June 18 (UPI) -- Analysis of genetic remains extracted from an ancient panda skull has revealed new giant panda lineage from Southern China.
Scientists were able to recover mitochondrial DNA from 22,000-year-old panda remains. The fossil was found in Cizhutuo Cave in China's Guangxi Province. Researchers sequenced the panda's genome, and found the specimen belonged to a unique, ancient lineage that separated from modern pandas between 144,000 and 227,000 years ago.
"Using a single complete mtDNA 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," Qiaomei Fu, researcher with the Chinese Academy of Sciences, said in a news release. "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."
The Cizhutuo panda's mitochondrial genome -- detailed in the journal Current Biology -- is the oldest genetic evidence of pandas yet recovered.
Modern pandas are confined to China's Shaanxi and Gansu provinces, but research suggests they were once much more widespread. However, scientists have struggled to determine the relationship between ancient panda groups and modern pandas.
Scientists used a novel technique to sequence and piece together the Cizhutuo panda's DNA fragments, successfully reconstructing the specimen's mitochondrial genome. Researchers compared the sequenced genome with those of related bear species, both modern and extinct.
The remains of the Cizhutuo panda were recovered from a subtropical environment, where it's hot and humid -- environs unfriendly to DNA. Scientists, however, were able to locate uncompromised DNA fragments inside the fossil's inner ear structure.
Researchers hope new comparative genomic analysis will help them understand whether Cizhutuo panda's unique habitat or ancient climate change might explain the lineage's genetic differences.
"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.