PG were studied using histological methods on sections stained with eosin and by the Fontana–Masson method. Results. The PG of the study species showed accumulations of the pigment melanin both at the periphery of the gland and around blood vessels. A high level of variability in gland pigmentation was noted visually, from unpigmented to intensely pigmented. The frequency of pigmented glands was influenced by age and species. In racoon dogs, pigmented PG were seen only in immature individuals (25%), while in foxes only in adults (21.4%). In Arctic foxes, pigmented PG were characteristic of both age groups, though the proportion decreased with age (from 21.4% to 7.1%). Conclusions. Extensive variability was seen in the extent of PG pigmentation in canids. Pigmented PG frequencies were species-specific and age-dependent. [ABSTRACT FROM AUTHOR]

Despite the availability of ever more data on population trends in Arctic waders, we still have limited insight into the factors influencing reproductive success and its resulting contribution to population trajectories. Here, we present data from Zackenberg in high Arctic Greenland that show no changes in timing of egg laying nor clutch size over more than two decades. With variation among species, we found earlier egg laying in seasons with earlier snowmelt, more invertebrates during the pre-laying period, earlier appearance of invertebrates and higher June temperatures. In addition, we found larger clutch sizes with earlier snowmelt, and lower clutch sizes with later nest initiation dates, together with increasing variability in clutch size during the study years in one species. Nest success was lower in late breeding seasons but seemed to increase with season progress, while nest success was much lower during the lasts 18 years of the study period than during the first part of the period. The reason for this could be both increased Arctic fox activity on the tundra and increased researcher activity at nests, which leaves olfactory clues for the foxes. Numbers of juvenile Dunlins produced seem to be negatively correlated with our index of fox activity on the tundra during nesting and fledging, whereas we found no correlations between fox activity and lemming abundance. The effects of severe events in a number of years are described, including a next to non-breeding year in 2018. Our study adds to our understanding that the Arctic is not a homogeneous biome but may show quite different regional patterns of climate change effects. [ABSTRACT FROM AUTHOR]

Measuring fecal glucocorticoid metabolites (fGCMs) is a widely used, non-invasive method for studies of stress in vertebrates. To study physiological responses in wild Arctic foxes (Vulpes lagopus) to perceived stressors such as fluctuating food availability, occurrence of competitors and predators and disturbance from human activities, a species-specific physiological validation of a method to evaluate adrenocortical activity is needed. Here we used 15 captive Arctic foxes (both males and females and juveniles and adults) to investigate fGCM concentrations following ACTH injection (physiological validation), or handling alone and compared them with their respective baseline concentrations prior to the treatments. A 5α-pregnane-3ß,11ß,21-triol-20-one enzyme immunoassay measured significant fGCM increases following both treatments. The time lags to reach peak fGCM values were 9.3 ± 1.3 h and 12.8 ± 1.7 h for ACTH and handling treatment, respectively. Concentrations of fGCMs varied a lot between individuals, but not attributed to sex nor age of the foxes. However, we found a negative relationship between boldness and fGCM concentrations. Faecal glucocorticoid metabolites concentrations did not change significantly over a period of 48 h in samples kept at temperatures reflecting winter and summer means. This would allow the collection of samples up to two days old in the wild regardless of the season. We conclude that our successfully validated method for measuring fGCMs can be used as a non-invasive tool for studies exploring various stressors both in wild and captive Arctic foxes. [ABSTRACT FROM AUTHOR]

Canine circovirus (canineCV) has been found to be associated with vasculitis, hemorrhage, hemorrhagic enteritis, and diarrhea of canines. CanineCV, like other circoviruses, may also be associated with lymphoid depletion and immunosuppression. This circovirus has been detected worldwide in different countries and species. Recombination and mutation events in the canineCV genome have been described, indicating that the virus is continuing to evolve. However, the origin, codon usage patterns, and host adaptation of canineCV remain to be studied. Here, the coding sequences of 93 canineCV sequences available in the GenBank database were used for analysis. The results showed that canineCV sequences could be classified into five genotypes, as confirmed by phylogenetic and principal component analysis (PCA). Maximum clade credibility (MCC) and maximum-likelihood (ML) trees suggested that canineCV originated from bat circovirus. G/T and A/C nucleotide biases were observed in ORF1 and ORF2, respectively, and a low codon usage bias (CUB) was found in canineCV using an effective number of codon (ENC) analysis. Correlation analysis, ENC plot analysis and neutrality plot analysis indicated that the codon usage pattern was mainly shaped by natural selection. Codon adaptation index (CAI) analysis, relative codon deoptimization index (RCDI) analysis, and similarity index (SiD) analysis revealed a better adaption to Vulpes vulpes than to Canis familiaris. Furthermore, a cross-species transmission hypothesis that canineCV may have evolved from bats (origin analysis) and subsequently adapted to wolves, arctic foxes, dogs, and red foxes, was proposed. This study contributes to our understanding of the factors related to canineCV evolution and host adaption. [ABSTRACT FROM AUTHOR]

