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Researcher turns brown algae phylogeny upside down

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24.06.2002

According to fellow phycologists, algae expert Stefan Draisma from the Leiden University has turned brown algae phylogeny completely upside down. His research shows that few of the currently assumed relationships between the orders are correct. Furthermore, it transpires that some simple species arose not earlier but later than more complex species.

Brown algae are multicellular algae. Brown pigments mask the green colour of the chlorophyll. Most of the species occur in temperate regions. The plants vary from very small thread-like algae to giants of more than 50 metres in length. These giants, called kelps, grow for example off the Californian coast where they form true underwater forests. In the Netherlands fucoids can form large inter- and sub-tidal monostands on dikes. Under the waterline Fucus serratus and Sargassum muticum grow.

As well as examining the external characteristics of the brown algae, the researchers from Leiden University and the University of Groningen also compared the DNA composition of the various species. Previous studies had also examined the DNA but this was done in a less structured and extensive manner than in the current study.

Biologists can use the new phylogeny to reorder the division Phaeophyta (brown algae). This new classification can be based on natural groups. Algae expert Draisma proposes a new classification of 20 orders. The old classification had 13 orders.

During the phylogenetic research, the biologists also discovered new species of brown alga. The researchers named this alga Sphacelaria tsengii after the Chinese phycologist and supplier of the research material, Prof. Tseng. The alga is found off the coast of South China, is one to two centimetres long and grows in small tufts, which with a bit of fantasy can be compared to the hair under the armpits. Characteristic for this newly discovered alga is the form of the propagules. These are branches used for asexual reproduction. The propagules have a tapered stalk and two tapered arms.

Michel Philippens | Source: alphagalileo

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