Protist Evolution and Phylogeny


The beginning of this century brought spectacular changes in our understanding of eukaryote phylogeny, especially the early evolution of microeukaryotic lineages commonly called protists. Phylogenomic studies based on analysis of more than 200 genes produced a relatively well‐resolved tree of eukaryotes. Metagenetic studies using environmental deoxyribonucleic acid (eDNA) revealed an extraordinary diversity of protist lineages, highlighting their great ecological and evolutionary importance. A new higher level classification of eukaryotes combining the results of microscopic and various ‘omics’ studies has been proposed. In this classification, the majority of eukaryotes are placed in seven monophyletic supergroups: Amoebozoa, Opisthokonta, Archaeplastida, Alveolata, Stramenopiles, Rhizaria and Excavata. Phylogenetic relationships between these supergroups and 11 independent eukaryotic lineages are relatively well established. However, there is no consensus concerning the position of the root of eukaryotic tree. Further single‐cell microscopic and genomic studies are also necessary for exploring the extraordinary diversity of protistan phyla revealed by the eDNA surveys.

Key Concepts:

  • Molecular phylogenies drastically changed our understanding of eukaryotes evolution.

  • Phylogenomic data are essential for reconstructing the deep relationships of eukaryotes.

  • Ribosomal phylogenies are useful for inferring relationships within protistan phyla and for species identification.

  • Current protist classification comprises 4–7 supergroups and a few independent lineages.

  • Important part of protist diversity has been uncovered by environmental DNA study.

Keywords: phylogenomics; metagenetics; protists; microeukaryotes; unicellular eukaryotes; protozoa; eukaryotes classification; ribosomal phylogenies

Figure 1.

Phylogenomic tree of eukaryotes. Modified after the analysis of 258 genes by Burki et al. () and other recent publications.



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Further Reading

Adl SM, Leander BS, Simpson AGB et al. (2007) Diversity, nomenclature and taxonomy of protists. Systematic Biology 56: 684–689.

Archibald JM (2009) The puzzle of plastid evolution. Current Biology 19: R81–R88.

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Pawlowski J (2013) The new microkingdoms of eukaryotes. BMC Biology 11: 40.

Pawlowski J and Burki F (2009) Untangling the phylogeny of amoeboid protists. Journal of Eukaryotic Microbiology 56: 16–25.

Roger A and Simpson AGB (2009) Evolution: revisiting the root of the eukaryotic tree. Current Biology 2009: R165–R167.

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How to Cite close
Pawlowski, Jan(Mar 2014) Protist Evolution and Phylogeny. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0001935.pub2]