Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, 100044, China; Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China; University of Chinese Academy of Sciences, 100049, China.
Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, 100044, China.
Curr Biol. 2018 Jun 18;28(12):R693-R694. doi: 10.1016/j.cub.2018.05.008.
Present-day giant pandas (Ailuropoda melanoleuca) are estimated to have diverged from their closest relatives, all other bears, ∼20 million years ago, based on molecular data [1]. With fewer than 2,500 individuals living today [2], it is unclear how well genetic data from extant and historical giant pandas [3] reflect the past [3]. To date, there has been no complete mitochondrial DNA (mtDNA) sequenced from an ancient giant panda. Here, we use ancient DNA capture techniques [4] to sequence the complete mitochondrial genome of a ∼22,000-year-old giant panda specimen (radiocarbon date of 21,910-21,495 cal BP with ± 2σ at 95.4% probability; Lab.no Beta-473743) from the Cizhutuo Cave, in Leye County, Guangxi Province, China (Figure 1A). Its date and location in Guangxi, where no wild giant pandas live today, as well as the difficulty of DNA preservation in a hot and humid region, place it as a unique specimen to learn about ancient giant pandas from the last glacial maximum. We find that the mtDNA lineage of the Cizhutuo panda coalesced with present-day pandas ∼183 thousand years ago (kya, 95% HPD, 227-144 kya), earlier than the time to the most recent common ancestor (TMRCA) of mtDNA lineages shared by present-day pandas (∼72 kya, 95% HPD, 94-55 kya, Supplemental Information). Furthermore, the Cizhutuo panda possessed 18 non-synonymous mutations across six mitochondrial genes. Our results show that the Cizhutuo mtDNA lineage underwent a distinct history from that of present-day populations.
目前根据分子数据估计，大熊猫（Ailuropoda melanoleuca）与其他所有熊类的亲缘关系在约 2000 万年前就已经分化[1]。如今现存的大熊猫数量不到 2500 只[2]，因此尚不清楚现生和历史大熊猫的遗传数据在多大程度上反映了过去[3]。迄今为止，还没有对古大熊猫进行过完整的线粒体 DNA（mtDNA）测序。在这里，我们使用古 DNA 捕获技术[4]对来自中国广西乐业县的 Cizhutuo 洞的一个约 22000 年前的大熊猫标本（放射性碳日期为 21910-21495 cal BP，95.4%概率的 ± 2σ；实验室编号 Beta-473743）的完整线粒体基因组进行测序（图 1A）。它的年代和地理位置在广西，如今那里没有野生大熊猫，而且在炎热潮湿的地区保存 DNA 的难度较大，这使它成为研究末次冰盛期古大熊猫的独特标本。我们发现，Cizhutuo 大熊猫的 mtDNA 谱系与现生大熊猫在约 18.3 万年前（95% HPD，227-144 kya）合并，早于现生大熊猫 mtDNA 谱系的最近共同祖先（TMRCA）（约 7.2 万年前，95% HPD，94-55 kya，补充信息）。此外，Cizhutuo 大熊猫在六个线粒体基因中发生了 18 个非同义突变。我们的研究结果表明，Cizhutuo mtDNA 谱系经历了与现生种群截然不同的历史。