The Arctic fox (Vulpes lagopus), occupying tundra habitats with highly variable resource distribution, is a convenient research model for studying the impact of food availability on space use. Previous studies have shown that the Arctic fox home ranges can vary from 4 to 125 km2. In areas with abundant food resources, home range sizes are smaller and overlap increases. It is theoretically assumed that with an excess of resources, territoriality should disappear. We investigated a fox settlement at the Northern fur seal rookery on Bering Island (North Pacific). We used GPS collars to track nine foxes in the summer of 2014 and 2016. GPS locations were recorded at 5-min intervals. In the home range estimation, we used the Brownian bridge movement model. We also calculated home range sizes using 100% minimum convex polygon (MCP100) and 95% fixed kernel methods to compare our results with previous studies. Home ranges were extremely small with an average of 0.5 km2 (range of 0.2–0.9 km2) by Brownian Bridge and 0.7 km2 (0.3–1.4 km2) by MCP100. We revealed no sex differences in home range size but discovered strong differentiation of activity spatial concentration between males and females. We found a surprisingly small overlap between neighboring foxes, reflecting high territoriality. This runs counter to the trend expected with an overabundant food source. We assume that the combination of the super small size of the home ranges and their exclusivity may be a feature of the island fox land tenure system, which prevents inbreeding and deters infanticide. [ABSTRACT FROM AUTHOR]

Human-wildlife problems often arise when predators kill livestock. This can develop into serious conflicts between traditional pastoralists and other stakeholders, such as government officials and conservationists. In the Yamal Peninsula (Russia), nearly half of the indigenous Nenets people are reindeer herders. They have recently faced many challenges, such as high mortality of reindeer from pasture icing or disease outbreaks. In addition, predation of arctic fox on reindeer calves is perceived as an increasing problem. Here, we use an interdisciplinary approach to study this emerging predation problem. We present here results from semi-structured interviews with indigenous people, as well as from biological monitoring of fox populations. Our field data were obtained in Erkuta, in the south of Yamal and in Sabetta in the north, close to a newly built industrial settlement. We show how different factors may have come together to create a problematic situation. These factors include the abandonment of the fur trade in the 1990s, the building of huge industrial facilities providing possible resource subsidies and the increasing frequency of abnormal weather events leading to weak reindeer, high reindeer mortality and abundant carcasses as resources for predators. We discuss how each of these factors affects the abundance of predators as well as the understanding of the herders. [ABSTRACT FROM AUTHOR]

The Arctic fox (Vulpes lagopus L.) population on the Kola Peninsula occupies an intermediate, and potentially connecting, position between foxes living on the Scandinavian Peninsula and populations further east in Russia, but very little is known about the status of this population. Here we summarize data from the literature, forgotten archival sources about research in the first half of the twentieth century, and the results of several independent expeditions undertaken over the past two decades. These materials include data on fur harvesting, incomplete monitoring data from official winter track counts of game animals, local knowledge, and our own observations. Our research revealed the extremely poor state of the Arctic fox population on the Kola Peninsula. According to our estimates, the current population is likely isolated and consists of no more than a few dozen adults. The fur return data, together with long-term data on small rodent abundance, suggest that irregular and fading out lemming cycles were a major driver of the Arctic fox population decline. The thorough research from the 1930s contrasts strongly with the lack of interest in studying and monitoring the population in recent decades, which is not even listed as a threatened species in the regional Red Data Book. In fact, the work performed here filled a more than a half-century gap in the study of the population and allowed us to determine the urgent need to resume research and immediately take active measures to protect and promote the recovery of the species in the region. [ABSTRACT FROM AUTHOR]

Studies of the effects of variation in resource availability are important for understanding the ecology of high-latitude mammals. This paper examines the potential of dental evidence (tooth wear and breakage) as a proxy for diet and food choice in Vulpes lagopus, the Arctic fox. It presents a preliminary study of dental microwear, gross wear score, and tooth breakage in a sample (n = 78 individuals) from the Yamal Peninsula of the Russian Arctic. While these measures have each been associated with feeding ecology in larger carnivorans (e.g., proportion of bone in the diet), they have yet to be combined in any study and have rarely been applied to smaller species or those from high latitudes. Arctic foxes from the north and south of the peninsula, and those from rodent peak and trough density periods, are compared to assess impact of changes in food availability across space and time. Results indicate that microwear textures vary in dispersion, with more variation in texture complexity, including higher values (suggesting more consumption of bone), in the rodent-poor period in the north of Yamal. Gross wear scores and tooth breakage are also significantly higher for the north of Yamal than the south. These data together suggest that dental evidence can provide important insights into variation in the feeding ecology of Arctic foxes and potentially into the impacts of changes in food abundance across space and time. [ABSTRACT FROM AUTHOR]

This paper proposes a model of selection by a sex-limited trait expressed in females. The model was modified to describe natural selection for such a trait in ecologically limited populations with an age structure. Simulation results are aimed at explaining the existing genetic variety in litter size in different (natural and artificial) populations of Arctic foxes (Alopex lagopus). The model assumes that the maintenance of polymorphism in litter size is associated with periodic changes in availability of food for natural populations of Arctic foxes and significantly depends on a parameter describing the relative survival advantage of individuals from small litters during years with low food supply. The work shows that selection by a sex-limited trait maintains the litter size polymorphism in a wider range of values of this parameter than selection by a trait not limited by sex, which is described by the classical selection model for the case where the survival and fecundity of an individual are determined only by its own genotype, regardless of sex. It is known that the presence of an age or stage structure in a population significantly increases the chances of maintaining genetic variety in a nonstationary environment. A generalization of the proposed selection model for a population with two stages of development made it possible to show that polymorphism in litter size is possible within even wider ranges of values of the considered parameter. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the infection rate and genetic diversity of Cryptosporidium spp. in minks, foxes, and raccoon dogs, farmed in the Xinjiang Uygur Autonomous Region, Northwest China. Fresh fecal specimens were collected from individual cages of farmed minks (n = 214), blue foxes (n = 35), and raccoon dogs (n = 39) and examined using nested PCR based on the Cryptosporidium spp. small subunit rRNA gene. Cryptosporidium spp. was detected in 35 cages (12.2%, 35/288), with a higher infection rate detected in raccoon dogs (20.5%) compared with minks (12.1%) and blue foxes (2.9%). Sequence analysis showed that Cryptosporidium canis was the only species identified in blue foxes and raccoon dogs, while in the 26 Cryptosporidium-positive mink specimens, Cryptosporidium mink genotype (n = 17), C. canis (n = 7), and Cryptosporidium parvum (n = 2) were identified. Further analysis based on the 60-kDa glycoprotein (gp60) gene determined that both C. parvum isolates belonged to the subtype IIdA15G1, while eight of the 17 Cryptosporidium mink genotype isolates were a novel subtype that we have named XeA5G1. To the best of our knowledge, this is the first report of C. parvum subtype IIdA15G1 infection in minks. Since all the Cryptosporidium species/genotypes identified in minks, foxes, and raccoon dogs from Xinjiang have been previously found in humans, our results suggest that these fur animals may play a role in the transmission of zoonotic Cryptosporidium. [ABSTRACT FROM AUTHOR]

As top or mesopredators, carnivores play a key role in food webs. Their survival and reproduction are usually thought to be influenced by prey availability. However, simultaneous monitoring of prey and predators is difficult, making it challenging to evaluate the impacts of prey on carnivores' demography. Using 13 years of field data on arctic foxes Vulpes lagopus in the Canadian High Arctic and a capture–recapture multi-event statistical approach, we investigated the hypothesis that increases in lemming abundance (a cyclic and unpredictable food source) and goose colony proximity (a stable but spatially and temporally limited food source) would be associated with increased apparent survival and reproduction probabilities of adults. Adult apparent survival varied greatly across years (0.13–1.00) but was neither affected by lemming nor goose variations in abundance. However, reproduction probabilities were strongly influenced by both lemming abundance and access to the goose colony. A fox breeding in the best conditions of food availability (year of high lemming density inside the goose colony) had a reproduction probability four times higher than one experiencing the worst conditions (year of low lemming density outside the goose colony). Breeding status of individuals also played a role, with breeders having a 10–20% higher probability of survival and 30% higher probability of reproduction the following year than non-breeders. As the Arctic ecosystem changes due to increased temperatures and species ranges, this study will allow better predictions of predator responses to management or environmental changes and a better understanding of ecosystem functioning. [ABSTRACT FROM AUTHOR]

Identifying resources driving long-term trends in predators is important to understand ecosystem changes and to manage populations in the context of conservation or control. The arctic fox population in Iceland has increased steadily over a period of 30 years, an increase that has been attributed to an overall increase in food abundance. We hypothesized that increasing populations of geese or seabirds were driving this growth. We analyzed stable isotopes in a long-term series of collagen samples to determine the role of these different resources. The isotopic signatures of arctic foxes differed consistently between coastal and inland habitats. While δ15N displayed a non-linear change over time with a slight increase in the first part of the period followed by a decline in both habitats, δ13C was stable. Stable isotope mixing models suggested that marine resources and rock ptarmigan were the most important dietary sources, with marine resources dominating in coastal habitats and rock ptarmigan being more important inland. Our results suggest that seabirds may have been driving the arctic fox population increase. The rapidly increasing populations of breeding geese seem to have played a minor role in arctic fox population growth, as rock ptarmigan was the most important terrestrial resource despite a considerable decrease in their abundance during recent decades. This study shows that a long-term population trend in a generalist predator may have occurred without a pronounced change in main dietary resources, despite ongoing structural changes in the food web, where one species of herbivorous birds increased and another decreased. [ABSTRACT FROM AUTHOR]

Holding particular biological resources, the Tibetan Plateau is a unique geologic-geographic-biotic interactively unite and hence play an important role in the global biodiversity domain. The Tibetan Plateau has undergone vigorous environmental changes since the Cenozoic, and played roles switching from "a paradise of tropical animals and plants" to "the cradle of Ice Age mammalian fauna". Recent significant paleontological discoveries have refined a big picture of the evolutionary history of biodiversity on that plateau against the backdrop of major environmental changes, and paved the way for the assessment of its far-reaching impact upon the biota around the plateau and even in more remote regions. Here, based on the newly reported fossils from the Tibetan Plateau which include diverse animals and plants, we present a general review of the changing biodiversity on the Tibetan Plateau and its influence in a global scale. We define the Tibetan Plateau as a junction station of the history of modern biodiversity, whose performance can be categorized in the following three patterns: (1) Local origination of endemism; (2) Local origination and "Out of Tibet"; (3) Intercontinental dispersal via Tibet. The first pattern is exemplified by the snow carps, the major component of the freshwater fish fauna on the plateau, whose temporal distribution pattern of the fossil schizothoracines approximately mirrors the spatial distribution pattern of their living counterparts. Through ascent with modification, their history reflects the biological responses to the stepwise uplift of the Tibetan Plateau. The second pattern is represented by the dispersal history of some mammals since the Pliocene and some plants. The ancestors of some Ice Age mammals, e.g., the wholly rhino, Arctic fox, and argali sheep first originated and evolved in the uplifted and frozen Tibet during the Pliocene, and then migrated toward the Arctic regions or even the North American continent at beginning of the Ice Age; the ancestor of pantherines (big cats) first rose in Tibetan Plateau during the Pliocene, followed by the disperse of its descendants to other parts of Asia, Africa, North and South America to play as top predators of the local ecosystems. The early members of some plants, e.g., Elaeagnaceae appeared in Tibet during the Late Eocene and then dispersed and were widely distributed to other regions. The last pattern is typified by the history of the tree of heaven (Ailanthus) and climbing perch. Ailanthus originated in the Indian subcontinent, then colonized into Tibet after the Indian-Asian plate collision, and dispersed therefrom to East Asia, Europe and even North America. The climbing perches among freshwater fishes probably rose in Southeast Asia during the Middle Eocene, dispersed to Tibet and then migrated into Africa via the docked India. These cases highlight the role of Tibet, which was involved in the continental collision, in the intercontinental biotic interchanges. The three evolutionary patterns above reflect both the history of biodiversity on the plateau and the biological and environmental effects of tectonic uplift. [ABSTRACT FROM AUTHOR]

Enterocytozoon bieneusi is an opportunistic enteric pathogen which can infect a wide range of animal species and humans. It is the most diagnosed species of Microsporidia in humans and has an impact on public health. Many infected animals including foxes may be a potential source for transmitting E. bieneusi to humans. However, limited information is available on the E. bieneusi prevalence and genotypes in farmed foxes in China. Therefore, in the present study, 344 fresh fecal samples were collected from farmed foxes (Vulpes vulpes and Vulpes lagopus) in Shandong Province, and the prevalence and genotypes of E. bieneusi were examined based on sequence analysis of the ribosomal internal transcribed spacer (ITS) region. The overall E. bieneusi prevalence was 9% (31/344); of them, 6.5% (9/138) in farmed silver foxes (V. vulpes) and 10.7% (22/206) in farmed arctic foxes (V. lagopus). Moreover, four known (Hum-q1, NCF2, HND-1, and Type IV) and two novel E. bieneusi genotypes (SDF1 and SDF2) were identified in farmed foxes in the present study. All of the E. bieneusi genotypes belonged to the zoonotic group based on phylogenetic analysis. In addition, 2, 4, 0, and 11 samples were successfully amplified at MS1, MS3, MS4, and MS7 loci, respectively. The present study reveals E. bieneusi prevalence and genotype distribution in farmed foxes in Shandong Province and enlarged the host and geographic information of E. bieneusi in China. [ABSTRACT FROM AUTHOR]

