scholarly journals Territorial landscapes: incorporating density-dependence into wolf habitat selection studies

2019 ◽  
Vol 6 (11) ◽  
pp. 190282 ◽  
Author(s):  
Shawn T. O'Neil ◽  
Dean E. Beyer ◽  
Joseph K. Bump

Habitat selection is a process that spans space, time and individual life histories. Ecological analyses of animal distributions and preferences are most accurate when they account for inherent dynamics of the habitat selection process. Strong territoriality can constrain perception of habitat availability by individual animals or groups attempting to colonize or establish new territory. Because habitat selection is a function of habitat availability, broad-scale changes in habitat availability or occupancy can drive density-dependent habitat functional responses. We investigated density-dependent habitat selection over a 19-year period of grey wolf ( Canis lupus ) recovery in Michigan, USA, using a generalized linear mixed model framework to develop a resource selection probability function (RSPF) with habitat coefficients conditioned on random effects for wolf packs and random year intercepts. In addition, we allowed habitat coefficients to vary as interactions with increasing wolf density over space and time. Results indicated that pack presence was driven by factors representing topography, human development, winter prey availability, forest structure, roads, streams and snow. Importantly, responses to many of these predictors were density-dependent. Spatio-temporal dynamics and population changes can cause considerable variation in wildlife–habitat relationships, possibly confounding interpretation of conventional habitat selection models. By incorporating territoriality into an RSPF analysis, we determined that wolves' habitat use in Michigan shifted over time, for example, exhibiting declining responses to winter prey indices and switching from positive to negative responses with respect to stream densities. We consider this an important example of a habitat functional response in wolves, driven by colonization, density-dependence and changes in occupancy during a time period of range expansion and population increase.

Ecography ◽  
2015 ◽  
Vol 39 (6) ◽  
pp. 515-523 ◽  
Author(s):  
Floris M. van Beest ◽  
Philip D. McLoughlin ◽  
Atle Mysterud ◽  
Ryan K. Brook

2019 ◽  
Vol 151 (6) ◽  
pp. 728-737
Author(s):  
William D. Halliday ◽  
Caroline Bourque ◽  
Gabriel Blouin-Demers

AbstractDensity-dependent habitat selection models inherently rely on the negative relationship between population density and mean fitness in different habitats. Habitats differing in quality, such as different food sources or habitat structure, can have different strengths of density-dependent relationships, which can then affect patterns of density dependence in habitat selection. We tested the hypothesis that density dependence in fitness dictates the patterns in density-dependent habitat selection: individuals should prefer higher-quality habitat over lower-quality habitat. We used controlled experiments with red flour beetles (Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)) to measure density dependence of fitness and to examine density-dependent habitat selection by beetles in wheat (Triticum Linnaeus (Poaceae)), corn (Zea mays Linnaeus (Poaceae)), and soy (Glycine max (Linnaeus) Merrill (Fabaceae)) flour habitats. Despite large differences in fitness between habitats (fitness was the highest in wheat flour, lower in corn flour, and zero in soy flour), beetles showed only weak preference for wheat over corn flour and for corn over soy flour, but showed strong preference for wheat over soy flour. These preferences were the strongest at low density. This study gives insight into the relationship between habitat quality and density-dependent habitat selection in flour beetles.


2021 ◽  
Author(s):  
Claudia Dupke ◽  
Anne Peters ◽  
Nicolas Morellet ◽  
Marco Heurich

