| 1. |
- Nummi, Petri, et al.
(author)
-
Individual foraging behaviour indicates resource limitation : an experiment with mallard ducklings
- 2000
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. - 0008-4301 ; 78:11, s. 1891-1895
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Journal article (peer-reviewed)abstract
- The linkage between individual behaviour and population processes has recently been emphasized. Within this framework we studied the effect of resource limitation on the behaviour of mallard (Anas platyrhynchos) ducklings in boreal lakes. One group of 12 human-imprinted ducklings (4-16 days old) were taken to 11 "rich" lakes, i.e., with a relatively high concentration of total phosphorus in the water, and the other group of 12 ducklings to 11 "poor" lakes to forage for a period of 6 h. During this, a time budget study lasting 5 min was done of each of the 12 ducklings. In the rich lakes, ducklings fed significantly more and moved less than in the poor ones. This difference was particularly striking in above-surface feeding. Variation in foraging performance was associated with change in body mass of the ducklings: the less distance the ducklings moved and the more they fed above water, the more they gained mass. Earlier results had suggested that at least some of the boreal wetlands that lack duck broods year after year (70% of the total in one study) do so because they do not harbour enough food. Hence, it is possible that mallard populations are resource-limited at the brood stage during the breeding season.
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| 2. |
- Angerbjörn, Anders, et al.
(author)
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Factors Influencing Winter Food Choice by Mountain Hares (Lepus-Timidus L) on Swedish Coastal Islands
- 1987
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In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 65:9, s. 2163-2167
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Journal article (peer-reviewed)abstract
- In mainland areas, mountain hares seem unable to survive on a single browse species. However, mountain hares on islands off the west coast of Sweden rely almost entirely on a plain heather diet during winter. Herein, we give as a possible explanation for this phenomenon that the high concentration of sodium in the heather in the coastal areas can buffer the high sodium excretion otherwise observed in hares feeding on heather under experimental conditions. Furthermore, hares selected heather with the highest nitrogen and phosphorus contents. We argue that the pattern of food choice exhibited by the hares in the coastal area is to be expected in homogenous habitats where hares rely on one dominant food species. In heterogenous habitats, the possibility of food selection on a nutritional level is to a considerable extent overridden by effects of digestibility and concentration of secondary compounds in the different food plants available.
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| 3. |
- Arnemo, Jon, et al.
(author)
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Effects of different doses of medetomidine and tiletamine-zolazepam on the duration of induction and immobilization in free-ranging yearling brown bears (Ursus arctos)
- 2012
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 90, s. 753-757
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Journal article (peer-reviewed)abstract
- We compared anesthetic protocols with different doses of tiletamine-zolazepam (TZ) combined with medetomidine (M) for 288 yearling brown bear (Ursus arctos L., 1758) immobilizations with the objective of finding a combination of doses that would provide fast induction with a duration of anesthesia long enough to minimize the need for administering additional drug. The duration of induction time and immobilization was dose-dependent. Increasing the M dose resulted in significantly shorter induction times and a lower probability of giving supplemental drugs. Increasing the TZ dose prolonged duration of anesthesia. For yearling brown bears in Scandinavia, captured shortly after den emergence in April and May, we recommend total dart doses of 1.0-1.66 mg M/dart, plus 62.5-125 mg TZ/dart, depending on the individual requirements for the length and depth of anaesthesia.
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| 4. |
- Arzel, C., et al.
(author)
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A flyway perspective of foraging activity in Eurasian Green-winged Teal, Anas crecca crecca
- 2007
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 85:1, s. 81-91
-
Journal article (peer-reviewed)abstract
- Time-activity budgets in the family Anatidae are available for the wintering and breeding periods. We present the first flyway-level study of foraging time in a long-distance migrant, the Eurasian Green-winged Teal, Anas crecca crecca L., 1758 ("Teal"). Behavioral data from early and late spring staging, breeding, and molting sites were collected with standardized protocols to explore differences between the,sexes, seasons, and diel patterns. Teal foraging activity was compared with that of the Mallard, Anas platyrhynchos L., 1758 and Northern Shoveler, Anas clypeata L., 1758, and the potential effects of duck density and predator-caused disturbance were explored. In early spring, foraging time was moderate (50.5%) and mostly nocturnal (45%). It increased dramatically in all three species at migration stopovers and during molt, mostly because of increased diurnal foraging, while nocturnal foraging remained fairly constant along the flyway. These patterns adhere to the "income breeding" strategy expected for this species. No differences between the sexes were recorded in either species studied. Teal foraging time was positively correlated with density of Teal and all ducks present, but negatively correlated with predator disturbance. Our study suggests that Teal, in addition to being income breeders, may also be considered as income migrants; they find the energy necessary to migrate at staging sites along the flyway.
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| 5. |
- Arzel, C., et al.
(author)
-
A flyway perspective of foraging activity in Eurasian Green-winged Teal, Anas crecca crecca
- 2007
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 85:1, s. 81-91
-
Journal article (peer-reviewed)abstract
- Time-activity budgets in the family Anatidae are available for the wintering and breeding periods. We present the first flyway-level study of foraging time in a long-distance migrant, the Eurasian Green-winged Teal, Anas crecca crecca L., 1758 ("Teal"). Behavioral data from early and late spring staging, breeding, and molting sites were collected with standardized protocols to explore differences between the,sexes, seasons, and diel patterns. Teal foraging activity was compared with that of the Mallard, Anas platyrhynchos L., 1758 and Northern Shoveler, Anas clypeata L., 1758, and the potential effects of duck density and predator-caused disturbance were explored. In early spring, foraging time was moderate (50.5%) and mostly nocturnal (45%). It increased dramatically in all three species at migration stopovers and during molt, mostly because of increased diurnal foraging, while nocturnal foraging remained fairly constant along the flyway. These patterns adhere to the "income breeding" strategy expected for this species. No differences between the sexes were recorded in either species studied. Teal foraging time was positively correlated with density of Teal and all ducks present, but negatively correlated with predator disturbance. Our study suggests that Teal, in addition to being income breeders, may also be considered as income migrants; they find the energy necessary to migrate at staging sites along the flyway.
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| 6. |
- Backström, Tobias, et al.
