scholarly journals Resource-driven encounters among consumers and implications for the spread of infectious disease

2017 ◽  
Vol 14 (135) ◽  
pp. 20170555 ◽  
Author(s):  
Rebecca K. Borchering ◽  
Steve E. Bellan ◽  
Jason M. Flynn ◽  
Juliet R. C. Pulliam ◽  
Scott A. McKinley
Keyword(s):  
Resource Availability ◽  
Food Resource ◽  
Maximum Distance ◽  
Spatially Explicit ◽  
Encounter Rate ◽  
Supplemental Food ◽  
Resource Density ◽  
Critical Resource ◽  
The Relationship ◽  
Theoretical Results

Animals share a variety of common resources, which can be a major driver of conspecific encounter rates. In this work, we implement a spatially explicit mathematical model for resource visitation behaviour in order to examine how changes in resource availability can influence the rate of encounters among consumers. Using simulations and asymptotic analysis, we demonstrate that, under a reasonable set of assumptions, the relationship between resource availability and consumer conspecific encounters is not monotonic. We characterize how the maximum encounter rate and associated critical resource density depend on system parameters like consumer density and the maximum distance from which consumers can detect and respond to resources. The assumptions underlying our theoretical model and analysis are motivated by observations of large aggregations of black-backed jackals at carcasses generated by seasonal outbreaks of anthrax among herbivores in Etosha National Park, Namibia. As non-obligate scavengers, black-backed jackals use carcasses as a supplemental food resource when they are available. While jackals do not appear to acquire disease from ingesting anthrax carcasses, changes in their movement patterns in response to changes in carcass abundance do alter jackals' conspecific encounter rate in ways that may affect the transmission dynamics of other diseases, such as rabies. Our theoretical results provide a method to quantify and analyse the hypothesis that the outbreak of a fatal disease among herbivores can potentially facilitate outbreaks of an entirely different disease among jackals. By analysing carcass visitation data, we find support for our model's prediction that the number of conspecific encounters at resource sites decreases with additional increases in resource availability. Whether or not this site-dependent effect translates to an overall decrease in encounters depends, unexpectedly, on the relationship between the maximum distance of detection and the resource density.

scholarly journals Resource-Driven Encounters and the Induction of Disease Among Consumers

2016 ◽  
Author(s):  
Rebecca K. Borchering ◽  
Steve E. Bellan ◽  
Jason M. Flynn ◽  
Juliet R.C. Pulliam ◽  
Scott A. McKinley
Keyword(s):  
National Park ◽  
Interaction Model ◽  
Spatially Explicit ◽  
Encounter Rate ◽  
Model Parameters ◽  
Expected Number ◽  
Spatially Explicit Model ◽  
Consumer Population ◽  
Using Data ◽  
The Relationship

AbstractSubmitted Manuscript 2016. Territorial animals share a variety of common resources, which can be a major driver of conspecific encounter rates. We examine how changes in resource availability influence the rate of encounters among individuals in a consumer population by implementing a spatially explicit model for resource visitation behavior by consumers. Using data from 2009 and 2010 in Etosha National Park, we verify our model's prediction that there is a saturation effect in the expected number of jackals that visit a given carcass site as carcasses become abundant. However, this does not directly imply that the overall resource-driven encounter rate among jackals decreases. This is because the increase in available carcasses is accompanied by an increase in the number of jackals that detect and potentially visit carcasses. Using simulations and mathematical analysis of our consumer-resource interaction model, we characterize key features of the relationship between resource-driven encounter rate and model parameters. These results are used to investigate a standing hypothesis that the outbreak of a fatal disease among zebras can potentially lead to an outbreak of an entirely different disease in the jackal population, a process we refer to as indirect induction of disease.

SWAZI ORAL LITERATURE, ECO-CULTURE AND ENVIRONMENTAL APOCALYPSE

2016 ◽  
Vol 26 (1) ◽  
Author(s):  
Enongene Mirabeau Sone
Keyword(s):  
Indigenous Knowledge ◽  
Environmental Sustainability ◽  
Oral Literature ◽  
Resource Base ◽  
Healthy Environment ◽  
Nature And Culture ◽  
Western Concept ◽  
Critical Resource ◽  
The Relationship ◽  
Conservation Of Biodiversity

The main objective of this paper is to show how oral literature is engaged by Swazis with regards to environmental sustainability. It demonstrates the relationship between nature and culture as reflected in Swazi oral literature and how indigenous knowledge embedded in this literature can be used to expand the concepts of eco-literature and eco-criticism. The paper argues that the indigenous environmental expertise among the Swazi people, encapsulated in their oral literature, can serve as a critical resource base for the process of developing a healthy environment. Furthermore, the paper contends that eco-criticism, which is essentially a Western concept, can benefit by drawing inspiration from the indigenous knowledge contained in Swazi culture and expressed in their oral literature. The paper concludes by recommending the need to strengthen traditional and customary knowledge and practices by protecting and recognising the values of such systems in the conservation of biodiversity for sustainable development.

