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| 2. |
- Angerbjörn, Anders, et al.
(författare)
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Carnivore conservation in practice : replicatedmanagement actions on a large spatial scale
- 2013
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 50:1, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- More than a quarter of the world’s carnivores are threatened, often due to multiple andcomplex causes. Considerable research efforts are devoted to resolving the mechanisms behindthese threats in order to provide a basis for relevant conservation actions. However, evenwhen the underlying mechanisms are known, specific actions aimed at direct support for carnivoresare difficult to implement and evaluate at efficient spatial and temporal scales.2. We report on a 30-year inventory of the critically endangered Fennoscandian arctic foxVulpes lagopus L., including yearly surveys of 600 fox dens covering 21 000 km2. These surveysshowed that the population was close to extinction in 2000, with 40–60 adult animalsleft. However, the population subsequently showed a fourfold increase in size.3. During this time period, conservation actions through supplementary feeding and predatorremoval were implemented in several regions across Scandinavia, encompassing 79% of thearea. To evaluate these actions, we examined the effect of supplemental winter feeding andred fox control applied at different intensities in 10 regions. A path analysis indicated that47% of the explained variation in population productivity could be attributed to lemmingabundance, whereas winter feeding had a 29% effect and red fox control a 20% effect.4. This confirms that arctic foxes are highly dependent on lemming population fluctuationsbut also shows that red foxes severely impact the viability of arctic foxes. This study also highlightsthe importance of implementing conservation actions on extensive spatial and temporalscales, with geographically dispersed actions to scientifically evaluate the effects. We note thatpopulation recovery was only seen in regions with a high intensity of management actions.5. Synthesis and applications. The present study demonstrates that carnivore populationdeclines may be reversed through extensive actions that target specific threats. Fennoscandianarctic fox is still endangered, due to low population connectivity and expected climate impactson the distribution and dynamics of lemmings and red foxes. Climate warming is expected tocontribute to both more irregular lemming dynamics and red fox appearance in tundra areas;however, the effects of climate change can be mitigated through intensive managementactions such as supplemental feeding and red fox control.
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| 3. |
- Cockerill, Christopher Alan, 1994-, et al.
(författare)
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Genomic Consequences of Fragmentation in the Endangered Fennoscandian Arctic Fox (Vulpes lagopus)
- 2022
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Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
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| 5. |
- Dalen, Love, et al.
(författare)
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Ancient DNA reveals lack of postglacial habitat tracking in the arctic fox
- 2007
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 104:16, s. 6726-6729
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Tidskriftsartikel (refereegranskat)abstract
- How species respond to an increased availability of habitat, for example at the end of the last glaciation, has been well established. In contrast, little is known about the opposite process, when the amount of habitat decreases. The hypothesis of habitat tracking predicts that species should be able to track both increases and decreases in habitat availability. The alternative hypothesis is that populations outside refugia become extinct during periods of unsuitable climate. To test these hypotheses, we used ancient DNA techniques to examine genetic variation in the arctic fox (Alopex lagopus) through an expansion/contraction cycle. The results show that the arctic fox in midlatitude Europe became extinct at the end of the Pleistocene and did not track the habitat when it shifted to the north. Instead, a high genetic similarity between the extant populations in Scandinavia and Siberia suggests an eastern origin for the Scandinavian population at the end of the last glaciation. These results provide new insights into how species respond to climate change, since they suggest that populations are unable to track decreases in habitat avaliability. This implies that arctic species may be particularly vulnerable to increases in global temperatures.
