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Google's web page ranking algorithm can detect critical species in ecosystems.

Byline: ANI

Washington, September 4 (ANI): Google has developed an algorithm for ranking web-pages, which can be used to determine which species are critical for sustaining ecosystems.

The algorithm, known as "PageRank", can be applied to the study of food webs, the complex networks describing who eats whom in an ecosystem, according to according to
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

 Drs. Stefano Allesina and Mercedes Pascual, researchers based at the National Center for Ecological Analysis and Synthesis The National Center for Ecological Analysis and Synthesis is a research center for the science of ecology, located in Santa Barbara, California, USA. Better known by its acronym NCEAS (pronounced N-seece), it opened in May, 1995, funded by the US National Science Foundation, the  at the University of California, Santa Barbara History
The predecessor to UCSB, Santa Barbara State College, focused on teacher training, industrial arts, home economics, and foreign languages. Intense lobbying by an interest group in the City of Santa Barbara led by Thomas Storke and Pearl Chase persuaded the State
 and at the University of Michigan (body, education) University of Michigan - A large cosmopolitan university in the Midwest USA. Over 50000 students are enrolled at the University of Michigan's three campuses. The students come from 50 states and over 100 foreign countries. .

The researchers have adapted the PageRank algorithm, which efficiently ranks web-pages according to search criteria, for ecological purposes.

In a world of ever greater human-generated change, there is a need to forecast the impact of species extinctions on ecosystems.

This presents challenges, as every species is embedded Inserted into. See embedded system.  in a complex network of relationships with others: a single extinction can cascade in further and seemingly unrelated species' loss.

Furthering the problem, there are too many extinction scenarios to investigate, as even for simple ecosystems the number of possibilities exceeds the number of atoms in the universe.

Using the PageRank method, Allesina and Pascual identify the set of species which are most critical for maintaining ecosystem functioning.

The method identifies the species of maximum importance by determining which extinctions lead to the fastest ecosystem collapse.

PageRank assigns importance to web-pages according to the rule "a page is important if important pages point to it".

This circular method of ranking, which can be solved through a clever application of college-level algebra algebra, branch of mathematics concerned with operations on sets of numbers or other elements that are often represented by symbols. Algebra is a generalization of arithmetic and gains much of its power from dealing symbolically with elements and operations (such as , is key to the process of identifying critical species.

Although this approach would seem inappropriate, as food webs are not truly circular, the researchers introduce an ecologically-sound way to make food webs circular by adding an artificial species, representing the recycling recycling, the process of recovering and reusing waste products—from household use, manufacturing, agriculture, and business—and thereby reducing their burden on the environment.  of nutrients from all dead organisms back towards the plants that form the base of food webs.

The researchers hope that this method will be applied far beyond ecology to solve critical problems in other network-related biological fields, such as in protein interaction and gene regulation. (ANI)

Copyright 2009 Asian News International The Asian News International (ANI) agency provides multimedia news to China and 50 bureaus in India. It covers virtually all of South Asia since its foundation and presently claims, on its official website, to be the leading South Asia-wide news agency.  (ANI) - All Rights Reserved.

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Publication:Asian News International
Date:Sep 4, 2009
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