(author)
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Short-term stress: effects on cortisol levels and carotenoid spots in Arctic char (Salvelinus alpinus)
- 2016
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94, s. 707-712
-
Journal article (peer-reviewed)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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| 7. |
- Ball, John
(author)
-
Seasonal differences in the relative importance of specific phenolics and twig morphology result in contrasting patterns of foraging by a generalist herbivore
- 2013
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 91, s. 338-347
-
Journal article (peer-reviewed)abstract
- The co-evolved relationship between the chemical composition of plants and herbivory is fundamental in understanding diet selection of herbivores and their impacts on plants and ecosystems. However, the impact of plant secondary chemistry on mammalian herbivory is not fully understood. We investigated seasonal influences of phenolics with low molecular weight (e.g., flavonoids, salicylates) and plant morphology of the tea-leaved willow (Salix phylicifolia L.) on moose (Alces alces (L., 1758)) foraging. We analysed the relationship of different phenolic compounds in twigs and browsing in winter, and in leaves and the degree of leaf stripping in summer, and the role of plant morphology. In winter, higher concentrations of phenolics, e.g., myricetin-related compounds (belonging to the flavonoids), had a negative impact on herbivory by moose. This impact was not associated with a single compound but instead seemed to be more a result of synergistic or additive effects of different compounds. In contrast, the models for summer browsing showed a pronounced effect of plant morphology. Our analyses reveal differences in the relative importance of phenolics of low molecular weight and plant morphology on diet selection between seasons. These findings are relevant for understanding feeding decisions and mechanisms deterring mammalian herbivores known for shaping the vegetation on the ecosystem level.
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| 8. |
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| 9. |
- Brännäs, Eva, et al.
(author)
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Density-dependent Effects of Prior Residence and Behavioural Strategy on Growth of Stocked Brown Trout (Salmo trutta)
- 2004
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 82:10, s. 1638-1646
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Journal article (peer-reviewed)abstract
- When animals face temporally periods of strong intraspecific competition, prior residency, available resources, and their competitive abilities in terms of size and behavioural strategy affect their chances of survival. Density, individual size, and behavioural strategy had the strongest effect on growth. The mean growth rate of both resident and intruding brown trout (Salmo trutta L., 1758) decreased with increasing density, and the largest individuals were the most successful ones independently of the density of prior residency. An aggressive behavioural factor was beneficial at the lowest and intermediate densities, whereas a nonaggressive behavioural factor was beneficial at higher densities. Prior residency had no overall significant effect on growth, as the effect was highly density-dependent. The difference in growth rate between introduced and resident individuals was significant only at high density and low food abundance per individual. The intruders had a significantly lower growth rate at high densities and fewer individuals had a high growth rate. These results suggest that stocking fish at densities exceeding the carrying capacity of the habitat results in fewer individuals that are able to compete for resources than if fewer individuals were stocked. Brood stock can then be used in a more efficient way.
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| 10. |
- Brönmark, Christer, et al.
(author)
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There and back again : migration in freshwater fishes
- 2014
-
In: Canadian Journal of Zoology. - Ottawa : CANADIAN SCIENCE PUBLISHING. - 0008-4301 .- 1480-3283. ; 92:6, s. 467-479
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Journal article (peer-reviewed)abstract
- Animal migration is an amazing phenomenon that has fascinated humans for long. Many freshwater fishes also show remarkable migrations, whereof the spectacular mass migrations of salmonids from the spawning streams are the most well known and well studied. However, recent studies have shown that migration occurs in a range of freshwater fish taxa from many different habitats. In this review we focus on the causes and consequences of migration in freshwater fishes. We start with an introduction of concepts and categories of migration, and then address the evolutionary causes that drive individuals to make these migratory journeys. The basis for the decision of an individual fish to migrate or stay resident is an evaluation of the costs and benefits of different strategies to maximize its lifetime reproductive effort. We provide examples by discussing our own work on the causes behind seasonal migration in a cyprinid fish, roach (Rutilus rutilus (L., 1758)), within this framework. We then highlight different adaptations that allow fish to migrate over sometimes vast journeys across space, including capacity for orientation, osmoregulation, and efficient energy expenditure. Following this we consider the consequences of migration in freshwater fish from ecological, evolutionary, and conservation perspectives, and finally, we detail some of the recent developments in the methodologies used to collect data on fish migration and how these could be used in future research.
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| 11. |
- Cheng, Ken, et al.
(author)
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NMR-based metabolomics reveals compartmental metabolic heterogeneity in liver of Arctic char (Salvelinus alpinus)
- 2016
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94, s. 665-669
-
Journal article (peer-reviewed)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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| 12. |
- Dalerum, Fredrik, et al.
(author)
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Exploring the diet of arctic wolves (Canis lupus arctos) at their northern range limit
- 2018
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 96:3, s. 277-281
-
Journal article (peer-reviewed)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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| 13. |
- Eklöv, Peter, et al.
(author)
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The trade-off between foraging activity and predation risk for Rana temporaria in different food environments
- 2000
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 78:5, s. 734-739
-
Journal article (peer-reviewed)abstract
- We evaluated the trade-off between foraging activity and predation risk for larvae of an anuran species presented with different types of food resources. In the laboratory we examined the effects of benthic and phytoplankton resources and the two types combined on the activity and mortality of larvae of the common frog, Rana temporaria, exposed to predatory larva, Dytiscus marginalis.Predation mortality of tadpoles increased with the duration of the experiment and was highest in the presence of the phytoplankton resource alone. This was explained by a decrease in prey activity in the benthic- and combined-resource treatments when the predator was present, whereas in the phytoplankton treatment, the activity of the tadpoles were similar in the presence or absence of the predator.In the presence of the predator, prey mainly used the bottom of the aquarium in the benthic- and combined-resource treatments. In contrast, in the phytoplankton treatment they used the water column more than in the other treatments. In the presence of the predator, the prey had a lower consumption rate in the phytoplankton treatment than in the other treatments.Predator activity did not change among treatments. The results suggest that the trade-off between foraging activity and predation mortality for anuran larvae is strongly affected by the types of food resources present in the environment.
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| 14. |
- Elmberg, Johan, 1960-, et al.
(author)
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Is the risk of nest predation heterospecifically density-dependent in precocial species belonging to different nesting guilds?
- 2011
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 89:12, s. 1164-1171
-
Journal article (peer-reviewed)abstract
- Nest predation is a key source of mortality and variation in fitness, but the effect co-occurring species belonging to different nesting guilds have on each other’s nest success is poorly understood. By using artificial nests, we tested if predation on cavity nests of Common Goldeneyes (Bucephala clangula (L., 1758)) is increased in the presence of ground nests of Mallards (Anas platyrhynchos L., 1758) and vice versa. Specifically, by adding ground nests in the vicinity of cavity nests, we tested the hypothesis that predation on cavity nests is heterospecifically density-dependent. A shared predator, the pine marten (Martes martes (L., 1758)), was intensively hunted in one of the study areas, but not in the other, leading to most individuals in the former being naïve immigrants. Cavity-nest fate was not affected by addition of ground nests. Similarly, ground-nest survival did not decrease when nearby cavity nests were depredated. Fate of nests in a given nest cavity was highly predictable between years in the study area with minimal removal of pine martens, but not in the one with intensive removal. Predation rate was higher on cavity nests than on ground nests. Predation on ground nests was lower in the study area with intensive removal of pine martens. We conclude there was neither apparent competition between guilds nor heterospecific density-dependence in predation risk.
