The Mystery of the Brown and White Panda
The Future of this Chinese Giant May Suffer Lack of Genetic Diversity
by Taylor Kilgore, age 14
As you may know, wild pandas all around the world are endangered. In the Foping Nature Reserve in China’s Qinling Mountains, scientists are finding out that pandas may be the cause of their own extinction.
There is debate around the fact that brown-and-white furred pandas, which are extremely rare, are showing up more in the Qinling population. The first brown-and-white panda was discovered in 1985. It was a female scientist named Dan-Dan. The brown-and-white panda was mated with a black-and-white panda while in captivity, and then gave birth to a normal black-and-white panda. A few years later, another brown-and-white panda was sighted in the wild, together with its black-and-white mother.
“These anecdotal observations strongly suggest the presence of a recessive gene or genes,” says Tiejun Wang. Wang is a spatial ecologist in the department of Natural Resources at the University of Twente in the Netherlands, who has worked in Foping for 20 years.
Then another researcher saw a seventh brown-and-white panda in the Qinling Mountains in November 2009. It was estimated to be about two months old.
Wang and his colleague, Andrew Skidmore, say inbreeding is one theory as to why the rare colored pandas are showing up and could be one reason pandas are at risk for extinction. Wang suggests that the Qinling pandas carry a dominant gene for black fur and a recessive gene for brown. This means that brown-and-white fur is only possible when the recessive brown gene is inherited from both mother and father. The possibility of this occurring is usually very low, unless the two pandas are closely related.
Inbreeding is something to worry about. It means that more animals than usual carry the same genes. This can also mean that too many individuals within a given population rely on the same set of genetic defenses to overcome environmental threats. This lack of genetic diversity increases their risk of extinction. As the recessive gene is passed on, it is more likely to be expressed in the offspring, resulting in more brown-and-white pandas
Shen-guo Fang, a researcher at Zhejiang University in Hangzhou, China, has a different idea. Fang and his colleagues have found that a lot of the Qinling black-and-white pandas have touches of brown in their chest fur. This suggests that there could be something specific to the Qinling region, such as the climate or a particular environmental chemical that affects one or more pigmentation genes. “The Qinling Mountains have shaped brown subspecies of other mammals, such as the golden takin,” Fang notes.
In spite of these findings, the most recent genetic analysis says that over the past few thousand years, remaining giant panda populations seem to have retained much of their genetic diversity.
Scientists have many ideas several theories about the brown-and-white pandas, but this mystery is yet to be solved.
[Source: Nature News]