Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print Dying frogs sign of a biodiversity crisis

Dying frogs sign of a biodiversity crisis

August 13, 2008

Devastating declines of amphibian species around the world are a sign of a biodiversity disaster larger than just frogs, salamanders and their ilk, according to researchers from the University of California, Berkeley.

In an article published online this week in the journal Proceedings of the National Academy of Sciences, the researchers argue that substantial die-offs of amphibians and other plant and animal species add up to a new mass extinction facing the planet.




"There's no question that we are in a mass extinction spasm right now," said David Wake, professor of integrative biology at UC Berkeley. "Amphibians have been around for about 250 million years. They made it through when the dinosaurs didn't. The fact that they're cutting out now should be a lesson for us."

The study, co-authored by Wake and Vance Vredenburg, research associate at the Museum of Vertebrate Zoology at UC Berkeley and assistant professor of biology at San Francisco State University, will appear in a special supplement to the journal featuring papers based on presentations from the December 2007 Arthur M. Sackler Colloquium of the National Academy of Sciences, "In the Light of Evolution II: Biodiversity and Extinction."

New species arise and old species die off all the time, but sometimes the extinction numbers far outweigh the emergence of new species. Extreme cases of this are called mass extinction events, and there have been only five in our planet's history, until now.

The sixth mass extinction event, which Wake and others argue is happening currently, is different from the past events. "My feeling is that behind all this lies the heavy hand of Homo sapiens," Wake said.

There is no consensus among the scientific community about when the current mass extinction started, Wake said. It may have been 10,000 years ago, when humans first came from Asia to the Americas and hunted many of the large mammals to extinction. It may have started after the Industrial Revolution, when the human population exploded. Or, we might be seeing the start of it right now, Wake said.

But no matter what the start date, empirical data clearly show that extinction rates have dramatically increased over the last few decades, Wake said.

The global amphibian extinction is a particularly bleak example of this drastic decline. In 2004, researchers found that nearly one-third of amphibian species are threatened, and many of the non-threatened species are on the wane.

Our own backyard provides a striking example, Wake said. He and his colleagues study amphibians in the Sierra Nevada, and the picture is grim there, as well.

"We have these great national parks here that are about as close as you can get to absolute preserves, and there have been really startling drops in amphibian populations there, too," Wake said.

Of the seven amphibian species that inhabit the peaks of the Sierra Nevada, five are threatened. Wake and his colleagues observed that, for two of these species, the Sierra Nevada Yellow-legged Frog and the Southern Yellow-legged Frog, populations over the last few years declined by 95 to 98 percent, even in highly protected areas such as Yosemite National Park. This means that each local frog population has dwindled to 2 to 5 percent of its former size. Originally, frogs living atop the highest, most remote peaks seemed to thrive, but recently, they also succumbed.

There are several frog killers in the Sierra Nevada, Wake said. The first hint of frog decline in this area came in the 1990s, and researchers originally thought that rainbow trout introduced to this area were the culprits - they like to snack on tadpoles and frog eggs. The UC Berkeley team did experiments in which it physically removed trout from some areas, and the result was that frog populations started to recover.

"But then they disappeared again, and this time there were carcasses," Wake said.

The culprit is a nasty pathogenic fungus that causes the disease chytridiomycosis. Researchers discovered the fungus in Sierra Nevada frogs in 2001. Scientists have documented over the last five years mass die-offs and population collapses due to the fungus in the mountain range.

But the fungus is not unique to California. It has been wiping out amphibians around the world, including in the tropics, where amphibian biodiversity is particularly high.

"It's been called the most devastating wildlife disease ever recorded," Wake said.

Global warming and habitat constriction are two other major killers of frogs around the world, Wake said. And the Sierra Nevada amphibians are also susceptible to poisonous winds carrying pesticides from Central Valley croplands. "The frogs have really been hit by a one-two punch," Wake said, "although it's more like a one-two-three-four punch."

The frogs are not the only victims in this mass extinction, Wake emphasized. Scientists studying other organisms have seen similarly dramatic effects.

"Our work needs to be seen in the context of all this other work, and the news is very, very grim," Wake said.

The National Science Foundation and National Institutes of Health helped support this study.

University of California, Berkeley



Related Biodiversity Current Events and Biodiversity News Articles Biodiversity Current Events and Biodiversity News RSS Biodiversity Current Events and Biodiversity News RSS
11,000 alien species invade Europe
For the first time it is now possible to get a comprehensive overview of which alien species are present in Europe, their impacts and consequences for the environment and society.

Climate change opens new avenue for spread of invasive plants
Plants that range northward because of climate change may be better at defending themselves against local enemies than native plants.

Alpine rivers hold important clues for preserving biodiversity and coping with climate change
Marginal plants, particularly trees, play a crucial role in sustaining the biodiversity of Europe's big river systems, according to a recently held workshop organised by the European Science Foundation (ESF).

Urgent action on international coral reef crisis
Coral reef scientists and policy makers from the world's most prominent coral reef nations are meeting in Australia this week to develop urgent action plans to rescue the world's richest centre of marine biodiversity from gradual decline.

Study Confirms Amphibians' Ability to Predict Changes in Biodiversity
Biologists have long suspected that amphibians, whose moist permeable skins make them susceptible to slight changes in the environment, might be good bellwethers for impending alterations in biodiversity during rapid climate change.