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| 15. |
- Elmberg, Johan, et al.
(author)
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Is the risk of nest predation heterospecifically density-dependent in precocial species belonging to different nesting guilds?
- 2011
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 89:12, s. 1164-1171
-
Journal article (peer-reviewed)abstract
- Nest predation is a key source of mortality and variation in fitness, but the effect co-occurring species belonging to different nesting guilds have on each other’s nest success is poorly understood. By using artificial nests, we tested if predation on cavity nests of Common Goldeneyes (Bucephala clangula (L., 1758)) is increased in the presence of ground nests of Mallards (Anas platyrhynchos L., 1758) and vice versa. Specifically, by adding ground nests in the vicinity of cavity nests, we tested the hypothesis that predation on cavity nests is heterospecifically density-dependent. A shared predator, the pine marten (Martes martes (L., 1758)), was intensively hunted in one of the study areas, but not in the other, leading to most individuals in the former being naïve immigrants. Cavity-nest fate was not affected by addition of ground nests. Similarly, ground-nest survival did not decrease when nearby cavity nests were depredated. Fate of nests in a given nest cavity was highly predictable between years in thestudy area with minimal removal of pine martens, but not in the one with intensive removal. Predation rate was higher on cavity nests than on ground nests. Predation on ground nests was lower in the study area with intensive removal of pine martens. We conclude there was neither apparent competition between guilds nor heterospecific density-dependence in predation risk.
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| 16. |
- Elmberg, Johan, 1960-
(author)
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Long-term survival, length of breeding season, and operational sex ratio in a boreal population of common frogs, Rana temporaria L.
- 1990
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. - 0008-4301 ; 68:1, s. 121-127
-
Journal article (peer-reviewed)abstract
- A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden. Annual return rate averaged 31% (range 16–51%) in males and 16% (range 5–33%) in females. Return rate was not size dependent but increased with every successful previous hibernation, indicating an increased survival rate with age. Return rate was not correlated with winter harshness. Once adult, males had on average 1.5 (maximum 6) seasons with the possibility of reproducing. Corresponding values for females were 1.4 and 4. Mean length of the breeding season was 20 (SD = 2) days. Calling generally started at water temperatures below 3 °C. The lowest spawning temperature was 1 °C. Average temperatures at spawning onset and peak spawning were 5 and 6 °C, respectively. Large males tended to arrive earlier at the pond than small males. Males arrived earlier and stayed longer than did females. The overall population sex ratio was close to unity. The operational sex ratio (OSR) varied during the breeding season, averaging 0.54 (one female to two males). No male was observed to mate more than once per season. I argue that survival selection is more important to male lifetime mating success than is competition in the breeding pond (sexual selection as affected by OSR and length of the breeding season).
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| 17. |
- Elmberg, Johan, 1960-, et al.
(author)
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Manipulated density of adult mallards affects nest survival differently in different landscapes
- 2007
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. - 0008-4301 ; 85:5, s. 589-595
-
Journal article (peer-reviewed)abstract
- Breeding success in many birds including wildfowl is mainly determined by nest predation. Few studies address cues used by predators to find duck nests, and the same is true for spacing patterns that ducks might use to reduce predation. We designed a crossover experiment in agricultural and forested settings to test the assumption that nest predation rate is related to density of adult birds on a lake. We used introduced wing-clipped mallards (Anas platyrhynchos L., 1758) to increase local pair density and semi-natural nests to assess predation rate. Depredation patterns were analyzed by model fitting in program MARK, using introduction and landscape type as main effects and abundance of avian predators and wild waterbirds as covariates. Depredation was higher at agricultural lakes than at forest lakes. Nest survival decreased with increasing abundance of wild waterfowl, whereas it tended to increase with the abundance of "other waterbirds". There was a landscape-dependent effect of increased mallard pair density: positive at agricultural lakes and negative at forest lakes. Avian predators found 91% of depredated "known-predator" nests at agricultural lakes and 25% at forest lakes; mammals found 9% at agricultural lakes and 75% at forest lakes. The landscape-dependent density effect may in part be due to different predator communities in these landscape types.
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| 18. |
- Elmberg, Johan, et al.
(author)
-
Manipulated density of adult mallards affects nest survival differently in different landscapes
- 2007
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 85:5, s. 589-595
-
Journal article (peer-reviewed)abstract
- Breeding success in many birds including wildfowl is mainly determined by nest predation. Few studies address cues used by predators to find duck nests, and the same is true for spacing patterns that ducks might use to reduce predation. We designed a crossover experiment in agricultural and forested settings to test the assumption that nest predation rate is related to density of adult birds on a lake. We used introduced wing-clipped mallards (Anas platyrhynchos L., 1758) to increase local pair density and semi-natural nests to assess predation rate. Depredation patterns were analyzed by model fitting in program MARK, using introduction and landscape type as main effects and abundance of avian predators and wild waterbirds as covariates. Depredation was higher at agricultural lakes than at forest lakes. Nest survival decreased with increasing abundance of wild waterfowl, whereas it tended to increase with the abundance of "other waterbirds". There was a landscape-dependent effect of increased mallard pair density: positive at agricultural lakes and negative at forest lakes. Avian predators found 91% of depredated "known-predator" nests at agricultural lakes and 25% at forest lakes; mammals found 9% at agricultural lakes and 75% at forest lakes. The landscape-dependent density effect may in part be due to different predator communities in these landscape types.
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| 19. |
- Elmhagen, Bodil, et al.
(author)
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Food-niche overlap between arctic and red foxes
- 2002
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 80, s. 1274-1285
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Journal article (peer-reviewed)abstract
- Arctic foxes (Alopex lagopus) in Fennoscandia have retreated to higher altitudes on the mountain tundra, possibly because of increased competition with red foxes (Vulpes vulpes) at lower altitudes. In this study we compare summer food niches of the two species in mountain tundra habitat. Arctic foxes consumed lemmings more often than red foxes did, while red foxes consumed field voles and birds more often. Yet despite substantial variation in the diet of each species among summers, food-niche overlaps between the species were consistently high in most summers, as arctic and red foxes responded similarly to temporal changes in prey availability. Occurrences of field voles and birds in fox scats were negatively Correlated with altitude, while the occurrences of lemmings tended to increase with altitude. Since arctic foxes bred at higher altitudes than red foxes, the differences between arctic and red fox diets were better explained by altitudinal segregation than by differences between their fundamental food niches. Arctic foxes should therefore endeavour to use the more productive hunting grounds at the lower altitudes of their former range, but interference competition with red foxes might decrease their access to these areas, and consequently cause a decrease in the size of in their realised niche.
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| 20. |
- Erlandsson, Rasmus, et al.
