Extinction seems to be in the news a lot lately; must be TV pilot ratings, or by-elections, or something. 😉
From “Not Always Safety in Numbers When It Comes to Extinction Risk” (ScienceDaily, May 8, 2012), we learn,
A basic tenet underpinning scientists’ understanding of extinction is that more abundant species persist longer than their less abundant counterparts, but a new University of Georgia study reveals a much more complex relationship.
A team of scientists analyzed more than 46,000 fossils from 52 sites and found that greater numbers did indeed help clam-like brachiopods survive the Ordovician extinction, which killed off approximately half of Earth’s life forms some 444 million years ago. Surprisingly, abundance did not help brachiopod species persist for extended periods outside of the extinction event.
Some years ago, paleontologist David M. Raup, a specialist in extinction, wrote Extinction: Bad Genes or Bad Luck? (New York: W. W. Norton, 1991), in which he raised the question whether some extinctions are caused by genetic flaws in the life form, rather than by changes in the ecology.
He felt this was worth looking at, especially in cases like the trilobites where, for example, they all went extinct.
Many recent studies of extinction by paleobiologists are coming out with findings that are contrary to what we see in modern environments and sometimes even contrary to what other paleontologists see in other geologic eras,” he said. “I think this is why paleobiology is so important-it’s the only way for us to examine ecology at multiple points in the Earth’s history, when perhaps the environmental and biological settings were different enough that even our most intuitive expectations don’t hold.”
In other words, Raup might have been right.