Diversity of trees in Ecuador's Amazon rainforest defies simple explanation
Trees in a hyper-diverse tropical rainforest interact with each other and their environment to create and maintain diversity, researchers report in the Oct. 24 issue of the journal Science.

New CU-Boulder study shows diversity decreases chances of parasitic disease
A new University of Colorado at Boulder study showing that American toads who pal around with gray tree frogs reduce their chances of parasitic infections known to cause limb malformations has strong implications for the benefits of biodiversity on emerging wildlife diseases.

Forest peoples' rights key to reducing emissions from deforestation
Unless based on respect for the rights of indigenous peoples and forest communities, efforts by rich countries to combat climate change by funding reductions in deforestation in developing countries will fail, and could even unleash a devastating wave of forest loss, cultural destruction and civil conflict, warned a leading group of forestry and development experts meeting in Oslo this week.

Revealing the evolutionary history of threatened sea turtles
It's confirmed: Even though flatback turtles dine on fish, shrimp, and mollusks, they are closely related to primarily herbivorous green sea turtles.

Warming in Yosemite National Park sends small mammals packing to higher, cooler elevations
Global warming is causing major shifts in the range of small mammals in Yosemite National Park, one of the nation's treasures that was set aside as a public trust 144 years ago, according to a new study by University of California, Berkeley, biologists.
More Biodiversity Current Events and Biodiversity News Articles


Sustaining Life: How Human Health Depends on Biodiversity

The Earth's biodiversity-the rich variety of life on our planet-is disappearing at an alarming rate. And while many books have focused on the expected ecological consequences, or on the aesthetic, ethical, sociological, or economic dimensions of this loss, Sustaining Life is the first book to examine the full range of potential threats that diminishing biodiversity poses to human health. ...



Conservation and Biodiversity Banking: A Guide to Setting Up and Running Biodiversity Credit Trading Systems (Environmental Markets Insight Series)

The conservation of biodiversity is now big business. Whether called conservation banking, species banking, habitat banking, biodiversity banking, biodiversity offsets, compensatory mitigation or ecological footprint offsetting, the idea of financially valuing biodiversity and using the market and businesses to promote conservation is growing rapidly.This handbook is a comprehensive guide to...



Climate Change and Biodiversity

Leading researchers discuss what is now known about the effects of climate change on the natural world. They examine recent trends in and projections about climate change; ways that particular organisms are responding to climate change; conservation challenges, including social and policy issues; and more. "This book will be a milestone in the emerging discipline of climate change biology. No...

Women and Plants: Gender Relations in Biodiversity Management and Conservation

This unique collection of in-depth case studies from Latin America, Asia, Africa, Europe and North America demonstrates the importance of women and gender relations in plant genetic resource management and conservation. It provides a state-of-the-art overview of the concepts, relationships and contexts explaining the relatively hidden gender dimensions of people-plant relations. The contributors...



Managing Biodiversity in Agricultural Ecosystems

Managing Biodiversity in Agricultural Ecosystems takes a look at how farmers manage, maintain, and benefit from biodiversity in agricultural production systems. The volume includes the most recent research and developments in the maintenance of local diversity at the genetic, species, and ecosystem levels. Chapters cover the assessment and farmer management practices for crop, livestock,...



One Planet: A Celebration of Biodiversity
by Nicolas Hulot

Our planet, with all its spectacular diversity, is a source of endless fascination-the stunning success of books like Earth from Above is proof of that. Now comes this spellbinding volume, filled with glorious images from the world's greatest nature photographers. This breathtaking work celebrates the amazing variety of species and ecosystems and how various forces affect them positively and...



Tree of Life: The Incredible Biodiversity of Life on Earth (Aspca Henry Bergh Children's Book Awards (Awards))
by Rochelle Strauss

If every known species on Earth were a leaf on a tree, that tree would have 1 750 000 leaves. Since humans count for just one leaf on the tree, we have a lot to learn about the millions of other forms of life with which we share the world. A dazzlingly illustrated and child-friendly introduction to biodiversity, Tree of Life shows how living things are classified into five kingdoms -- and how...



Biodiversity (Papers from the 1st National Forum on Biodiversity, September 1986, Washington, D.C.)

This important book for scientists and nonscientists alike calls attention to a most urgent global problem: the rapidly accelerating loss of plant and animal species to increasing human population pressure and the demands of economic development. Based on a major conference sponsored by the National Academy of Sciences and the Smithsonian Institution, "Biodiversity" creates a systematic framework...



Scaling Biodiversity (Ecological Reviews)

We know that there are tens of millions of plant and animal species, but we do not know enough to be able to describe the patterns and processes that characterise the distribution of species in space, time and taxonomic groups. Given that in practical terms it is impossible to expect to be able to document biodiversity with any degree of completeness other approaches must be used. Scaling rules...

Business and Biodiversity: A Guide for the Private Sector
by R. David Stone, Kristina Ringwood, Frank Vorhies

This guide explains how and why business should be involved in the biodiversity debate. It explains the main principles of the Convention on Biological Diversity and describes some of the Convention's potential implications. It also examines the many links between biodiversity and the private sector and highlights the need for a new, more rational approach to the manner in which biological...

© 2008 BrightSurf.com