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| 6. |
- Dalén, Love, 1975-
(författare)
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Distribution and abundance of genetic variation in the arctic fox
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis investigates how changes in population size and spatial movements of individuals have shaped the distribution and abundance of neutral genetic variation in the arctic fox. This is done through mitochondrial and microsatellite DNA analyses on samples covering most of the species’ distribution, but with special emphasis on Scandinavia. On the species level, nucleotide diversity was relatively low, which indicated a historical expansion in population size in connection with the onset of the last Ice Age. It is thus possible that the glacial cycles have affected the arctic fox, and other cold-adapted species, in a way opposite to their effect on temperate species. Gene flow seemed to be high among arctic fox populations on a circumpolar scale, especially between populations where lemmings are the main food source, which could be explained by the spatial synchrony in lemming fluctuations. In Scandinavia, the arctic fox went through a severe demographic bottleneck in the beginning of the 20th century. Although some genetic variation was lost during this bottleneck, the loss was much smaller than expected, probably due to post-bottleneck gene flow from Russia. The arctic fox in Scandinavia is divided into four relatively isolated populations. Within each population, dispersal seemed to be high despite the high availability of empty territories close to natal dens, which supported the hypothesis that lemming fluctuations influence arctic fox dispersal. Genetic analyses on samples collected between 1989 and 2004 indicated an ongoing genetic drift and inbreeding within the Scandinavian populations. Furthermore, individual genetic variation was negatively associated with fitness, which could be attributed to an ongoing inbreeding depression. Analyses on faecal samples suggested that arctic foxes move higher up in the mountains and farther from the tree-line during summer compared to winter. This seasonal shift in distribution is probably caused by interspecific competition from the red fox, which is likely to be higher during summer due to red fox predation on arctic fox cubs. The results presented in this thesis have several implications for the conservation of the Scandinavian arctic fox. The finding of four isolated populations within Scandinavia and an ongoing inbreeding depression suggests that the risk of extinction is higher than previously thought. Conservation actions need to be taken in all populations to be effective, and could include genetic restoration through translocation.
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| 7. |
- Dalén, Love, et al.
(författare)
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DNA analysis on fox faeces and competition induced niche shifts
- 2004
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 13:8, s. 2389-2392
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Tidskriftsartikel (refereegranskat)abstract
- Interference competition can force inferior competitors to change their distribution patterns. It is, however, possible that the dominant competitor poses a higher threat during certain times of the year, for example during reproduction. In such cases, the inferior competitor is expected to change its distribution accordingly. We used a molecular species identification method on faeces to investigate how the spatial overlap between arctic and red foxes changes between seasons. The results show that arctic and red foxes are sympatric during winter, but allopatric in summer as arctic foxes retreat to higher altitudes further from the tree-line during the breeding season
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| 8. |
- Dalén, Love, et al.
(författare)
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Is the endangered Fennoscandian arctic fox (Alopex lagopus) population genetically isolated?
- 2002
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Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 105:2, s. 171-178
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Tidskriftsartikel (refereegranskat)abstract
- The arctic fox population in Fennoscandia is on the verge of going extinct after not being able to recover from a severe bottleneck at the end of the 19th century. The Siberian arctic fox population, on the other hand, is large and unthreatened. In order to resolve questions regarding gene flow between, and genetic variation within the populations, a 294 bp long part of the mitochondrial hypervariable region 1 was sequenced. This was done for 17 Swedish, 15 Siberian and two farmed foxes. Twelve variable nucleotide sites were observed, which resulted in 10 different haplotypes. Three haplotypes were found in Sweden and seven haplotypes were found in Siberia. An analysis of molecular variance showed a weak, but significant, differentiation between the populations. No difference in haplotype diversity was found between the populations. A phylogenetic analysis revealed that the three Swedish haplotypes were not monophyletic compared to the Siberian haplotypes. These results indicate a certain amount of gene flow between the two populations. both before and after the bottleneck. Restocking the Fennoscandian population with arctic foxes from Siberia might therefore be a viable option.
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| 9. |
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| 10. |
- Dalén, Love, et al.
(författare)
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Population history and genetic structure of a circumpolar species : the arctic fox
- 2005
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 84:1, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- The circumpolar arctic fox Alopex lagopus thrives in cold climates and has a high migration rate involving long-distance movements. Thus, it differs from many temperate taxa that were subjected to cyclical restriction in glacial refugia during the Ice Ages. We investigated population history and genetic structure through mitochondrial control region variation in 191 arctic foxes from throughout the arctic. Several haplotypes had a Holarctic distribution and no phylogeographical structure was found. Furthermore, there was no difference in haplotype diversity between populations inhabiting previously glaciated and unglaciated regions. This suggests current gene flow among the studied populations, with the exception of those in Iceland, which is surrounded by year-round open water. Arctic foxes have often been separated into two ecotypes: ‘lemming’ and ‘coastal’. An analysis of molecular variance suggested particularly high gene flow among populations of the ‘lemming’ ecotype. This could be explained by their higher migration rate and reduced fitness in migrants between ecotypes. A mismatch analysis indicated a sudden expansion in population size around 118 000 BP, which coincides with the last interglacial. We propose that glacial cycles affected the arctic fox in a way opposite to their effect on temperate species, with interglacials leading to short-term isolation in northern refugia.
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