Diet selection in Arctic lemmings (Lemmus sibiricus and Dicrostonyx groenlandicus): forage availability and natural diets

1986 ◽  
Vol 64 (8) ◽  
pp. 1684-1689 ◽  
Author(s):  
Arthur R. Rodgers ◽  
Martin C. Lewis
Keyword(s):  
Northwest Territories ◽  
Selection Process ◽  
Diet Selection ◽  
Population Fluctuations ◽  
Site Specific ◽  
Forage Availability ◽  
Dicrostonyx Groenlandicus ◽  
Salix Arctica ◽  
Winter Diets ◽  
Deciduous Shrub

We describe forage availability and diets of the lemmings Lemmus sibiricus and Dicrostonyx groenlandicus at Igloolik Island, Northwest Territories. Summer and winter diets of Dicrostonyx were dominated by the evergreen shrub Dryas integrifolia and supplemented by the deciduous shrub Salix arctica. Lemmus ate mainly graminoids and some mosses in summer but the reverse in winter. In both species, winter diets were similar in different habitats. Comparison with diets of lemmings in Alaska show sufficient similarity to explain the synchrony of population fluctuations over wide geographical areas. Site-specific differences occur, however, and these are accounted for by an examination of the diet selection process in each species. These differences have important implications for the demography of lemmings at different sites.

Diet selection in Arctic lemmings (Lemmus sibericus and Dicrostonyx groenlandicus): food preferences

1985 ◽  
Vol 63 (5) ◽  
pp. 1161-1173 ◽  
Author(s):  
Arthur R. Rodgers ◽  
Martin C. Lewis
Keyword(s):  
Selection Process ◽  
Food Preferences ◽  
Secondary Compounds ◽  
Diet Selection ◽  
Caloric Content ◽  
Dicrostonyx Groenlandicus ◽  
In Captivity ◽  
Preference Patterns ◽  
The Stability ◽  
Physical And Chemical

Testing of hypotheses relating lemming population dynamics to their food supply requires a detailed understanding of several major components of the diet selection process such as requirements, availability, preference, and selectivity. In this study, food preferences of Arctic lemmings were determined in cafeteria trials: Lemmus preferred graminoids and moss, while Dicrostonyx preferred shrubs and herbs. The stability of these preference patterns in each species was tested in further experimental cafeteria trials. Individuals of both species were pretreated on one of several diets, and two main types of trial were conducted involving limited and unlimited availability of test foods. Naive animals of both species, born and raised in captivity on artificial diets, were also used in the trials. In all cases, preference patterns in each species were maintained, suggesting that they are strongly heritable. Comparison of preference indices to the physical and chemical characteristics of tundra plants indicates that preference patterns in both species are related primarily to macronutrients and caloric content. Differences between Lemmus and Dicrostonyx are determined by secondary compounds and the physical characteristics of the plant species preferred by each. Comparison of ingestion rates and digestibility coefficients indicate that Dicrostonyx has a greater capacity than Lemmus in dealing with the negative characteristics of plants, such as secondary compounds or the presence of plant "hairs."

scholarly journals Recent advances in covalent, site-specific protein immobilization

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2303 ◽  
Author(s):  
Morten Meldal ◽  
Sanne Schoffelen
Keyword(s):  
Selection Process ◽  
Specific Protein ◽  
Sortase A ◽  
Site Specific ◽  
Recent Advances ◽  
Determining Factors ◽  
Protein Molecules ◽  
Specific Manner ◽  
Immobilized Proteins ◽  
A Site

The properties of biosensors, biomedical implants, and other materials based on immobilized proteins greatly depend on the method employed to couple the protein molecules to their solid support. Covalent, site-specific immobilization strategies are robust and can provide the level of control that is desired in this kind of application. Recent advances include the use of enzymes, such as sortase A, to couple proteins in a site-specific manner to materials such as microbeads, glass, and hydrogels. Also, self-labeling tags such as the SNAP-tag can be employed. Last but not least, chemical approaches based on bioorthogonal reactions, like the azide–alkyne cycloaddition, have proven to be powerful tools. The lack of comparative studies and quantitative analysis of these immobilization methods hampers the selection process of the optimal strategy for a given application. However, besides immobilization efficiency, the freedom in selecting the site of conjugation and the size of the conjugation tag and the researcher’s expertise regarding molecular biology and/or chemical techniques will be determining factors in this regard.

