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Old 12-07-2011, 08:19 PM   #1
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Default Predator or prey? Maybe both...

A New Model For Understanding Biodiversity.

A new model for understanding biodiversity

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What they discovered was that a "branching network" maintained by generalist species, like foxes or coyotes, that are able to move around and prey on different species in different locations, have an important role in promoting complex food webs and thereby in maintaining biodiversity. The researchers concluded that these generalist species have the advantage of being able to find prey no matter where they are as they move from one place to another, and this sustains the network.
Scientists Find Universal Rules For Food-Web Stability

Scientists Find Universal Rules For Food-web Stability

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"Small ecosystems apparently follow different rules than large ecosystems," says Ulf Dieckmann. "Systems with fewer species are more stable if there are strong interactions between some species, but only weak interactions between others. For food webs with many species, exactly the opposite is true. Extremely strong or weak predator-prey links in nature should therefore be the rarer the more species a food web contains," he concludes
Human Activity Displaces Predators More Than Prey

Human activity displaces predators more than prey
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Old 12-08-2011, 10:31 AM   #2
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The abstract gives a bit more information but I would love to read the entire article at PNAS. They want $10 for two days of access but maybe I'll give the university library a try. It would be interesting to find out bit more detail.


P. Pillai, A. Gonzalez, M. Loreau. Metacommunity theory explains the emergence of food web complexity. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1106235108

abstract
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Here we show that metacommunity theory can explain the emergence of species-rich food webs with complex network topologies. Our analysis shows that network branching in the food web is maximized at intermediate colonization rates and limited dispersal scales, which also leads to concomitant peaks in species diversity. Increased food web complexity and species diversity are made possible by the structural role played by network branches that are supported by omnivore and generalist feeding links. Thus, in contrast to traditional food web theory, which emphasizes the destabilizing effect of omnivory feeding in closed systems, metacommunity theory predicts that these feeding links, which are commonly observed in empirical food webs, play a critical structural role as food webs assemble in space. As this mechanism functions at the metacommunity level, evidence for its operation in nature will be obtained through multiscale surveys of food web structure. Finally, we apply our theory to reveal the effects of habitat destruction on network complexity and metacommunity diversity.
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Old 12-15-2011, 02:00 PM   #3
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Predators cause changes in population density and behavior patterns of prey.
Predator behavior is affected more by human traffic patterns.
Biodiversity is lessened by the overpopulation and behavior adjustment when unafraid, of some prey species which is the result of fewer predators, and by human traffic disturbance of prey.
I can get this...

A new model for understanding biodiversity

Quote:
They found that humans and prey species co-occurred together more often than humans and predators at camera sites, and that predators and prey were less likely to be in the same area if there was heavy human traffic. Their results showed that prey were three times more abundant on roads and trails used by more than 32 humans a day, but predators were less abundant on roads and trails used by more than 18 humans a day.
Limits for mountain trail use identified

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In particular, the study found that wolves and elk avoided areas within 50 metres of trail routes travelled by one person per hour or greater; and up to 400 metres from trails with human activity above two persons per hour. Such avoidance behaviours are consistent with previous scientific research; however, the identification of threshold levels at which this occurs is new.

Prey Not Hard-wired To Fear Predators

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The goal of re-introduction isn't simply to save a species; it is to restore the natural functions of wild places. When the predator-prey relationship comes back into balance, impacts ripple through the system. For example, when wolves returned to the Yellowstone region, they caused a cascade of events including a change in elk distribution, more wariness in moose, and a change in coyote densities.
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Old 12-19-2011, 01:54 PM   #4
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If you get that article.... can you pass it to me?
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