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Meijer, Tomas
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Publications (10 of 18) Show all publications
Dalerum, F., Freire, S., Angerbjörn, A., Lecomte, N., Lindgren, A., Meijer, T., . . . Dalén, L. (2018). Exploring the diet of arctic wolves (Canis lupus arctos) at their northern range limit. Canadian Journal of Zoology, 96(3), 277-281
Open this publication in new window or tab >>Exploring the diet of arctic wolves (Canis lupus arctos) at their northern range limit
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2018 (English)In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 96, no 3, p. 277-281Article in journal (Refereed) Published
Abstract [en]

The grey wolf (Canis lupus Linnaeus, 1758) is one of the most widespread large carnivores on Earth, and occurs throughout the Arctic. Although wolf diet is well studied, we have scant information from high Arctic areas. Global warming is expected to increase the importance of predation for ecosystem regulation in Arctic environments. To improve our ability to manage Arctic ecosystems under environmental change, we therefore need knowledge about Arctic predator diets. Prey remains in 54 wolf scats collected at three sites in the high Arctic region surrounding the Hall Basin (Judge Daly Promontory, Ellesmere Island, Canada, and Washington Land and Hall Land, both in northwestern Greenland) pointed to a dietary importance of arctic hare (Lepus arcticus Ross, 1819; 55% frequency of occurrence) and muskoxen (Ovibos moschatus (Zimmermann, 1780); 39% frequency of occurrence), although we observed diet variation among the sites. A literature compilation suggested that arctic wolves (Canis lupus arctos Pocock, 1935) preferentially feed on caribou (Rangifer tarandus (Linnaeus, 1758)) and muskoxen, but can sustain themselves on arctic hares and Greenland collared lemmings (Dicrostonyx groenlandicus (Traill, 1823)) in areas with limited or no ungulate populations. We suggest that climate change may alter the dynamics among wolves, arctic hare, muskoxen, and caribou, and we encourage further studies evaluating how climate change influences predator-prey interactions in high Arctic environments.

Keywords
arctic wolf, Canis lupus arctos, food habits, diet, high Arctic, arctic hare, Lepus arcticus, muskoxen, Ovibos moschatus
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-154795 (URN)10.1139/cjz-2017-0054 (DOI)000427385500013 ()
Available from: 2018-04-17 Created: 2018-04-17 Last updated: 2022-02-26Bibliographically approved
Erlandsson, R., Meijer, T., Wagenius, S. & Angerbjörn, A. (2017). Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus): a matter of maternal experience and litter attendance. Canadian Journal of Zoology, 95, 239-246
Open this publication in new window or tab >>Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus): a matter of maternal experience and litter attendance
2017 (English)In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 95, p. 239-246Article in journal (Refereed) Published
Abstract [en]

Reproductive experience affects juvenile survival in a wide range of species with possible links to differences in foraging capacity and predation. Using supplementary feeding, we aimed to limit direct effect of prey abundance to investigate indirect effects of small-rodent availability and maternal experience on juvenile summer survival rates in an endangered population of arctic fox (Vulpes lagopus (L., 1758)). We used data spanning 7 years, included a complete small-rodent cycle, comprising 49 litters and 394 cubs. The effect of small-rodent abundance on juvenile survival depended on maternal breeding experience. Cubs born by first-time-breeding females had lower survival rate when small-rodent abundance was low compared with juveniles born to experienced mothers who remained unaffected. It was unlikely due to starvation, as physical condition was unrelated to survival. Instead, we favour the explanation that intraguild predation was an important cause of mortality. There was a negative relationship between survival and amount of time cubs were left unattended, suggesting that parental behaviour affected predation. We propose that a prey switch related to small-rodent abundance caused fluctuations in intraguild predation pressure and that inexperienced females were less able to cope with predation when small rodents were scarce.

