ibclogo XVI International Botanical Congess


Abstract Number: 4318
Session = 3.1.1


EVOLUTION OF COCCOID GREEN ALGAE AS INFERRED FROM DNA SEQUENCE ANALYSES:AN OVERVIEW


Thomas Friedl, Experimental Phycology, Univ. Goettingen, Germany


Coccal green algae are the predominant life form of plants that form a sister group with the land plants. Ultrastructural and molecular studies show that they are of multiple origins, occurring in the Trebouxiophyceae and Chlorophyceae, with few coccal forms in the Ulvophyceae and prasinophytes. A close relationship with filamentous algae is suggested by rRNA and Actin gene phylogenies. Similar vegetative cells may occur in evolutionarily removed lineages and flagellated reproductive stages may have been lost independently. Thus, a natural classification using vegetative cell morphology alone is difficult. A natural circumscription may be reached where ITS rDNA phylogenies correspond with certain characters (wall structure, chloroplast morphology). Unique ITS sequence elements may allow unambiguous identification where only minor morphological differences occur.


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