scholarly journals Untangling the influence of biotic and abiotic factors on habitat selection by a tropical rodent

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Georgia Ward-Fear ◽  
Gregory P. Brown ◽  
David Pearson ◽  
Richard Shine
Keyword(s):  
Breeding Season ◽  
Perceived Risk ◽  
Large Scale ◽  
Abiotic Factors ◽  
Ziziphus Mauritiana ◽  
Feral Horses ◽  
Animal Populations ◽  
Risk Of Predation ◽  
Giving Up Density ◽  
Open Woodland

AbstractUnderstanding how animal populations respond to environmental factors is critical because large-scale environmental processes (e.g., habitat fragmentation, climate change) are impacting ecosystems at unprecedented rates. On an overgrazed floodplain in north-western Australia, a native rodent (Pale Field Rat, Rattus tunneyi) constructs its burrows primarily beneath an invasive tree (Chinee Apple, Ziziphus mauritiana) rather than native trees. The dense thorny foliage of the Chinee Apple may allow high rat densities either because of abiotic effects (shade, in a very hot environment) or biotic processes (protection from trampling and soil compaction by feral horses, and/or predation). To distinguish between these hypotheses, we manipulated Chinee Apple foliage to modify biotic factors (access to horses and predators) but not shade levels. We surveyed the rat population with Elliott traps under treatment and control trees and in the open woodland, in two seasons (the breeding season—January, and the nesting season—May). In the breeding season, we ran giving-up density experiments (GUD) with food trays, to assess the perceived risk of predation by rats across our three treatments. Selective trimming of foliage did not affect thermal regimes underneath the trees but did allow ingress of horses and we observed two collapsed burrows as a consequence (although long term impacts of horses were not measured). The perceived predation risk also increased (GUD values at food trays increased) and was highest in the open woodland. Our manipulation resulted in a shift in rat sex ratios (indicating female preference for breeding under control but not foliage-trimmed trees) and influenced rat behaviour (giving-up densities increased; large dominant males inhabited the control but not treatment trees). Our data suggest that the primary benefit of the Chinee Apple tree to native rodents lies in physical protection from predators and (potentially) feral horses, rather than in providing cooler microhabitat.

Foraging Response to Risks of Predation and Competition in Artificial Pools

2010 ◽  
Vol 56 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Gil Stav ◽  
Burt P. Kotler ◽  
Leon Blaustein
Keyword(s):  
Perceived Risk ◽  
Foraging Activity ◽  
Left Behind ◽  
Similar Tendency ◽  
Green Toad ◽  
Risk Of Predation ◽  
Giving Up Density ◽  
Culiseta Longiareolata ◽  
The Rich ◽  
Resource Patches

Although ecologists have learned much about the influence of competitors and perceived risk of predation on foraging in terrestrial systems by measuring giving-up density (GUD, the amount of food left behind in a resource patch following exploitation), GUDs have rarely been used in aquatic environments. Here we use foraging activity (proportion foraging) and GUDs to assess the effects that two periphyton consumers and potential competitors, green toad (Bufo viridis) tadpoles and mosquito (Culiseta longiareolata) larvae, have on each other. We also examine the effects of perceived risk of predation imposed by a dragonfly nymph (Anax imperator). To do so, we conducted an artificial pool experiment and developed a food patch appropriate for measuring GUDs for periphyton grazers. MoreCulisetaindividuals foraged in rich food patches than in poor patches.Bufoshowed a similar tendency. FewerBufoforaged in both patch types in the presence of cagedAnax. Culisetashowed a similar tendency. However, in the rich patches, onlyBuforeduced foraging activity when the caged predator was present. BothBufoandCulisetadepleted food patches through exploitation, resulting in lower GUDs. Both competitors together resulted in lower GUDs than did food depletion of each species alone. However, the presence of cagedAnaxhad little or no effects on GUDs. Overall, bothBufoandCulisetarespond to food and safety. They are able to direct foraging effort to richer patches and devote more time to those patches, and they respond to predation risk by choosing whether or not to exploit resource patches.

