Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Disease opened door to invading species in California

14.03.2007
Plant and animal diseases can play a major and poorly appreciated role in allowing the invasion of exotic species, which in turn often threatens biodiversity, ecological function and the world economy, researchers say in a new report.

In particular, a plant pathogen appears to have opened the gate for the successful invasion of non-native grasses into much of California, one of the world's largest documented cases of invading species and one that dramatically changed the history and ecology of a vast grassland ecosystem.

The study, published today in Proceedings of the National Academy of Sciences, a professional journal, should improve the understanding of invasive species and possibly suggest new tools to combat them, said researchers at Oregon State University.

"Even if we can't control all the diseases that help species invade, at least now we know to consider diseases when studying invasion," said Elizabeth Borer, an assistant professor of zoology at OSU. "In analyzing the ecology of exotic plant or animal species, it's clear that diseases are one part of the equation."

About 50,000 exotic species have been introduced into the United States, and the havoc they wreak upon agricultural crops, wildlife, ranch animals, forests and grasslands costs about $137 billion a year, scientists say. Invading species are also responsible for about half of all native species that go extinct, studies show.

One of the primary theories of successful invading species, experts say, until now had been the "enemy release hypothesis," in which an invasive species is no longer constrained by whatever predators or control mechanisms kept it in check in its native habitat.

The new study, however, suggests diseases that are native to a region, or imported along with invasive species, may also play a key role in whether or not the invader becomes a significant problem.

In the case of California, some of the first Spanish settlers in the 1600s and 1700s brought with them cattle, grazing, and new annual grasses that, even though they appeared to be inferior competitors, rapidly displaced native perennial grasses in California and also parts of the Pacific Northwest.

"The complete change in grassland ecosystems brought with it more damaging fire regimes, shorter grazing seasons, and altered water and carbon cycles" said Eric Seabloom, an OSU assistant professor of zoology and co-author of the study. "Annual grasses like wild oats, barley, and ripgut brome helped to damage what had been one of the richest and most diverse plant communities in the world."

What the OSU researchers found, however, was that the invading grasses might never have become dominant were it not for a plant pathogen called barley yellow dwarf virus, which reduces plant growth, lowers seed production and increases mortality. In the absence of this pathogen, the native plants would have been able to rebuff the invaders and persist, rather than being overtaken, the study concluded.

"Not only were the native grasses under constant challenge from this disease, but the characteristics of the new grasses helped to spread the disease much more efficiently," Borer said. "It just beat them down, and they were not able to compete successfully."

This virus had been in the native California grasses for a long time, the scientists said, but when the annual grasses were added to the mix, they changed the infection rates in the native perennial grasses. The higher infection rate in the natives probably allowed the annuals to invade and take over this vast grassland.

The research was conducted with a $1.8 million grant from the National Science Foundation, under the Ecology of Infectious Disease grant program, and in collaboration with scientists at Princeton University.

This is the first study to quantitatively demonstrate that an existing pathogen could have allowed exotic species to invade where they would not have invaded in the absence of the pathogen, the researchers said. Knowledge of this phenomenon may be important to understanding past invasions and predicting or controlling future ones, they said.

Identification of this virus as a key to the loss of native plants may not aid in their recovery, because it's very difficult to breed disease resistance to this plant pathogen. But in other situations where diseases are opening the door to invading species, there may be opportunities for intervention when this process is better understood, scientists said.

Elizabeth Borer | EurekAlert!
Further information:
http://www.oregonstate.edu

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | 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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>