Palaeoceanographic implications of genetic variation in living North Atlantic Neogloboquadrina pachyderma

• Published in: Nature
• Main Authors: Bauch, D, Darling, K, Simstich, J, Bauch, HA, Erlenkeuser, H, Kroon, Dick
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2003
• Subjects: Palaeoceanographic; genetic variation; North Atlantic; Neogloboquadrina; pachyderma; Foraminifera; Neogloboquadrina pachyderma
• Online Access: http://hdl.handle.net/1842/680; https://doi.org/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 Ocean1-3. 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 sediments1,2,4,5. Recently discovered cryptic genetic diversity in planktonic foraminifers6-8 now poses signifi- cant 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 speciesdependent incremental shift in right-coiling N. pachyderma shell calcite d 18O between the Last Glacial Maximum and full Holocene conditions. Guided by the percentage dextral coiling ratio, our findings enhance the use of d 18O records of rightcoiling 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.