scholarly journals Relationships between resource availability and elevation vary between metrics creating gradients of nutritional complexity

Oecologia ◽  
2021 ◽  
Vol 195 (1) ◽  
pp. 213-223
Author(s):  
Mark A. Lee ◽  
Grace Burger ◽  
Emma R. Green ◽  
Pepijn W. Kooij
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Resource Availability ◽  
Plant Biomass ◽  
Plant Species Richness ◽  
Mineral Contents ◽  
Nutritive Values ◽  
Animal Community ◽  
Nutritional Chemistry ◽  
The Relationship

AbstractPlant and animal community composition changes at higher elevations on mountains. Plant and animal species richness generally declines with elevation, but the shape of the relationship differs between taxa. There are several proposed mechanisms, including the productivity hypotheses; that declines in available plant biomass confers fewer resources to consumers, thus supporting fewer species. We investigated resource availability as we ascended three aspects of Helvellyn mountain, UK, measuring several plant nutritive metrics, plant species richness and biomass. We observed a linear decline in plant species richness as we ascended the mountain but there was a unimodal relationship between plant biomass and elevation. Generally, the highest biomass values at mid-elevations were associated with the lowest nutritive values, except mineral contents which declined with elevation. Intra-specific and inter-specific increases in nutritive values nearer the top and bottom of the mountain indicated that physiological, phenological and compositional mechanisms may have played a role. The shape of the relationship between resource availability and elevation was different depending on the metric. Many consumers actively select or avoid plants based on their nutritive values and the abundances of consumer taxa vary in their relationships with elevation. Consideration of multiple nutritive metrics and of the nutritional requirements of the consumer may provide a greater understanding of changes to plant and animal communities at higher elevations. We propose a novel hypothesis for explaining elevational diversity gradients, which warrants further study; the ‘nutritional complexity hypothesis’, where consumer species coexist due to greater variation in the nutritional chemistry of plants.

scholarly journals Social eavesdropping allows for a more risky gliding strategy by thermal-soaring birds

2018 ◽  
Vol 15 (148) ◽  
pp. 20180578 ◽  
Author(s):  
Hannah J. Williams ◽  
Andrew J. King ◽  
Olivier Duriez ◽  
Luca Börger ◽  
Emily L. C. Shepard
Keyword(s):  
Resource Availability ◽  
Personal Information ◽  
Social Information ◽  
Social Cues ◽  
Surrounding Area ◽  
Circling Behaviour ◽  
Factors Affecting ◽  
Critical Resource ◽  
Speed Selection ◽  
Soaring Birds

Vultures are thought to form networks in the sky, with individuals monitoring the movements of others to gain up-to-date information on resource availability. While it is recognized that social information facilitates the search for carrion, how this facilitates the search for updrafts, another critical resource, remains unknown. In theory, birds could use information on updraft availability to modulate their flight speed, increasing their airspeed when informed on updraft location. In addition, the stylized circling behaviour associated with thermal soaring is likely to provide social cues on updraft availability for any bird operating in the surrounding area. We equipped five Gyps vultures with GPS and airspeed loggers to quantify the movements of birds flying in the same airspace. Birds that were socially informed on updraft availability immediately adopted higher airspeeds on entering the inter-thermal glide; a strategy that would be risky if birds were relying on personal information alone. This was embedded within a broader pattern of a reduction in airspeed (approx. 3 m s −1 ) through the glide, likely reflecting the need for low speed to sense and turn into the next thermal. Overall, this demonstrates (i) the complexity of factors affecting speed selection over fine temporal scales and (ii) that Gyps vultures respond to social information on the occurrence of energy in the aerial environment, which may reduce uncertainty in their movement decisions.

scholarly journals Wicksell's Problem in Local Stereology

2013 ◽  
Vol 45 (4) ◽  
pp. 925-944
Author(s):  
Ó. Thórisdóttir ◽  
M. Kiderlen
Keyword(s):  
Reference Point ◽  
Simulated Data ◽  
Domain Of Attraction ◽  
Spherical Particles ◽  
Section Profile ◽  
Particle Parameters ◽  
The Individual ◽  
The Relationship ◽  
Theoretical Results ◽  
Isotropic Random

Wicksell's classical corpuscle problem deals with the retrieval of the size distribution of spherical particles from planar sections. We discuss the problem in a local stereology framework. Each particle is assumed to contain a reference point and the individual particle is sampled with an isotropic random plane through this reference point. Both the size of the section profile and the position of the reference point inside the profile are recorded and used to recover the distribution of the corresponding particle parameters. Theoretical results concerning the relationship between the profile and particle parameters are discussed. We also discuss the unfolding of the arising integral equations, uniqueness issues, and the domain of attraction relations. We illustrate the approach by providing reconstructions from simulated data using numerical unfolding algorithms.

