A phylogeny of Kingdom ProtistaBiology 2: Form and Function

Overview• Highly diverse, likely polyphyletic group• Classification based on morphology

(presence/absence of flagella/cilia), pigmentation, types of mitosis, mitochondrial design, molecular genetics, modes of nutrition and locomotion, and presence of body armor

• Occupy diverse ecological habitats and include photosynthesizers, heterotrophs, decomposers, parasites and pathogens

• Differences between some groups are great enough to indicate separate endosymbiotic events

Heterotrophs with no permanent locomotor apparatus

• Characterized by locomotion through pseudopodia• Actinopodia and Foraminifera are armored with silica

tests - pseudopodia extrude through pores in the glassy coating

• Rhizopoda includes the classic protist species Amoeba

Rhizopoda

Actinopodia

Foraminifera

Flagellate protists

• Includes:• Pyrrhophyta (dinoflagellates), photosynthetic

(chlorophyll a, c, carotenoids)• Euglenophyta (euglenoids), photosynthetic

(chlorophyll a, b, carotenoids)• Zoomastigina (includes choanoflagellates,

probably the ancestor of Kingdom Animalia)

Algae• Both unicellular and multicellular (seaweed) forms.• Each phyla obtained chloroplasts in separate

endosymbiotic events– Chlorophyta (green alga), chlorophyll a, b,

carotenoids– Rhodophyta (red alga), chlorophyll a,

carotenoids, phycobilins– Phaeophyta (brown alga) chlorophyll a, c,

carotenoids

Diatoms (Chrysophyta)

• Classified based on radial or bilateral symmetry of silica shell

• Important component of phytoplankton - responsible for high proportion of global productivity

• Unique forms of sexual and asexual reproduction

Ciliaphora (Ciliates)

• Covered in hair-like cilia• Tough outer pellicle• Specialized vacuoles for ingestion and water

balance regulation• Organelle systems• Includes Paramecium

Apicomplexa (Sporozoans)

• Complex life cycles• Many are parasitic or pathenogenic (e.g., Plasmodium [malaria])

• Thick walled cysts make many sporozoans resistant to drug treatments

Slime molds

• Acrasiomycota (cellular slime molds)• Myxomycota (plasmodial slime molds)• Oomycota