(author)
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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
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 95, s. 239-246
-
Journal article (peer-reviewed)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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| 21. |
- Farrell, A. P., et al.
(author)
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Niche expansion of the shorthorn sculpin (Myoxocephalus scorpius) to Arctic waters is supported by a thermal independence of cardiac performance at low temperature
- 2013
-
In: Canadian Journal of Zoology-Revue Canadienne De Zoologie. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 91:8, s. 573-580
-
Journal article (peer-reviewed)abstract
- Cardiovascular adaptations that permit successful exploitation of polar marine waters by fish requires a capacity to negate or compensate for the depressive effects of low temperatures on physiological processes. Here, we examined the effects of acute and chronic temperature change on the maximum cardiac performance of shorthorn sculpin (Myoxocephalus scorpius (L., 1758)) captured above the Arctic Circle. Our aim was to establish if the sculpin's success at low temperatures was achieved through thermal independence of cardiac function or via thermal compensation as a result of acclimation. Maximum cardiac performance was assessed at both 1 and 6 degrees C with a working perfused heart preparation that was obtained after fish had been acclimated to either 1 or 6 degrees C. Thus, tests were performed at the fish's acclimation temperature and with an acute temperature change. Maximum cardiac output, which was relatively large (> 50 mL.min(-1).kg(-1) body mass) for a benthic fish at a frigid temperature, was found to be independent of both acclimation temperature and test temperature. While maximum beta-adrenergic stimulation produced positive chronotropy at both acclimation temperatures, inotropic effects were weak or absent. We conclude that thermal independence of cardiac performance at low temperature likely facilitated the exploitation of polar waters by the shorthorn sculpin.
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| 22. |
- Finn, K. T., et al.
(author)
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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
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 96:8, s. 920-927
-
Journal article (peer-reviewed)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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| 23. |
- Givskov Sørensen, Jesper, et al.
(author)
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Effects of predator exposure on Hsp70 expression and survival in tadpoles of the Common Frog (Rana temporaria)
- 2011
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 89:12, s. 1249-1255
-
Journal article (peer-reviewed)abstract
- Predator-induced changes in prey behavior and morphology are widespread, but little is known about physiological and cellular-level responses in prey in response to predation risk. We investigated whether predator (larvae of the dragonfly Aeshna Fabricius, 1775) presence elevated the expression level of heat-shock protein 70 (Hsp70)-a commonly found response to stress-in tadpoles of the Common Frog (Rana temporaria L., 1758). In another experiment, we tested the survival of tadpoles in the presence of a free-ranging predator. Prior to this encounter, the tadpoles were exposed to either an Hsp-inducing environmental stress in the form of heat (31 degrees C) or to predator cues from a caged predator. We found no evidence for increased Hsp70 expression in tadpoles either in the presence of fed or starved predators. We did not find any effects of prior exposure to neither heat nor predator presence on survival at the end of experiment. Our results do not point to either Hsp70-mediated effect of predator-induced responses or to beneficial effects of the stress response on survival under predation risk.
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| 24. |
- Greenberg, Larry, 1955-, et al.
(author)
-
Body shape and fin size in juvenile Atlantic salmon (Salmo salar) : effects of temperature during embryogenesis
- 2021
-
In: Canadian Journal of Zoology. - : CANADIAN SCIENCE PUBLISHING. - 0008-4301 .- 1480-3283. ; 99:5, s. 381-389
-
Journal article (peer-reviewed)abstract
- Temperature during egg incubation and early development influences later life stages of fishes, potentially influencing survival. Throughout its distribution, Atlantic salmon (Salmo salar Linnaeus, 1758) have experienced population declines, and in view of ongoing global warming, we tested if temperature during the earliest developmental stages modified body shape and fin size when temperatures averaged 2.6 vs. 5.6 degrees C. This temperature difference simulates increases predicted in climate change scenarios. Based on previous studies, we hypothesized that salmon originating from eggs subjected to cold incubation temperatures would have slimmer bodies and larger pectoral and dorsal fins than salmon from eggs that experienced warmer temperatures. After hatching, the juveniles were raised for 1 year under identical temperatures, after which we measured their body shape and fin areas. We found no support for our hypothesis regarding body shape. Indeed, we found the opposite, with cold-incubated salmon having deeper bodies than warm-incubated salmon. For fin size, the pectoral fins of cold-incubated salmon were larger than for warm-incubated salmon as predicted, but there was no difference in dorsal fin size. These results suggest that global warming may lead to altered body shape and fin size, possibly affecting swimming performance, and thus raise questions about the ecological consequences of the changes.
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| 25. |
- Gunnarsson, Gunnar, 1976-, et al.
(author)
-
Why are there so many empty lakes? : food limits survival of mallard ducklings
- 2004
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 82:11, s. 1698-1703
-
Journal article (peer-reviewed)abstract
- Food is an important factor affecting survival in many bird species, but this relationship has rarely been explored experimentally with respect to reproductive output of precocial birds. In a field experiment we tested the hypothesis that food abundance limits reproductive output in breeding dabbling ducks. Onto 10 oligotrophic lakes in northern Sweden we introduced one wing-clipped female mallard (Anas platyrhynchos L., 1758) and a brood of 10 newly hatched ducklings, and survival was monitored for 24 days. Food was added ad libitum at five of the lakes, but not at the other five. Duckling survival was best modelled to include a treatment effect, with higher survival on lakes with food added, and a negative effect of harsh weather. As expected, duckling survival increased nonlinearly with age. Only one female remained on control lakes after 24 days, whereas four remained on lakes with food added. This is the first experimental demonstration that food may limit survival and reproductive output in breeding precocial birds. We argue that food limitation may be one reason why duckling mortality is high and why many lakes throughout the Holarctic have no breeding dabbling ducks.
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| 26. |
- Gunnarsson, Gunnar, et al.
(author)
-
Why are there so many empty lakes? : food limits survival of mallard ducklings
- 2004
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 82:11, s. 1698-1703
-
Journal article (peer-reviewed)abstract
- Food is an important factor affecting survival in many bird species, but this relationship has rarely been explored experimentally with respect to reproductive output of precocial birds. In a field experiment we tested the hypothesis that food abundance limits reproductive output in breeding dabbling ducks. Onto 10 oligotrophic lakes in northern Sweden we introduced one wing-clipped female mallard (Anas platyrhynchos L., 1758) and a brood of 10 newly hatched ducklings, and survival was monitored for 24 days. Food was added ad libitum at five of the lakes, but not at the other five. Duckling survival was best modelled to include a treatment effect, with higher survival on lakes with food added, and a negative effect of harsh weather. As expected, duckling survival increased nonlinearly with age. Only one female remained on control lakes after 24 days, whereas four remained on lakes with food added. This is the first experimental demonstration that food may limit survival and reproductive output in breeding precocial birds. We argue that food limitation may be one reason why duckling mortality is high and why many lakes throughout the Holarctic have no breeding dabbling ducks.