Large-scale mapping of the catenas vegetation in Subarctic tundra

1995 ◽  
pp. 3-21
Author(s):  
S. S. Kholod
Keyword(s):  
Spatial Distribution ◽  
Vegetation Cover ◽  
Large Scale ◽  
Block Diagram ◽  
Abiotic Factors ◽  
Ecological Factors ◽  
Spatial Arrangement ◽  
Geological Time ◽  
Ecological Barriers ◽  
Functional Zones

One of the most difficult tasks in large-scale vegetation mapping is the clarification of mechanisms of the internal integration of vegetation cover territorial units. Traditional way of searching such mechanisms is the study of ecological factors controlling the space heterogeneity of vegetation cover. In essence, this is autecological analysis of vegetation. We propose another way of searching the mechanisms of territorial integration of vegetation. It is connected with intracoenotic interrelation, in particular, with the changing role of edificator synusium in a community along the altitudinal gradient. This way of searching is illustrated in the model-plot in subarctic tundra of Central Chukotka. Our further suggestion concerns the way of depicting these mechanisms on large-scale vegetation map. As a model object we chose the catena, that is the landscape formation including all geomorphjc positions of a slope, joint by the process of moving the material down the slope. The process of peneplanation of a mountain system for a long geological time favours to the levelling the lower (accumulative) parts of slopes. The colonization of these parts of the slope by the vegetation variants, corresponding to the lowest part of catena is the result of peneplanation. Vegetation of this part of catena makes a certain biogeocoenotic work which is the levelling of the small infralandscape limits and of the boundaries in vegetation cover. This process we name as the continualization on catena. In this process the variants of vegetation in the lower part of catena are being broken into separate synusiums. This is the process of decumbation of layers described by V. B. Sochava. Up to the slope the edificator power of the shrub synusiums sharply decreases. Moss and herb synusium have "to seek" the habitats similar to those under the shrub canopy. The competition between the synusium arises resulting in arrangement of a certain spatial assemblage of vegetation cover elements. In such assemblage the position of each element is determined by both biotic (interrelation with other coenotic elements) and abiotic (presence of appropriate habitats) factors. Taking into account the biogeocoenotic character of the process of continualization on catena we name such spatial assemblage an exolutionary-biogeocoenotic series. The space within each evolutionary-biogeocoenotic series is divided by ecological barriers into some functional zones. In each of the such zones the struggle between synusiums has its individual expression and direction. In the start zone of catena (extensive pediment) the interrelations of synusiums and layers control the mutual spatial arrangement of these elements at the largest extent. Here, as a rule, there predominate edificator synusiums of low and dwarfshrubs. In the first order limit zone (the bend of pediment to the above part of the slope) one-species herb and moss synusiums, oftenly substituting each other in similar habitats, get prevalence. In the zone of active colonization of slope (denudation slope) the coenotic factor has the least role in the spatial distribution of the vegetation cover elements. In particular, phytocoenotic interactions take place only within separate microcoenoses of herbs, mosses and lichens. In the zone of the attenuation of continualization process (the upper most parts of slope, crests) phytocoenotic interactions are almost absent and the spatial distribution of vegetation cover elements depends exclusively on the abiotic factors. The principal scheme of the distribution of vegetation cover elements and the disposition of functional zones on catena are shown on block-diagram (fig. 1).

scholarly journals Repeated surveying over 6 years reveals that fine-scale habitat variables are key to tropical mountain ant assemblage composition and functional diversity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mulalo M. Muluvhahothe ◽  
Grant S. Joseph ◽  
Colleen L. Seymour ◽  
Thinandavha C. Munyai ◽  
Stefan H. Foord
Keyword(s):  
Climate Change ◽  
Species Composition ◽  
High Altitude ◽  
Functional Diversity ◽  
Large Scale ◽  
Climate Models ◽  
Spatial Scales ◽  
Abiotic Factors ◽  
Composition Analysis ◽  
Fine Scale

AbstractHigh-altitude-adapted ectotherms can escape competition from dominant species by tolerating low temperatures at cooler elevations, but climate change is eroding such advantages. Studies evaluating broad-scale impacts of global change for high-altitude organisms often overlook the mitigating role of biotic factors. Yet, at fine spatial-scales, vegetation-associated microclimates provide refuges from climatic extremes. Using one of the largest standardised data sets collected to date, we tested how ant species composition and functional diversity (i.e., the range and value of species traits found within assemblages) respond to large-scale abiotic factors (altitude, aspect), and fine-scale factors (vegetation, soil structure) along an elevational gradient in tropical Africa. Altitude emerged as the principal factor explaining species composition. Analysis of nestedness and turnover components of beta diversity indicated that ant assemblages are specific to each elevation, so species are not filtered out but replaced with new species as elevation increases. Similarity of assemblages over time (assessed using beta decay) did not change significantly at low and mid elevations but declined at the highest elevations. Assemblages also differed between northern and southern mountain aspects, although at highest elevations, composition was restricted to a set of species found on both aspects. Functional diversity was not explained by large scale variables like elevation, but by factors associated with elevation that operate at fine scales (i.e., temperature and habitat structure). Our findings highlight the significance of fine-scale variables in predicting organisms’ responses to changing temperature, offering management possibilities that might dilute climate change impacts, and caution when predicting assemblage responses using climate models, alone.

