12345671 of 14
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey
Stockholm University, Faculty of Science, Department of Zoology. (Svenska fjällrävsprojektet)ORCID iD: 0000-0002-9207-5709
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is well known that competition, predation and fluctuating food resources can have strong effect on individual fitness and population dynamics. The complexity of natural systems can make it complicate to disentangle those processes, but environments with relatively simple food webs, and strong cyclic population dynamics offer contrasting conditions resembling experimental treatments. This thesis concerns the spatial and temporal implications of fluctuations in small rodent abundance on two trophic levels in a highly cyclic ecosystem, the Scandinavian mountain tundra. The first two chapters focus on plant biomass and spatiotemporal distribution in the Norwegian lemming (Lemmus lemmus), while the three last papers focus on the direct and indirect effects of small rodent fluctuations and territory quality on reproductive success, juvenile survival and group living in a lemming specialist mesopredator, the arctic fox (Vulpes lagopus). By developing, validating and applying a novel application of aerial photos for remote sensing of plant biomass (Chapter I), we found that food availability predicted lemming distribution during population peaks, but that they were more habitat specific during increase years when intraspecific competition was lower (Chapter II). Arctic fox reproduction is tightly connected to small rodent abundance but the effects of geographical variation in food availability is less well known. We used 17 years of population surveys of an arctic fox subpopulation in mid Sweden (Helagsfjällen) to investigate potential effects. During small rodent increase years, we found that arctic fox litter sizes were smaller in territories of intermediate plant productivity, compared to both more and less productive territories (Chapter III). This could be an effect of limited food availability together with increased presence of red foxes (Vulpes vulpes), a stronger and potentially lethal competitor. However, when small rodents peaked, and competition would be expected to decrease, we saw no effect of territory productivity. Based on a smaller data set concerning juvenile summer survival, we found that the mortality rate among juveniles born by first time breeding arctic fox females were more sensitive to low small rodent prey abundance (Chapter IV). We explain it with an increased predation pressure from top-predators that switch from small rodents to alternative prey when small rodents decline, as suggested by an observed positive effect on juvenile survival by adult presence on den sites. Arctic foxes are socially flexible, and several adults can share a den with the resident pair, potentially increasing juvenile survival and help in territorial defence. Returning to the 17-year data set, we tested the Resource Dispersion Hypothesis predicting that increased resource availability should increase group size (Chapter V). We found support for this prediction as group living increased during the small rodent peak phase. However, it remained unexpectedly high during the decrease phase, when resources are scarce. This could however be related to increased predation pressure, and an increasing benefit of group living.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University , 2019. , p. 17
Keywords [en]
population dynamics, cyclic, mountain tundra, arctic fox, Norwegian lemming, small rodents, mesopredator, predation, survival, reproduction
National Category
Zoology Ecology
Research subject
Animal Ecology
Identifiers
URN: urn:nbn:se:su:diva-162539ISBN: 978-91-7797-540-3 (print)ISBN: 978-91-7797-541-0 (electronic)OAI: oai:DiVA.org:su-162539DiVA, id: diva2:1267147
Public defence
2019-01-25, Vivi Täckholmsalen (Q-salen), NPQ-huset, Svante Arrhenius väg 20, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 5: Manuscript.

Available from: 2018-12-19 Created: 2018-11-30 Last updated: 2018-12-19Bibliographically approved
List of papers
1. An innovative use of orthophotos – Possibilities to assess plant productivity from colour infrared aerial orthophotos
Open this publication in new window or tab >>An innovative use of orthophotos – Possibilities to assess plant productivity from colour infrared aerial orthophotos
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Ecology Remote Sensing
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-162534 (URN)
Projects
Svenska fjällrävsprojektet
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-12-04Bibliographically approved
2. Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle
Open this publication in new window or tab >>Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle
Show others...
2018 (English)In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, no 7, p. 1391-1403Article in journal (Refereed) Published
Abstract [en]

Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming (Lemmus lemmus) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.

Keywords
Small rodents, Density-dependent, Competition, Habitat, Primary productivity
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-153974 (URN)10.1007/s00300-018-2293-6 (DOI)000437102400007 ()
Projects
Svenska fjällrävsprojektet
Funder
Interreg Sweden-Norway
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2018-12-04Bibliographically approved
3. Limitations of a weaker competitor – Implications of territory quality on the reproductive output of a tundra specialist
Open this publication in new window or tab >>Limitations of a weaker competitor – Implications of territory quality on the reproductive output of a tundra specialist
(English)Manuscript (preprint) (Other academic)
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-162536 (URN)
Projects
Svenska fjällrävsprojektet
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-12-04Bibliographically approved
4. Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus): a matter of maternal experience and litter attendance
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: 2018-12-04Bibliographically approved
5. The resource dispersion hypothesis – a test with a cyclic mesopredator
Open this publication in new window or tab >>The resource dispersion hypothesis – a test with a cyclic mesopredator
(English)Manuscript (preprint) (Other academic)
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-162538 (URN)
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-12-04Bibliographically approved

Open Access in DiVA

Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey(674 kB)17 downloads
File information
File name FULLTEXT01.pdfFile size 674 kBChecksum SHA-512
c9700b37a8cd8dc83fb640868c934dffcea19e0a7a36e7708afe218fa3bb4d0f3554eba282c2d60bb8aa030c54a5c4ce74391c2cf00a804c337607b1f98f7e3f
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Erlandsson, Rasmus
By organisation
Department of Zoology
ZoologyEcology

Search outside of DiVA

GoogleGoogle Scholar
Total: 17 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 138 hits
12345671 of 14
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf