Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Penn Biologists Say Species Accumulate on Earth at Slower Rates Than in the Past

30.09.2010
Computational biologists at the University of Pennsylvania say that species are still accumulating on Earth but at a slower rate than in the past.

In the study, published in the journal PLoS Biology, Penn researchers developed a novel computational approach to infer the dynamics of species diversification using the family trees of present-day species. Using nine patterns of diversification as alternative models, they examined 289 phylogenies, or evolutionary trees, representing amphibians, arthropods, birds, mammals, mollusks and flowering plants.

The study demonstrated that diversity is generally not at equilibrium. Nonetheless, speciation rates have typically decayed over time, suggesting that the diversification of species is somehow constrained, and that equilibrium may eventually be reached.

There are many competing theories for how species diversify and become extinct. Some suggest that species continually accumulate in time, always finding new ecological niches. Other theories suggest that the number of coexisting species is limited and that we will eventually have equilibrium. In other words, a species will be born only when another goes extinct.

The question that intrigued the Penn researchers was whether species diversity on Earth is in equilibrium or is still expanding. They also wondered whether the world has an invisible stop sign on species diversity that would eventually limit the diversity on the planet.

“What we see is diversification rates that are declining but not yet to zero,” said Joshua Plotkin, assistant professor in the Department of Biology in the School of Arts and Sciences at Penn. “We are not yet in equilibrium. Either there is a limit to the total species number and we haven’t reached it yet, or there is no such limit. But the rates of diversification are typically falling; when we will hit zero is not yet obvious.”

While it is clear that Earth has recently lost species due to human impact, this study dealt with much longer, geologic time scales. Understanding these long-term dynamics is central to our understanding of what controls present-day biodiversity across groups and regions.

Even though the study did not deal with the current anthropogenic loss of biodiversity, researchers were surprised at how little extinction they actually saw in the evolutionary trees of species. The fossil record shows that many species have gone extinct over geologic time. For example, the diversity of whales has decreased during the last ~12 million years. But extinction was rarely apparent in this analysis of evolutionary trees.

The study also shows how analyzing molecular phylogenies can shed light on patterns of speciation and extinction; future work may reconcile this approach with the fossil record.

“By taking advantage of existing data from the flood of genomic research, we hope to combine efforts with paleontologists gathering fossil data,” Plotkin said.

The study was conducted by Hélène Morlon and Plotkin of the Department of Biology in Penn’s School of Arts and Sciences and Matthew D. Potts of the University of California, Berkeley.

It was funded by the Burroughs Wellcome Fund, David and Lucile Packard Foundation, James S. McDonnell Foundation and Alfred P. Sloan Foundation.

Jordan Reese | EurekAlert!
Further information:
http://www.upenn.edu
http://www.upenn.edu/pennnews/news/penn-biologists-say-species-accumulate-earth-slower-rates-past

More articles from Life Sciences:

nachricht Joining forces for immune research
13.08.2018 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft

nachricht The “TRiC” to folding actin
10.08.2018 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

Im Focus: A molecular switch may serve as new target point for cancer and diabetes therapies

If certain signaling cascades are misregulated, diseases like cancer, obesity and diabetes may occur. A mechanism recently discovered by scientists at the Leibniz- Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin and at the University of Geneva has a crucial influence on such signaling cascades and may be an important key for the future development of therapies against these diseases. The results of the study have just been published in the prestigious scientific journal 'Molecular Cell'.

Cell growth and cell differentiation as well as the release and efficacy of hormones such as insulin depend on the presence of lipids. Lipids are small...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

NRL's sun imaging telescopes fly on NASA Parker Solar Probe

13.08.2018 | Physics and Astronomy

UT-ORNL team makes first particle accelerator beam measurement in six dimensions

13.08.2018 | Physics and Astronomy

ASU astrophysicist helps discover that ultrahot planets have starlike atmospheres

13.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>