Microhabitat utilisation, home ranges, and movement patterns of the collared lemming (Dicrostonyx groenlandicus) in the central Canadian Arctic

2000 ◽  
Vol 78 (11) ◽  
pp. 1885-1890 ◽  
Author(s):  
Martin Predavec ◽  
Charles J Krebs
Keyword(s):  
Habitat Use ◽  
Northwest Territories ◽  
Canadian Arctic ◽  
Movement Patterns ◽  
Home Ranges ◽  
Microhabitat Use ◽  
Dicrostonyx Groenlandicus ◽  
Males And Females ◽  
Degree Of Overlap

We investigated patterns of home ranges, movements, and microhabitat use of the collared lemming (Dicrostonyx groenlandicus) on Kent Peninsula, Northwest Territories. Eleven animals were fitted with radio collars and intensively radio-tracked for 2 months. Males and females differed in their home ranges and movement patterns. Males moved, on average, 47.4 m and females 10.5 m in a 2-h period. Corresponding to the larger movements, males had larger home ranges than did females and the degree of overlap was greater in males. In both sexes activity was centred on burrows, but this was more evident in females. Collared lemmings differentially used available microhabitats, preferring areas with larger hummocks, a larger number of burrows, and greater cover of Salix lanata. It is suggested that this pattern of microhabitat use is related to reducing detection and capture by predators. Collared lemmings appear to be highly conservative in their patterns of habitat use and home ranges across their distribution.

Spatial and behavioral response of white-tailed deer to forage depletion

1994 ◽  
Vol 72 (3) ◽  
pp. 506-513 ◽  
Author(s):  
Stephan G. Kohlmann ◽  
Kenneth L. Risenhoover
Keyword(s):  
Odocoileus Virginianus ◽  
Behavioral Response ◽  
Diet Selection ◽  
Patch Selection ◽  
Foraging Effort ◽  
Movement Rates ◽  
Forage Availability ◽  
Poor Indicator ◽  
Vegetative Biomass ◽  
Different Levels

We tested predictions regarding the effects of forage depletion on patterns of foraging effort, diet selection and quality, and patch selection by white-tailed deer (Odocoileus virginianus). Two deer were allowed access to four 150-m2 enclosures (patches) for 8, 16, 24, and 32 days, resulting in the exposure of the patches to deer for 16, 32, 48, and 64 animal-days and different levels of forage depletion. When the deer were given simultaneous access to all four enclosures, feeding patch selection was markedly skewed toward heavily and lightly grazed environments, while moderately depleted patches were selected least. Deer primarily consumed woody browse in patches with low (16 days) and high (64 days) forage depletion, and forbs in patches that were moderately depleted (32 and 48 days). Deer responded to forage depletion by foraging less selectively, reducing movement rates, and increasing average bite size. During the last phase of the trial, biting rates on forbs declined but increased on woody browse in response to declining forage availability. Diel foraging times remained unaffected by changes in forage availability. The behavior of deer foraging in experimental patches appeared to be consistent with predictions based on the maximization of nutrient (protein) gain, although use of the most depleted patch was greater than expected. We conclude that vegetative biomass alone is a poor indicator of foraging rewards for highly selective herbivores.

Space use by polar bears in and around Auyuittuq National Park, Northwest Territories, during the ice-free period

1997 ◽  
Vol 75 (10) ◽  
pp. 1585-1594 ◽  
Author(s):  
Steven H. Ferguson ◽  
François Messier ◽  
Mitchell K. Taylor
Keyword(s):  
Sea Ice ◽  
Northwest Territories ◽  
National Park ◽  
Polar Bear ◽  
Satellite Telemetry ◽  
Space Use ◽  
Polar Bears ◽  
Site Specific ◽  
Pregnant Females ◽  
High Elevations

We investigated patterns of space use by polar bears (Ursus maritimus) in and around Auyuittuq National Park, Northwest Territories, during the ice-free period in 1991–1995, using satellite telemetry and capture locations. Female polar bears showed general fidelity to the region but no site-specific fidelity. The pattern of sea-ice ablation influenced when and where bears were forced to leave the ice for land, usually at the end of August. While awaiting the return of sea ice, bears conserved energy by reducing movement and activity. Bears left the land after ice formed that was strong enough to support them, usually in mid-November. During the ice-free period, females with cubs of the year were farther inland, closer to fjords, and less likely to use islands than were males. Males found close to females with cubs of the year were thinner than the average male, suggesting that segregation may result from the threat of intraspecific predation. Females with cubs of the year left the ice for land earlier than other classes of bears and rarely used snow shelters. After about 1 week on land, pregnant females entered a maternal den for the winter. Unlike those in other polar bear populations, most females with 1-year-olds entered a shelter after about 3 weeks on land and remained there for about 2 months. Dens and shelters were located at high elevations and far from the coast, and sheltering bears weighed more than nonsheltering bears.

scholarly journals Additions and Range Extensions to the Vascular Plant Flora of the Continental Northwest Territories and Nunavut, Canada III

2005 ◽  
Vol 119 (2) ◽  
pp. 276 ◽  
Author(s):  
William J. Cody ◽  
Kenneth L. Reading
Keyword(s):  
Northwest Territories ◽  
Vascular Plant ◽  
Najas Flexilis ◽  
Salix Arctica ◽  
Shepherdia Canadensis ◽  
Salix Glauca

Fifteen native taxa are reported as new to either District of Keewatin (now Nunavut in part) or District of Mackenzie (Nunavut contains the northeastern portion): Aster puniceus, Astragalus eucosmus, Astragalus eucosmus f. albinus, Carex media, Epilobium latifolium f. albiflorum, Eriophorum viridi-carinatum, Erysiumum pallasii, Moneses uniflora, Najas flexilis, Potamogeton obtusifolius, Salix arctica x glauca, Salix glauca ssp. callicarpae, Salix myrtillifolia, Salix rotundifolia, Shepherdia canadensis, taxa are new to Northwest Territories overall. Significant range extensions for 157 native taxa are included.

