Navigation Links
Extinction runs in the family
Date:8/8/2009

Global calamities like the one that doomed most dinosaurs forever alter the varieties of life found on Earth, but new research shows that it doesn't take a catastrophe to end entire lineages. An analysis of 200 million years of history for marine clams found that vulnerability to extinction runs in evolutionary families, even when the losses result form ongoing, background rates of extinction.

"Biologists have long suspected that the evolutionary history of species and lineages play a big role in determining their vulnerability to extinction, with some branches of the tree of life being more extinction-prone than others," said Kaustuv Roy, a biology professor at the University of California, San Diego, noting that human activities threaten some evolutionary lineages of living vertebrates more than others. "Now we know that such differential loss is not restricted to extinctions driven by us but is a general feature of the extinction process itself."

Roy and colleagues Gene Hunt of the Smithsonian Institution and David Jablonski of the University of Chicago report their findings in Science this week.

Their study focused on marine bivalves such as clams, oysters, mussels, and scallops, whose tough shells fossilize well to provide a rich record for study. By analyzing a global database of bivalve fossils stretching from the Jurassic Period to the present, the researchers noted when each genus disappeared and whether their relatives disappeared at the same time.

On average, closely related clusters of clams vanished together more often than expected by chance.

"Both background extinctions, which represent most extinctions in the history of life, and mass extinctions tend to be clumped into particular evolutionary lineages," Jablonski said.

The effect was particularly strong during the mass extinction at the end of the Cretaceous period, when clam lineages with the highest 'background' rates of extinction during more normal times were hardest hit. Three families with the highest background rates disappeared entirely. Two others, with rates more than twice the median, suffered heavy losses and have not recovered to this day.

"Big extinctions have a filtering effect. They tend to preferentially cull the more vulnerable lineages, leaving the resistant ones to proliferate afterwards," Hunt said.

When extinctions are scattered randomly across the evolutionary tree, the breadth of evolutionary history remains represented among living things, even when many species are lost. Clumped extinctions do the opposite, disproportionately removing the deeper history.

"Extinctions in the past and presumably in the future will lop off chunks of evolutionary trees, not just prune the trees and leave most of the history intact," Jablonski said.

The message for conservation is to focus efforts on vulnerable lineages, the authors say. To preserve the full spectrum of evolutionary history found among living things today, the most fragile families will need careful protection.

Even relatively low levels of threat could eliminate large limbs, Roy said. "If you have whole lineages more vulnerable than others, then very soon, even with relatively moderate levels of extinction, you start to lose a lot of evolutionary history."


'/>"/>

Contact: Kaustuv Roy
kroy@ucsd.edu
University of California - San Diego
Source:Eurekalert

Related biology news :

1. Surviving mass extinction by leading a double life
2. Evidence of the Lost World -- did dinosaurs survive the end Cretaceous extinctions?
3. Study shows competition, not climate change, led to Neanderthal extinction
4. Current mass extinction spurs major study of which plants to save
5. Geologist who linked cosmic strike to dinosaurs extinction takes top prize
6. UGA study reveals ecosystem-level consequences of frog extinctions
7. Extinction by asteroid a rarity
8. Mass extinctions and the evolution of dinosaurs
9. Study of islands reveals surprising extinction results
10. A recipe for saving the worlds oceans from an extinction crisis
11. Extinction most likely for rare trees in the Amazon rainforest
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/23/2017)... robotic gym for the rehabilitation and functional motor sense evaluation of lower ... . The first 30 robots will be available from June in ... The technology was developed and patented at the IIT laboratories and has ... to a 10 million euro investment from entrepreneur Sergio Dompè. ... ...
(Date:5/6/2017)... 5, 2017 RAM Group , ... new breakthrough in biometric authentication based on a ... properties to perform biometric authentication. These new sensors are ... created by Ram Group and its partners. This sensor ... supply chains and security. Ram Group is a ...
(Date:4/18/2017)...  Socionext Inc., a global expert in SoC-based imaging and computing ... M820, which features the company,s hybrid codec technology. A demonstration utilizing ... Inc., will be showcased during the upcoming Medtec Japan at Tokyo ... Las Vegas Convention Center April 24-27. ... Click here for an image ...
Breaking Biology News(10 mins):
(Date:6/22/2017)... Ca (PRWEB) , ... June 22, 2017 , ... The ... It took 20 years until the first data on cross-contamination of human cell lines ... has been an increasing issue in cell culture labs and is associated with dramatic ...
(Date:6/20/2017)... ... 20, 2017 , ... CTNext , Connecticut’s go-to resource ... a Higher Education Entrepreneurship Advisory Committee to implement the recommendations of the master ... representatives from 35 higher education institutions across the state over the past six ...
(Date:6/20/2017)... , June 20, 2017  Kibow Biotech Inc., a ... announce the issuance of a new patent covering a ... by the U.S. Patent and Trademark Office on May ... of the Buzz of Bio award in 2014 in ... to developing non-drug approaches to chronic disease. Renadyl™, the ...
(Date:6/20/2017)... ... June 20, 2017 , ... GigaGen Inc ., a ... repertoires, announces launch of its new Surge(TM) Discovery service at the ... GigaGen, will present on Surge at the conference. , Surge is the new, ...
Breaking Biology Technology: