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:3/11/2016)... , March 11, 2016 ... new market research report "Image Recognition Market by Technology ... (Marketing and Advertising), by Deployment Type (On-Premises and Cloud), ... To 2022", published by MarketsandMarkets, the global market is ... to USD 29.98 Billion by 2020, at a CAGR ...
(Date:3/10/2016)... 2016   Unisys Corporation (NYSE: UIS ) ... (CBP) is testing its biometric identity solution at the Otay ... to help identify certain non-U.S. citizens leaving the country. ... to help determine the efficiency and accuracy of using biometric ... will run until May 2016. --> the ...
(Date:3/9/2016)... , March 9, 2016 ... identified that more than 23,000 public service employees either ... been receiving their salary unlawfully.    --> ... government identified that more than 23,000 public service employees ... had been receiving their salary unlawfully.    --> ...
Breaking Biology News(10 mins):
(Date:5/25/2016)... ... May 25, 2016 , ... Lajollacooks4u has become a rising hotspot ... rated one of its top attractions. Fortune 500 companies, such as Illumina, Hewlett-Packard, ... unique and intimate team-building experience. , Each event kicks off with an olive oil ...
(Date:5/25/2016)... ... 2016 , ... Scientists at the University of Athens say they have evidence ... hampering the research that could lead to one good one. Surviving Mesothelioma has just ... , The team evaluated 98 mesothelioma patients who got a second ...
(Date:5/24/2016)... 2016   MedyMatch Technology Ltd ., the data analytics ... decision support tools in the emergency room, announced today that ... Advanced Technology Industries (IATI) BioMed Conference. The ... 15th National Life Sciences and Technology Week, and is being ... in Tel Aviv, Israel . Gene ...
(Date:5/23/2016)... , May 23, 2016 Zimmer Biomet Holdings, ... healthcare, today announced that its Board of Directors has approved ... the second quarter of 2016. The cash ... about July 29, 2016 to stockholders of record as of ... of dividends are subject to approval of the Board of ...
Breaking Biology Technology: