Assessing competition intensity along productivity gradients using a simple model

2001 ◽  
Vol 79 (12) ◽  
pp. 1486-1491 ◽  
Author(s):  
Ken Arii ◽  
Roy Turkington
Keyword(s):  
Simple Model ◽  
Resource Availability ◽  
Plant Ecology ◽  
Competition Intensity ◽  
Productivity Gradient ◽  
Surface Variation ◽  
Intensity Changes ◽  
Productivity Gradients ◽  
Resource Levels ◽  
Theory Competition

One of the most highly debated issues in plant ecology has been the manner in which competition intensity changes along productivity gradients. We have used a simple model to attempt to demonstrate that in theory, competition intensity can vary quite considerably along productivity gradients. Our model incorporates three key components: (i) changes in resource availability along a productivity gradient, (ii) changes in resource availability when neighbours are removed, and (iii) growth characteristics of the target species and (or) individuals to varying resource levels (i.e., response surface). Variation and interactions among these three components can potentially give rise to various, and occasionally complex, changes in competition intensity along productivity gradients. This partly explains the divergent, and sometimes contradictory, results reported in previous studies.Key words: competition intensity, productivity gradient, nutrient, light, model.

scholarly journals Communication Among Harvesters Leads to Sustainable Fishing Behaviour in a Continuous Time Common Pool Resource Experiment

2021 ◽  
Vol 8 ◽  
Author(s):  
Kwabena A. Owusu ◽  
Micaela M. Kulesz ◽  
Agostino Merico
Keyword(s):  
Resource Availability ◽  
Continuous Time ◽  
Empirical Studies ◽  
Sustainable Use ◽  
Large Body ◽  
Common Pool ◽  
Use Of Resources ◽  
Extraction Behaviour ◽  
The Commons ◽  
Resource Levels

The sustainable use of common pool resources (CPRs) such as fisheries constitutes a major challenge for society. A large body of empirical studies conducted in discrete time indicates that resource users are able to prevent the ‘tragedy of the commons' under institutional arrangements that can promote cooperation. However, the variability exhibited by the human behaviour and the dynamic nature of renewable resources require continuous time experiments to fully explain the mechanisms underpinning the sustainable use of resources. We conducted CPR experiments in continuous time to investigate how the extraction behaviour of resource users changes in real-time in response to changes in resource availability under communication and no communication. We find that when communication is allowed, users adjust their extraction efforts based on knowledge of previous resource availability. In contrast, when communication is not allowed, users do not incorporate resource availability into their utility function. These results suggest that communication does not merely provide a forum for coordination but mediates a causal relationship between resource levels and extraction behaviour. Our findings may help the development of effective resource management policies.

Competition intensity as a function of resource availability in a semiarid ecosystem

Oecologia ◽  
1998 ◽  
Vol 116 (3) ◽  
pp. 365-372 ◽  
Author(s):  
O. Briones ◽  
C. Monta�a ◽  
E. Ezcurra
Keyword(s):  
Resource Availability ◽  
Competition Intensity ◽  
Semiarid Ecosystem

scholarly journals Resource availability affects the structure of a natural bacteria–bacteriophage community

2010 ◽  
Vol 7 (2) ◽  
pp. 201-204 ◽  
Author(s):  
Timothée Poisot ◽  
Gildas Lepennetier ◽  
Esteban Martinez ◽  
Johan Ramsayer ◽  
Michael E. Hochberg
Keyword(s):  
Resource Availability ◽  
Bipartite Network ◽  
Environmental Perturbations ◽  
In The Wild ◽  
Resource Levels

Antagonistic networks are known to be structured in the wild, but knowledge on how this structure may change as a response to environmental perturbations is scarce. We describe a natural bipartite network between bacteria and lytic bacteriophages, and investigate how it is affected by environmental productivity in the form of different resource levels for the bacteria. We report that low amounts of resource decrease phage generality and lead to less robust and less stable communities. We discuss how resource levels in nature may alter the structure of complex communities.

