Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Amphibians in losing race with environmental change

02.05.2007
Even though they had the ability to evolve and survive for hundreds of millions of years - since before the time of the dinosaurs and through many climatic regimes - the massive, worldwide decline of amphibians can best be understood by their inability to keep pace with the current rate of global change, a new study suggests.

The basic constraints of evolution and the inability of species to adapt quickly enough can explain most of the causes that are leading one species after another of amphibians into decline or outright extinction, say researchers from Oregon State University, in a study published today in the journal BioScience.

"We know that there are various causes for amphibian population declines, including UV-B light exposure, habitat loss, pesticide pollution, infections and other issues," said Andrew Blaustein, a professor of zoology at OSU and one of the world's leading experts on amphibian decline.

"But looked at in a different way, it's not just that there are threats and pressures amphibians have to deal with," Blaustein said. "There have always been threats, and these have been some of the most adaptive and successful vertebrate animals on Earth. They were around before the dinosaurs, have lived in periods with very different climates, and continued to thrive while many other species went extinct. But right now, they just can't keep up."

It has been estimated that the rate of plant and animal extinction is greater now than any known in the last 100,000 years, the researchers note in their report. Amphibians are of particular interest because their physiology and complex life cycle often exposes them to a wider range of environmental changes than other species must face – they have permeable skin, live on both land and water, their eggs have no shells.

In the face of these challenges, amphibians appear to be losing the battle – of 5,743 known species of amphibians on Earth, 43 percent are in decline, 32 percent are threatened and 168 species are believed extinct. The impacts of changes are far more pervasive on amphibians than many other vertebrates, such as birds or mammals.

"Historically, amphibians were adept at evolving to deal with new conditions," Blaustein said. "What they are doing is showing us just how rapid and unprecedented are the environmental changes under way. Many other species will also be unable to evolve fast enough to deal with these changes. Because of their unique characteristics, the amphibians are just the first to go."

In their analysis, the OSU scientists point out that evolution is not a precise or perfect process - it takes time, is constrained by historic changes and compromises, and does not always allow a species to adapt in a way that meets rapidly changing conditions. Through genetic variation and natural selection pressures, some species or populations will be able to adapt – while others fail and go extinct.

The systems developed over millions of years to give amphibians survival advantages have now turned against them, scientists say. Examples include:

Many amphibians lay their eggs in shallow, open water in direct sunlight to provide a more oxygenated environment, increase growth rate of larvae and reduce predation. But the increased levels of UV-B radiation in today's sunlight, due to erosion of the Earth's ozone layer, is causing mutations, impaired immune systems and slower growth rates. Through evolution, amphibians were able to adapt to changing UV-B levels in the past, but the current change has occurred too rapidly.

In the past, water was reasonably pure and clean. But increased "eutrophication" of freshwater ponds due to use of modern fertilizers and waste from grazing animals has led to higher rates of parasite infections, and chemical contamination of aquatic systems is also more common.

Many animal species lay their eggs communally or congregate socially, often to avoid predation or improve resource use. But global warming has caused higher levels of certain infectious diseases of some amphibians, and it spreads more easily in closely connected communities.

"Although relatively rapid evolution may occur within some amphibian populations when a novel threat arises, other threats may be too intense and too new for amphibians to cope with them," the researchers wrote in their report. "Behaviors and ecological attributes that have probably persisted, and were probably beneficial, for millions of years . . . under today's conditions may subject amphibians to a variety of damaging agents."

Natural selection and species adaptation may, in time, allow amphibians to react to and recover from the new environmental insults, Blaustein said, if they don't go extinct first.

But evolution is an erratic, often slow and imperfect system, and the complexities of amphibian life cycles makes them more immediately vulnerable than many other species, the researchers said.

Andrew Blaustein | EurekAlert!
Further information:
http://www.oregonstate.edu

More articles from Ecology, The Environment and Conservation:

nachricht Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>