Tag Archives: diversity

Javan rhino now extinct in Vietnam

BBC News – Javan rhino ‘now extinct in Vietnam’.

A Javan rhino is captured on camera in Vietnam's Cat Tien National Park (Image: WWF Greater Mekong) Genetic analysis of rhino dung samples revealed that there was only one individual left in Vietnam

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A critically endangered species of rhino is now extinct in Vietnam, according to a report by conservation groups.

The WWF and the International Rhino Foundation said the country’s last Javan rhino was probably killed by poachers, as its horn had been cut off.

Experts said the news was not a surprise, as only one sighting had been recorded in Vietnam since 2008.

Fewer than 50 individuals are now estimated to remain in the wild.

“It is painful that despite significant investment in Vietnamese rhino conservation, efforts failed to save this unique animal, ” said WWF’s Vietnam director Tran Thi Minh Hien.

“Vietnam has lost part of its natural heritage.”

The authors of the report, Extinction of the Javan Rhino from Vietnam, said genetic analysis of dung samples collected between 2009-2010 in the Cat Tien National Park showed that they all belonged to just one individual.

Shortly after the survey was completed, conservationists found out that the rhino had been killed. They say it was likely to have been the work of poachers because it had been shot in a leg and its horn had been cut off.

Globally, there has been a sharp increase in the number of rhino poaching cases. Earlier this year, the International Union for Conservation of Nature (IUCN) published a report that said rhino populations in Africa were facing their worst poaching crisis for decades.

An assessment carried out by Traffic, the global wildlife trade monitoring network, said the surge in the illegal trade in rhino horns was being driven by demands from Asian medicinal markets.

Conservation blow

The Vietnam rhino, as well as being the last of the species on mainland Asia, was also the last known surviving member of the Rhinoceros sondaicus annamiticus subspecies – one of three recognised groups of Javan rhino populations.

In detail: Javan rhinoceros

  • Scientific name: Rhinoceros sondaicus
  • The species is listed as Critically Endangered because fewer than 50 individuals remain
  • Weight: 900kg – 2,300kg
  • Height: 1.5m – 1.7m
  • Length: 2.0m – 4.0m
  • Male Javan rhinos possess a single horn about 25cm long
  • It is estimated that they can live for 30-40 years
  • Females reach sexual maturity between 5-7 years, and then give birth to a calf about once every three years

(Source: IUCN/IRF)

Another is already extinct. R. sondaicus inermis was formerly found in north-eastern India, Bangladesh and Burma.

The remaining subspecies, R. sondaicus sondaicus, is now found on Java, Indonesia. However, since the 1930s, the animals – now estimated to number no more than 50 – have been restricted to the westernmost parts of the island.

Bibhab Kumar Talukdar, chairman of the IUCN’s Asian Rhino Specialist Group, said the demise of the Javan rhino in Vietnam was “definitely a blow”.

“We all must learn from this and need to ensure that the fate of the Javan rhino in [Indonesia] won’t be like that of Cat Tien in near future,” he told BBC News.

“Threats to rhinos for their horn is definitely a major problem. But in Indonesia, due to active work done by rhino protection units and national park authorities, no Javan rhino poaching has been recorded in Indonesia for past decade.”

Dr Talukdar observed: “What is key to the success of the species is appropriate habitat management as the Javan rhinos are browser and it needs secondary growing forests.”

He warned that the habitat within the national park on Java serving as the final refuge for the species was being degraded by an invasive species of palm.

“As such, control of arenga palm and habitat management for Javan rhinos in Ujung Kulon National Park is now become important for future of the species.”

Mass Extinctions Change the Rules of Evolution

Mass Extinctions Change the Rules of Evolution | Wired Science | Wired.com.

ANOTHER giant ‘DUH’ for science: mass extinctions make things happen differently thereafter.

A reinterpretation of the fossil record suggests a new answer to one of evolution’s existential questions: whether global mass extinctions are just short-term diversions in life’s preordained course, or send life careening down wholly new paths.