The goal of this study is to compare the gut microbiota of domestic blue fox (Alopex lagopus) and raccoon dog (Nyctereutes procyonoides) to provide better understanding of their intestinal gut microbiota. We analyzed the structure of fecal microbes in 40 blue foxes and 40 raccoon dogs that were raised under same conditions, using high-throughput Illumina sequencing targeting the V3–V4 region of the 16S rRNA gene. In total, 295,146 sequence reads were obtained. The average number of operational taxonomical units in the two group samples was 194 to 286. Firmicutes (blue fox 73.40%, raccoon dog 46.90%) and Bacteroidetes (blue fox 21.92%, raccoon dog 44.25%) were the most abundant phyla in the gut of blue fox and raccoon dog. At the genus level, Prevotella (blue fox 16.89%, raccoon dog 36.22%), Blautia (blue fox 9.02%, raccoon dog 13.72%), and Peptostreptococcaeae_incertae_sedi (blue fox 22.41%, raccoon dog 2.84%) were commonly presented in the gut of two kinds of animal. Principal coordinates analysis showed that the microbial communities were different between blue fox and raccoon dog. The Firmicutes-to-Bacteroidetes ratio was higher in blue foxes (3:1) than in raccoon dogs (1:1). Moreover, Peptostreptococcaeae_incertae_sedi and Prevotella, were more abundant in the gut of blue fox, whereas the abundance of Prevotella and Blautia were higher in the gut of raccoon dog. In conclusion, the present study revealed the difference of the gut microbial composition between blue fox and raccoon dog under the same diet conditions. [ABSTRACT FROM AUTHOR]

The characteristics of the distribution and ecology of the terrestrial mammals on Kolguev, Vaygach and Dolgii islands located in the Pechora Sea are presented. The data of the field surveys carried out in these regions during the summer and winter seasons in 2001–2017 served as a material underlying this work. Overall, nine species of the terrestrial mammals were recorded, while only two of them, the Arctic fox (Alopex lagopus (Linnaeus 1758)) and the polar bear (Ursus maritimus (Phipps 1774)) can be found in all the explored insular land areas. The climatic and geographical features of these territories determine the diversity of terrestrial mammals on the islands. The main summer diet of the Arctic fox includes birds and their nestlings and egg clutches in the absence of the small mammals on the islands. A close relation between the reproductive success of this predator on Dolgii Island and the anseriformes spring migration period is established. The red fox (Vulpes vulpes (Linnaeus 1758)) on Kolguev Island is a species with a sparse breeding population. Data on the sedentary patterns for this species on other Eurasian islands within the tundra zone are unavailable. Kolguev Island is probably a single Arctic insular land area forming a part of the breeding ground for the red fox in Eurasia. The reduction in the period for the sea ice extent and the decline in the sea ice cover in the southeastern part of the Barents Sea, observed over the last decade, can affect the migration routes of the polar bear toward the Pechora Sea and the reindeer (Rangifer tarandus (Linnaeus 1758)) inhabiting the Novaya Zemlya archipelago to Vaygach Island. [ABSTRACT FROM AUTHOR]

We have developed a spatially explicit individual-based model that imitates the population dynamics of the Arctic fox on Mednyi Island. In the Red Data Book of the Russian Federation, the Mednyi Arctic fox is listed as an endangered species. The model developed is based on data collected over 19 years of fieldwork. Annual marking of cubs in the study area allowed us to identify up to 80% of animals individually and to collect their life-history data. As a result, we identified the mortality rates of males and females of all age groups, the probabilities of breeding, litter sizes, the sex ratios of animals in different age groups, social structures, dispersion distances, and the patterns of making decisions in the selection of social partners and habitat patches. The model is spatially explicit, i.e., the heterogeneity of the habitat patches is defined in explicit form. The model works with a time step of one year. In simulations, demographic parameters such as population dynamics, population age structure, sex ratio in different age groups, and the structure and size of families conformed to the empirical data. An analysis of the model sensitivity to variations in mortality rates in different age groups showed that the sensitivity to shifts in cub mortality is much higher compared to adults of all age groups. Through increasing the cub mortality rate to 95% over a period of one to five years, we simulated the effect of the otodectic mange epizootic, which was observed in a real population of the Mednyi Arctic fox. The population recovery time after the end of the impact in the simulation was significantly longer compared to field data. We suggest that, in reality, with a low population size, the productivity of the population increases. This feedback that accelerates population recovery has not yet been introduced into the model. In conclusion, we discuss advantages of the individual-based modeling based on long-term field studies. [ABSTRACT FROM AUTHOR]