Keywords
arctic fox, Vulpes lagopus, juvenile survival, small rodents, cyclic, maternal experience, behaviour, intraguild predation
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-140943 (URN)10.1139/cjz-2016-0103 (DOI)000399167300002 ()
Projects
Svenska fjällrävsprojektet
Available from: 2017-03-24 Created: 2017-03-24 Last updated: 2022-02-28Bibliographically approved
Norén, K., Angerbjörn, A., Wallén, J., Meijer, T. & Sacks, B. N. (2017). Red foxes colonizing the tundra: genetic analysis as a tool for population management. Conservation Genetics, 18(2), 359-370
Open this publication in new window or tab >>Red foxes colonizing the tundra: genetic analysis as a tool for population management
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2017 (English)In: Conservation Genetics, ISSN 1566-0621, E-ISSN 1572-9737, Vol. 18, no 2, p. 359-370Article in journal (Refereed) Published
Abstract [en]

Climate change accelerates biodiversity alterations in northern ecosystems. A prevalent example is that tundra regions are invaded by boreal species. This impacts negatively on native species through competition, predation and transmission of zoonoses. Scandinavian red foxes (Vulpes vulpes) have emerged into the tundra and have altered the structure and function of the tundra community. For instance, they threaten persistence of the endangered Swedish Arctic fox (Vulpes lagopus). County board administrations implement control of the tundra red foxes, but little is known about the underlying expansion dynamics. A broad-scale study revealed high connectivity where northern areas were supplemented with red foxes from surrounding population. However, red fox expansion is most prevalent in tundra regions and the fine-scaled expansion dynamics in these areas have not yet been disseminated. With the aim of identifying the invasive pathways of tundra red foxes, we present microsatellite data for 205 Swedish red foxes and mitochondrial sequence variation in 102 foxes sampled across the historical boreo-nemoral distribution and recently colonized tundra regions. Genetic structuring was low with high levels of ongoing, asymmetric dispersal from surrounding boreal zones into tundra habitats causing high genetic admixture. In both tundra and boreo-nemoral regions, inter-individual relatedness decreased with increasing geographic distance and data suggests male-biased dispersal patterns. Overall, fine-scaled expansion patterns were affected by multiple factors and we discuss its implications for future red fox management.

Keywords
Conservation, Inter-specific competition, Expansion, DNA analysis, Asymmetric dispersal, Relatedness
National Category
Zoology
Identifiers
urn:nbn:se:su:diva-135743 (URN)10.1007/s10592-016-0910-x (DOI)000396341900009 ()
Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2022-03-23Bibliographically approved
Dalerum, F., Dalén, L., Fröjd, C., Lecomte, N., Lindgren, Å., Meijer, T., . . . Angerbjörn, A. (2017). Spatial variation in Arctic hare (Lepus arcticus) populations around the Hall Basin. Polar Biology, 40(10), 2113-2118
Open this publication in new window or tab >>Spatial variation in Arctic hare (Lepus arcticus) populations around the Hall Basin
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2017 (English)In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 40, no 10, p. 2113-2118Article in journal (Refereed) Published
Abstract [en]

Arctic environments have relatively simple ecosystems. Yet, we still lack knowledge of the spatio-temporal dynamics of many Arctic organisms and how they are affected by local and regional processes. The Arctic hare (Lepus arcticus) is a large lagomorph endemic to high Arctic environments in Canada and Greenland. Current knowledge about this herbivore is scarce and the temporal and spatial dynamics of their populations are poorly understood. Here, we present observations on Arctic hares in two sites on north Greenland (Hall and Washington lands) and one adjacent site on Ellesmere Island (Judge Daly Promontory). We recorded a large range of group sizes from 1 to 135 individuals, as well as a substantial variation in hare densities among the three sites (Hall land: 0 animals/100 km(2), Washington land 14.5-186.7 animals/100 km(2), Judge Daly Promontory 0.18-2.95 animals/100 km(2)). However, pellet counts suggested that both Hall land and Judge Daly Promontory hosted larger populations at other times. We suggest that our results could have been caused by three spatially differentiated populations with asynchronous population fluctuations. With food limitation being a likely driver behind the observed variation, we argue that food limitation likely interacts with predation and competition in shaping the spatial dynamics of Arctic hares in this region.

