29 June 2010

China’s pandas not a genetic dead end

By and Ben Bravery
Cosmos Online
In 2011, the Chinese Government will begin a major survey of wild pandas. Using new, molecular counting techniques, scientists think they'll find many more pandas this time round.
Panda in snow

A snow-covered panda in Foping Nature Reserve, Shaanxi Province. HIT PLAY, above, to see more photos. Credit: Fuwen Wei

Panda in tree

A panda in Foping Nature Reserve, Shaanxi Province. HIT PLAY, above, to see more photos. Credit: Fuwen Wei

Panda in the bush

A panda in Foping Nature Reserve, Shaanxi Province. HIT PLAY, above, to see more photos. Credit: Fuwen Wei

On 12 May 2008, Sichuan province in China was hit by a category 8.0 earthquake, killing almost 70,000 people. At the time of the quake I was in Beijing. Like all Chinese people, I felt deeply saddened by the loss of life. On top of the human losses, I was also concerned about the welfare of my research subjects: giant pandas.

I started studying giant pandas in 1984 as a postgraduate student of the world-renowned giant panda specialist Jinchu Hu, mostly in their natural habitat in the central China provinces of Sichuan, Shaanxi and Gansu. Since then, I have been involved in conservation efforts.

Only 60 km from the epicentre of the 2008 quake is the Wolong National Nature Reserve, one of three national breeding centres for giant panda. It is home to more than 150 captive-bred and wild pandas. All the highways in the region had been damaged during the natural disaster, resulting in massive problems for relief efforts.

I assumed the worst when I heard about the earthquake. I thought the reserve had been destroyed. It was very difficult to find out what had happened, as most of the phone towers in the area had been damaged.

But we able to assess the damage to captive pandas quickly: in total, one panda was found dead among the rubble and six pandas escaped.

HOWEVER, WE STILL DON’T know the effect, if any, of the quake on wild pandas. In March, I attended the 2010 giant panda conservation and management meeting in Sichuan, hosted by the China State Forestry Administration (SFA), to decide how we should evaluate the damage.

The meeting was attended by 50 Chinese administrators and scientists. During the meeting we discussed our plans for the future of giant panda conservation, and the SFA announced it would conduct the fourth national survey of giant pandas. The survey will begin in 2011, and will continue for two years.

The previous surveys were conducted in 1974-1977, 1985-1988 and 1998-2002. The most recent survey estimated that there are 1,600 wild pandas, plus another 266 in captivity. It is worth noting that we can only estimate the population of pandas. The world population of humans is, after all, only an estimate too.

In a 2006 article published in the journal Current Biology, my research group proposed that the number of wild pandas may be much higher than previously stated, based on a small test case. This discrepancy makes the upcoming survey even more important, and exciting.

Using Wanglang Nature Reserve in Sichuan province as a test case, we found that previous counting methods underestimated the panda population. The third national survey found 27 animals in the reserve, while we found 66 individuals using molecular counting techniques.

Previously, the number of pandas was estimated by analysing the size of bamboo fragments found in panda faeces and pandas’ home range size. We would then work out the panda’s age and estimate how many different pandas the scats had come from.

These are relatively inexpensive and quick methods of estimating a panda population, though they have their limitations and should be complemented by newer techniques.

Molecular counting involves extracting panda DNA from their faecal samples, found on the forest floor. Through this use of DNA fingerprinting we know exactly how many different pandas live in the same area.

For the upcoming survey we will use bamboo fragment size assessments in regions with low density panda populations, while in high density panda areas, we will analyse bamboo fragment size and use new molecular counting techniques.

These methods are more accurate than assessing the size of fragments, but take longer and are more expensive. We believe that the additional cost is necessary for high-density populations, as shown in our study of Wanglang Nature Reserve.

The low density and solitary nature of pandas makes it very difficult to obtain blood samples from wild pandas. That is why we analyse something that pandas leave behind: faeces. Pandas predominantly consume bamboo, which has very little nutritional value, so they have to eat approximately 12 kg of bamboo each day.

This means pandas produce many scats: up to 120 per day. This makes the work of my research team much easier! They take a sample of mucus found on the outside of the scat for microsatellite analysis of DNA, and with this technique we can differentiate faecal samples between different pandas by analysing their genes.

