Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Break Down Patterns in Nature

15.04.2003



Nature has many patterns and ecologists seek to both describe and understand them. Nature also is very complex. One challenge is to find patterns in that complexity and to ask whether simple explanations lie beneath them.

Ecologists have tackled this challenge for decades, erecting various hypotheses and debating their plausibility. In an important paper featured in the current issue of the Proceedings of the National Academy of Sciences (PNAS), an international team of ecologists describes a fundamental theory that unites several patterns that previously had been viewed as unrelated.

The theory simplifies various aspects of ecological complexity with an elegant model that unites all of them. It provides a theory for quantifying biodiversity.




George Sugihara of Scripps Institution of Oceanography, UCSD, (USA) led a team that included Lord Robert May and Sir Richard Southwood of Oxford University (United Kingdom), Louis-Félix Bersier of the University of Neuchâtel (Switzerland), and Stuart Pimm of Duke University (USA).

The first pattern they considered involves the relationships between various roles played by the species present in an area (their niches). These relationships are often described in ecology as something akin to an "evolutionary tree" in which the branches reflect how ecological communities are organized—a tree-like organizational chart of ecological roles. One "branch" might be all those bird species that feed on insects, another "branch" those species that feed on seeds.

From these main branches, different small branches might be the various insect-feeding species that glean insects from leaves (such as warblers) or bark (such as nuthatches), or those species that catch insects in flight (such as flycatchers). As niches are specified more exactly, we move to the "terminal twigs" in the analogy: the individual species themselves. One "twig" might be a particular bird that gleans insects from the top leaves of a tree, another twig the different species that glean insects from the bottom leaves.

Sugihara and his colleagues found that these common representations have far more information in them than was previously recognized. The pair of species in the terminal twigs have a relationship to each other—they are splitting up the resource that is the total of the insects feeding on the tree.

The PNAS paper finds that abundances of pairs of species in terminal twigs behave in a very special way. "Just like two pieces of rock that once belonged together," Pimm says. "Take a rock and split it into two pieces. On average, the bigger piece will be three-quarters of the rock, the smaller a quarter of the rock. If you take any two rocks, there won’t be such a pattern. The sizes of those rocks are unrelated."

The paper shows that this applies to all the branches in the tree: such as the total abundance of all seed-eating birds versus the total abundance of insect-eating birds.


What can you do with this insight? Plenty, Sugihara argues. "For one thing, a species represented by a ‘twig’ should be much less common than a species that is represented by a ‘branch,’" says Sugihara. "A bird that feeds on small insects from leaves on the top of a tree should be rarer than one that can feed on all sizes of insects anywhere. That prediction holds up."

It can apply to human niches too: The more specialized a profession, the fewer customers the business will have. A general store usually caters to more customers than one that sells just one kind of product.

The insight also suggests a pattern to species abundances across many species. It’s the exact pattern one would get from breaking a rock once, then picking one of the pieces and splitting it, then picking another piece and splitting it, and so on. That sequential splitting generates a characteristic pattern in the sizes of rocks—and the abundance of species. It’s also exactly the one we observe in nature.

In short, Sugihara and colleagues have produced a fundamental theory of the patterns of nature free from any numbers that have to be estimated. (It’s "parameter-free" in scientific jargon—a holy grail in science). The logical consequences of the idea have surprising explanatory power.

There is another extension to these ideas that has been known for some time, but for which Sugihara’s group provides a firm anchor. Suppose we try to place those rock pieces in a sieve. Some will be so small they will pass through the sieve. Hitting the rock more often doesn’t give us more pieces, for we just lose more through the cracks. So it is with species: some become too rare to survive. The bigger the rock, the more pieces we can have before we start to lose them.

Of course, human impacts are shrinking the rock in this metaphor—diminishing the resources available to all species.

Shrink the rock and, as long as you keep sequentially breaking it, you reduce the species in a precise mathematical way. This happens to be exactly the way species drop out as human actions diminish the world by shrinking the habitats (such as tropical forests) on which species depend.

The study was supported by the Office of Naval Research, Merton College Oxford University, the Swiss National Science Foundation, Novartis Foundation, and the Leverhulme Trust.

Mario Aguilera | Scripps News
Further information:
http://scrippsnews.ucsd.edu/pressreleases/sugihara-PNAS.html

More articles from Ecology, The Environment and Conservation:

nachricht How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New Method of Characterizing Graphene

Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.

Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

3D printer inks from the woods

30.05.2017 | Life Sciences

How circadian clocks communicate with each other

30.05.2017 | Life Sciences

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible

30.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>