Resource availability and competition intensity in the carnivore guild of the Early Pleistocene site of Venta Micena (Orce, Baza Basin, SE Spain)

2017 ◽  
Vol 164 ◽  
pp. 154-167 ◽  
Author(s):  
Guillermo Rodríguez-Gómez ◽  
Paul Palmqvist ◽  
Sergio Ros-Montoya ◽  
M. Patrocinio Espigares ◽  
Bienvenido Martínez-Navarro
Keyword(s):  
Resource Availability ◽  
Early Pleistocene ◽  
Competition Intensity ◽  
Se Spain ◽  
Venta Micena

scholarly journals A simple model for post-landfall intensity changes of tropical cyclone over India, Bangladesh and Myanmar coasts

2013 ◽  
Vol 122 (4) ◽  
pp. 967-977
Author(s):  
C M KISHTAWAL ◽  
SHIVANI SHAH ◽  
SASHMITA CHAURASIA ◽  
NEERU JAISWAL
Keyword(s):  
Simple Model ◽  
Tropical Cyclone ◽  
Intensity Changes

scholarly journals A simple model for the influence of habitat resource availability on lateral clonal spread

2015 ◽  
Vol 282 (1806) ◽  
pp. 20150327 ◽  
Author(s):  
Martin Weiser ◽  
Jan Smyčka
Keyword(s):  
Simple Model ◽  
Resource Availability ◽  
Clonal Growth ◽  
Null Model ◽  
Availability Analysis ◽  
Optimal Distance ◽  
High Prevalence ◽  
Below Ground ◽  
Clonal Spread ◽  
Plant Community Assembly

Plant clonal spread is ubiquitous and of great interest, owing both to its key role in plant community assembly and its suitability for plant behaviour research. However, mechanisms that govern spreading distance are not well known. Here we link spacer costs and below-ground competition in a simple model of growth in a homogeneous below-ground environment, in which optimal distance between ramets is based on minimizing the sum of these costs. Using this model, we predict a high prevalence of clonal growth that does not employ spacers in resource-poor environments and a nonlinear increase in spreading distance in response to increasing below-ground resource availability. Analysis of database data on clonal growth in relationship to below-ground resource availability revealed that patterns of the spread based on stolons is compatible with the model's predictions. As expected, model prediction failed for rhizomatous species, where spacer sizes are likely to be selected mainly to play roles other than spread. The model's simplicity makes it useful as a null model in testing hypotheses about the effects of environmental heterogeneity on clonal spread.

scholarly journals Maternal effects in disease resistance: poor maternal environment increases offspring resistance to an insect virus

2012 ◽  
Vol 279 (1744) ◽  
pp. 4009-4014 ◽  
Author(s):  
Mike Boots ◽  
Katherine E. Roberts
Keyword(s):  
Disease Resistance ◽  
Maternal Effects ◽  
Resource Availability ◽  
Evolutionary Dynamics ◽  
Disease Risk ◽  
Insect Virus ◽  
Maternal Environment ◽  
Resource Levels ◽  
Host Parasite ◽  
Parasite Exposure

Maternal effects can be adaptive and because of their intrinsic time delays may have important effects on population dynamics. In vertebrates, and increasingly invertebrates, it is well established that offspring defence is in part determined by maternal parasite exposure. It has also been suggested that there may be indirect maternal effects on immunity mediated by other components of the maternal environment, including density and resource availability. Here, we examine the effect maternal resource availability has on the immunity of offspring in an insect—virus system. We use five different maternal resource levels and examine immunity in the offspring both directly, by challenge with a virus, and by measuring a major component of the immune system, across three offspring environments. Both the direct infection assay and the measure of immunocompetence show clearly that offspring from mothers in poor environments are more resistant to parasites. This may result from life-history optimization of mothers in poor environments, or because the poor environment acts as a cue for higher disease risk in the next generation. This emphasizes the importance of maternal effects on disease resistance, mediated through indirect environmental factors that will have important implications to both the ecological and evolutionary dynamics of host–parasite interactions.

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