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International Journal on Algae
SJR: 0.219 SNIP: 0.261 CiteScore™: 0.24

ISSN Print: 1521-9429
ISSN Online: 1940-4328

International Journal on Algae

DOI: 10.1615/InterJAlgae.v4.i3.10
pages 1-38

Modern views on the position of algae in the system of the organic world

N. P. Masyuk
N.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2, Tereshchenkovskaya St., 01001 Kiev, Ukraine
I. Yu. Kostikov
Department of Plant Biology, Institute of Biology and Medicine, Taras Shevchenko National University of Kiev, 2 Acad. Glushkov Ave., Kiev 03022, Ukraine


The data of studies of algae at the ultrastructural and molecular levels confirm that the lower photoautotrophic plants comprise a heterogeneous group of taxa, which originated from heterotrophic organisms phylogenetically connected to various groups. According to the theory of endosymbiotic origin of eukaryotes, we attempted to outline in the article the patterns of phylogenetic relationships of eukaryotic algae separately by their nuclear, mitochondrial and plastid genomes, with the subsequent synthesis of the phylogenetic patterns obtained. Schemes of relationships of algae according to nuclear and mitochondrial genomes are basically similar, but the relationships reconstructed according to the plastid genomes essentially differ from the previous two patterns. The comparison of the three phylogenetic trees has confirmed the status of 16 divisions of algae that were outlined earlier by phenotypic (including ultrastructural) characters, that testifies to a high resolution of the latter. According to the available data, all divisions of algae (except Dinophyta) are monophyletic by each of three basic genomes contained in their cells. In the scheme of relationships of the basic groups of living organisms based on the modem data, algae occupy not a compact position, as in former systems, but a rather diffuse placement. The most ancient group of eukaryotic algae, Euglenophyta together with closely related Kinetoplastida, are restricted to the transitional middle portion of the phylogenetic tree of life; other phyla, which have arisen almost simultaneously during the large-scale evolutionary radiation of eukaryotes, are concentrated in its crown area. Relationships of Dinophyta with others heterotrophic Alveolates (Ciliophora and Apicomplexa), phylogenetie links of Chlorarachniophyta with heterotrophic amoeboflagellates, relationships of chromophytic algae (Raphidophyta, Chrysophyta, Eustigmatophyta, Xanthophyta, Phaeophyta, Bacillariophyta, Dictyochophyta) with heterotrophic Stramenopiles; and relationships of the "plant line" (Glaucocystophyta — Cryptophyta — Rhodophyta — Chlorophyta + higher plants) with Fungi and Metazoa have been confirmed. Application of new research methods and techniques of phylogenetic taxonomy has resulted in the shift of paradigms that necessitates the unification of efforts of zoologists and botanists, bacteriologists and virologists, cytologists, biochemists and molecular biologists for developing the concept of main taxonomic categories and creating the general system of the living world.