scholarly journals High biogeographic and latitudinal variability in gastropod drilling predation on molluscs along the eastern Indian coast: Implications on the history of fossil record of drillholes

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256685
Author(s):  
Subhronil Mondal ◽  
Hindolita Chakraborty ◽  
Sandip Saha ◽  
Sahana Dey ◽  
Deepjay Sarkar
Keyword(s):  
Spatial Variability ◽  
Large Scale ◽  
Abiotic Factors ◽  
Eastern Coast ◽  
Detailed Knowledge ◽  
Biogeographic Pattern ◽  
Drilling Predation ◽  
History Of ◽  
Latitudinal Patterns ◽  
Consecutive Time

Studies on the large-scale latitudinal patterns of gastropod drilling predation reveal that predation pressure may decrease or increase with increasing latitude, or even show no trend, questioning the generality of any large-scale latitudinal or biogeographic pattern. Here, we analyze the nature of spatio-environmental and latitudinal variation in gastropod drilling along the Indian eastern coast by using 76 samples collected from 39 locations, covering ~2500 km, incorporating several ecoregions, and ~15° latitudinal extents. We find no environmental or latitudinal gradient. In fact, drilling intensity varies highly within the same latitudinal bin, or oceanic sub-basins, or even the same ecoregions. Moreover, different ecoregions with their distinctive biotic and abiotic environmental variables show similar predation intensities. However, one pattern is prevalent: some small infaunal prey taxa, living in the sandy-muddy substrate—which are preferred by the naticid gastropods—are always attacked more frequently over others, indicating taxon and size selectivity by the predators. The result suggests that the biotic and abiotic factors, known to influence drilling predation, determine only the local predation pattern. In the present case, the nature of substrate and prey composition determines the local predation intensity: soft substrate habitats host dominantly small, infaunal prey. Since the degree of spatial variability in drilling intensity within any time bin can be extremely high, sometimes greater than the variability across consecutive time bins, temporal patterns in drilling predation can never be interpreted without having detailed knowledge of the nature of this spatial variability within a time bin.

scholarly journals Effects of a New Pedestrian Pathway in Grand Teton National Park on Breeding Sagebrush Songbirds

2008 ◽  
Vol 31 ◽  
pp. 3-7
Author(s):  
Anna Chalfoun
Keyword(s):  
Perceived Risk ◽  
Breeding Habitat ◽  
Energy Budgets ◽  
Human Presence ◽  
Wildlife Species ◽  
Fitness Consequences ◽  
Risk Of Predation ◽  
Natural Landscapes ◽  
Wildlife Populations ◽  
Induced Changes

Human-induced changes to natural landscapes have become ubiquitous, resulting in exposure of wildlife populations to novel stressors (Munns 2006). While it is clear that changes such as habitat loss can directly impact wildlife species, less clear is the extent to which human presence itself functions as a disturbance that influences wildlife behaviors with important fitness consequences. Animals clearly respond to perceived risk of predation by natural predators via, for example, fleeing, or altering foraging and/or breeding habitat selection (Marzluff 1988, Hakkarainen et al. 2001, Frid and Dill2002, Blumstein 2006, Borkowski et al. 2006, Fontaine and Martin 2006). Such responses can alter access to important resources, energy budgets, and therefore attributes such as body condition (Bechet et al. 2004) with potential impacts to survival and reproductive output. Of critical importance to the management of wildlife populations is therefore to determine 1) whether wildlife species perceive human presence as predation risk, 2) how individuals respond to such risk, and 3) how such responses influence fitness consequences and therefore population dynamics and community structure.