Not only can we determine the current population of pandas using genetic counting, but we can estimate the past effective population size as well. In one dramatic case we found that in an isolated group of pandas the effective population size dropped from 2,570 to 40 in just 300 years. This was almost certainly due to the rapid increase in human population and agriculture in the area.

We face many challenges in our conservation efforts to save giant pandas. In the past, poaching and illegal logging were major threats to pandas. Education and law enforcement campaigns run by the Chinese Government have helped solve these problems, but the situation facing pandas is still difficult.

Development pressures are an ongoing problem: habitat loss and habitat fragmentation are increasingly impacting on the populations of pandas. In the Xiaoxiangling Mountains, in the Sichuan province, a highway was built through the middle of a panda habitat, effectively splitting the local panda population into two groups.

As we showed this year in the journal Conservation Biology, these populations are now too small to survive on their own, as they are at risk of genetic erosion and are susceptible to environmental degradation. There is also a high rate of juvenile mortality, and overlapping generations. Pandas now require human intervention to ensure localised extinctions do not occur.

The construction of hydro-electric power stations in the mountainous regions that pandas favour is another concerning matter, as it destroys their habitat and creates poorly functioning ecosystems. Last, mining is a worldwide problem for conservation efforts, and this is true in the case of panda populations as well.

The government and panda conservation scientists are investigating and implementing a number of strategies to protect pandas from extinction. Panda populations have decreased dramatically as a result of human disturbance throughout history, and pandas now depend on human assistance for their survival.

Habitat protection and restoration are vitally important to the survival of pandas. Pandas have relatively limited mobility, and require bamboo as a food source. Protection of current panda habitat and restoration of past ones are established conservation efforts.

In regions of habitat fragmentation, such as in the Xiaoxiangling Mountains where the highway and Dadu river cut the panda population into four parts, habitat corridor construction has been proposed. A strip of panda habitat is under construction to allow pandas to move between separated populations, which will increase the gene flow between these populations.

We have also begun an ambitious plan to ensure the survival of pandas. We have started translocating female pandas from larger panda populations to smaller populations, to ensure the populations remain genetically viable and do not die off.

This technique is necessary in the short term, but the long term plan is to train captive-bred pandas so they can be reintroduced into those panda populations at high risk of extinction, or to build a new population in the area pandas previously inhabited.

Pandas need to learn how to eat, mate and protect themselves in the wild, and the training process will take many years for pandas to be released into the wild and be able to cope with the natural habitat. More research is required for training programs, but current successes are promising.

EVEN AFTER 26 YEARS of researching pandas, I am still learning more about this elusive animal. More research is required to help discover novel and effective conservation techniques to help pandas.

I am trying to restore their image as a viable species and not an ‘evolutionary dead end’. In response to the growing perception that pandas are somehow not suited to life on Earth, or have evolved overspecialised traits such as eating bamaboo which do not enhance their survival but hinder it, I took part in a large genetic study of pandas across five of their six mountain strongholds.

The amount of genetic variation within a species is a key indicator of its ability to persist and continue to evolve. We found that pandas possess high genetic diversity, even higher than in other bears.

Studies of panda DNA revealed that their numbers started to decline several thousand years ago – around the same time as the human population in this region began to grow.

The level of genetic diversity and gradual decline are not reasons for labelling this animal a ‘dead end’. This pattern in pandas is consistent with the patterns and fates of countless other large mammals that are struggling to co-exist with humans.

In fact, pandas have fared better than many other species: pandas are still here, and holding on – just.

The giant panda is recognised worldwide as a symbol of China. I believe that current and future conservation efforts bode well for pandas. The challenge now is to improve upon the positive changes that have already been made, and to demonstrate to the world the best conservation practices.

The fourth national survey of giant pandas is vital for our conservation efforts. We will be able to ascertain the damage from the Sichuan earthquake, while also investigating the effectiveness of past conservation techniques.

We cannot control nature, but we can control the impact of the human population’s past, present and future. Habitat restoration, education and captive-bred panda training programs are all tools we will use to save the subject of my life’s work.

Fuwen Wei is a professor of ecology and conservation biology at the Institute of Zoology, Chinese Academy of Sciences. He is a key advisor to the Chinese Government on giant panda conservation and also leads research projects on a number of other high-profile endangered species within China and internationally.

Tim O’Mahony and Ben Bravery are science communicators with Kexue Communications, based in Beijing. They both have a science degree and a communication degree and now work with Chinese researchers to disseminate Sino science to the English-speaking world.


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