Some scientists have suggested the former. Rates of species diversification — the speed at which groups adapt and fill open ecological niches — seemed to predict what’s flourished in the aftermath of past planetary cataclysms. But according to the calculations of Macquarie University paleobiologist John Alroy, that’s just not the case.

“Mass extinction fundamentally changes the dynamics. It changes the composition of the biosphere forever. You can’t simply predict the winners and losers from what groups have done before,” he said.

Alroy was once a student of paleontologist Jack Sepkoski, who in the 1980s formalized the notion that Earth has experienced five mass extinctions in the 550 million years since life became durable enough to leave a fossil record. Graphs of taxonomic abundance depict lines rising steadily as life diversifies, plunging precipitously during each extinction, and rising again as life proliferates anew.

As the fossil record is patchy and long-term evolutionary principles still debated, paleobiologists have historically disagreed about what these extinctions mean. Some held that, in the absence of extinctions, species would diversify endlessly. The Tree of Life could sprout new branches forever. Others argued that each taxonomic group had limits; once it reached a certain size, each branch would stop growing.

Sepkoski’s calculations put him on the limits side of this argument. He also proposed that, by looking at the rate at which each group produced new species, one could predict the winners and losers of each mass extinction’s aftermath. Groups that diversified rapidly would flourish. Their destiny was already established.

“It’s a clockmaker vision of evolution. Each group has fixed dynamics, and if there’s an extinction, it just messes it up a bit,” said Alroy. “That’s what I’m challenging in this paper. There are limits, and that’s why we don’t have a trillion species. But those limits can change.”

Alroy crunched marine fossil data in the Paleobiology Database, which gathers specimen records from nearly 100,000 fossil collections around the world. He used a statistical adjustment method designed to reduce the skewing influences of paleontological circumstance — the greater chances of finding young fossils rather than old, the ease of studying some types of rock rather than others.

Historical species diversity among marine animals of Cambrian, Paleozoic and Modern origin.

The analysis, published September 2 in Science, produced what Alroy considers to be the most accurate reflection of extinction dynamics to date. And while his data supported the notion that each group’s diversity eventually hits a limit, he didn’t find Sepkoski’s correlation between pre-mass-extinction diversity rates and post-extinction success. Each mass extinction event seemed to change the rules. Past didn’t indicate future.

In an accompanying commentary, paleontologist Charles Marshall of the University of California, Berkeley noted that Alroy’s statistical methods still need review by the paleobiology community. The Paleobiological Database, for all its thoroughness, might also be incomplete in as-yet-unappreciated ways. “There will be no immediate consensus on the details of the pattern of diversity,” he wrote. But “the pieces are falling into place.”

Enough pieces have come together for Alroy to speculate on his findings’ implication for the future, given that Earth is now experiencing another mass extinction. Starting with extinctions of large land animals more than 50,000 years ago that continued as modern humans proliferated around the globe, and picking up pace in the Agricultural and Industrial ages, current extinction rates are far beyond levels capable of unraveling entire food webs in coming centuries. Ecologists estimate that between 50 and 90 percent of all species are doomed without profound changes in human resource use.

In the past, many evolutionary biologists thought life would eventually recover its present composition, said Alroy. In 100 million years or so, the same general creatures would again roam the Earth. “But that isn’t in the data,” he said.

Instead Alroy’s analysis suggests that the future is inherently unpredictable, that what comes next can’t be extrapolated from what is measured now, no more than a mid-Cretaceous observer could have guessed that a few tiny rodents would someday occupy every ecological niche then ruled by reptiles.

“The current mass extinction is not going to simply put things out of whack for a while, and then things will go back to where we started, or would have gone anyway,” said Alroy. Mass extinction “changes the rules of evolution.”

Images: 1) A fossil skull of Dunkleosteus, an apex predator fish that lived between 380 million and 360 million years ago, and had what is believed to be history’s most powerful bite./Michael LaBarbera, courtesy of The Field Museum. 2) Graph of species diversity among marine animals of Cambrian, Paleozoic and Modern origin./Science.

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