Keywords
Synchrony, Population dynamics, Geographic variation, Ellesmere Island, North Greenland, Lagomorpha
National Category
Biological Sciences
Research subject
Systematic Zoology
Identifiers
urn:nbn:se:su:diva-147849 (URN)10.1007/s00300-017-2116-1 (DOI)000411873100017 ()
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2022-02-28Bibliographically approved
Norén, K., Godoy, E., Dalén, L., Meijer, T. & Angerbjörn, A. (2016). Inbreeding depression in a critically endangered carnivore. Molecular Ecology, 25(14), 3309-3318
Open this publication in new window or tab >>Inbreeding depression in a critically endangered carnivore
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2016 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 25, no 14, p. 3309-3318Article in journal (Refereed) Published
Abstract [en]

Harmful effects arising from matings between relatives (inbreeding) is a long-standing observation that is well founded in theory. Empirical evidence for inbreeding depression in natural populations is however rare because of the challenges of assembling pedigrees supplemented with fitness traits. We examined the occurrence of inbreeding and subsequent inbreeding depression using a unique data set containing a genetically verified pedigree with individual fitness traits for a critically endangered arctic fox (Vulpes lagopus) population. The study covered nine years and was comprised of 33 litters with a total of 205 individuals. We recorded that the present population was founded by only five individuals. Over the study period, the population exhibited a tenfold increase in average inbreeding coefficient with a final level corresponding to half-sib matings. Inbreeding mainly occurred between cousins, but we also observed two cases of full-sib matings. The pedigree data demonstrated clear evidence of inbreeding depression on traditional fitness traits where inbred individuals displayed reduced survival and reproduction. Fitness traits were however differently affected by the fluctuating resource abundande. Inbred individuals born at low-quality years displayed reduced first-year survival, while inbred individuals born at high-quality years were less likely to reproduce. The documentation of inbreeding depression in fundamental fitness traits suggests that inbreeding depression can limit population recovery. Introducing new genetic material to promote a genetic rescue effect may thus be necessary for population long-term persistence.

Keywords
conservation, extinction vortex, inbreeding coefficient, life history, microsatellites
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-129381 (URN)10.1111/mec.13674 (DOI)000379614400006 ()
Available from: 2016-04-21 Created: 2016-04-21 Last updated: 2022-02-23Bibliographically approved
Angerbjörn, A., Eide, N. E., Dalén, L., Elmhagen, B., Hellström, P., Ims, R. A., . . . Henttonen, H. (2013). Carnivore conservation in practice: replicatedmanagement actions on a large spatial scale. Journal of Applied Ecology, 50(1), 59-67
Open this publication in new window or tab >>Carnivore conservation in practice: replicatedmanagement actions on a large spatial scale
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2013 (English)In: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 50, no 1, p. 59-67Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Alopex, arctic, climate, extinction, population cycles, restoration, SEFALO, Vulpes
National Category
Biological Sciences
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-87916 (URN)10.1111/1365-2664.12033 (DOI)000314520500008 ()
Available from: 2013-02-25 Created: 2013-02-25 Last updated: 2022-04-25Bibliographically approved
Meijer, T., Elmhagen, B., Eide, N. E. & Angerbjörn, A. (2013). Life history traits in a cyclic ecosystem: a field experiment on the arctic fox. Oecologia, 173(2), 439-447
Open this publication in new window or tab >>Life history traits in a cyclic ecosystem: a field experiment on the arctic fox
2013 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 173, no 2, p. 439-447Article in journal (Refereed) Published
Abstract [en]