The arctic fox (Vulpes lagopus), an apex predator with an omnipresent distribution in the Arctic, is a potential source of intestinal parasites that may endanger people and pet animals such as dogs, thus posing a health risk. Non-invasive methods, such as coprology, are often the only option when studying wildlife parasitic fauna. However, the detection and identification of parasites are significantly enhanced when used in combination with methods of molecular biology. Using both approaches, we identified unicellular and multicellular parasites in faeces of arctic foxes and carcasses of sibling voles (Microtus levis) in Svalbard, where molecular methods are used for the first time. Six new species were detected in the arctic fox in Svalbard, Eucoleus aerophilus, Uncinaria stenocephala, Toxocara canis, Trichuris vulpis, Eimeria spp., and Enterocytozoon bieneusi, the latter never found in the arctic fox species before. In addition, only one parasite was found in the sibling vole in Svalbard, the Cryptosporidium alticolis, which has never been detected in Svalbard before. [ABSTRACT FROM AUTHOR]

Life history theory predicts that individuals will differ in their risk-taking behavior according to their expected future fitness. Understanding consequences of such individual variation within a behavioral trait is crucial in explaining potential trade-offs between different traits and in predicting future dynamics in changing environments. Here, we studied individuals in a wild arctic fox population to explore if (1) individual variation in risk-taking behaviors of adult arctic foxes and in stress-dealing behaviors of their juveniles exist and are consistent over time to verify the existence of personality traits; (2) those behavioral traits in adults and juveniles are correlated; (3) they can explain fitness-related components (i.e., juvenile physical condition, mortality rate). We presented simple field experiments assessing behavioral traits by observing adult reactions toward approaching observers, and juvenile behaviors while trapping. Through the experiments, we found highly consistent individual variation of adults in vigilance and boldness levels, and more flexible juvenile behavioral traits categorized as investigating, passive, and escaping. The offspring of bolder adults exhibited more investigating behaviors and were less passive than the offspring of shy adults. Juvenile physical condition was not related to their mortality nor any behavioral traits of either parents or themselves. Lastly, highly investigating and active juveniles with bold parents had significantly lower mortality rates. This shows that interactions between parent personality and juvenile behavioral traits affect a fitness-related component in the life history of individuals. Significance statement: The recent surge of interest in consistent individual difference in behavior, also called as animal personality, has already focused on its fitness consequences, but few studies have investigated the interactions between parent and offspring personality, and their ecological consequences. Moreover, this has rarely been studied in wild canids. The arctic fox is a charismatic species showing wide individual variation in behaviors. They live in highly fluctuating tundra ecosystems providing different selection regimes, making it even more eco-evolutionarily intriguing. Yet, few studies looked into behavioral traits and their importance in this system. While introducing simple methods to improve personality research in the wild, we provide a unique example of how variation in both parents and their juveniles collectively works for group dynamics in a cyclic population. This provides a firm basic for understanding behavior-mediated dynamics and opens up broader questions on how fluctuating environments exert varying pressures on individual differences. [ABSTRACT FROM AUTHOR]

The study was aimed at determining tissue antioxidant levels in three closely related albeit ecologically different Canidae species: the raccoon dog (Nyctereutes procyonoides), silver fox (Vulpes vulpes) and blue fox (Vulpes lagopus), aged 0.5 (juvenile), 1.5–3.5 (adult) and 4.5–5.5 (aging) years. Some tested parameters were found to be species-specific: as compared to other species, raccoon dogs and blue foxes exhibited higher α-tocopherol levels in the liver and kidney, blue foxes were characterized by a higher activity of the antioxidant enzymes in the kidneys, while silver foxes had higher glutathione (GSH) levels in the liver, kidneys and heart. The antioxidant defense system in all organs of the tested species was distinguished by a relative stability. In raccoon dogs, the retinol level in the heart increased with age, while in silver foxes it is only superoxide dismutase (SOD) activity in the kidneys and the GSH level in the liver and heart that underwent significant changes with age. In blue foxes, aging was accompanied by an increase in liver retinol and kidney α-tocopherol levels as well as a decrease in the kidney GSH level. Besides, sex differences were found in antioxidant levels in blue foxes. Our results are consistent with the data obtained by other authors for other animal species, indicating a mixed pattern of age-related changes in the antioxidant defense system of carnivorous canids. While some antioxidants rise and the other fall, the functionality of the whole system does not appear to be disturbed. Ecological and physiological features of different mammalian species may determine the adaptive potential of animals and affect the tested indicators of the antioxidant defense system during late postnatal ontogenesis. [ABSTRACT FROM AUTHOR]

