在更新世冰川周期中,连接北美和欧亚大陆的白令大陆桥定期暴露并被海平面波动淹没。这种陆地连接允许动物的间歇性扩散,包括人类,在西柏林根(东北亚)和东柏林根(北美西北部)之间,改变了两大洲的动物群落组成。更新世冰川周期也对温度产生了深远的影响,降水和植被,影响动物群落结构和人口统计。虽然这些古环境影响已经在许多来自柏林根的大型草食动物中进行了研究(例如,野牛,猛犸象,马),该地区存在的各种食肉动物行会的更新世种群动态知之甚少,由于它们的丰度较低。在这项研究中,我们分析了来自古代棕熊(Ursusarctos;n=103)和狮子(Pantheraspp。;n=39),在更新世期间分散到北美的两个大型食肉动物。我们的结果揭示了白莲狮子和棕熊种群动态的惊人同步性,白令大陆桥上的多波散布与低海平面的冰川时期相吻合,以及在海洋同位素第3阶段东部白兰州的同步局部灭绝。这两个类群的进化历史强调了白令陆桥在分布中的关键生物地理作用,北美巨型动物群的周转和维持。
The Bering Land Bridge connecting North America and Eurasia was periodically exposed and inundated by oscillating sea levels during the Pleistocene glacial cycles. This land connection allowed the intermittent dispersal of animals, including humans, between Western Beringia (far northeast Asia) and Eastern Beringia (northwest North America), changing the faunal community composition of both continents. The Pleistocene glacial cycles also had profound impacts on temperature, precipitation and vegetation, impacting faunal community structure and demography. While these palaeoenvironmental impacts have been studied in many large herbivores from Beringia (e.g., bison, mammoths, horses), the Pleistocene population dynamics of the diverse guild of carnivorans present in the region are less well understood, due to their lower abundances. In this study, we analyse mitochondrial genome data from ancient brown bears (Ursus arctos; n = 103) and
lions (Panthera spp.; n = 39), two megafaunal carnivorans that dispersed into North America during the Pleistocene. Our results reveal striking synchronicity in the population dynamics of Beringian
lions and brown bears, with multiple waves of dispersal across the Bering Land Bridge coinciding with glacial periods of low sea levels, as well as synchronous local extinctions in Eastern Beringia during Marine Isotope Stage 3. The evolutionary histories of these two taxa underline the crucial biogeographical role of the Bering Land Bridge in the distribution, turnover and maintenance of megafaunal populations in North America.