The reproduction of many species depends strongly on variation in food availability. The main prey of the arctic fox in Fennoscandia are cyclic small rodents, and its number of litters and litter size vary depending on the phase of the rodent cycle. In this experiment, we studied if the arctic fox adjusts its reproduction as a direct response to food abundance, in accordance with the food limitation hypothesis, or if there are additional phase-dependent trade-offs that influence its reproduction. We analysed the weaning success, i.e. proportion of arctic fox pairs established during mating that wean a litter in summer, of 422 pairs of which 361 were supplementary winter fed, as well as the weaned litter size of 203 litters of which 115 were supplementary winter fed. Females without supplementary winter food over-produced cubs in relation to food abundance in the small rodent increase phase, i.e. the litter size was equal to that in the peak phase when food was more abundant. The litter size for unfed females was 6.38 in the increase phase, 7.11 in the peak phase and 3.84 in the decrease phase. The litter size for supplementary winter-fed litters was 7.95 in the increase phase, 10.61 in the peak phase and 7.86 in the decrease phase. Thus, feeding had a positive effect on litter size, but it did not diminish the strong impact of the small rodent phase, supporting phase-dependent trade-offs in addition to food determining arctic fox reproduction.

Keywords
Litter size, Conservation, Alopex lagopus, Supplementary feeding, Life history
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:su:diva-95424 (URN)10.1007/s00442-013-2641-8 (DOI)000325028500011 ()
Note

AuthorCount:4;

Available from: 2013-10-31 Created: 2013-10-28 Last updated: 2022-02-24Bibliographically approved
Meijer, T. (2013). To survive and reproduce in a cyclic environment – demography and conservation of the Arctic fox in Scandinavia. (Doctoral dissertation). Stockholm: Department of Zoology, Stockholm University
Open this publication in new window or tab >>To survive and reproduce in a cyclic environment – demography and conservation of the Arctic fox in Scandinavia
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns the conservation and life history of the Arctic fox (Vulpes lagopus) in Scandinavia. The Arctic fox was historically a widely distributed species in the Scandinavian mountain tundra with a population size of approximately 10 000 individuals during years with high resource availability, i.e. rodent peaks. However, due to over-harvest in the end of the 19th century, the population numbers declined to a few hundred individuals. Although legally protected for more than 80 years, the population has remained small. The main causes of the non-recovery have been attributed to irregularities in the lemming cycle and increased competitions with the larger red fox. 

Through conservation actions including red fox culling and supplementary feeding, the population has started to recover in parts of its former distribution range. The Arctic fox is highly adapted to the lemming cycle and determine whether to reproduce or not and adjust the litter size relation to small rodent phase in combination with food abundance. In the small rodent increase phase, females produce litters equal to the peak phase, despite higher food abundance in the later. This overproduction of cubs can be selected for through a higher juvenile survival and reproductive value of cubs born in the increase phase compared to the other phases. The most important component affecting the reproductive value seem to be the survival during the first year after birth. In the small rodent increase phase 32% of the cubs survives their first year compared to 9% in the decrease phase. The Arctic fox in Scandinavia constitute an example of how a species can adapt their reproductive strategy to a fluctuating environment by adjustment of the reproduction.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2013. p. 31
Keywords
Conservation, life-history, Alopex lagopus, survival
National Category
Zoology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-87404 (URN)978-91-7447-647-7 (ISBN)
Public defence
2013-04-12, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 4: Accepted manuscript; Paper 5: Manuscript.

Available from: 2013-03-21 Created: 2013-02-05 Last updated: 2022-02-24Bibliographically approved
Norén, K., Hersteinsson, P., Samelius, G., Eide, N. E., Fuglei, E., Elmhagen, B., . . . Angerbjörn, A. (2012). From monogamy to complexity: social organization of arctic foxes (Vulpes lagopus) in contrasting ecosystems. Canadian Journal of Zoology, 90(9), 1102-1116
Open this publication in new window or tab >>From monogamy to complexity: social organization of arctic foxes (Vulpes lagopus) in contrasting ecosystems
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2012 (English)In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 90, no 9, p. 1102-1116Article in journal (Refereed) Published
Abstract [en]

