Chapter 6. The Evolution of the Diatoms

  1. Prof. Dr. Edmund Bäuerlein
  1. Wiebe H. C. F. Kooistra

Published Online: 20 MAR 2008

DOI: 10.1002/9783527619443.ch6

Handbook of Biomineralization: Biological Aspects and Structure Formation

Handbook of Biomineralization: Biological Aspects and Structure Formation

How to Cite

Kooistra, W. H. C. F. (2007) The Evolution of the Diatoms, in Handbook of Biomineralization: Biological Aspects and Structure Formation (ed E. Bäuerlein), Wiley-VCH Verlag GmbH, Weinheim, Germany. doi: 10.1002/9783527619443.ch6

Editor Information

  1. Max-Planck-Institute for Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18 A, 82152 Planegg, Germany

Publication History

  1. Published Online: 20 MAR 2008
  2. Published Print: 25 MAY 2007

ISBN Information

Print ISBN: 9783527316410

Online ISBN: 9783527619443

SEARCH

Keywords:

  • auxospore;
  • centrics;
  • diatom;
  • fossil record;
  • frustule;
  • ortho-silicic acid;
  • pennates;
  • phylogeny;
  • silica cycle;
  • thalassiosira

Summary

Diatoms constitute the single-most diverse group of microalgae. Their hallmark is the compound silica cell wall, the frustule, which encases the cell completely but, nevertheless, permits growth and cell division. Silica cell wall elements are encountered also in their resting stages and during the brief sexual phase in the diatom life cycle, namely during the formation of a specialized zygote, the auxospore. Frustule shape and ultrastructural details vary considerably across the diversity and are at the foundation of taxonomic treatment. Generally, diatoms are grouped into radial centrics, polar centrics, and pennates. Molecular phylogenies reveal that the former two categories constitute ancestral groups (grades), whereas the latter forms a clade. Fossil evidence confirms these findings. Diatoms are ubiquitous in marine, freshwater and temporarily humid terrestrial habitats, and they dominate the plankton in many coastal and oceanic regions. It is therefore no surprise that diatoms constitute major players in the geochemical cycles of carbon and silica - a role they have played since at least the Lower Cretaceous, as their fossil record reveals. Several explanations can be given for the apparent success of the diatoms, but their remarkable morphological and ecological diversity is a key aspect. For example, the planktonic lifestyle developed from benthic ancestry several times, independently.