Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Bown, P. R. Search for Related Content GeoRef GeoRef Citation

Calcareous nannoplankton evolution: a tale of two oceans

Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK e-mail: p.bown{at}ucl.ac.uk

Calcareous nannoplankton diversity, evolutionary rates and species longevity show markedly different characters above and below the Cretaceous/Tertiary boundary. Excluding mass extinction events, and the initial origination and radiation, Mesozoic nannoplankton diversity is characterized by relatively continuous increase with low background evolutionary rates and high species longevity. Cenozoic diversity is more variable and features significant Eocene and Neogene diversity declines, with little or no recovery. Cenozoic evolutionary rates are also consistently higher than those of the Mesozoic, and species longevity is low. The response of nannoplankton to climate cooling in the two eras is particularly revealing: cold intervals in the Cretaceous saw greater paleobiogeographical differentiation and high-latitude nannoplankton provinces that supported diversifying communities, whereas, cooling in the Eocene and Neogene coincided with diversity declines, the selective extinction of warm-water taxa, and high-latitude provinces with reduced diversity. It appears likely that the presence of widespread stable, subtropical and tropical oligotrophic water masses promoted the diversification of the broadly K-strategist calcareous nannoplankton (and dinoflagellates) for much of the Mesozoic and into the early Paleogene. The switch to an icehouse climate, however, transformed the oceans, favouring the r-strategist diatoms at the expense of the other phytoplankton groups. The profound Eocene cooling established new, cold-water habitats that limited calcareous nannoplankton habitation and diversification, but promoted diatom expansion and diversification at high latitudes. Diatoms became the most competitive of the phytoplankton groups, flourishing in all environments but particularly those with high and pulsed nutrient inputs, although their expansion may also have been aided by tectonic and biological factors that increased the flux of biolimiting silica to the oceans.

This article has been cited by other articles:

				H. Liu, I. Probert, J. Uitz, H. Claustre, S. Aris-Brosou, M. Frada, F. Not, and C. de Vargas Extreme diversity in noncalcifying haptophytes explains a major pigment paradox in open oceans PNAS, August 4, 2009; 106(31): 12803 - 12808. [Abstract] [Full Text] [PDF]

				M.-P. Aubry A major Pliocene coccolithophore turnover: Change in morphological strategy in the photic zone Geological Society of America Special Papers, January 1, 2007; 424(0): 25 - 51. [Abstract] [Full Text] [PDF]