Nutrient and Phytoplankton Dynamics in a Sewage-Impacted Gulf Coast Estuary: A Field Test of the PEG-Model and Equilibrium Resource Competition Theory

Estuaries ◽  
1997 ◽  
Vol 20 (4) ◽  
pp. 725 ◽  
Author(s):  
D. L. Roelke ◽  
L. A. Cifuentes ◽  
P. M. Eldridge
Keyword(s):  
Field Test ◽  
Resource Competition ◽  
Gulf Coast ◽  
Phytoplankton Dynamics ◽  
Competition Theory

scholarly journals Stable Coexistence in a Field-Calibrated Individual-Based Model of Mangrove Forest Dynamics Caused by Inter-Specific Crown Plasticity

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 955
Author(s):  
Uwe Grueters ◽  
Mohd Rodila Ibrahim ◽  
Hartmut Schmidt ◽  
Katharina Tiebel ◽  
Hendrik Horn ◽  
...  
Keyword(s):  
Forest Dynamics ◽  
Mangrove Forest ◽  
Resource Competition ◽  
Standing Stock ◽  
Mean Field ◽  
Individual Based Model ◽  
Local Competition ◽  
Competition Theory ◽  
Crown Plasticity ◽  
Classical Competition

(1,2) In this theoretical study, we apply MesoFON, a field-calibrated individual-based model of mangrove forest dynamics, and its Lotka–Volterra interpretations to address two questions: (a) Do the dynamics of two identical red mangrove species that compete for light resources and avoid inter-specific competition by lateral crown displacement follow the predictions of classical competition theory or resource competition theory? (b) Which mechanisms drive the dynamics in the presence of inter-specific crown plasticity when local competition is combined with global or with localized seed dispersal? (3) In qualitative support of classical competition theory, the two species can stably coexist within MesoFON. However, the total standing stock at equilibrium matched the carrying capacity of the single species. Therefore, a “non-overyielding” Lotka–Volterra model rather than the classic one approximated best the observed behavior. Mechanistically, inter-specific crown plasticity moved heterospecific trees apart and pushed conspecifics together. Despite local competition, the community exhibited mean-field dynamics with global dispersal. In comparison, localized dispersal slowed down the dynamics by diminishing the strength of intra-/inter-specific competition and their difference due to a restriction in the competitive race to the mean-field that prevails between conspecific clusters. (4) As the outcome in field-calibrated IBMs is mediated by the competition for resources, we conclude that classical competition mechanisms can override those of resource competition, and more species are likely to successfully coexist within communities.

scholarly journals Biogeochemical versus ecological consequences of modeled ocean physics

2017 ◽  
Vol 14 (11) ◽  
pp. 2877-2889 ◽  
Author(s):  
Sophie Clayton ◽  
Stephanie Dutkiewicz ◽  
Oliver Jahn ◽  
Christopher Hill ◽  
Patrick Heimbach ◽  
...  
Keyword(s):  
Primary Production ◽  
Ocean Circulation ◽  
Mixed Layer ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Resource Competition ◽  
Nutrient Supply ◽  
Zooplankton Biomass ◽  
Global Ocean ◽  
Competition Theory

Abstract. We present a systematic study of the differences generated by coupling the same ecological–biogeochemical model to a 1°, coarse-resolution, and 1∕6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions might be more easily understood.

scholarly journals Opposing offspring sex ratio variations with increasing age and weight in mouflon mothers (Ovis musimon)

2001 ◽  
Vol 49 (3) ◽  
pp. 257-268 ◽  
Author(s):  
T. Landete-Castillejos ◽  
A. Garcia ◽  
S. Langton ◽  
I. Inglis ◽  
L. Gallego ◽  
...  
Keyword(s):  
Resource Competition ◽  
Offspring Sex Ratio ◽  
Local Resource Competition ◽  
Competition Theory ◽  
Offspring Sex ◽  
Complex Picture ◽  
Game State ◽  
Ovis Musimon ◽  
Variance In Reproductive Success ◽  
Sex Biases

There are two main theories explaining offspring sex biases in polygynous mammals. Trivers and Willard (1973) argue that mothers with greater reproductive resources should invest in the sex with the greater variance in reproductive success, usually sons. In contrast, because daughters in many polygynous mammals stay with their mother and compete with her for food, Local Resource Competition theory (e.g. Clark, 1978; Silk, 1983) predicts that the mothers with the greatest reproductive resources should invest in daughters. We investigated the strategy of sex allocation of a captive, outdoor population of 139 mouflon mothers, Ovis musimon, kept in a game state. A complex picture emerged in which, despite weight and body condition being correlated with age in female mouflons, mothers lambed more daughters with increasing age but also, within a given age, gave birth to more sons with increasing weight. Results may be useful in game management aimed at increasing the recruitment or quality o f males in managed populations.

scholarly journals Understanding predicted shifts in diazotroph biogeography using resource competition theory

