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Ancient sedimentary DNA shows rapid post-glacial colonisation of Iceland followed by relatively stable vegetation until the Norse settlement (Landnám) AD 870
Quaternary Science Reviews ( IF 4 ) Pub Date : 2021-04-08 , DOI: 10.1016/j.quascirev.2021.106903
Inger Greve Alsos , Youri Lammers , Sofia E. Kjellman , Marie Kristine Føreid Merkel , Emma M. Bender , Alexandra Rouillard , Egill Erlendsson , Esther Ruth Guðmundsdóttir , Ívar Örn Benediktsson , Wesley R. Farnsworth , Skafti Brynjólfsson , Guðrún Gísladóttir , Sigrún Dögg Eddudóttir , Anders Schomacker

Understanding patterns of colonisation is important for explaining both the distribution of single species and anticipating how ecosystems may respond to global warming. Insular flora may be especially vulnerable because oceans represent severe dispersal barriers. Here we analyse two lake sediment cores from Iceland for ancient sedimentary DNA to infer patterns of colonisation and Holocene vegetation development. Our cores from lakes Torfdalsvatn and Nykurvatn span the last c. 12,000 cal yr BP and c. 8600 cal yr BP, respectively. With near-centennial resolution, we identified a total of 191 plant taxa, with 152 taxa identified in the sedimentary record of Torfdalsvatn and 172 plant taxa in the sedimentary record of Nykurvatn. The terrestrial vegetation at Torfdalsvatn was initially dominated by bryophytes, arctic herbs such as Saxifraga spp. and grasses. Around 10,100 cal yr BP, a massive immigration of new taxa was observed, and shrubs and dwarf shrubs became common whereas aquatic macrophytes became dominant. At Nykurvatn, the dominant taxa were all present in the earliest samples; shrubs and dwarf shrubs were more abundant at this site than at Torfdalsvatn. There was an overall steep increase both in the local accumulated richness and regional species pool until 8000 cal yr BP, by which time ¾ of all taxa identified had arrived. The period 4500-1000 cal yr BP witnessed the appearance of a a small number of bryophytes, graminoids and forbs that were not recorded in earlier samples. The last millennium, after human settlement of the island (Landnám), is characterised by a sudden disappearance of Juniperus communis, but also reappearance of some high arctic forbs and dwarf shrubs. Notable immigration during the Holocene coincides with periods of increased incidence of sea ice, and we hypothesise that this may have acted as a dispersal vector. Thus, although ongoing climate change might provide a suitable habitat in Iceland for a large range of species only found in the neighbouring regions today, the reduction of sea ice may in fact limit the natural colonisation of new plant species.



中文翻译:

古代沉积DNA显示出冰岛冰期后的快速定居,随后植被相对稳定,直到北欧定居点(Landnám)公元870年

了解殖民化的模式对于解释单一物种的分布以及预测生态系统如何应对全球变暖至关重要。岛上的植物可能特别脆弱,因为海洋代表了严重的扩散障碍。在这里,我们分析了来自冰岛的两个湖泊沉积物核心的古代沉积DNA,以推断殖民化和全新世植被发育的模式。我们来自Torfdalsvatn和Nykurvatn湖的核心跨越最后一个c。12,000 cal yr BP和c。BP分别为8600 cal yr。通过近百年的解析,我们总共确定了191种植物分类单元,其中在Torfdalsvatn的沉积记录中鉴定了152种分类单元,在Nykurvatn的沉积记录中鉴定了172种植物分类单元。Torfdalsvatn的陆地植被最初主要是苔藓植物,北极草本植物如虎耳草spp。和草。在BP大约10,100 cal yr年,观察到大量新的类群迁移,灌木和矮灌木丛变得很普遍,而水生植物则占主导地位。在Nykurvatn,最早的样本中都存在优势类群。灌木丛和矮灌木丛比Torfdalsvatn的灌木丛丰富。直到8000 cal BP为止,本地累积的丰富度和区域物种库总体上都急剧增加,到那时,已查明的所有分类单元的¾到来了。在4500-1000 cal yr BP期间,出现了少量的苔藓植物,类粉虫和前生草,这些是早期样品中未记录到的。近千年,海岛(Landnám)的人类定居后,特点是突然消失刺柏群落,而且还会出现一些高高的北极前哨和矮灌木丛。全新世期间的显着移民与海冰发生率增加的时期相吻合,我们假设这可能充当了传播媒介。因此,尽管不断发生的气候变化可能为今天仅在邻近地区发现的大量物种提供了合适的冰岛栖息地,但海冰的减少实际上可能限制了新植物物种的自然定殖。

更新日期:2021-04-08
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