Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Report challenges common ecological hypothesis about species abundance

05.10.2006
A new report finds little empirical evidence to support a widely held ecological assumption that species are most abundant near the centers of their geographic ranges and decline in abundance near the ranges' edges.

"When we reviewed data from published studies that looked at species abundance at multiple sites across a range, we found almost no evidence that supported the so-called 'abundant-center hypothesis' and strong evidence that contradicted it," said Raphael D. Sagarin, associate director for oceans and coastal policy at Duke University's Nicholas Institute for Environmental Policy Solutions.

"This is troubling," Sagarin said, "because a lot of current thinking on ecological and evolutionary issues -- including how species will respond to climate change, how to identify probable locations of pest outbreaks, how genetic diversity is distributed among populations and where to locate habitat preserves -- has been based on the hypothesis."

The validity of these ideas now needs to be re-examined using empirical studies, he said.

Sagarin is one of the principal authors of the report, which appeared in the September 2006 issue of the journal Trends in Ecology and Evolution. Other authors are Steven D. Gaines of the University of California-Santa Barbara's Marine Science Institute and Department of Ecology, Evolution and Marine Biology; and Brian Gaylord of the University of California-Davis's Bodega Marine Laboratory and Section of Evolution and Ecology.

For their analysis, the authors reviewed not only published studies but also some new sets of data that they had compiled from field observations in a number of coastal locations of such invertebrate species as sea urchins, sea anemones and snails. They found that most of the studies showed that patterns of abundance were affected by a complex interplay of environmental, physical, biological, genetic and geographical factors that the abundant-center hypothesis failed to take into account.

Population clusters and high abundance sometimes occurred right at the geographic edges of the species' ranges, they found.

"Ecologists need to go back into the field and sample populations, taking advantage of new technologies that allow us to see what populations are actually like on scales not previously possible," Sagarin said. "In some way, it's a return to old-school ecology, but armed with high-tech tools we didn't have 30 years ago."

Advances in remote sensing, biophysical monitoring, ecological physiology, molecular genetics and genomics are rapidly enhancing scientists' ability to identify population and individual patterns across large spatial scales, he said. Scientists can collect data on such factors as growth rates, genetics, climate, human-caused impacts and species interactions in different parts of a population's range, and then look at the overlay of these variables and see the larger story, rather than making a simplifying assumption based on one variable.

"Theory and experimentation have their place," Sagarin said. "They can play important roles in helping us predict, in general, future changes in species' ranges due to climate change. But you need empirical field-based data to know, more specifically, how this is going to look on the ground. When a range shifts, is it going to look like the gradual arrival of a new species, or like an actual invasion? Theory alone can't tell us that."

Tim Lucas | EurekAlert!
Further information:
http://www.duke.edu

More articles from Ecology, The Environment and Conservation:

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>