Food hoarding is often considered an adaptive behaviour to extend the period of availability of food resources. Finding the right caching site for storage and retrieval is of paramount importance, yet how caching sites are selected is poorly known. Here, we examine site selection for egg caching by a tundra predator, the arctic fox, Vulpes lagopus, which can overcome large seasonal prey variations by extensive caching. During the short arctic summer, colonial breeding birds like geese produce in a short time period many eggs, which provide a large quantity of predictable resources for consumption and caching. We predicted that foxes would select caching sites with specific characteristics, such as shallow permafrost, and tall hummocks (small mounds in tundra landscapes, which should facilitate caching and provide visual cues for subsequent retrieval). We sampled the main physical characteristics of 48 caches and paired random sites inside a Greater Snow Goose (Chen caerulescens) colony. Our study shows that foxes favour cache sites characterized by hummocks nearly twice as higher than at nearby random sites. The depth of the active layer of permafrost did not influence cache site selection. Foxes may select tundra features that possibly enhance caching efficiency and retrieval probability. Our study elucidates one aspect of food hoarding behaviour in extreme habitats characterized by strong variations of resource availability. [ABSTRACT FROM AUTHOR]

Mating patterns are highly context-dependent and the outcome of selection pressures formed by ecological factors, inbreeding levels and access to available partners. In small and inbred populations, matings are limited by high kin encounter rates and access to mates. In this paper, we use background pedigree data to investigate mating patterns and inbreeding avoidance in an isolated and critically endangered Arctic fox (Vulpes lagopus) population. Empirical data showed avoidance of matings within natal family. Based on 35 documented matings, we only recorded two full-sibling matings and these occurred between individuals from different natal families. Matings between second-order relatives, however, occurred to the same extent as between unrelated individuals. To test how this influenced the population development of inbreeding (f), we simulated scenarios of random mating, exclusion of natal family and exclusion of individuals in already existing pair bonds. The observed development of inbreeding did not correspond the expected scenario of random mating (linear regression, r2 = 0.354, P = 0.20), but showed a comparable outcome as the simulated development of discriminating natal family (linear regression, r2 = 0.980, P < 0.001). We conclude that behavioural, pre-copulatory inbreeding avoidance strategies occur in this population and that exclusion of mating with natal family causes a slower increase in inbreeding levels compared to random mating. This study demonstrates how long-term monitoring, pedigree construction and simulations can generate information valuable for an in-depth understanding of both conservation genetics and behavioural ecology in threatened populations. [ABSTRACT FROM AUTHOR]

Breeding geese are the preferred prey of the Arctic fox Vulpes lagopus in the high-Arctic Svalbard archipelago. According to the apparent competition hypothesis (ACH), less-abundant prey species (e.g. ptarmigan, waders and small passerines) will experience higher predation rates when breeding in association with the more common prey (geese), due to spill-over predation by the shared predator. As many of these less-abundant species are endemic and/or red-listed, increased predation can have negative repercussions on their populations. We used a one-year baited artificial nest study to assess relative nest predation risk on Svalbard Rock Ptarmigan Lagopus muta hyperborea, small waders (Purple Sandpiper Calidris maritima, Dunlin Calidris alpina, plovers Charadrius spp., and phalaropes Phalaropus spp.) and Snow bunting Plectrophenax nivalis in two study locations contrasted by nesting density of Arctic breeding geese (Pink-footed Goose Anser brachyrhynchus and Barnacle Goose Branta leucopsis). We predicted higher predation risk for the less-abundant species in the study location with higher goose abundance. However, we found that relative nest predation risk was lower in the study location with higher goose abundance, thus being compatible with apparent mutualism and/or prey swamping mechanisms. Our results contrast with those from more structurally complex Arctic ecosystems and suggest that allochtonous subsidies from temperate ecosystems structure the predation pattern in this high-Arctic tundra ecosystem. [ABSTRACT FROM AUTHOR]

