Bauch D, Darling K, Simstich J, Bauch H A, Erlenkeuser H, Kroon D
GEOMAR, Wischhofstrasse 1-3, 24148-Kiel, Germany.
Nature. 2003 Jul 17;424(6946):299-302. doi: 10.1038/nature01778.
The shells of the planktonic foraminifer Neogloboquadrina pachyderma have become a classical tool for reconstructing glacial-interglacial climate conditions in the North Atlantic Ocean. Palaeoceanographers utilize its left- and right-coiling variants, which exhibit a distinctive reciprocal temperature and water mass related shift in faunal abundance both at present and in late Quaternary sediments. Recently discovered cryptic genetic diversity in planktonic foraminifers now poses significant questions for these studies. Here we report genetic evidence demonstrating that the apparent 'single species' shell-based records of right-coiling N. pachyderma used in palaeoceanographic reconstructions contain an alternation in species as environmental factors change. This is reflected in a species-dependent incremental shift in right-coiling N. pachyderma shell calcite delta18O between the Last Glacial Maximum and full Holocene conditions. Guided by the percentage dextral coiling ratio, our findings enhance the use of delta18O records of right-coiling N. pachyderma for future study. They also highlight the need to genetically investigate other important morphospecies to refine their accuracy and reliability as palaeoceanographic proxies.
浮游有孔虫厚皮新球藻的壳体已成为重建北大西洋冰期 - 间冰期气候条件的经典工具。古海洋学家利用其左旋和右旋变体，目前以及晚第四纪沉积物中，这两种变体在动物丰度上呈现出与温度和水体相关的独特反向变化。最近在浮游有孔虫中发现的隐秘遗传多样性，给这些研究带来了重大问题。在此，我们报告遗传证据，表明古海洋学重建中使用的基于右旋厚皮新球藻壳体的明显“单一物种”记录，会随着环境因素变化而出现物种交替。这体现在末次盛冰期和全新世全盛期之间，右旋厚皮新球藻壳体方解石δ18O的物种依赖性增量变化上。在右旋盘绕比例百分比的指导下，我们的发现增强了右旋厚皮新球藻δ18O记录在未来研究中的应用。它们还凸显了对其他重要形态物种进行遗传学研究的必要性，以提高其作为古海洋学代理指标的准确性和可靠性。
