Wang Xiaoming, Tseng Zhijie Jack, Li Qiang, Takeuchi Gary T, Xie Guangpu
Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu Province 210046, People's Republic of China Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA.
Proc Biol Sci. 2014 Jul 22;281(1787). doi: 10.1098/rspb.2014.0893. Epub 2014 Jun 11.
The 'third pole' of the world is a fitting metaphor for the Himalayan-Tibetan Plateau, in allusion to its vast frozen terrain, rivalling the Arctic and Antarctic, at high altitude but low latitude. Living Tibetan and arctic mammals share adaptations to freezing temperatures such as long and thick winter fur in arctic muskox and Tibetan yak, and for carnivorans, a more predatory niche. Here, we report, to our knowledge, the first evolutionary link between an Early Pliocene (3.60-5.08 Myr ago) fox, Vulpes qiuzhudingi new species, from the Himalaya (Zanda Basin) and Kunlun Mountain (Kunlun Pass Basin) and the modern arctic fox Vulpes lagopus in the polar region. A highly hypercarnivorous dentition of the new fox bears a striking resemblance to that of V. lagopus and substantially predates the previous oldest records of the arctic fox by 3-4 Myr. The low latitude, high-altitude Tibetan Plateau is separated from the nearest modern arctic fox geographical range by at least 2000 km. The apparent connection between an ancestral high-elevation species and its modern polar descendant is consistent with our 'Out-of-Tibet' hypothesis postulating that high-altitude Tibet was a training ground for cold-environment adaptations well before the start of the Ice Age.
世界“第三极”是对喜马拉雅-青藏高原的一个恰当比喻，它指的是这片广阔的冻土区域，虽地处低纬度但海拔高，其冰冻地形可与北极和南极相媲美。生活在西藏和北极的哺乳动物都有适应寒冷温度的特征，比如北极麝牛和西藏牦牛都有又长又厚的冬季皮毛，而食肉动物则有更具掠夺性的生态位。在此，据我们所知，我们报告了来自喜马拉雅地区（札达盆地）和昆仑山脉（昆仑山口盆地）的上新世早期（距今360万至508万年）狐狸——邱氏狐新物种与极地地区现代北极狐之间的首个进化联系。这种新狐狸高度特化的食肉牙齿与北极狐的牙齿极为相似，且比之前北极狐最古老的记录早了300万至400万年。低纬度、高海拔的青藏高原与最近的现代北极狐地理范围至少相隔2000公里。一个远古高海拔物种与其现代极地后代之间明显的联系，与我们的“走出西藏”假说相符，该假说假定在冰河时代开始之前，高海拔的西藏就已经是寒冷环境适应的训练场。
