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Gray Ratsnake (Elaphe spiloides) - Registre public des espèces en
Gray Ratsnake (Elaphe spiloides) - Registre public des espèces en

... Gray Ratsnakes are both predators and prey of numerous species. They feed mainly on small mammals (~65%) and birds (~30%) and known predators include a number of large birds of prey (e.g. red shouldered hawk (Buteo lineatus), osprey (Pandion haliaetus), red tailed hawk (Buteo jamaicensis)) and mediu ...
2 How to Build Up a Model
2 How to Build Up a Model

... Essential resources being, in general, limited, intraspecific competition reduces the growth rate, which eventually goes to zero. The simplest way to take this feature into account is to introduce into the model carrying capacities for both the prey and the predator. A predator has to devote a certai ...
A GENERAL HYPOTHESIS OF SPECIES DIVERSITY Many
A GENERAL HYPOTHESIS OF SPECIES DIVERSITY Many

... inversely correlated with the maximum size of the population, or the carrying capacity, but this relationship is not essential for the model. 3. Changes in certain environmental variables will affect all competing populations in basically the same way; that is, the population growth rates of all may ...
carrying capacity literature reviews
carrying capacity literature reviews

... will decline” (Paehlke 110). When this occurs the population of the species will “level off and eventually cease to grow or even suffer from a severe decline” (Paehlke 110). In addition, carrying capacity is a “key concept in the management of rangelands, referring specifically to the number of anim ...
Population Growth
Population Growth

... – Is the maximum population size the environment can support with no net increase or decrease – The value of K varies, depending on species ...
ch18 - Eco
ch18 - Eco

... A in model), but can lose the potential to regulate prey at this level if prey density increases above point B in the model: a predator controlling an agricultural pest can lose control of that pest if the predator is suppressed by another factors for a time: once the pest population exceeds point ...
- Wiley Online Library
- Wiley Online Library

... –February) resulting in the capture of roughly half the roe deer present in the forest each year (Gaillard et al. 2003). At capture, all animals are weighed, inspected for marks or newly marked (with both leather numbered collars and ear-tags) and, at Chize only, the reproductive status of females ...
hansen2011 - Montana State University
hansen2011 - Montana State University

... expected because of the assumption that intraspecific density-dependent competition for the good habitat would lead to the fittest individuals occupying the source and force subdominant individuals into the sinks (Pulliam, 1988; Delibes et al., 2001a). This is highly relevant to protected areas beca ...
Coexistence of two stage-structured intraguild predators
Coexistence of two stage-structured intraguild predators

... larger body size. Because species with a similar size-range will have similar diets and hence strong niche overlap, all but one of these species will generally be outcompeted in resulting food webs. According to size spectrum models, coexistence of multiple omnivores is therefore only possible betwe ...
From arctic lemmings to adaptive dynamics
From arctic lemmings to adaptive dynamics

... We shall examine the impact of Charles S. Elton’s 1924 article on periodic fluctuations in animal populations on the development of modern population ecology. We argue that his impact has been substantial and that during the past 75 years of research on multi-annual periodic fluctuations in numbers ...
The future of fisheries oceanography lies in the pursuit of multiple
The future of fisheries oceanography lies in the pursuit of multiple

... To further develop the applied aspects of fisheries oceanography, the differences between these four general hypotheses need to be recognized and links need to be made among their implied processes and mechanisms (Figure 1, Table 1). For example, over the past 25 years, a large amount of effort has ...
Problem: American Elk - The International Mathematical Modeling
Problem: American Elk - The International Mathematical Modeling

... population, the slope of the population function is positive, never negative. In application, the elk population’s net change is constantly increasing, not decreasing. By using this density-dependent or logistic model, we can safely conclude that the current population of 140 Manitoba elk in the Gre ...
fulltext
fulltext

... Species are embedded in communities in which they interact in complex ways with other species. Complexity increases even further because population structure is not only determined by intraspecific interactions but also by interspecific interactions that all change as individuals grow. Which stages ...
Growth strategies of ectothermic animals in temperate
Growth strategies of ectothermic animals in temperate

... ectotherms this is particularly true. The life cycles of temperate ectotherms must be completed within the limits set by seasonality, and the timing of life history events will have a strong influence on fitness. For example, reproductive success typically depends on the occurrence of resources that ...
draft species conservation plan
draft species conservation plan

... known to inhabit both the nature reserve and a remnant on adjacent private property. Little is known about the population size and trend of this BFRW population. Owing to difficulties with access, fox control was undertaken at Mount Stirling only recently and a small, remnant population persists at ...
Predation 2
Predation 2

... Here, the hump is to the right of the predator isocline, and we get an unstable system. Why? The predator population is capable of growing even at very low prey density the predator is an efficient humter. As the predator becomes less efficient, the predator isocline shifts to the right. ...
On evolutionary stability in predator–prey models with fast
On evolutionary stability in predator–prey models with fast

... ecology. To unify these programmes, several theoretical approaches that are based on timescale separation have been developed. One of the first approaches to use time-scale separation is the early work on the functional response that integrates some details of animal behaviour (e.g. pursuit and capt ...
Antagonistic effects of seed dispersal and herbivory
Antagonistic effects of seed dispersal and herbivory

... along the northern range margin and the former southern extent of glacial ice (taken from Dyke et al. 2003). The largest of these values represents the minimum migration distance for T. grandiflorum during the late-glacial and Holocene, assuming there were populations near the glacial boundary 21 00 ...
Path-integral calculation for the emergence of rapid evolution from
Path-integral calculation for the emergence of rapid evolution from

... and perhaps nowhere more so than in ecology. The classical literature on predator-prey systems [25] assumes that evolution occurs on such long time scales that it can be neglected, but it is not obvious that this is always valid [26]. Recent work using rotifers (predator) and algae (prey) in a chemo ...
Levin, S.A. (editor). Encyclopedia
Levin, S.A. (editor). Encyclopedia

... consequences of spatial pattern on the functioning of populations, communities, and ecosystems. Nature is generally not homogenous with respect to ecological properties. Those properties include gradients in abiotic factors, such as the temperature, moisture, and the abundance of required resources; ...
The tragedy of our legacy
The tragedy of our legacy

... their so-called Yield-per-Recruit (Y/R) model, which is purely theoretical, they showed that for long-lived species, with a low natural mortality, one can maximize the theoretical potential yield by delaying the age-at-capture to a certain optimum. This so-called ‘eumetric fishing’ principle invokin ...
Lineage Loss in Serengeti Cheetahs
Lineage Loss in Serengeti Cheetahs

... as an endangered species (Nowell & Jackson 1996), the Serengeti population does not appear to be systematically declining because, on average, it is nearly self replacing (␭ ⫽ 0.997) ( Kelly & Durant 2000). The population, however, is still at risk of extinction due to demographic and environmental ...
Annex C
Annex C

... Within Argentina E. notaeus occurs only in aquatic inland ecosystems, specifically swamps, seasonally flooded marshes, or riverine habitats, associated with the Paraguay River and the middle sector of the Paraná River (Strüssmann and Sazima, 1993; Henderson et al., 1995; Dirksen, 2002) The yellow an ...
practice populations test (with answers)
practice populations test (with answers)

... or unavailable, and prevents an organism from achieving this potential? 76. Distinguish between the terms "habitat" and "niche". 77. Explain the concept of "resource partitioning," and explain how it may increase the chance of species success. 78. Prey species often develop passive defense mechanism ...
West Indian Manatee Carrying Capacity
West Indian Manatee Carrying Capacity

... warm water capacity, SAV, and available fresh water. For the manatee, these are the only naturally occurring and constantly present limitations to population – or in other words the elements defining CC. The greatest danger of continued mis-classification of the manatee is the inability to actually ...
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Maximum sustainable yield

In population ecology and economics, maximum sustainable yield or MSY is theoretically, the largest yield (or catch) that can be taken from a species' stock over an indefinite period. Fundamental to the notion of sustainable harvest, the concept of MSY aims to maintain the population size at the point of maximum growth rate by harvesting the individuals that would normally be added to the population, allowing the population to continue to be productive indefinitely. Under the assumption of logistic growth, resource limitation does not constrain individuals’ reproductive rates when populations are small, but because there are few individuals, the overall yield is small. At intermediate population densities, also represented by half the carrying capacity, individuals are able to breed to their maximum rate. At this point, called the maximum sustainable yield, there is a surplus of individuals that can be harvested because growth of the population is at its maximum point due to the large number of reproducing individuals. Above this point, density dependent factors increasingly limit breeding until the population reaches carrying capacity. At this point, there are no surplus individuals to be harvested and yield drops to zero. The maximum sustainable yield is usually higher than the optimum sustainable yield and maximum economic yield.MSY is extensively used for fisheries management. Unlike the logistic (Schaefer) model, MSY has been refined in most modern fisheries models and occurs at around 30% of the unexploited population size. This fraction differs among populations depending on the life history of the species and the age-specific selectivity of the fishing method.However, the approach has been widely criticized as ignoring several key factors involved in fisheries management and has led to the devastating collapse of many fisheries. As a simple calculation, it ignores the size and age of the animal being taken, its reproductive status, and it focuses solely on the species in question, ignoring the damage to the ecosystem caused by the designated level of exploitation and the issue of bycatch. Among conservation biologists it is widely regarded as dangerous and misused.
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