| 1. |
- Backström, Tobias, et al.
(författare)
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Short-term stress: effects on cortisol levels and carotenoid spots in Arctic char (Salvelinus alpinus)
- 2016
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94, s. 707-712
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Tidskriftsartikel (refereegranskat)abstract
- Earlier studies have shown that the carotenoid pigmentation in Arctic char (Salvelinus alpinus (L., 1758)) is connected to stress responsiveness. These studies also suggested that the pigmentation is dynamic and can change quickly. Therefore, we wanted to investigate the effect of a short-term stressor on the number of carotenoid spots before and after certain time intervals after the stressor. Individuals were exposed to a net-restraint stressor for 1 min and then assigned a recovery time of either 0, 1, 2, 8, or 24 h. Photographs were taken before the stressor and after the recovery time to count carotenoid spots and to look at the relative changes over time. Behaviour during the stressor and cortisol levels after the assigned recovery time were evaluated. We found that the change in spottiness, measured as the ratio of spots after and before the stressor, changed with recovery time on the right side but not on the left side. Furthermore, left-side spots were correlated with struggling activity. Thus, carotenoid pigmentation seems to be lateralized, with more static spots on the left side connected to stress responsiveness, whereas spots on the right side seem to be more dynamic.
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| 2. |
- Cheng, Ken, et al.
(författare)
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NMR-based metabolomics reveals compartmental metabolic heterogeneity in liver of Arctic char (Salvelinus alpinus)
- 2016
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94, s. 665-669
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Tidskriftsartikel (refereegranskat)abstract
- Metabolomics involves systematic study of low-molecular-mass metabolites in cells, tissues, or biofluids and is nowadays widely applied to characterize the physiological status of aquatic organisms under a set of conditions, such as disease and toxin exposure. Liver, an important metabolic center in the fish body, is often used for metabolomics analysis. Compared with the whole fish liver, the proportion of liver sample needed for metabolomics analysis is relatively small. The homogeneity of metabolites in liver is thus an important issue, especially for comparative studies and biomarker discovery. This study examined the homogeneity of the metabolic profile in liver of Arctic char (Salvelinus alpinus (L., 1758)) using a NMR-based metabolomics approach. For the analysis, whole liver samples were cut into four parts along the direction of gall bladder and at right angles to this, and metabolites in each part of the liver were extracted and analyzed by multivariate and univariate data analyses. Although the multivariate model was not significant due to variation within the data, the metabolic differences in polar portion of liver extract between the parts were seen, indicating non-homogeneity of Arctic char liver. Therefore, when sampling fish liver for further metabolomics studies, this heterogeneity should be taken into consideration.
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| 3. |
- Dalerum, Fredrik, et al.
(författare)
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Exploring the diet of arctic wolves (Canis lupus arctos) at their northern range limit
- 2018
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 96:3, s. 277-281
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Erlandsson, Rasmus, et al.
(författare)
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Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus) : a matter of maternal experience and litter attendance
- 2017
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 95, s. 239-246
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Finn, K. T., et al.
(författare)
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Contrasts in body size and growth suggest that high population density results in faster pace of life in Damaraland mole-rats (Fukomys damarensis)
- 2018
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 96:8, s. 920-927
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Tidskriftsartikel (refereegranskat)abstract
- We studied the correlates of population density and body size, growth rates, litter size, and group size in Damaraland mole-rats (Fukomys damarensis (Ogilby, 1838)) at two study sites with contrasting population densities. Group size, litter size, and the probability of recapture were independent of study site. However, body size differed between the two study sites, suggesting that population density may affect life-history traits in social mole-rats. At the low-density site (0.13 groups/ha), individuals were significantly larger and subordinate males showed higher growth rates than at the high-density site (0.41 groups/ha), which may indicate that high population density in subterranean rodents enhances pace of life. The larger size of nonreproductive individuals at the low-density site could adapt individuals at lower population densities to larger dispersal distances.
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| 6. |
- Hyeun-Ji, Lee, et al.
(författare)
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Compensating for a bad start : compensatory growth across life stages in an organism with a complex life cycle
- 2016
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94:1, s. 41-47
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Tidskriftsartikel (refereegranskat)abstract
- Organisms with a complex life cycle are characterized by a life-history shift through metamorphosis and include organisms such as insects and amphibians. They must optimize their use of resources and behaviour across different life stages to maximize their fitness. An interesting question with regard to such life-history shifts is whether growth in the juvenile stage can be compensated for in the adult stage. Here we ask whether emerald damselflies (Lestes sponsa (Hansemann, 1823)) are able to compensate for depressed growth during the juvenile aquatic stage in their terrestrial adult stage. Lestes sponsa emerge at a fixed adult body size, but feed during the adult stage and are thus able to gain mass as adults. We performed a mark-recapture study to answer whether individuals that emerge from metamorphosis with a low mass are able to compensate by subsequent mass gain during the adult stage. Results showed that compensatory mass gain occurred in the adult stage such that small individuals gained more mass than large individuals. We also found that females gained more mass than males. However, individuals that emerged at a low mass still had lower mass as mature adults than individuals that emerged at a high mass, suggesting that compensation was not complete. This suggests that larval ecology and adult fitness are tightly linked and future research should focus more on elucidating the nature of this relationship.
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| 7. |
- Öhmark, Sara, 1980-, et al.
(författare)
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Spatially segregated foraging patterns of moose (Alces alces) and mountain hare (Lepus timidus) in a subarctic landscape: different tables in the same restaurant?
- 2015
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Ingår i: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 93:5, s. 391-396
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Tidskriftsartikel (refereegranskat)abstract
- Differences in body sizes of mountain hares (Lepus timidus L., 1758) and moose (Alces alces (L., 1758)) affect their abilityto perceive and respond to environmental heterogeneity and plant density. Therefore, we expect these species to show nicheseparation at different scales in the same environment. Results showed that the numbers of mountain birches (Betula pubescenssubsp. czerepanovii L.) browsed by moose per unit area was inversely related to hare browsing. Moose browsed larger birchescompared with hares, and while hares targeted areas with high birch densities regardless of tree sizes, moose preferentiallybrowsed areas with high densities of large birches. Moose browsing was clustered at spatial intervals of 1000–1500 m, while harebrowsing was clustered at intervals of less than 500 m. Willows (genus Salix L.) in the study area were heavily browsed by moose,while few observations of hare browsing on willow were made. Regarding both hare and moose, numbers of birch stems withnew browsing per sample plot were positively correlated with the numbers of birch stems with old browsing, indicating thathare and moose preferred the same foraging sites from year to year. These findings have implications for management of thespecies because they show the importance of scale and landscape perspectives in planning and actions.
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