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| 27. |
- Hipfner, J. M., et al.
(author)
-
Dietary segregation between two cohabiting species of sparrows revealed with stable isotope analysis
- 2013
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 1480-3283 .- 0008-4301. ; 91:1, s. 37-40
-
Journal article (peer-reviewed)abstract
- Fox Sparrows (Passerella iliaca (Merrem, 1786)) and Song Sparrows (Melospiza melodia (A. Wilson, 1810)) cohabit on many islands along the Pacific coast of North America, and previous studies suggest that they rely on similar prey types. We used delta C-13 and delta N-15 stable isotope analysis on blood collected from breeding adults of both species in each of two habitats on Triangle Island, British Columbia, Canada, to test the hypothesis that the two species exhibit a consistent pattern (direction) of dietary segregation in different habitat types. Both delta C-13 and especially delta N-15 values differed between habitats, indicating that the two habitats were isotopically distinct. As predicted, delta N-15 values differed consistently between the two species in the two habitats, averaging similar to 1.5% higher in the smaller Song Sparrow than in the larger Fox Sparrow in both. We infer that Song Sparrows included more animal matter and less plant matter in their diets than Fox Sparrows, and suggest that fixed traits related to body size might underlie the dietary (trophic) differences. In contrast, delta C-13 values did not differ between species. We conclude that dietary segregation could help to facilitate the widespread cohabitation of these two species of sparrows.
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| 28. |
- Hyeun-Ji, Lee, et al.
(author)
-
Compensating for a bad start : compensatory growth across life stages in an organism with a complex life cycle
- 2016
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 94:1, s. 41-47
-
Journal article (peer-reviewed)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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| 29. |
- Jonsson, P, et al.
(author)
-
Effects of litter size on pup defence and weaning success of neighbouring bank vole females
- 2002
-
In: Canadian Journal of Zoology. - 1480-3283. ; 80:1, s. 1-5
-
Journal article (peer-reviewed)abstract
- Reproductive success of territorial female mammals depends partly on their capability to defend their young from conspecific intruders. However, how this is related to the characteristics of females and their litter sizes is largely unknown. The defence activity of 25 female bank voles (Clethrionomys glareolus) in relation to the number of offspring was studied in a behavioural arena by manipulating litter sizes (-2 pups or +2 pups). Infanticidal male bank voles were used as intruders-predators. Moreover, the weaning success (weaned at least one offspring or none) of 15 pairs of neighbouring females was investigated in a large indoor runway system. In each pair of females, the litter size of one female was reduced (-2 pups) and the litter size of the other enlarged (+2 pups). Defence activity of females increased with the number of offspring and the mother's size. However, weaning success of neighbours was related only to their body mass, and litter-size manipulation did not affect weaning success. Present results indicate that, although bank vole females increase their defence intensity with an increase in the number of pups, the weaning success of neighbouring females may be primarily determined by their size and dominance rank.
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| 30. |
- Karlsson, Magnus, 1971-, et al.
(author)
-
No evidence for developmental plasticity of colour patterns in response to rearing substrate in pygmy grasshoppers
- 2009
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 87:11, s. 1044-1051
-
Journal article (peer-reviewed)abstract
- Color polymorphisms in animals may result from genetic polymorphisms, developmental plasticity, or a combination where some phenotypic components are under strong genetic control and other aspects are influenced by developmental plasticity. Understanding how color polymorphisms evolve demands knowledge of how genetic and epigenetic environmental cues influence the development and phenotypic expression of organisms. Pygmy grasshoppers (Orthoptera, Tetrigidae) vary in color pattern within and among populations. Color morphs differ in morphology, behavior, and life history, suggesting that they represent alternative ecological strategies. Pygmy grasshoppers also show fire melanism, a rapid increase in the frequency of black and dark-colored phenotypes in populations inhabiting fire-ravaged areas. We examined the influence of plasticity on color polymorphism in the pygmy grasshopper Tetrix subulata (L., 1761) using a split-brood design. Individuals were experimentally raised in solitude on either crushed charcoal or white aquarium gravel. Our analyses uncovered no plasticity of either color pattern or overall darkness of coloration in response to rearing substrate. Instead, we find a strong resemblance between maternal and offspring color patterns. We conclude that pygmy grasshopper color morphs are strongly influenced by genetic cues or maternal effects, and that there is no evidence for developmental plasticity of coloration in response to rearing conditions in these insects.
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| 31. |
- Kindberg, Jonas
(author)
-
Coping with human disturbance: spatial and temporal tactics of the brown bear (Ursus arctos)
- 2010
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 88, s. 875-883
-
Journal article (peer-reviewed)abstract
- In human-dominated landscapes, species with large spatial requirements, such as large carnivores, have to deal with human infrastructure and activities within their home ranges. This is the case for the brown bear (Ursus arctos L., 1758) in Scandinavia, which is colonizing more human-dominated landscapes, leading inevitably to an overlap between their home ranges and anthropogenic structures. In this study, we investigated fine-scale habitat selection by brown bears to examine how they deal with this potential disturbance. Using Global Positioning System (GPS) data, we studied (i) habitat selection of female brown bears within their home range and (ii) the influence of diurnal variation in human disturbance on fine-scale habitat use. As expected, females selected habitats within their home range that provided abundant food resources and minimized human-caused disturbance. In addition, our temporal analysis of habitat selection revealed an avoidance of disturbed areas and a selection of slopes by bears during periods of highest human activities, i. e., during daylight hours. We clearly demonstrate the importance of considering the fluctuations in human activity when studying habitat selection, especially at fine spatial scales. Failing to do so may considerably reduce the power to detect important fine-scale habitat-selection behaviors.
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| 32. |
- Krebs, C. J., et al.
(author)
-
Synchrony in lemming and vole populations in the Canadian Arctic
- 2002
-
In: Canadian Journal of Zoology-Revue Canadienne De Zoologie. ; 80:8, s. 1323-1333
-
Journal article (peer-reviewed)abstract
- Population fluctuations may occur in synchrony among several rodent species at a given site, and they may occur in synchrony over large geographical areas. We summarize information on synchrony in lemmings and voles from the Canadian Arctic for the past 20 years. The most detailed available information is from the central Canadian Arctic, where snap-trap samples have been taken annually at several sites for periods of up to 15 years. Geographical synchrony in the same species among different sites was strong, especially for the central and eastern Canadian Arctic. Synchrony among different species at a given site was also generally high. When one species is at high density, densities of all species at that site tend to be high. These results do not easily fit the mobile-predator hypothesis proposed to explain regional synchrony, and are more consistent with the weather hypothesis, which we suggest both entrains synchrony among sites and enforces synchrony among species within a site. We tentatively support the weather hypothesis for geographical synchrony in lemmings, and recommend the establishment of a circumpolar program to monitor lemming cycles and predator movements that would advance our understanding of these large-scale patterns of cyclic synchrony.
