An Introduction to Molecular Biotechnology. Группа авторов

6.3), and animals (Table 6.3; Figures 6.4 and 6.5) will be more closely characterized (a good short overview can be found in Campbell et al. (2018)). Apparently, the protozoa do not form a monophyletic clade as formerly assumed, but several independent evolutionary lineages. Traditionally, algae, and sometimes even fungi and bacteria, have been included in plants. As can be seen from Figures 6.1 and 6.2, only the metabionta with red algae, green algae, and land plants forms a monophyletic unit. Fungi cluster with Opisthokonta and thus much closer to animals and then to plants. Among animals, the Protostomia have now been separated in Ecdysozoa and Lophotrochozoa on account of molecular and anatomical data (Figure 6.4). According to the rules of cladistics, only monophyletic groups should be accepted. This requires a restructuring of some of the groups of organisms that had been grouped together, such as protists, mosses, fishes, and reptiles (Lecointre and Le Guyader 2007).

Table 6.1 Important groups of protists (model organisms or diseases caused by pathogens).

Major protist clades	Characteristics	Example
Tetramastigota	Secondary loss of mitochondria
Diplomonadida	Two separate cell nuclei	Giardia
Parabasalia
Trichomonadida	Undulating membrane	Trichomonas
Euglenozoa	Flagellates with or without photosynthesis
Euglenophyta	Paramylon as storage polysaccharide	Euglena
Kinetoplastida	With kinetoplast	Trypanosoma (sleeping sickness)
Chromalveolata	With chloroplasts from secondary endosymbiosis
Alveolata	Alveoli under the cell surface
Dinoflagellata	Shell from cellulose plates	Pfiesteria
Apicomplexa (Sporozoa)	Apical complex for penetration of hosts	Plasmodium (malaria), Toxoplasma
Ciliata (ciliates)	Cilium for movement and nutrient uptake	Paramecium
Stramenopilata or heterokonts	With trailing and flimmer flagellum
Oomyceta	Hypha; cell walls from cellulose
Bacillariophyceae (diatoms)	Glassy; walls separated into two	Pinnularia
Chrysophyceae (golden algae)	Two flagellate cells	Dinobryon
Phaeophyceae (brown algae)	Brown accessory pigments	Laminaria
Metabionta	With chloroplasts from primary endosymbiosis
Rhodobionta (red algae)	Without flagellate stage; phycoerythrin	Porphyra
Chlorobionta (green algae)	With chloroplasts (similar to land plants)	Chlamydomonas
Charophyceae
→ Land plants
Unikonta
Amoebozoa	With sheet‐like form pseudopods	Amoeba
Mycetozoa (slime mold)	Saprophyte; amoeboid stages form colonies	Physarum, Dictyostelium
Opisthokonta	Protruding flagellum
Fungi (Ascomycetes, Basidiomycetes)	Cell walls from chitin, saprophytic	Saccharomyces cerevisiae (yeast)
Amanita phalloides (deadly agaric)
Choanoflagellata	With microvilli
→ Metazoa (animals)

      The red, brown, and green algae were previously grouped with the plants; due to new molecular systematics, a new order has been proposed.

      Important model organisms are given in bold.

Figure 6.2 Phylogenetic relationships between protists and transition to plants and animals.

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