Isotopic constraints on water balance of tundra lakes and watersheds affected by permafrost degradation, Mackenzie Delta region, Northwest Territories, Canada

2020 ◽  
Author(s):  
Chengwei Wan ◽  
Zhou Zhou
Keyword(s):  
Water Balance ◽  
Northwest Territories ◽  
Balance Model ◽  
Water Yield ◽  
Permafrost Degradation ◽  
Mackenzie Delta ◽  
Ongoing Research ◽  
Site Specific ◽  
Permafrost Thaw ◽  
History Of

<p>Widespread permafrost thaw in Canada's western Arctic has led to formation of shoreline retrogressive thaw slumps (SRTS), a process influential in modifying water and biogeochemical balances of tundra lakes. To investigate hydrological effects of SRTS, water sampling campaigns were conducted in 2004, 2005 and 2008 for paired lakes (pristine vs catchments disturbed by SRTS) in the upland region adjacent to the Mackenzie Delta, Northwest Territories, Canada. An isotope balance model to estimate evaporation/inflow, precipitation/inflow, water yield and runoff ratio was developed incorporating seasonal evaporative drawdown effects and a vapour mixing model to simulate gradients in Beaufort Sea marine air versus continental moisture sources. Site- specific water balance results reveal systematically higher evaporation/inflow and precipitation/inflow for lakes with active SRTS compared to undisturbed lakes, and typically higher ratios for lakes with stabilized versus active SRTS. For lake catchments, water yield is found to be higher for active SRTS sites compared to undisturbed and stabilized SRTS sites, suggesting that slumping is an initial but not a sustained source of water delivery to lakes. Catchments with history of wildfire are found to have lower water yields, attributed to reduced permafrost influence. Conceptually, we define a thaw trajectory whereby undisturbed sites, active SRTS, stabilized SRTS, and ancient- SRTS define progressive stages of permafrost thaw. We postulate that release of additional runoff is mainly due to permafrost thaw in active SRTS which also promotes lake expansion, talik formation, and subsurface connectivity. Eventual stabilization of slumps and reduced runoff is expected once permafrost thaw sources are exhausted, at which time lakes may become more reliant on replenishment by direct precipitation. The effect of snow catch in slumps appears to be subordinate to thawing based on eventual decline in runoff once thaw slumps stabilize. Improved, site-specific hydrologic understanding will assist ongoing research into carbon cycling and biogeochemical feedbacks.</p>

Evaluating preference in laboratory studies of diet selection

1990 ◽  
Vol 68 (1) ◽  
pp. 188-190 ◽  
Author(s):  
Arthur R. Rodgers
Keyword(s):  
Individual Variation ◽  
Foraging Behaviour ◽  
Consumption Rate ◽  
Selection Process ◽  
Area Under The Curve ◽  
Field Studies ◽  
Food Choices ◽  
Diet Selection ◽  
Food Type ◽  
Selection Of

The food habits of animals may be studied in the laboratory or in the field. Field studies describe diet selection of populations but do not permit analysis of the factors causing individual variation in the foraging behaviour of animals. Although numerous indices have been developed to compare use and availability of foods in field diets of animals, little attention has been given to laboratory approaches for comparing food choices. Tests of food choice must account for the order, consumption rate, and total amount of each food type eaten. Current measures fail to account for one or more of these parameters. This often results in highly ambiguous preference rankings, making comparisons among individuals or species difficult. To solve this problem, I propose using the area under the curve of the cumulative proportion eaten versus time for each food type. This index may be used to assess individual variation and determine the relative importance of each major component of the diet selection process in animals.

scholarly journals Ontology-Based Diet Recommendation System

2019 ◽  
Vol 8 (3) ◽  
pp. 5811-5815
Keyword(s):  
Query Processing ◽  
Recommender Systems ◽  
Recommendation System ◽  
Selection Process ◽  
Diet Selection ◽  
Nutrient Requirements ◽  
Food Items

Recommender systems are needed to find food items of one’s interest. We propose a food personalization framework that assists the user with the actual diet selection process. The Ontology-based process, recommend an appropriate diet for the user. The system analyses the user’s queries based on their requirements and recommends diet, based on their diseases and deficiencies. The system is tested for its efficiency in terms of query processing for users nutrient requirements.

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