scholarly journals Flowers, fruits, and the abundance of the yellow-chevroned parakeet (Brotogeris chiriri) at a gallery forest in the South Pantanal (Brazil)

2004 ◽  
Vol 64 (4) ◽  
pp. 867-877 ◽  
Author(s):  
J. Ragusa-Netto
Keyword(s):  
Food Resource ◽  
Flood Plain ◽  
Fruit Production ◽  
Fleshy Fruit ◽  
Foraging Activity ◽  
Gallery Forest ◽  
Plant Resources ◽  
Major Food ◽  
Palm Fruits ◽  
The Relationship

Parakeets usually forage for massive and ephemeral plant resources at forest canopies. Fruit pulp is widely cited as a major food resource for these birds, which often eat seeds and nectar. In this study, I assessed flower and fruit production at a gallery forest in the Pantanal flood plain (Brazil) in order to evaluate the relationship between food resource production and abundance of a common parakeet, Brotogeris chiriri. Also, I evaluated the relationship between food resource production and foraging activity. Parakeet abundance varied markedly along the year, coinciding with massive episodes of flower and fleshy fruit availability. Inga vera nectar, intensely used during the latter part of dry season, was by far the most exploited food item by parakeets when they were very abundant. The nectar comprised 34% of the parakeets' diet (N = 131 feeding records) at the gallery forest, while fleshy fruits made up the rest. Parakeets principally exploited fruits of Cecropia pachystachya and Ficus luschnathiana, besides palm fruits and Inga vera arils. The consistent relationship between foraging activity and parakeet abundance, as well as the coincidence between fluctuations of these parameters and availability of major food resources, suggests that food availability mostly influenced B. chiriri occurrence in the gallery forest. Furthermore, I found no evidence for gallery forest use for roosting and/or breeding, in spite of the fact that such factors usually influence local parakeet abundance.

scholarly journals The relationship between resource abundance and insect herbivory on islands

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256183
Author(s):  
Bora Shin ◽  
Jae-Young Lee ◽  
Nang-Hee Kim ◽  
Sei-Woong Choi
Keyword(s):  
Plant Species ◽  
Forest Cover ◽  
Food Resource ◽  
Phytophagous Insects ◽  
Feeding Guild ◽  
Resource Abundance ◽  
Variable Effect ◽  
The Relationship ◽  
External Feeding ◽  
Number Of Plant Species

We examined the relationship between resource abundance and the feeding activity of phytophagous insects on three common island plants. The aim was to investigate the correlation between phytophagous insects’ abundance and availability of food and island geography. We collected 30,835 leaves from three tree species groups (Mallotus japonicus, Prunus species, and Quercus species) on 18 islands in southwest Korea. The number of plant resources for herbivores varied: the number of leaves per shoot was the highest in Mallotus, leaf weight and the water content per leaf was significantly lower in Quercus species. External feeding was higher for Prunus and Quercus species, whereas the internal feeding type was significantly higher for Quercus species. Geography (area and distance), elevation and food resource (elevation, number of plant species, and the forest cover rate) had a variable effect on phytophagous insects feeding activities: distance and the number of plant species were more explainable to the external feeding guild. In contrast, area and forest cover were more to the internal feeding guild.

scholarly journals Conflict-Directed Backjumping Revisited

2001 ◽  
Vol 14 ◽  
pp. 53-81 ◽  
Author(s):  
X. Chen ◽  
P. Van Beek
Keyword(s):  
Constraint Satisfaction Problems ◽  
Local Consistency ◽  
Backtracking Search ◽  
Arc Consistency ◽  
Look Ahead ◽  
Variable Ordering ◽  
Look Back ◽  
The Look ◽  
The Relationship ◽  
Theoretical Results

In recent years, many improvements to backtracking algorithms for solving constraint satisfaction problems have been proposed. The techniques for improving backtracking algorithms can be conveniently classified as look-ahead schemes and look-back schemes. Unfortunately, look-ahead and look-back schemes are not entirely orthogonal as it has been observed empirically that the enhancement of look-ahead techniques is sometimes counterproductive to the effects of look-back techniques. In this paper, we focus on the relationship between the two most important look-ahead techniques---using a variable ordering heuristic and maintaining a level of local consistency during the backtracking search---and the look-back technique of conflict-directed backjumping (CBJ). We show that there exists a ``perfect'' dynamic variable ordering such that CBJ becomes redundant. We also show theoretically that as the level of local consistency that is maintained in the backtracking search is increased, the less that backjumping will be an improvement. Our theoretical results partially explain why a backtracking algorithm doing more in the look-ahead phase cannot benefit more from the backjumping look-back scheme. Finally, we show empirically that adding CBJ to a backtracking algorithm that maintains generalized arc consistency (GAC), an algorithm that we refer to as GAC-CBJ, can still provide orders of magnitude speedups. Our empirical results contrast with Bessiere and Regin's conclusion (1996) that CBJ is useless to an algorithm that maintains arc consistency.

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