This article is based on data that were collected in the years 2000-2007, 2012, and 2014 in the vicinities of Medusa Bay (73°21' N, 80°32' E) and in 2002 at the mouth of the Uboynaya River (73°37' N, 82°10' E), in the northwestern part of the Taimyr Peninsula. In years when the abundance of lemmings is high, brent geese may breed not only near nests of snowy owls and rough-legged buzzards, but also sparsely in the mainland tundra, often without any protection. Some such nests are successfully incubated until hatching. A considerable part of these dispersed nests appears to be associated with a nest or territory of pomarine skuas that are able to scare away the main tundra predator, the arctic fox, to a distance of about 500 m from their nests. Brent geese that breed within this distance to theses nests gain additional protection against arctic foxes. However, brent geese do not display a tendency to place their nests closer to pomarine skua nests. The mean distance from geese nests to pomarine skua nests or centers of their territories comprised 2/3 of the mean distance between nests of pomarine skuas and turned out to be quite stable over the years and in two different tundra areas. [ABSTRACT FROM AUTHOR]

Global climate change induces species range shifts and population expansion to higher latitudes in response to rising temperatures. One consequence of climate-induced range shifts is an increased sympatry between related but previously isolated species, potentially resulting in interspecific interactions and hybridization. The Arctic is more rapidly affected by climate warming than any region on Earth and resident species may be prone to interspecific hybridization due to the immigration of new colonizing species. The red fox Vulpes vulpes expanded its range into the Arctic during the twentieth century and is now in sympatry with the native Arctic fox Vulpes lagopus in many places. In this context, an Arctic-like fox displaying an unusual reddish winter coat was observed in 2013 in Nunavut, Canada, a phenotype unknown by Inuit people to date. In this study, we assessed the biological origin of this specimen with a multigenic approach using markers located on mitochondrial DNA, sex (X and Y) chromosomes, and autosomes (microsatellites and the melanocortin 1 receptor (MC1R) gene; a gene involved in the color polymorphism in canids). Our comparative analyses with genetic material from Arctic and red foxes displaying 'classic' phenotypes ( N = 14 and 16, respectively) suggested a pure Arctic fox origin of the specimen. Specifically, this fox yielded mtDNA, X-linked, Y-linked, and MC1R alleles specific to Arctic fox. Bayesian genetic assignment based on 16 microsatellite loci assigned it to Arctic fox with high confidence ( q = 99.7%). Thus, a recent hybrid origin for this specimen is excluded. This alternative winter coat color polymorphism in Arctic fox requires further analyses to determine its underlying genetic mechanism. [ABSTRACT FROM AUTHOR]

The muscles of herbivores commonly harbor sarcocysts of parasites belonging to species in the genus Sarcocystis, but such muscle parasites are rare in carnivores. Here, we report Sarcocystis arctica-like sarcocysts in muscles of Arctic foxes ( Vulpes lagopus) from Alaska, USA, for the first time. The tongues of 56 foxes were examined for Sarcocystis infection using several methods. Sarcocystis bradyzoites were detected in pepsin digests of 13 (23.2%), and sarcocysts were found in histological sections stained with hematoxylin and eosin (HE) of 9 (16.0%). By light microscopy, sarcocysts were up to 4 mm long and up to 245 μm wide. In HE-stained sections, the sarcocyst wall appeared smooth and up to 1.5 μm thick without visible protrusions. By transmission electron microscopy, the sarcocyst wall had a wavy parasitophorous vacuolar membrane (pvm) folded as pleomorphic villar protrusions (vp), sometimes with anastomoses of villar tips. The vp and the ground substance (gs) layer were smooth and without microtubules. The gs was up to 2.0 μm thick. The total width of the wall including vp and the gs was up to 4.0 μm. The vp were up to 3.0 μm long and most closely resembled 'type 9c.' All sarcocysts were mature and contained numerous 8.1 × 2.1 μm sized bradyzoites. Molecular characterization (at 18S rDNA , 28S rDNA, ITS-1, and cox1) showed the highest affinity for S. arctica of the Arctic fox ( V. lagopus) from Norway. In the present investigation, we provide evidence that sarcocysts are common in tongues of Alaskan Arctic foxes suggesting that these carnivores are serving as intermediate hosts, and we also provide ultrastructure of S. arctica from the Arctic fox for the first time. [ABSTRACT FROM AUTHOR]

The article offers information on the Canine distemper virus (CDV) as the cause of most of the epizootics. Topics discussed include information on the understanding how the disease spreads in the Arctic environment and ecosystem; discussions on the role of the historical records in providing valuable input for understanding the Arctic epizootic; and the information on the health-related challenges that the Greenland sled dogs face.