2014 ◽  
Vol 11 (19) ◽  
pp. 5445-5461 ◽  
Author(s):  
S. Dutkiewicz ◽  
B. A. Ward ◽  
J. R. Scott ◽  
M. J. Follows
Keyword(s):  
Global Change ◽  
Resource Competition ◽  
Nutrient Concentrations ◽  
Change Models ◽  
Competition Theory ◽  
Nitrogen Fixers ◽  
Warming Climate ◽  
Model Predictions ◽  
Underlying Mechanisms ◽  
Central Atlantic

Abstract. We examine the sensitivity of the biogeography of nitrogen fixers to a warming climate and increased aeolian iron deposition in the context of a global earth system model. We employ concepts from the resource-ratio theory to provide a simplifying and transparent interpretation of the results. First we demonstrate that a set of clearly defined, easily diagnosed provinces are consistent with the theory. Using this framework we show that the regions most vulnerable to province shifts and changes in diazotroph biogeography are the equatorial and South Pacific, and central Atlantic. Warmer and dustier climates favor diazotrophs due to an increase in the ratio of supply rate of iron to fixed nitrogen. We suggest that the emergent provinces could be a standard diagnostic for global change models, allowing for rapid and transparent interpretation and comparison of model predictions and the underlying mechanisms. The analysis suggests that monitoring of real world province boundaries, indicated by transitions in surface nutrient concentrations, would provide a clear and easily interpreted indicator of ongoing global change.

Species Coexistence in Ecosystems with Specialist Predation: Trophic Regulation in Gradients of Resource Productivity

2014 ◽  
Vol 1073-1076 ◽  
pp. 1178-1181
Author(s):  
Lei Zhao ◽  
Hua Yong Zhang ◽  
Wang Tian ◽  
Fang Zhao
Keyword(s):  
Species Coexistence ◽  
Resource Competition ◽  
Underlying Mechanism ◽  
Resource Concentration ◽  
Resource Productivity ◽  
Competition Theory ◽  
Tritrophic System ◽  
High Resource ◽  
Weak Competitor ◽  
Specialist Predators

Specialist predation is believed to play a crucial role in maintaining biodiversity of ecosystems, whereas its underlying mechanism is still unclear. Here we analyzed a general model of a tritrophic system containing specialist predators. A new graphical approach based on the balance of resource recruitment and consumption was used. The analyses show that specialist predation can promote coexistence of producer species by increasing resource availability, which waken the exploitive competition between producers. TheR* rule, the dominant rule in traditional resource competition theory, is still dominant in infertile environment. In rich environment, the occurrence of specialist predator increases the equilibrium resource concentration and thus leads to the coexistence of the weak competitor. In high resource productivity environment all the species can coexist.

The fundamentals of competitive interactions

2019 ◽  
pp. 118-140
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Species Coexistence ◽  
Resource Competition ◽  
Apparent Competition ◽  
Negative Effects ◽  
Competition Theory ◽  
Structure Of Communities ◽  
Negative Effect

Interspecific competition is a major factor influencing the structure of communities. This chapter examines the principles of interspecific completion, defined as a reduction in the population growth rate of one species due to presence of one (or more) other species due to their shared use of limiting resources or active interference. The chapter begins with a presentation of the classic Lotka–Volterra competition model, but quickly moves on to more recent consumer–resource competition models. Conditions leading to competitive exclusion and species coexistence are discussed, as are empirical tests of the predictions of resource competition theory. In general, coexistence requires that each species has a greater negative effect on its own population growth rate than on the population growth rate of another species. Shared predation also can result in species having negative effects on each other’s population growth rate, a condition known as “apparent competition”.

scholarly journals Understanding predicted shifts in diazotroph biogeography using resource competition theory

2014 ◽  
Vol 11 (5) ◽  
pp. 7113-7149 ◽  
Author(s):  
S. Dutkiewicz ◽  
B. A. Ward ◽  
J. R. Scott ◽  
M. J. Follows
Keyword(s):  
Global Change ◽  
Resource Competition ◽  
Nutrient Concentrations ◽  
Change Models ◽  
Competition Theory ◽  
Nitrogen Fixers ◽  
Warming Climate ◽  
Model Predictions ◽  
Underlying Mechanisms ◽  
Central Atlantic

Abstract. We examine the sensitivity of the biogeography of nitrogen fixers to a warming climate and increased aeolian iron deposition in the context of a global Earth System Model. We employ concepts from Resource Ratio Theory to provide a simplifying and transparent interpretation of the results. First we demonstrate that a set of clearly defined, easily diagnosed provinces are consistent with the theory. Using the framework we show that the regions most vulnerable to province shifts and changes in diazotroph biogeography are the Equatorial and South Pacific, and central Atlantic. Warmer and dustier climates favor diazotrophs due to an increase in the ratio of supply rate of iron to fixed nitrogen. The analysis suggests that monitoring of real world province boundaries, indicated by transitions in surface nutrient concentrations, would provide a clear and easily interpreted indicator of ongoing global change. We suggest that the emergent provinces could be a standard diagnostic for global change models, allowing for rapid and transparent interpretation and comparison of model predictions and the underlying mechanisms.

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