Functioning of microphytobenthos in estuaries
Abstract This mini review describes the newest classification of diatoms based on their evolution, which was obtained from molecular data. Because centric forms were found earlier in the geological record it is assumed that the pennate diatoms evolved from the centric forms and 3 classes were descri...
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| Format: | Text |
| Language: | English |
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2006
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1070.6866 http://www.vliz.be/imisdocs/publications/138745.pdf |
| Summary: | Abstract This mini review describes the newest classification of diatoms based on their evolution, which was obtained from molecular data. Because centric forms were found earlier in the geological record it is assumed that the pennate diatoms evolved from the centric forms and 3 classes were described: the centric diatoms, the araphid pennate and the raphid pennate diatoms. However, molecular data showed that the centric diatoms are most likely paraphyletic and the diatoms are now divided into two groups: Clade 1 contains the radial centric diatoms and Clade 2 contains two subClades: the first sub-Clade contains the bipolar centrics and the Thalassiosirales and the second sub-Clade contains the pennate diatoms to which many of the microphytobenthos species belong. These Clades and additional morphological support for this new taxonomy is discussed in this mini review. The diatoms are one of the most easily recognisable groups of major eukaryotic algae, because of their unique silicifi ed cell wall, which consists of two overlapping thecae, each in turn consisting of a valve plus a number of hoop-like or segmented girdle bands. Such structures are present in all living diatoms (except following secondary loss, e.g., in the case of the endosymbiotic diatoms living in foraminifera), and also in early, well-preserved fossil diatoms from the early Albian (Lower Cretaceous) of what is now the Weddell Sea, Antarctica Functioning of microphytobenthos in estuaries. |
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