Canids display pronounced intraspecific variation in social organization, ranging from single breeding females to large and complex groups. Despite several hypotheses in this matter, little is understood about the ecological factors underlying this flexibility. We have used the arctic fox (Vulpes lagopus (L., 1758)) to investigate how contrasting ecosystem conditions concerning resources and predation influence group formation. We predicted that complex groups are more common in resource-rich ecosystems with predators, whereas simple groups occur in more marginal ecosystems without predators. Samples from 54 groups were collected from four populations of arctic foxes with contrasting prey resources and predation and these samples were genotyped in 10 microsatellite loci. We found considerable variation between ecosystems and a significant relationship between resources and formation of complex groups. We conclude that sufficient amounts of food is a prerequisite for forming complex groups, but that defense against predation further increases the benefits of living in larger groups. We present a conceptual model suggesting that a trade-off between the cost of resource depletion and the benefits obtained for guarding against predators explain the differences in social organization. The variable ecology of  the arctic foxes makes it is a plausible model species for understanding the connection between ecology and social organization also in other species.

Keywords
Vulpes lagopus, arctic fox, resource dispersion hypothesis, predation, parentage, microsatellites, trade-off
National Category
Biological Sciences
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-78870 (URN)10.1139/Z2012-077 (DOI)000308772300005 ()
Available from: 2012-08-16 Created: 2012-08-16 Last updated: 2022-02-24Bibliographically approved
Meijer, T., Mattsson, R., Angerbjörn, A., Osterman-Lind, E., Fernandez-Aguilar, X. & Gavier-Widen, D. (2011). Endoparasites in the endangered Fennoscandian population of arctic foxes (Vulpes lagopus). European Journal of Wildlife Research, 57(4), 923-927
Open this publication in new window or tab >>Endoparasites in the endangered Fennoscandian population of arctic foxes (Vulpes lagopus)
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2011 (English)In: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, no 4, p. 923-927Article in journal (Refereed) Published
Abstract [en]

The Fennoscandian arctic fox (Vulpes lagopus) population is endangered due to overharvest and competition with the larger red fox (Vulpes vulpes). In this study, we have screened the population in Sweden for endoparasites by analysis of non-invasively faecal samples collected at reproductive dens during two summers, one with low food abundance (2008) and the other with high food abundance (2010). Eggs, larvae and oocysts of a total of 14 different endoparasites were identified with a species richness per inhabited den of 3.2 (CI95% +/- 0.48) in 2008 and 2.7 (CI95% +/- 0.72) in 2010. Capillariidae-like eggs was identified at 59% of the dens in 2008 and 57% in 2010 and Toxocara canis with 7% (2008) and 30% (2010); Toxascaris leonina with 93% (2008) and 65% (2010); Uncinaria stenocephala 65% (2008) and 39% (2010); Crenosoma vulpis 3% (2008) and 4% (2010); Trichuris sp. 7% (2008) and 4% (2010); Cystoisospora canis-like oocysts 28% (2008) and 26% (2010); Cystoisospora ohiensis-like oocysts 38% (2008) and 4% (2010); Eimeria sp. 7% (2008) and 9% (2010); Sarcocystis sp. 3% (2008) and 9% (2010); Taenia sp. 10% (2008) and 4% (2010); Mesocestoides sp. 3% (2008) and 0% (2010); Balantidium sp. 0% (2008) and 9% (2010) and Spiruroidea-like eggs 0% (2008) and 4% (2010). To our knowledge, Balantidium sp., Sarcocystis sp. and Trichuris sp. has never been described before in wild arctic foxes.

Keywords
Alopex lagopus; Parasites; Conservation; Wildlife disease; Sweden
National Category
Zoology Ecology Environmental Sciences
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-65933 (URN)10.1007/s10344-011-0505-2 (DOI)000292932500022 ()
Available from: 2011-12-16 Created: 2011-12-16 Last updated: 2022-02-24Bibliographically approved
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