Not everything in life is always black and white. This sentiment holds true for giant pandas as well. For years, scientists and the public in China have been captivated by Qizai, the world’s only captive brown-and-white panda. Qizai was discovered abandoned in the wild and now resides at the Louguantai Wild Animal Breeding and Protection Center in Xi’An. He is one of only seven brown-and-white pandas ever documented, all originating from the Qinling mountain range in Shaanxi province.
Recently, a team of researchers has uncovered the genetic reason behind Qizai’s unique fur, which may also apply to wild brown pandas. The study, published in the Proceedings of the National Academy of Sciences, reveals that the brown pandas are missing a short sequence of DNA in a pigmentation-related gene called Bace2.
Hu Yibo, a co-author of the paper and a conservation geneticist at the Institute of Zoology at the Chinese Academy of Sciences, explains that Qinling pandas differ significantly from those in Sichuan, the province where most giant pandas inhabit. Previous studies suggest that Qinling pandas diverged from Sichuan pandas approximately 300,000 years ago.
To investigate further, Hu and his colleagues studied the genomic information of three “family trios” associated with two brown pandas and 29 other black-and-white pandas. The trios consisted of Qizai and his parents, Qizai, his mate, and their cub, and Dandan, the first brown panda documented in China, along with her mate and their cub. Among these trios, only Qizai and the now-deceased Dandan displayed brown and white fur.
The researchers discovered that the brown pandas are homozygous for a specific version of the Bace2 gene, meaning they have identical copies of the gene. Genetic sequencing confirmed that both copies of Bace2 in the brown bears lacked a 25-base-pair segment, disrupting the coding sequence for the protein and leading to its malfunction.
Further analysis of 192 other black-and-white pandas in captivity revealed that none of them were homozygous for this version of Bace2. In a laboratory experiment, mice genetically modified to have the same mutation exhibited light-colored coats. Additionally, the team observed that the hairs of brown pandas had fewer and smaller melanosomes, the organelles responsible for hair and skin pigmentation, compared to black pandas.
Shi Peng, an evolutionary geneticist at the CAS Kunming Institute of Zoology, describes the finding as a breakthrough, highlighting that the absence of a gene or genetic segment can result in a change in color. From a genetics perspective, this discovery is groundbreaking.
Moving forward, Hu and his colleagues plan to investigate how the 25-base-pair deletion affects the size and number of melanosomes in brown pandas. This research will provide further insights into the mechanisms behind the unique fur coloration of these rare pandas.
Qizai, with his captivating brown-and-white fur, continues to fascinate both scientists and the public alike. His story serves as a reminder that nature often surprises us with its diversity and complexity, even within the iconic black-and-white world of giant pandas.
