Abstract：
Historical climate data indicate that the Earth has passed through multiple geological periods with much warmer-than-present climates, including epochs of the Miocene (23-5.3 mya BP) with temperatures 3-4°C above present, and more recent interglacial stages of the Quaternary, for example, Marine Isotope Stage 11c (approx. 425-395 ka BP) and Middle Holocene thermal maximum (7.5-4.2 ka BP), during which continental glaciers may have melted entirely. Such warm periods would have severe consequences for ice-obligate fauna in terms of their distribution, biodiversity and population structure. To determine the impacts of these climatic events in the Nordic cryosphere, we surveyed ice habitats throughout mainland Norway and Svalbard ranging from maritime glaciers to continental ice patches (i.e. non-flowing, inland ice subjected to deep freezing overwinter), finding particularly widespread populations of ice-inhabiting bdelloid rotifers. Combined mitochondrial and nuclear DNA sequencing identified approx. 16 undescribed, species-level rotifer lineages that revealed an ancestry predating the Quaternary (> 2.58 mya). These rotifers also displayed robust freeze/thaw tolerance in laboratory experiments. Collectively, these data suggest that extensive ice refugia, comparable with stable ice patches across the contemporary Norwegian landscape, persisted in the cryosphere over geological time, and may have facilitated the long-term survival of ice-obligate Metazoa before and throughout the Quaternary.
摘要：
历史气候数据表明，地球经历了多个地质时期，气候比现在温暖得多，包括温度高于3-4°C的Miocene（23-5.3myaBP），以及第四纪更近的间冰期，例如,海洋同位素阶段11c（约425-395kaBP）和中全新世热力最大值（7.5-4.2kaBP），在此期间，大陆冰川可能完全融化了。这样的温暖时期将对含冰动物区系的分布产生严重后果，生物多样性和人口结构。为了确定这些气候事件对北欧冰冻圈的影响，我们调查了整个挪威大陆和斯瓦尔巴群岛的冰栖息地，从海上冰川到大陆冰片(即不流动，内陆冰遭受深冻越冬)，发现特别广泛的冰栖轮虫种群。线粒体和核DNA组合测序鉴定出大约16个未描述，物种级轮虫谱系揭示了一种早于第四纪（>2.58mya）的祖先。这些轮虫在实验室实验中还显示出强大的冻融耐受性。总的来说，这些数据表明广泛的冰避难所，与当代挪威风景中稳定的冰片相当，在地质时期坚持在冰冻圈，并可能在第四纪之前和整个第四纪中促进了含冰后生动物的长期生存。
