Allee Effects In Ecology And Conservation Pdf

allee effects in ecology and conservation pdf

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Allee effects

Allee effects are broadly defined as a decline in individual fitness at low population size or density, that can result in critical population thresholds below which populations crash to extinction. As such, they are very relevant to many conservation programmes, where scientists and managers are often working with populations that have been reduced to low densities or small numbers. There are a variety of mechanisms that can create Allee effects, including mating systems, predation, environmental modification, and social interactions among others. The abrupt and unpredicted collapses of many The abrupt and unpredicted collapses of many exploited populations is just one illustration of the need to bring Allee effects to the forefront of conservation and management strategies. This book provides an overview of the topic, collating and integrating a widely dispersed literature from various fields: marine and terrestrial, plant and animal, theoretical and empirical, academic and applied. Keywords: conservation biology , population , density dependence , population size , population threshold , population density , individual fitness.

Allee effects are broadly defined as a decline in individual fitness at low population size or density, that can result in critical population thresholds below which populations crash to extinction. As such, they are very relevant to many conservation programmes, where scientists and managers are often working with populations that have been reduced to low densities or small numbers. There are a variety of mechanisms that can create Allee effects, including mating systems, predation, environmental modification, and social interactions among others. The abrupt and unpredicted collapses of many The abrupt and unpredicted collapses of many exploited populations is just one illustration of the need to bring Allee effects to the forefront of conservation and management strategies.

Allee effects

All relevant data are within the paper, no Supporting Information file enclosed and no any relevant data in other public repository. Understanding Allee effect has crucial importance for ecological conservation and management because it is strongly related to population extinction. Due to various ecological mechanisms accounting for Allee effect, it is necessary to study the influence of multiple Allee effects on the dynamics and persistence of population. We here focus on organism-environment feedback which can incur strong, weak, and fatal Allee effect AE-by-OEF , and further examine their interaction with the Allee effects caused by other ecological mechanisms AE-by-OM. The results show that multiple Allee effects largely increase the extinction risk of population either due to the enlargement of Allee threshold or the change of inherent characteristic of Allee effect, and such an increase will be enhanced dramatically with increasing the strength of individual Allee effects. Our simulations explicitly considering spatial structure also demonstrate that local interaction among habitat patches can greatly mitigate such superimposed Allee effects as well as individual Allee effect.

Low density populations can be subject to Allee effects, also known as positive density dependence, which result in reduced population growth rate and increased risk of extinction in small populations. These dynamics are crucial to the success of invasive species, management of harvested populations and conservation of threatened and endangered species. My research focuses on understanding the mechanisms and consequences of positive density dependence, which is important in aquatic species from sea urchins to salmon to copepods. Current projects include experimental tests for Allee effects in aquatic microbes, studying mate limitation and predator satiation in zooplankton populations, and studying the evolution of Allee effects. PDF Project.

Colonization is of longstanding interest in theoretical ecology and biogeography, and in the management of weeds and other invasive species, including insect pests and emerging infectious diseases. Due to accelerating invasion rates and widespread economic costs and environmental damages caused by invasive species, colonization theory has lately become a matter of considerable interest. Here we review the concept of propagule pressure to inquire if colonization theory might provide quantitative tools for risk assessment of biological invasions. By formalizing the concept of propagule pressure in terms of stochastic differential equation models of population growth, we seek a synthesis of invasion biology and theoretical population biology. We focus on two components of propagule pressure that affect the chance of invasion: 1 the number of individuals initially introduced, and 2 the rate of subsequent immigration. We also examine how Allee effects, which are expected to be common in newly introduced populations, may inhibit establishment of introduced propagules.

Do social groups prevent Allee effect related extinctions?: The case of wild dogs

Allee effects are broadly defined as a decline in individual fitness at low population size or density. They can result in critical population thresholds below which populations crash to extinction. As such, they are very relevant to manyMoreAllee effects are broadly defined as a decline in individual fitness at low population size or density.

Allee Effects in Ecology and Conservation

Heiko U. Wittmer, Courchamp, F. Berec, and J. A llee E ffects in E cology and C onservation. In the s and s research by Warder C.

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The aim of this study was to propose and evaluate an eco-epidemiological model with Allee effect and nonlinear harvesting in predators. It was assumed that there is an SI-type of disease in prey, and only portion of the prey would be attacked by the predator due to the fleeing of the remainder of the prey to a safe area. It was also assumed that the predator consumed the prey according to modified Holling type-II functional response. All possible equilibrium points were determined, and the local and global stabilities were investigated. The possibility of occurrence of local bifurcation was also studied.


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Sifitdiver1992

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1. What are Allee effects? 2. Mechanisms for Allee effects 3. Population dynamics​: modelling demographic Allee effects 4. Genetics and evolution 5.

Nmasosacpai

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Low density populations can be subject to Allee effects, also known as positive density dependence, which result in reduced population growth rate and increased risk of extinction in small populations.

Tersfullaylo

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