Interactions between small rodents and their food plants in tundra habitats

Papers 2, 3, 4 and 5 are not available in Munin: 2. Soininen E.M., Zinger L., Gielly L., Bellemain, E., Br athen, K.A., Brochmann, C., Epp, L.S., Gussarova, G., Hassel, K., Henden, J.-A., Killengreen, S.T., R am a, T., Sten ien, H.K., Yoccoz, N.G. and Ims, R.A.: 'Shedding new light on the diet...

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Main Author: Soininen, Eeva Marjatta
Format: Doctoral or Postdoctoral Thesis
Language:English
Published: Universitetet i Tromsø 2012
Subjects:
Online Access:https://hdl.handle.net/10037/4574
id ftunivtroemsoe:oai:munin.uit.no:10037/4574
record_format openpolar
institution Open Polar
collection University of Tromsø: Munin Open Research Archive
op_collection_id ftunivtroemsoe
language English
topic VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488
spellingShingle VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488
Soininen, Eeva Marjatta
Interactions between small rodents and their food plants in tundra habitats
topic_facet VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488
description Papers 2, 3, 4 and 5 are not available in Munin: 2. Soininen E.M., Zinger L., Gielly L., Bellemain, E., Br athen, K.A., Brochmann, C., Epp, L.S., Gussarova, G., Hassel, K., Henden, J.-A., Killengreen, S.T., R am a, T., Sten ien, H.K., Yoccoz, N.G. and Ims, R.A.: 'Shedding new light on the diet of Norwegian lemmings : metabarcoding of stomach DNA' (manuscript) 3. Soininen E.M., Ravolainen V.T., Br athen K.A., Yoccoz N.G., Gielly, L. and Ims R.A.: 'Arctic small rodents have diverse diets and exible food preferences' (manuscript) 4. Soininen E.M., Ehrich D., Lecomte N., Yoccoz N.G., Tarroux A., Berteaux D., Gauthier G., Gielly L. and Ims R.A.: 'Sources of variation in small rodent trophic niche : new insights from DNA metabarcoding and stable isotope analysis' (manuscript) 5. Soininen E.M., Br athen, K.A., Jusdado J.G.H, Reidinger S., Hartley S.E.: 'More than herbivory : levels of silica-based plant defences in grasses varies with genotype, species and location', Oikos (2012), Online before print. Available at http://dx.doi.org/10.1111/j.1600-0706.2012.20689.x Small rodents are key herbivores of arctic ecosystems, where their cyclic population dynamics have important implications for vegetation dynamics. The role of vegetation for shaping small rodent population dynamics remains, however, unclear. Evaluation of this interaction has been greatly hampered by the rather fragmentary knowledge of small rodents feeding ecology, which in turn is due to methodological challenges in studying small rodent diets. In this thesis, I investigated interactions between small rodents and vegetation, focusing on variability of both diets and plant defences induced by rodent herbivory. In order to overcome limitations set by methods, I have evaluated the use of two recently developed methods and one traditionally used method for studying small rodent diets. I found that novel DNA metabarcoding methods give the best taxonomic resolution whereas traditional microhistological methods may still be useful to elucidate which plant parts have been eaten. Moreover, use of stable isotope analysis in research of small rodent feeding habits can be useful when evaluating the temporal persistence of diets. In three observational studies, I described diets of small rodents in tundra habitats and assessed sources of variability in them. I found that diets of my study species were more diverse than previously believed, suggesting that diversity is an important but previously underrated trait of small rodent diets. Nutritional quality seems to determine which food items are preferred, as small rodents selected in general for most palatable food items. In addition to nutritional drivers, my results suggest that various ecological drivers, such as food availability, competition and predation risk avoidance, are important determinants of for small rodent diets in the wild. A better incorporation of ecological and nutritional drivers into a common framework is therefore needed to understand what shapes diets of small rodents, and herbivores in general, in natural habitats. I evaluated the impact of herbivory on grass silica defences in an experimental study. I found that levels of such defences vary between locations, probably due to heritable differences among grass populations in the response to herbivory and differences in local growth conditions. Based on such spatial variation and the large proportion of other food items included in the diets of the focal small rodent populations, it is unlikely that silica-based defences would have a strong direct role in shaping small rodent population dynamics in Finnmark. However, increased levels of silica in grasses reduce grass palatability for rodents, and hence probably impact rodent diet quality indirectly, through a shift to diets with less grasses. I therefore suggest that availability of alternative food items is likely to be an important factor shaping the interaction between small rodents and grasses. Variability in both small rodent diets and plant defences suggests that interaction between vegetation and a small rodent species may show pronounced spatial variation. This, together with my findings on the diversity of diets and its increase during high population densities, indicates that a single plant defence mechanism is unlikely to shape rodent-vegetation interactions. I suggest that deeper understanding of the role of food for small rodent population dynamics could rather be gained by focusing on the compensatory nutritional effects of different food items as well as diet diversity.
format Doctoral or Postdoctoral Thesis
author Soininen, Eeva Marjatta
author_facet Soininen, Eeva Marjatta
author_sort Soininen, Eeva Marjatta
title Interactions between small rodents and their food plants in tundra habitats
title_short Interactions between small rodents and their food plants in tundra habitats
title_full Interactions between small rodents and their food plants in tundra habitats
title_fullStr Interactions between small rodents and their food plants in tundra habitats
title_full_unstemmed Interactions between small rodents and their food plants in tundra habitats
title_sort interactions between small rodents and their food plants in tundra habitats
publisher Universitetet i Tromsø
publishDate 2012
url https://hdl.handle.net/10037/4574
long_lat ENVELOPE(-67.458,-67.458,-68.850,-68.850)
ENVELOPE(-63.583,-63.583,-64.833,-64.833)
ENVELOPE(-164.467,-164.467,-86.467,-86.467)
geographic Arctic
Berteaux
Gauthier
Hassel
geographic_facet Arctic
Berteaux
Gauthier
Hassel
genre Arctic
Finnmark
Tundra
Finnmark
genre_facet Arctic
Finnmark
Tundra
Finnmark
op_relation https://hdl.handle.net/10037/4574
URN:NBN:no-uit_munin_4313
op_rights openAccess
Copyright 2012 The Author(s)
_version_ 1766348921668370432
spelling ftunivtroemsoe:oai:munin.uit.no:10037/4574 2023-05-15T15:18:44+02:00 Interactions between small rodents and their food plants in tundra habitats Soininen, Eeva Marjatta 2012-10-19 https://hdl.handle.net/10037/4574 eng eng Universitetet i Tromsø University of Tromsø https://hdl.handle.net/10037/4574 URN:NBN:no-uit_munin_4313 openAccess Copyright 2012 The Author(s) VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 Doctoral thesis Doktorgradsavhandling 2012 ftunivtroemsoe 2021-06-25T17:53:25Z Papers 2, 3, 4 and 5 are not available in Munin: 2. Soininen E.M., Zinger L., Gielly L., Bellemain, E., Br athen, K.A., Brochmann, C., Epp, L.S., Gussarova, G., Hassel, K., Henden, J.-A., Killengreen, S.T., R am a, T., Sten ien, H.K., Yoccoz, N.G. and Ims, R.A.: 'Shedding new light on the diet of Norwegian lemmings : metabarcoding of stomach DNA' (manuscript) 3. Soininen E.M., Ravolainen V.T., Br athen K.A., Yoccoz N.G., Gielly, L. and Ims R.A.: 'Arctic small rodents have diverse diets and exible food preferences' (manuscript) 4. Soininen E.M., Ehrich D., Lecomte N., Yoccoz N.G., Tarroux A., Berteaux D., Gauthier G., Gielly L. and Ims R.A.: 'Sources of variation in small rodent trophic niche : new insights from DNA metabarcoding and stable isotope analysis' (manuscript) 5. Soininen E.M., Br athen, K.A., Jusdado J.G.H, Reidinger S., Hartley S.E.: 'More than herbivory : levels of silica-based plant defences in grasses varies with genotype, species and location', Oikos (2012), Online before print. Available at http://dx.doi.org/10.1111/j.1600-0706.2012.20689.x Small rodents are key herbivores of arctic ecosystems, where their cyclic population dynamics have important implications for vegetation dynamics. The role of vegetation for shaping small rodent population dynamics remains, however, unclear. Evaluation of this interaction has been greatly hampered by the rather fragmentary knowledge of small rodents feeding ecology, which in turn is due to methodological challenges in studying small rodent diets. In this thesis, I investigated interactions between small rodents and vegetation, focusing on variability of both diets and plant defences induced by rodent herbivory. In order to overcome limitations set by methods, I have evaluated the use of two recently developed methods and one traditionally used method for studying small rodent diets. I found that novel DNA metabarcoding methods give the best taxonomic resolution whereas traditional microhistological methods may still be useful to elucidate which plant parts have been eaten. Moreover, use of stable isotope analysis in research of small rodent feeding habits can be useful when evaluating the temporal persistence of diets. In three observational studies, I described diets of small rodents in tundra habitats and assessed sources of variability in them. I found that diets of my study species were more diverse than previously believed, suggesting that diversity is an important but previously underrated trait of small rodent diets. Nutritional quality seems to determine which food items are preferred, as small rodents selected in general for most palatable food items. In addition to nutritional drivers, my results suggest that various ecological drivers, such as food availability, competition and predation risk avoidance, are important determinants of for small rodent diets in the wild. A better incorporation of ecological and nutritional drivers into a common framework is therefore needed to understand what shapes diets of small rodents, and herbivores in general, in natural habitats. I evaluated the impact of herbivory on grass silica defences in an experimental study. I found that levels of such defences vary between locations, probably due to heritable differences among grass populations in the response to herbivory and differences in local growth conditions. Based on such spatial variation and the large proportion of other food items included in the diets of the focal small rodent populations, it is unlikely that silica-based defences would have a strong direct role in shaping small rodent population dynamics in Finnmark. However, increased levels of silica in grasses reduce grass palatability for rodents, and hence probably impact rodent diet quality indirectly, through a shift to diets with less grasses. I therefore suggest that availability of alternative food items is likely to be an important factor shaping the interaction between small rodents and grasses. Variability in both small rodent diets and plant defences suggests that interaction between vegetation and a small rodent species may show pronounced spatial variation. This, together with my findings on the diversity of diets and its increase during high population densities, indicates that a single plant defence mechanism is unlikely to shape rodent-vegetation interactions. I suggest that deeper understanding of the role of food for small rodent population dynamics could rather be gained by focusing on the compensatory nutritional effects of different food items as well as diet diversity. Doctoral or Postdoctoral Thesis Arctic Finnmark Tundra Finnmark University of Tromsø: Munin Open Research Archive Arctic Berteaux ENVELOPE(-67.458,-67.458,-68.850,-68.850) Gauthier ENVELOPE(-63.583,-63.583,-64.833,-64.833) Hassel ENVELOPE(-164.467,-164.467,-86.467,-86.467)