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--- 2014:groups:g8:start [2014/01/30 10:54] – [Trophic Cascades] kraenkel
+++ 2014:groups:g8:start [2024/01/09 18:45] (current) – external edit 127.0.0.1
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 Wiki site of the practical exercise of the [[http://www.ictp-saifr.org/?page_id=4634|III Southern-Summer School on Mathematical Biology]].
-Here you find the exercise assigment and the group's products.
+Here you will find the exercise assigment and the group's products.
-If you are a group member login to edit this page, create new pages from that, and upload files.
+If you are a group member login to edit this page, create new pages from it, and upload files.
+===Final Presentation ===
+{{:2014:groups:g8:presentation-8.pdf| GROUP 8 PRESENTATION}}
 ===== Group =====
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   * Zamani, Maryam; //Shahid Beheshti University, Department of Physics, Iran//
+----
+===Assistants===
+  * Ayana Martins
+  * Juliana Berbert
+----
 ===== Assignment =====
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 Taken from http://www.nature.com/scitable/knowledge/library/trophic-cascades-across-diverse-plant-ecosystems-80060347
-One example of trophic cascades occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level. A simple example is depicted in Figure (1). Understanding trophic cascades is important to assess vulnerability of ecological communities and extinction risks.
+One example of trophic cascades occurs when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level. A simple example is depicted in Figure (1). Understanding trophic cascades is important to assess vulnerability of ecological communities and extinction risks.
 Example of Figure (1) involves two trophic links. The present project will be based on an experiment where more species are present.
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 of carnivores//, which appeared in Ecology Letters, 16, pp. 664-669 (2013), available at http://onlinelibrary.wiley.com/doi/10.1111/ele.12096/abstract .
-The authors present results from an experiment with insect communities consisting of a food plant, three aphid species, and three parasitoid wasp species.  Each parasitoid is a specialist on one of the aphid species. Aphid species compete for the same plant species.  The experiment consists in harvesting one of the parisitoid species. The main results is that harvesting of single carnivorous parasitoid species led to a significant increase in extinction rate of other parasitoid species, separated by four trophic links.
+The authors present results from an experiment with insect communities consisting of a food plant, three aphid species, and three parasitoid wasp species.  Each parasitoid is a specialist on one of the aphid species. Aphid species compete for the same plant species.  The experiment consists in harvesting one of the parisitoid species. The main result is that harvesting of single carnivorous parasitoid species led to a significant increase in extinction rate of other parasitoid species, separated by four trophic links.
-The baseline explanation for this is that harvesting one of the parisitoids released its prey, leading to stronger competition between aphid species, lowering the population of the other aphids. This resulted in increased extinction rates of non-harvested parasitoid species when their prey had become rare relative to other aphids.  Harvesting  one parasitoid lowered the abundance of other parasitoids....
+The baseline explanation for this is that harvesting one of the parisitoids released its prey, leading to stronger competition between aphid species, lowering the population of the other aphids. This resulted in increased extinction rates of non-harvested parasitoid species when their prey had become rare relative to other aphids.  Harvesting  one parasitoid lowered the abundance of other parasitoids.
 But, wait!  If you carefully read the //Discussion// section of the paper you will note that, although the broad view outlined above provides a rationale for the observed results, some details show  that life is not so simple! Indeed, competitive exclusion of hosts, due to release from top-down control, did not always occur.  As they state, in no case, any aphid population got extinct. Only in one case, one of the aphid population clearly declined. The paper advances some speculative reasons for this.