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| 33. |
- Krebs, C. J., et al.
(author)
-
Terrestrial trophic dynamics in the Canadian Arctic
- 2003
-
In: Canadian Journal of Zoology-Revue Canadienne De Zoologie. ; 81, s. 827-843
-
Journal article (peer-reviewed)abstract
- The Swedish Tundra Northwest Expedition of 1999 visited 17 sites throughout the Canadian Arctic. At 12 sites that were intensively sampled we estimated the standing crop of plants and the densities of herbivores and predators with an array of trapping, visual surveys, and faecal-pellet transects. We developed a trophic-balance model using ECOPATH to integrate these observations and determine the fate of primary and secondary production in these tundra ecosystems, which spanned an 8-fold range of standing crop of plants. We estimated that about 13% of net primary production was consumed by herbivores, while over 70% of small-herbivore production was estimated to flow to predators. Only 9% of large-herbivore production was consumed by predators. Organization of Canadian Arctic ecosystems appears to be more top-down than bottom-up. Net primary production does not seem to be herbivore-limited at any site. This is the first attempt to integrate trophic dynamics over the entire Canadian Arctic.
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| 34. |
- Lacoursière, Jean O., 1958-
(author)
-
A laboratory study of fluid flow and microhabitat selection by larvae of Simulium vittatum (Diptera: Simuliidae)
- 1992
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 70:3, s. 582-596
-
Journal article (peer-reviewed)abstract
- Microhabitat selection by Simulium vittatum Zetterstedt larvae in a flume was studied at different mainstream velocities on two substrates; a thin flat plate parallel to the flow and a cylinder in cross flow. The results do not support the generally accepted assumptions that simuliid larvae keep within the boundary layer to avoid the direct influence of mainstream current and that they select the fastest velocity available when offered a longitudinal velocity gradient within their tolerance range. Instead, larvae gathered along the zone of boundary layer separation and remained along the stagnation line at the leading point of the cylinder when artificially positioned there. Further, under most conditions, larvae avoided zones of maximum surface shear stress. Larval reaction to hydraulic changes was immediate. It is hypothesized that S. vittatum larvae first scan the velocity profile at the substrate, initially moving toward increasing flow velocity (or water acceleration). They than cue on a steep velocity gradient along the body as part of the processes involved in choosing a location for suspension feeding.
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| 35. |
- Lacoursière, Jean O.
(author)
-
A laboratory study of fluid flow and microhabitat selection by larvae of Simulium vittatum (Diptera: Simuliidae)
- 1992
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 70:3, s. 582-596
-
Journal article (peer-reviewed)abstract
- Microhabitat selection by Simulium vittatum Zetterstedt larvae in a flume was studied at different mainstream velocities on two substrates; a thin flat plate parallel to the flow and a cylinder in cross flow. The results do not support the generally accepted assumptions that simuliid larvae keep within the boundary layer to avoid the direct influence of mainstream current and that they select the fastest velocity available when offered a longitudinal velocity gradient within their tolerance range. Instead, larvae gathered along the zone of boundary layer separation and remained along the stagnation line at the leading point of the cylinder when artificially positioned there. Further, under most conditions, larvae avoided zones of maximum surface shear stress. Larval reaction to hydraulic changes was immediate. It is hypothesized that S. vittatum larvae first scan the velocity profile at the substrate, initially moving toward increasing flow velocity (or water acceleration). They than cue on a steep velocity gradient along the body as part of the processes involved in choosing a location for suspension feeding.
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| 36. |
- Lacoursière, Jean O., 1958-, et al.
(author)
-
Fluid transmission and filtration efficiency of the labral fans of black fly larvae (Diptera: Simuliidae) : Hydrodynamic, morphological, and behavioural aspects
- 1993
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 71:1, s. 148-162
-
Journal article (peer-reviewed)abstract
- Body stance and water flow through the labral fans of suspension-feeding Simulium vittatum Zetterstedt larvae were examined using dead and live larvae. Transmission of flowing water through the fans were determined by means of dye injections. Feeding stance is the outcome of an active feedback process between flow forces and behavioural reactions that maintains the fans in an optimal filtering position. Fans responded to velocity increases through structural reconfiguration, which resulted in an increase in aperture size. As the velocity decreased, an increased fraction of the water directly approaching the fan aperture flowed around its perimeter, with no flow through the fans below 2.5 cm/s. Fluid transmission never exceeded 30-35%, even at velocities up to 50 cm/s. Calculations of suspension-feeding efficiency are reformulated to reflect labral fan transmission and behavioural components of the feeding process. Simulium vittatum larvae are consequently showed to be 4-26 times more efficient in filter feeding than has been previously assessed. The effect of flow on labral fan transmission is discussed in relation to known habitat choices and feeding behaviours of simuliid larvae.
|
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| 37. |
- Lacoursière, Jean O., et al.
(author)
-
Fluid transmission and filtration efficiency of the labral fans of black fly larvae (Diptera: Simuliidae) : Hydrodynamic, morphological, and behavioural aspects
- 1993
-
In: Canadian Journal of Zoology. - : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 71:1, s. 148-162
-
Journal article (peer-reviewed)abstract
- Body stance and water flow through the labral fans of suspension-feeding Simulium vittatum Zetterstedt larvae were examined using dead and live larvae. Transmission of flowing water through the fans were determined by means of dye injections. Feeding stance is the outcome of an active feedback process between flow forces and behavioural reactions that maintains the fans in an optimal filtering position. Fans responded to velocity increases through structural reconfiguration, which resulted in an increase in aperture size. As the velocity decreased, an increased fraction of the water directly approaching the fan aperture flowed around its perimeter, with no flow through the fans below 2.5 cm/s. Fluid transmission never exceeded 30-35%, even at velocities up to 50 cm/s. Calculations of suspension-feeding efficiency are reformulated to reflect labral fan transmission and behavioural components of the feeding process. Simulium vittatum larvae are consequently showed to be 4-26 times more efficient in filter feeding than has been previously assessed. The effect of flow on labral fan transmission is discussed in relation to known habitat choices and feeding behaviours of simuliid larvae.
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| 38. |
- Mattisson, Jenny, et al.
