Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fossils pinpoint tropics as Earth's most fruitful biodiversity spawning ground

06.10.2006
Study indicates loss of tropical biodiversity would affect entire globe

A team of scientists has completed a study that explains why the tropics are so much richer in biodiversity than higher latitudes. And they say that their work highlights the importance of preserving those species against extinction.

"If you came from outer space and you started randomly observing life on Earth, at least before people were here, the first thing you'd see was this incredible profusion of life in the tropics," said the report's lead author, David Jablonski, the William Kenan Jr. Professor in Geophysical Sciences at the University of Chicago. "This is the single most dramatic biodiversity pattern on this planet."

Jablonski and his co-authors, Kaustuv Roy, of the University of California, San Diego, and James Valentine, of the University of California, Berkeley, present their new findings on the origins of this global diversity trend in the Oct. 6 issue of the journal Science.

Why the tropics are so much richer in species and evolutionary lineages than elsewhere on Earth has loomed as one of the largest questions facing biologists for more than a century. Biologists have proposed virtually every possible combination of origination, extinction and immigration to explain the pattern at one time or another. But for the past 30 years, they have tended to view the tropics either as a cradle of diversity, where new species originate, or as a museum of diversity, where old species persist. And no resolution has been in sight.

The fossil data of the past 11 million years has broken this logjam. It shows that it's not an either/or proposition. The new study is the first to amass enough data to dissect the roles of extinction, origination and immigration directly. "I think we've killed the idea that the tropics is either a cradle or a museum of biodiversity. It's both," said Valentine, professor emeritus of integrative biology at UC Berkeley.

As the engine of global biodiversity, the tropics are where new species evolve and persist while spreading to higher latitudes, said Roy, a UCSD biology professor. "The world is connected. It's a global village, even for organisms. Along the California coast here, most of the marine species belong to lineages that originated in the tropics."

The Science study underscores the need to avert a tropical diversity crises, its authors said.

"Human-caused extinctions in the tropics will eventually start to affect the biological diversity in the temperate and high latitudes," Roy said. "This is not going to be apparent in the next 50 years, but it will be a long-term consequence."

Noted Valentine: "We should preserve the tropics, because without them, we've lost a key source for diversity in higher latitudes."

The fossil record indicates that the tropics have enjoyed a richness of biodiversity spanning at least 250 million years. Jablonski compared the population of species on Earth to the population of a modern town. To understand how that population mix came about would entail an examination of birth records, cemetery records and immigration records.

The team acquired its data for the Science study by analyzing bivalves, a class of marine life that includes clams, scallops and oysters. "They live everywhere," Jablonski said. "They're found from the Arctic Ocean to the hottest part of the tropics, and they have left a great fossil record."

This record permitted the team to track more than 150 bivalve lineages back through time and answer a series of key questions: Where do they start? How long do they last? Where do they persist? And where do they spread?

As the paleontologists traced the lineages back into geologic time, they found a consistent pattern in each slice of time, regardless of the prevailing climatic conditions. Over the entire 11-million-year period, they found that more than twice as many bivalve lineages started in the tropics than at higher latitudes. Meanwhile, only 30 varieties of organisms that lived only in the tropics went extinct, compared to 107 that lived outside the tropics, or at all latitudes.

"It's a really striking, surprising pattern," Jablonski said. "And it appears that other animals and plants were playing the same game, even on land," now that previous studies are looked at with new eyes.

The three paleontologists began working on the problem more than a decade ago. The first step involved completing a massive standardization of all living and many fossil bivalve species to ensure their consistent and proper classification.

To accomplish the task, Jablonski churned through stacks of monographs, some dating back to the 19th century, and combed drawer after drawer of bivalve specimens in the Smithsonian Institution and other natural history museums in Chicago, London, Brussels, Belgium; and Leiden, the Netherlands.

The forces behind the flood of evolutionary activity that flows from the tropics remain a mystery. "But now that we have a handle on the dynamics that set up this spectacular planet-sized gradient, we can begin to get at the underlying processes in a whole new way," Jablonski said.

Jablonski, Roy and Valentine will attempt to address this and related questions as they push their analysis further back in time.

Steve Koppes | EurekAlert!
Further information:
http://www.uchicago.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>