Female mouthbrooders adjust incubation duration to perceived risk of predation

2004 ◽  
Vol 68 (6) ◽  
pp. 1275-1281 ◽  
Author(s):  
Barbara Taborsky ◽  
Katharina Foerster
Keyword(s):  
Perceived Risk ◽  
Risk Of Predation ◽  
Incubation Duration

scholarly journals Anticipating the emergence of infectious diseases

2017 ◽  
Vol 14 (132) ◽  
pp. 20170115 ◽  
Author(s):  
Tobias S. Brett ◽  
John M. Drake ◽  
Pejman Rohani
Keyword(s):  
Large Scale ◽  
Simulated Data ◽  
Disease Emergence ◽  
General Applicability ◽  
Slowing Down ◽  
Animal Populations ◽  
Theoretical Predictions ◽  
Parameter Values ◽  
Model Structures ◽  
Good Support

In spite of medical breakthroughs, the emergence of pathogens continues to pose threats to both human and animal populations. We present candidate approaches for anticipating disease emergence prior to large-scale outbreaks. Through use of ideas from the theories of dynamical systems and stochastic processes we develop approaches which are not specific to a particular disease system or model, but instead have general applicability. The indicators of disease emergence detailed in this paper can be classified into two parallel approaches: a set of early-warning signals based around the theory of critical slowing down and a likelihood-based approach. To test the reliability of these two approaches we contrast theoretical predictions with simulated data. We find good support for our methods across a range of different model structures and parameter values.

scholarly journals Testing biodiversity theory using species richness of reef-building corals across a depth gradient

2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Coral Species ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Empirical Support ◽  
Null Model ◽  
Local Scale ◽  
Small Scale ◽  
Energy Availability

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

The impact of “omics” technologies for grapevine (Vitis vinifera) research

2020 ◽  
pp. 1-15
Author(s):  
Nicolas Fischer ◽  
Thomas Efferth
Keyword(s):  
Vitis Vinifera ◽  
Large Scale ◽  
Abiotic Factors ◽  
Rapid Evolution ◽  
Vitis Vinifera L ◽  
Wine Quality ◽  
Omics Technologies ◽  
Biological Studies ◽  
Holistic Understanding ◽  
The Impact

BACKGROUND: Grapevine (Vitis vinifera L.) as basis for winemaking is one of the most economically important plants in modern agriculture. As requirements in viticulture are increasing due to changing environments, terroir and pests, classical agriculture techniques reach their limits. OBJECTIVE: We summarize the impact of modern “omics” technologies on modern grapevine breeding and cultivation, as well as for dealing with challenges in viniculture caused by environmental or terroir changes and pests and diseases. In this review, we give an overview on current research on the influence of “omics” technologies on modern viticulture. RESULTS: Considerable advances in bioinformatics and analytical techniques such as next generation sequencing or mass spectrometry fueled new molecular biological studies. Modern “omics” technologies such as “genomics”, “transcriptomics”, “proteomics” and “metabolomics” allow the investigation on a large-scale data basis and the identification of key markers. Holistic understanding of genes, proteins and metabolites in combination with external biotic and abiotic factors improves vine and wine quality. CONCLUSION: The rapid evolution in wine quality was only enabled by the progress of modern biotechnological methods developing enology from a handcraft to science.

Effect of Turbidity on the Predator Avoidance Behaviour of Juvenile Chinook Salmon (Oncorhynchus tshawytscha)

1993 ◽  
Vol 50 (2) ◽  
pp. 241-246 ◽  
Author(s):  
Robert S. Gregory
Keyword(s):  
Chinook Salmon ◽  
Perceived Risk ◽  
Predator Avoidance ◽  
Oncorhynchus Tshawytscha ◽  
Avoidance Behaviour ◽  
Fish Predator ◽  
Juvenile Chinook Salmon ◽  
Risk Of Predation ◽  
Juvenile Chinook ◽  
Predator Risk

The effect of turbidity on the predator avoidance behaviour of juvenile chinook salmon (Oncorhynchus tshawytscha) was determined in controlled laboratory experiments. Bird and fish models were used to simulate predator risk. In the absence of risk, juvenile chinook were distributed randomly within an experimental arena in turbid conditions (≈23 NTU), but in clear conditions (<1 NTU) they associated with the bottom. When introduced to bird and fish predator models, the chinook altered their distribution and occupied deeper parts of the arena regardless of turbidity level. However, their responses in turbid conditions were less marked and of shorter duration. Turbidity apparently reduced the perceived risk of predation in juvenile chinook.

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