Pandas in past were much more widespread, says 22,000-year-old fossil
DNA sequence finds a distinct mitochondrial lineage, suggesting that the Cizhutuo panda.
The report, published in the journal Current Biology, shows that the ancient panda found in Cizhutuo Cave in the Guangxi Province of China separated from present-day pandas 144,000 to 227,000 years ago, suggesting that it belonged to a distinct group not found today.
"Using a single complete mitochondrial (mt) DNA sequence, we find a distinct mitochondrial lineage, suggesting that the Cizhutuo panda, while genetically more closely related to present-day pandas than other bears, has a deep, separate history from the common ancestor of present-day pandas," said Qiaomei Fu from the Chinese Academy of Sciences.
"This really highlights that we need to sequence more DNA from ancient pandas to really capture how their genetic diversity has changed through time and how that relates to their current, much more restricted and fragmented habitat," said Fu.
Very little has been known about pandas' past, especially in regions outside of their current range in Shaanxi province or Gansu and Sichuan provinces.
That is a particular challenge because the specimen comes from a subtropical environment, which makes preservation and recovery of DNA difficult.
The researchers successfully sequenced nearly 150,000 DNA fragments and aligned them to the giant panda mitochondrial genome reference sequence to recover the Cizhutuo panda's complete mitochondrial genome.
The researchers said that those amino acid changes may be related to the ancient panda's distinct habitat in Guangxi or perhaps climate differences during the Last Glacial Maximum.
The researchers said that their success in capturing the mitochondrial genome also suggests that they might successfully isolate and analyse DNA from the ancient specimen's much more expansive nuclear genome.
"Comparing the Cizhutuo panda's nuclear DNA to present-day genome-wide data would allow a more thorough analysis of the evolutionary history of the Cizhutuo specimen, as well as its shared history with present-day pandas," Fu said.
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