Image credit: Chi King/Flickr
Giant pandas are rare in the wild—WWF estimates the population is around 1,600—but seeing a giant panda with brown fur instead of black is nearly unheard of. When a brown and white panda cub was discovered in China in November, it became the seventh ever observed.
While it is not certain what causes the variation, new research suggests that it might be the result of inbreeding which would have serious implications for the viability of the giant panda population in the wild."It's time we had a debate about what is causing this because it could be telling us something very important," Tiejun Wang, a spatial ecologist at the University of Twente in Enschede, the Netherlands, explained.
Based on historical and anecdotal observations, Wang believes that the variation may be caused by a double recessive gene. If this is the case, both the mother and father of a brown-furred cub would have to posses the recessive trait.
This would explain why the variation is so rare. It would also suggest that its appearance is indicative of inbreeding in the population. Wang explained:
Such inbreeding is a concern for conservationists because it leads to a population that relies on the same set of adaptations to overcome threats, increasing the probability of extinction.
Pandas Are Not Necessarily Inbreeding
Though inbreeding is a plausible explanation for the variation, and would signal a need for new conservation strategies, it has not been confirmed as the cause for brown coloration. Sheng-guo Fang, a researcher who studies panda genetics at Zhejiang University in Hangzhou, commented that the theory warrants further exploration.
However, other factors, he explained, could be causing the variation. He points to the presence of small brown patches in otherwise black pandas. This attribute is unique to pandas in the Qinling Mountains, where the all-brown cub was discovered. Fang believes that something specific to Qinling—a variation in climate or a chemical in the environment—could influence the bears' pigmentation genes.
Studies of the genome, too, have shown that little inbreeding has occurred among pandas. At this point, researchers said, only a careful study of gene sequences and morphology can determine whether the source of the brown panda variation is in the air, the soil, or the shrinking genetic diversity of the giant pandas.