Abstract Background: Holling (1959) was the first to describe a functional response between a predator’s consumption-rate and the density of its prey. The same concept may be applied to the habitat selection of herbivores, by considering the change in relative habitat use with the change in habitat availability. Functional responses in habitat selection at a home-range scale has been reported for several large herbivores. However, a link to Holling’s original functional response types has never been drawn despite its potential to understand availability dependence in habitat selection more profoundly. Methods: Discrete choice models were implemented as mixed-effects baseline-category logit models to analyze the variation in habitat selection of a large herbivore over seasonal and diurnal scales. Specifically, changes in habitat use with respect to habitat availability were investigated by monitoring 11 habitat types commonly used by roe deer ( Capreolus capreolus ) in the Bavarian Forest National Park, Germany. Functional response curves were then fitted using Holling’s formulas. Results: Strong evidence of non-linear functional responses was obtained for almost all of the examined habitat types. The shape of the functional response curves varied depending on the season, time of day and in some cases between sexes. These responses could be referenced to Holling’s types, with a predominance of type II.Conclusions: Our results indicate that Holling’s types could be applied to describe general patterns in habitat selection behaviour of herbivores. Functional response in habitat selection may occur in situations of trade-off in the selection of habitats offering different resources, due to temporally varying physiological needs of herbivores. Moreover, the two associated parameters defining the curves helps to identify the temporal variations and clarify how strongly the cost-to-benefit ratio is pronounced for a specific habitat. The presented novel approach of using Holling’s equations to describe functional response in habitat selection of herbivores could be used for assigning general habitat attraction values, independent of habitat availability, which might facilitate the identification of suitable habitats.


Ecosphere ◽  
2014 ◽  
Vol 5 (10) ◽  
pp. art132 ◽  
Author(s):  
Olivia Tardy ◽  
Ariane Massé ◽  
Fanie Pelletier ◽  
Julien Mainguy ◽  
Daniel Fortin

2020 ◽  
Author(s):  
Joseph A. LaManna ◽  
Scott A. Mangan ◽  
Jonathan A. Myers

AbstractRecent studies showing bias in the measurement of density dependence have the potential to sow confusion in the field of ecology. We provide clarity by elucidating key conceptual and statistical errors with the null-model approach used in Detto et al. (2019). We show that neither their null model nor a more biologically-appropriate null model reproduces differences in density-dependent recruitment between forests, indicating that the latitudinal gradient in negative density dependence is not an artefact of statistical bias. Finally, we suggest a path forward that combines observational comparisons of density dependence in multiple fitness components across localities with mechanistic and geographically-replicated experiments.


2021 ◽  
Author(s):  
Carlos León-Sobrino ◽  
Jean-Baptiste Ramond ◽  
Clément Coclet ◽  
Ritha-Meriam Kapitango ◽  
Gillian Maggs-Kölling ◽  
...  

Rainfall is rare in hyperarid deserts but, when it occurs, it triggers large biological responses which are considered to be essential for the long-term maintenance of biodiversity. In such environments, microbial communities have major roles in nutrient cycling, but their functional responses to short-lived resource opportunities are poorly understood. We used whole community metatranscriptomic data to demonstrate structured and sequential functional responses in desiccated desert soils to a simulated rainfall event over a seven-day time frame. Rapid transcriptional activation of Actinobacteria, Alpha-proteobacteria and phage transcripts was followed by a marked increase in protist and myxobacterial activity, before returning to the original state. In functional terms, motility systems were activated in the early phases, whereas competition-toxicity systems increased in parallel to the activity from predators and the drying of soils. The dispersal-predation dynamic was identified as a central driver of microbial community responses to watering. Carbon fixation mechanisms that were active under dry condition were rapidly down-regulated in wetted soils, and only reactivated on a return to a near-dry state, suggesting a reciprocal balance between carbon fixation and fixed-carbon acquisition processes. Water addition induced a general reduction in the transcription of stress response genes, most prominently HSP20, indicating that this chaperone is particularly important for life in desiccated ecosystems. Based on these data, we propose a rainfall response model for desert soil microbiomes.


Oryx ◽  
2016 ◽  
Vol 51 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Xuchang Liang ◽  
Aili Kang ◽  
Nathalie Pettorelli

AbstractWe tested a series of hypotheses on drivers of habitat selection by the Vulnerable wild yak Bos mutus, combining distribution-wide sighting data with species distribution modelling approaches. The results indicate that climatic conditions are of paramount importance in shaping the wild yak's distribution on the Tibetan Plateau. Habitat selection patterns were seasonal, with yaks appearing to select areas closer to villages during the vegetation-growing season. Unexpectedly, our index of forage quantity had a limited effect in determining the distribution of the species. Overall, our results suggest that expected changes in climate for this region could have a significant impact on habitat availability for wild yaks, and we call for more attention to be focused on the unique wildlife in this ecosystem.


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