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Researchers reconstruct population history of the giant panda

Researchers led by the Institute of Zoology of Chinese Academy of Sciences and BGI have reconstructed the giant panda’s population history from its origin to the present. The research team discovered that human influences have driven recent population deviation and decline. In the past, however, climate changes were the primary drivers in panda population fluctuation. Researchers hope that their research will help guide conservation efforts for the giant panda and other endangered species.

Giant pandas live in several mountain ranges in central China, in Sichuan, Shaanxi, and Gansu provinces. While they once lived in lowland areas, farming, forest clearing, and other human activities now keep giant pandas in the mountains, according to the Smithsonian. The giant panda is listed as endangered in the Word Conservation Union’s Red List of Threatened Species. Currently, there are approximately 1,600 left in the wild and more than 300 in zoos and breeding centers around the world.

As the rarest member of the bear family, the giant panda is a well-known symbol of international wildlife conservation. Threatened by habitat loss, human persecution and many other problems, some believe that the giant panda is at an “evolutionary dead end” because of its dietary specialization, habitat isolation and reproductive constraints.

Researchers successfully completed the whole genome resequencing of 34 wild giant pandas and discovered that the current six geographic populations of giant pandas could be split into three genetic populations. They also identified two population expansions, two “bottlenecks” and two population deviations.

The giant panda’s ancestor was omnivorous or carnivorous. Millions of years ago the warm and wet weather helped the spread of bamboo forests which led to the first population expansion of the giant panda. However, researchers learned that approximately 700,000 years ago, the panda population began to decline because of the two largest Pleistocene glaciations in China. They also found that the giant panda’s first population bottleneck took place about 300,000 years ago.

The giant panda’s second population explosion occurred after the retreat of the Penultimate Glaciations, peaking between 30,000-50,000 years ago. Researchers believe that the warm weather in the Greatest Lake Period and alpine confer forest may have helped the growth of the panda population. The second population bottleneck occurred, however, during the period of last glacial maximum when the climate was cold and dry. The climate conditions led to extensive habitat loss for the giant panda.

Researchers found that in the giant panda’s recent population history, the panda population spit into three genetic populations: Qinling (QIN), Minshan (MIN) and Qionglai-Daxiangling-Xiaoxiangling-Liangshan (QXL). They classified the signal of panda’s local adaptation, finding that the biggest group of selected genes in these populations was connected to the sensory system.

“We have identified three genetic populations of giant panda for the current six geographic populations lived in western of China. The varied local adaptations found in our study provide invaluable resource for researchers to better select effective conservation methods to rescue the giant panda even other endangered species. The translocation of wild-caught individuals or releasing the captive-bred ones may be a feasible approach,” said Shancen Zhao, project manager from BGI, in a statement.

The study’s findings were recently described in detail in the journal Nature Genetics.

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