Endangered species may become extinct 100 times faster than previously thought

[Pastor Dale Morgan]

*Perilous Times

Wildlife extinction rates 'seriously underestimated'*

* Ian Sample
* guardian.co.uk,
* Wednesday July 2, 2008

Endangered species may become extinct 100 times faster than previously
thought, scientists warned today, in a bleak re-assessment of the threat
to global biodiversity.

Writing in the journal Nature, leading ecologists claim that methods
used to predict when species will die out are seriously flawed, and
dramatically underestimate the speed at which some plants and animals
will be wiped out.

The findings suggest that animals such as the western gorilla, the
Sumatran tiger and the Malayan sun bear, the smallest of the bear
family, may become extinct much sooner than conservationists feared.

Ecologists Brett Melbourne at the University of Colorado at Boulder and
Alan Hastings at the University of California, Davis, said conservation
organisations should use updated extinction models to urgently
re-evaluate the risks to wildlife.

"Some species could have months instead of years left, while other
species that haven't even been identified as under threat yet should be
listed as endangered," said Melbourne.

The warning has particular implications for the International Union for
the Conservation of Nature, which compiles an annual "red list" of
endangered species. Last year, the list upgraded western gorillas to
critically endangered, after populations of a subspecies were found to
be decimated by Ebola virus and commercial trade in bush meat. The
Yangtze river dolphin was listed as critically endangered, but is
possibly already extinct.

The researchers analysed mathematical models used to predict extinction
risks and found that while they included some factors that are crucial
to predicting a species' survival, they overlooked others. For example,
models took into account that some animals might die from rare
accidents, such as falling out of a tree. They also included chance
environmental threats, such as sudden heatwaves or rain storms that
could kill animals off.

But Melbourne and Hastings highlighted two other factors that extinction
models fail to include, the first being the proportion of males to
females in a population, the second the difference in reproductive
success between individuals in the group. When they factored these into
risk assessments for species, they found the danger of them becoming
extinct rose substantially.

"The older models could be severely overestimating the time to
extinction. Some species could go extinct 100 times sooner than we
expect," Melbourne said.

The researchers showed that the missing factors - the number of males to
females, and variations in the number of offspring - were capable of
causing unexpected, large swings in the size of a population, sometimes
causing it to grow, but also increasing the risk that a population could
crash and become extinct.

To test the new models, Melbourne's team studied populations of beetles
in the laboratory. "The results showed the old models misdiagnosed the
importance of different types of randomness, much like miscalculating
the odds in an unfamiliar game of cards because you didn't know the
rules," he said.

For some endangered species, such as mountain gorillas, conservationists
could collect data on specific individuals and plug them into models to
predict their chances of survival. "For many other species, like stocks
of marine fish, the best biologists can do is to measure abundances and
population fluctuations," Melbourne added.

Craig Hilton-Taylor, who manages the IUCN red list in Cambridge, said
extinction estimates are often inadequate. "We are certainly
underestimating the number of species that are in danger of becoming
extinct, because there are around 1.8 million described species and
we've only been able to assess 41,000 of those," he said.

The latest study could help refine models used to decide which species
are put on the red list, he said. "We are constantly looking at how we
evaluate extinction risk, and it may be they have hit on something that
can help us," he said.

More than 16,000 species worldwide are currently threatened with
extinction, according to a 2007 report from the IUCN. One in four mammal
species, one in eight bird species and one in three amphibian species
are on the organisation's red list. An updated list is due to be
published in October.

Next week, the IUCN is expected to highlight the dire state of the
world's corals after surveying the condition of more than 1,000 species
around the world.