(author)
-
Temporal and spatial interactions between an obligate predator, the Eurasian lynx (Lynx lynx), and a facultative scavenger, the wolverine (Gulo gulo)
- 2011
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 89, s. 79-89
-
Journal article (peer-reviewed)abstract
- Interspecific interactions between sympatric carnivores can be important for the behaviour and demography of involved species. We studied spatial and temporal interactions between an obligate predator, the Eurasian lynx (Lynx lynx (L., 1758)), and a facultative scavenger, the wolverine (Gulo gulo (L., 1758)). Wolverines are known to utilize lynx-killed reindeer (Rangifer tarandus tarandus (L., 1758)) and may benefit from being sympatric with lynx if interference competition is low. We used individual location data from 9 lynx and 17 wolverines to analyse interaction between inter- and intra-specific dyads (n = 195). We found no spatial segregation between lynx and wolverines and we observed no attraction or avoidance between individuals of the two species, independent of proportion of home-range overlap. This opposed our prediction that wolverines will show direct or delayed attraction to lynx. Wolverines may still benefit by scavenging lynx-killed reindeer while avoiding direct encounters with the lynx. Within species, we found attraction between males and females, increasing with proportion of overlap for lynx. Attraction was also found between consexual lynx, while consexual wolverines showed little home-range overlap (7%-9%) and neutral temporal interaction, indicating territoriality. Individual space use may be more influenced by conspecific interactions than by other species.
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| 39. |
- Mayer, Ian, et al.
(author)
-
Plasma-levels of sex steroids in 3 species of pipefish (Syngnathidae)
- 1993
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 71:9, s. 1903-1907
-
Journal article (peer-reviewed)abstract
- The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the ''normal'' teleost pattern. To that end, plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), 11beta-hydroxytestosterone, 11-ketoandrostenedione, and 11beta-hydroxyandrostenedione (OHA), together with 17alpha-hydroxy-20beta-dihydroprogesterone (17,20-P) and 17beta-estradiol (E2), were measured by means of radioimmunoassay in three species of pipefish: Nerophis ophidion, Syngnathus typhle, and Syngnathus acus. Plasma levels of OT, the dominant circulating androgen in breeding males of most teleost species, was found to be highest in breeding males and low or non-detectable later in the brooding males. This observed decline in male OT levels from the prespawning to the postspawning (=brooding) period is in general agreement with what has been found in other teleosts. In both breeding and brooding S. acus males, T was quantitatively the dominant androgen, whereas OHA was the major androgen in S. acus females, as well as in the females and breeding or brooding males of both S. typhle and N. ophidion. In breeding S. acus and S. typhle males the levels of T, OHT, and OT were higher than in corresponding brooding males and females. The 17,20-P level was below detection limit. E2 was also usually non-detectable, but was most consistently found in breeding Syngnathus males.
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| 40. |
- Mellbrand, Kajsa, et al.
(author)
-
Coastal niches for terrestrial predators: a stable isotope study.
- 2010
-
In: Canadian Journal of Zoology. - Ottawa : National Research Council of Canada. - 0008-4301 .- 1480-3283. ; 88, s. 1077-1085
-
Journal article (peer-reviewed)abstract
- The purpose of this study was to identify the use of marine versus terrestrial food items by terrestrial arthropod predators on Baltic Sea shores. The inflow of marine nutrients in the area consists mainly of marine algal detritus and emerging aquatic insects (e.g., chironomids). Diets of coastal arthropods were examined using carbon and nitrogen stable isotope analysis in a two source mixing model. The results suggest that spiders are the terrestrial predators mainly utilizing nutrients and energy of marine origin on Baltic Sea shores, whereas insect predators such as beetles and heteropterans mainly utilize nutrients and energy derived from terrestrial sources, possibly owing to differences in hunting behaviour. That spiders are the predators which benefit the most from the marine inflow suggest that eventual effects of marine subsidies for the coastal ecosystem as a whole are likely mediated by spiders.
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| 41. |
- Neumann, Wiebke, et al.
(author)
-
Effect of immobilizations on the activity and space use of female moose (Alces alces)
- 2011
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 89, s. 1013-1018
-
Journal article (peer-reviewed)abstract
- Studies of free-ranging wildlife often involve animal capture and fitting of tracking devices. Capturing wildlife may result in behavioral alterations. Thus, there is a need to evaluate the effects of capture on study animals to identify potential biases influencing the research. We assessed the short-term response of 15 GPS/GSM-collared adult female moose (Alces alces (L., 1758)) and immobilization and handling by comparing moose rates of movement and net square displacement before and after recapture. Moose were more active up to 7 h and increased their spatial displacement for 4.5 days after recapture compared with movement patterns before recapture. Opposite to our predictions, moose did not reduced their movement rates after their initial displacement following capture and recovery, i.e., moose did not show any indication for a residual effect. We recommend using individuals as their own controls in analyses of capture impacts to account adequately for individual behavioral differences. We recommend omitting data of at least the first 5 days following capture for analyses of moose movement and distribution.
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| 42. |
- Norén, Karin, et al.
(author)
-
From monogamy to complexity : social organization of arctic foxes (Vulpes lagopus) in contrasting ecosystems
- 2012
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 90:9, s. 1102-1116
-
Journal article (peer-reviewed)abstract
- 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.
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| 43. |
- Nässel, Dick R.
(author)
-
Insulin producing cells and their regulation in physiology and behavior of Drosophila
- 2012
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 90:4, s. 476-488
-
Research review (peer-reviewed)abstract
- Insulin-like peptide signaling regulates development, growth, reproduction, metabolism, stress resistance, and life span in a wide spectrum of animals. Not only the peptides, but also their tyrosine kinase receptors and the downstream signaling pathways are conserved over evolution. This review summarizes roles of insulin-like peptides (DILPs) in physiology and behavior of Drosophila melanogaster Meigen, 1830. Seven DILPs (DILP1-7) and one receptor (dInR) have been identified in Drosophila. These DILPs display cell and stage specific expression patterns. In the adult, DILP2, 3, and 5 are expressed in insulin-producing cells (IPCs) among the median neurosecretory cells of the brain, DILP7 in 20 neurons of the abdominal ganglion, and DILP6 in the fat body. The DILPs of the IPCs regulate starvation resistance, responses to oxidative and temperature stress, and carbohydrate and lipid metabolism. Furthermore, the IPCs seem to regulate feeding, locomotor activity, sleep and ethanol sensitivity, but the mechanisms are not elucidated. Insulin also alters the sensitivity in the olfactory system that affects food search behavior, and regulates peptidergic neurons that control aspects of feeding behavior. Finally, the control of insulin production and release by humoral and neuronal factors is discussed. This includes a fat body derived factor and the neurotransmitters GABA, serotonin, octopamine, and two neuropeptides.
