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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >Ancient DNA reveals late survival of mammoth and horse in interior Alaska
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Ancient DNA reveals late survival of mammoth and horse in interior Alaska

机译：古代DNA揭示了阿拉斯加内部猛ma象和马的晚期生存

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Causes of late Quaternary extinctions of large mammals (“megafauna”) continue to be debated, especially for continental losses, because spatial and temporal patterns of extinction are poorly known. Accurate latest appearance dates (LADs) for such taxa are critical for interpreting the process of extinction. The extinction of woolly mammoth and horse in northwestern North America is currently placed at 15,000–13,000 calendar years before present (yr BP), based on LADs from dating surveys of macrofossils (bones and teeth). Advantages of using macrofossils to estimate when a species became extinct are offset, however, by the improbability of finding and dating the remains of the last-surviving members of populations that were restricted in numbers or confined to refugia. Here we report an alternative approach to detect ‘ghost ranges’ of dwindling populations, based on recovery of ancient DNA from perennially frozen and securely dated sediments (sedaDNA). In such contexts, sedaDNA can reveal the molecular presence of species that appear absent in the macrofossil record. We show that woolly mammoth and horse persisted in interior Alaska until at least 10,500 yr BP, several thousands of years later than indicated from macrofossil surveys. These results contradict claims that Holocene survival of mammoths in Beringia was restricted to ecologically isolated high-latitude islands. More importantly, our finding that mammoth and horse overlapped with humans for several millennia in the region where people initially entered the Americas challenges theories that megafaunal extinction occurred within centuries of human arrival or were due to an extraterrestrial impact in the late Pleistocene.
机译：大型哺乳动物（“大型动物”）晚第四纪灭绝的原因仍在争论中，尤其是对于大陆灭绝，因为人们对灭绝的时空格局知之甚少。此类分类单元的准确最新出现日期（LAD）对于解释灭绝过程至关重要。根据对大型化石（骨骼和牙齿）的年代调查得出的LAD，目前北美北美西北地区的猛ma象和马的灭绝被定为现在的15,000–13,000历年。然而，由于无法找到数量有限或仅限于避难所的最后幸存成员的遗骸并为其定年，因此抵消了使用大型化石来估计物种何时灭绝的优势。在这里，我们报告了一种替代方法，该方法可根据从多年冻存和日期安全的沉积物（sedaDNA）中回收的古代DNA来检测不断减少的“幽灵范围”。在这种情况下，sedaDNA可以揭示大化石记录中似乎不存在的物种的分子存在。我们表明，阿拉斯加内部的猛ma象和马一直存在到至少10500年BP，比大型化石调查显示晚了数千年。这些结果与声称白令猛ia象的全新世生存仅限于生态隔离的高纬度岛屿有关。更重要的是，我们发现，在人们最初进入美洲的地区，猛ma象和马象与人类重叠了几千年了。这一理论对以下理论提出了质疑：大型动物灭绝是在人类到达几个世纪之内发生的，或者是由于晚更新世的外星影响所致。

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