Monday, March 7, 2011
There are about 500 Amur tigers currently surviving in the wild, but the effective population accounts for genetic diversity. BBC reports that the tiger has a very low diversity, which means that any disease or rare genetic disorders will probably be passed on to the next generation. A more diverse genetic population would increase the tiger's chance of survival -- it would be able to "cancel out" diseases and disorders with healthy genes.
The Amur tiger is the largest cat in the world. It once lived across China, Korea, and Russia, until the early 20th Century, when human settlements, habitat loss, and poaching drove the cats to near extinction. By the 1940's, less than 30 individual tigers survived in the wild -- this has now led to a "genetic bottleneck," destroying the Amur tiger gene pool. The results of this are seen today in the tiger's lack of genetic diversity.
Not just Amur tigers are at risk of extinction. The World Wildlife Fund reports that climate change may be shrinking tigers' habitat by 96%. Bengal tigers are shrinking in size due to stress over environmental changes. The WWF goes so far as to state that if no action is taken, tigers may become extinct in the next 12 years.
This past November, a summit was held focused on saving tigers from extinction. The summit's biggest news? It was probably that Leonardo DiCaprio survived a plane accident and still managed to attend. But also at the summit, countries agreed to double the tiger population by 2022 and crack down on poaching and illegal trade of tiger parts. It is an uphill battle, but one worth fighting.
Thursday, March 3, 2011
But the headline grabbing figure that the big cat’s effective population is just 15 is less of a threat than loss of habitat, environmentalists say.
There are about 500 Amur tigers living in the wild – but genetic researchers have found that they are descended from just 15 animals.
And that, they claim, raises the spectre of genetic disorders and other illnesses in the population.
“The worryingly low effective population size challenges the optimism for the recovery of the huge Siberian cat,” the researchers from Russia, Germany and Spain wrote in the paper published in the magazine Mammalian Biology.
Russia has invested heavily in protecting its tiger population, with Vladimir Putin personally endorsing the campaign at an international forum in St. Petersburg last year.
The research, and its gloomy conclusion, may not take into account the different effects of genetic diversity on different species, ecologists say.
“For example cats are less sensitive to it than dogs,” Vladimir Krever, biological diversity programme co-ordinator at WWF’s Moscow office, told the Moscow News.
And he pointed to the successful reintroduction of European bison into the wild to prove that the genetic pool might not be the main criteria for saving threatened creatures.
Since 1951 the European bison has returned to the wild, despite the fact that in the early 20th century there were fewer than 50 surviving animals, all living in captivity.
Tigers need trees
Today’s tigers are threatened by illegal woodcutting just as much as their ancestors were devastated by poaching.
“Currently the most burning issue is conservation of the habitat area,” Vladimir Krever said.
Poachers haven’t disappeared today, but luckily they don’t make any serious impact on the number of feline predators, Krever said, while stripping away their natural habitat clearly does.
Preserving the forests would help maintain stocks of hoofed mammals – tigers’ natural prey – and ensure that the big cats have enough to eat.
“And if we are aiming to increase their number further, it’s definitely forests restoration to start with,” Krever concluded.