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| 44. |
- Olsén, K. Håkan, 1952-
(author)
-
Development of the olfactory organ of the Arctic charr, Salvelinus alpinus (L.) (Teleostei, Salmonidae)
- 1993
-
In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 71:10, s. 1973-1984
-
Journal article (peer-reviewed)abstract
- The structure of the olfactory epithelium in developing Arctic charr, Salvelinus alpinus, was studied by light and scanning electron microscopy. Embryos, larvae, free-swimming fry, and individuals up to the age of 96 months after hatching were studied. In larvae about 10 days after hatching, microvillar and ciliated olfactory receptor cells were located in a pit and no nares were differentiated. Fifty days after hatching, two nares were present on each side of the head, and about 20 days later one or two lamellae had started to differentiate and were visible as an elevation in the caudal part of the floor of the olfactory chamber. Six months after hatching there were 5 – 10 club-shaped lamellae, which in older fish acquired a more disk-like appearance. The number and size of lamellae increased with the size of the fish, reaching the maximum number, 10 – 15 per rosette, 18 – 30 months after hatching. At 18 months, secondary folding of the lamellae had started. Eighteen months later, differentiated secondary lamellae were present and most of the central raphe was composed of indifferent epithelium. The olfactory receptors were located in the depressions between the secondary folds. The development of the olfactory organ is discussed in relation to the results of behavioural studies.
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| 45. |
- Orizaola, German, et al.
(author)
-
Growing with kin does not bring benefits to tadpoles in a genetically impoverished amphibian population
- 2008
-
In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 86:1, s. 45-50
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Journal article (peer-reviewed)abstract
- The effect of intraspecific competition can be modified through the interaction with genetic relatedness among the competing individuals. Theory of kin selection predicts that organisms should modify their behaviour to increase the fitness of their relatives and consequently their inclusive fitness. However, in populations with low genetic variation, the recognition of kin and nonkin individuals could be compromised. In this study, we tested the influence of density and relatedness on larval development in a genetically impoverished population of the pool frog (Rana lessonae Camerano, 1882), exposing individuals from four families to two densities and to competition by full-sibling and nonkin larvae. Larvae in high-density treatment were smaller than those in low-density treatment. No effect of kin, or interaction between density and kin, was detected. However, significant differences were detected in body size among the families and high heritability for size was found in both densities. Lack of variation in recognition alleles may explain the lack of kin effects on growth, whereas variation has been maintained in life-history traits either owing to their polygenic inheritance or owing to maternal effects.
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| 46. |
- Orizaola, German, et al.
(author)
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Intraspecific variation of temperature-induced effects on metamorphosis in the pool frog (Rana lessonae)
- 2009
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 87:7, s. 581-588
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Journal article (peer-reviewed)abstract
- Understanding the factors that affect the process of metamorphosis in species with complex life cycles, and in particular their variation within and among populations, has been rarely explored until recently. We examined the effects of temperature environment on several metamorphic characteristics in three populations of the pool frog (Rana lessonae Camerano, 1882) by rearing individuals at two temperature environments (20 and 25 degrees C). Higher temperature shortened the metamorphic period and reduced the absolute mass loss, although there was no difference between the temperatures in the percentage of mass lost. No differences among the populations were detected, but there was significant intrapopulation variation both in the mean and in the plasticity for the duration of metamorphosis. These results indicate that several aspects of metamorphosis are plastic in amphibians, these traits may have considerable intrapopulation variation, and that temperature is a strong factor affecting the process of metamorphosis.
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| 47. |
- Ortiz, Sara Torres, et al.
(author)
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Group hunting in harbour porpoises (Phocoena phocoena)
- 2021
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In: Canadian Journal of Zoology. - : Canadian Science Publishing. - 0008-4301 .- 1480-3283. ; 99:6, s. 511-520
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Journal article (peer-reviewed)abstract
- Cooperative hunting involves individual predators relating in time and space to each other’s actions to more efficiently track down and catch prey. The evolution of advanced cognitive abilities and sociality in animals are strongly associated with cooperative hunting abilities as has been shown in lions, chimpanzees, and dolphins. Much less is known about cooperative hunting in seemingly unsocial animals, such as the harbour porpoise (Phocoena phocoena (Linnaeus, 1758)). Using drones, we were able to record 159 hunting sequences of porpoises, out of which 95 sequences involved more than one porpoise. To better understand if the harbour porpoises were individually attracted by the fish school or formed an organized hunting strategy, the behaviour of each individual porpoise in relation to the targeted fish school was analysed. The results indicate role specialization, which is considered the most sophisticated form of collaborative hunting and only rarely seen in animals. Our study challenges previous knowledge about harbour porpoises and opens up for the possibility of other seemingly non-social species employing sophisticated collaborative hunting methods.
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| 48. |
- Outomuro, David, et al.
(author)
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Allometry of secondary, primary and non-sexual traits in the beautiful demoiselle (Calopteryx virgo)
- 2012
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 90, s. 1094-1101
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Journal article (peer-reviewed)abstract
- The static allometry between the size of a trait and the body size results from the net selection forces acting on the evolution of both the trait and the body size. An increased knowledge of the functional significance of traits is necessary to understand observed allometric patterns. We studied several traits of males of the beautiful demoiselle (Calopteryx virgo meridionalis Selys, 1873), for which there is a good functional knowledge of the genitalic traits and ornaments. We found positive allometry for the wing spot size (considered a secondary sexual trait) and for the distal width (but not length) of the anal appendages, which are used for grasping the female prior to copulation. Regarding the male secondary genitalia, the length but not the width of the big horns of the aedeagus showed an isometric pattern. The aedeagus shaft length showed a negative allometric pattern, while its distal width did not show a significant regression. The slopes of the regressions were higher when using wing length than when using body length as estimators of body size, with the exception of wing spot length. Results are discussed based on the functional significance of the study traits, as well as the pre- and post-copulatory selective pressures acting on them.
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| 49. |
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| 50. |
- Persson, Jens
(author)
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The bioclimatic envelope of the wolverine (Gulo gulo): do climatic constraints limit its geographic distribution?
- 2010
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 88, s. 233-246
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Journal article (peer-reviewed)abstract
- We propose a fundamental geographic distribution for the wolverine (Golo gulo (L., 1758)) based on the hypothesis that the occurrence of wolverines is constrained by their obligate association with persistent spring snow cover for successful reproductive denning and by an upper limit of thermoneutrality. To investigate this hypothesis, we developed a composite of MODIS classified satellite images representing persistent snow cover from 24 April to 15 May. which encompasses the end of the wolverine's reproductive denning period. To investigate the wolverine's spatial relationship with average maximum August temperatures, we used interpolated temperature maps. We then compared and correlated these climatic factors with spatially referenced data on wolverine den sites and telemetry locations from North America and Fennoscandia, and our contemporary understanding of the wolverine's circumboreal ranee. All 562 reproductive dens from Fennoscandia and North America occurred at sites with persistent spring snow cover. Ninety-five percent of summer and 86% of winter telemetry locations were concordant with spring snow coverage. Average maximum August temperature was a less effective predictor of wolverine presence. although wolverines preferred summer temperatures lower than those available. Reductions in spring snow cover associated with climatic warming will likely reduce the extent of wolverine habitat, with an associated loss of connectivity.
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