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The Giant Panda Lived in Leye-Fengshan UNESCO Global Geopark 22,000 Years Ago Mitochondrial Genome R

Sources:    Time:2018-06-26

As a protected species of endangered animals, giant pandas were once distributed in southern China and Southeast Asia, covering a vast area. The surviving giant pandas now have only a few different genetic populations in Shanxi, Gansu and Sichuan provinces. The surviving giant pandas now have only a few different genetic populations in Shanxi, Gansu and Sichuan provinces.

The genetic re-establishment of the existing giant panda population may not accurately describe the evolutionary history of this species. No scientist has been able to extract new clues from mitochondrial genome or nuclear genomes in ancient giant panda fossils. However, a recent study by Current Biology, a researcher from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and a team led by researcher Wei Fuwen from the Institute of Zoology of the Chinese Academy of Sciences, has brought about changes. They extracted, captured and sequenced a complete mitochondrial genome of a giant panda 22,000 years ago. The panda individual was discovered in the Cizhutuo Cave by the team member Zhang Yingqi and the Beijing Cave Expedition during the Paleontological survey in Dashiwei Tiankeng Group of Leye Guangxi in 2014. (Picture 1-2). The ancient pandas survived in the age of the Last Glacial Period, and can be said to be the oldest giant panda for gene sequencing and the first complete mitochondrial genome of ancient pandas.

In the hot and humid climate of southern China, the preservation of DNA is very difficult. It is even more difficult to reconstruct the ancient samples gene here, especially the samples of tens of thousands of years ago. The Chinese Academy of Sciences's Fu Qiaomei laboratory was able to successfully sequence the giant panda individuals from the Last Glacial Period to complete mitochondrial DNA, mainly because they developed ancient DNA capture technology to enable the concentration of extremely small amount of DNA still present in the ancient giant pandas bone material.

The Chinese Academy of Sciences, Fu Qiaomei and his team compared the mitochondria of individual giant panda in Cizhutuo Cave with the mitochondria of 138 existing bear families and 31 ancient bear families, found that the mitochondrial DNA of the Cizhutuo Cave giant panda showed the closest genetic relationship with the existing giant pandas compared with other bears. The giant panda and other bears have the most direct maternal common ancestor 12 to 8 million years ago.

However, the mitochondria of the individuals in Cizhutuo Cave belong to a different mitochondrial ancestry besides the mitochondrial sequence variation of the existing giant pandas, indicating that its population was separated from and coexists with the ancestors of the existing giant pandas. The study concluded that the separation of Cizhutuo individuals from the maternal ancestors of existing giant pandas could be traced back to the Middle Pleistocene (227-144,000 years ago),   far before the age of the most direct maternal common ancestor of the existing giant panda (9.4 -55,000 years ago).

In addition, they also found that there are 18 amino acid sequence changes between the Cizhutuo Cave individual and the existing giant panda mitochondrial coding region, further confirming that the giant panda individuals of Cizhutuo Cave have different mitochondrial ancestry. These amino acid changes may be potentially related to their habitat in Guangxi, or due to the adaptation to the Last Glacial climate.

Based on maternal genetic data alone, the history of ancient giant pandas has presented a more diverse and unique look than we know. However, mitochondrial DNA provides a basic data point. Because nuclear DNA undergoes genetic recombination, the nuclear DNA from both parents is mixed to form the nuclear DNA of the offspring, which can provide tens of thousands of data points, more representative of the average level of population history.

The scientific results obtained by the institute indicate that the acquisition of ancient nuclear DNA from giant pandas is just around the corner, and future data will play a crucial role in accurately studying the evolutionary history of giant pandas.

The study was funded by the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Howard Hughes Medical Institute of the United States. 

Picture 1 Giant Panda Fossil of Cizhutuo Cave - Completed Mitochondrial Genome Sequencing ( Photoed by Zhang Yingqi, P.S by Xu Yong)

Picture 2 Cizhutuo Cave - Excavation site of the giant panda fossil of Cizhutuo (photoed by Zhang Yingqi)

Picture 3: The location of the discovery of the giant panda sample of Cizhutuo and the compute tomography of its skull (A); The mitochondrial phylogenetic map of giant pandas, which extends from the phylogeny of all bear species, shows that their unique mitochondrial lineage and that it had the common ancestor with the existing giant panda population about 183,000 years ago (B) .