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Evolutionary Origin of Euglena.

Bożena Zakryś1, Rafał Milanowski2, Anna Karnkowska2

  • 1Department of Molecular Phylogenetics and Evolution, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089, Warsaw, Poland. zakrys@biol.uw.edu.pl.

Advances in Experimental Medicine and Biology
|April 22, 2017
PubMed
Summary
This summary is machine-generated.

Euglenids are single-celled flagellates defined by their unique pellicle. Photosynthetic euglenids evolved via secondary endosymbiosis, with Euglena remaining a polyphyletic genus despite extensive study.

Keywords:
EuglenaEuglenalesEuglenophyceaeExcavataeuglenidsevolutionphylogenytaxonomy

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Area of Science:

  • Protistology
  • Evolutionary Biology
  • Cell Biology

Background:

  • Euglenids are diverse, free-living, single-celled flagellates characterized by a unique pellicle.
  • Their nutrition varies, including phagotrophy and photosynthesis, with photosynthetic species forming a distinct subclade (Euglenophyceae).
  • Photosynthetic euglenids originated from secondary endosymbiosis with a green alga.

Purpose of the Study:

  • To review the evolutionary lineages and classification of photosynthetic euglenids.
  • To highlight the challenges in classifying the genus Euglena due to morphological similarities and polyphyly.
  • To underscore the importance of Euglena gracilis as a model organism.

Main Methods:

  • Phylogenetic analysis based on morphological and molecular data (implied).
  • Review of existing taxonomic classifications and literature.
  • Comparative analysis of morphological features across different genera.

Main Results:

  • Three evolutionary lineages of photosynthetic euglenids are identified: Rapaza viridis (basal), Eutreptiales (marine), and Euglenales (freshwater).
  • Euglenales are divided into Phacaceae and Euglenaceae families, with Euglena identified as polyphyletic.
  • Morphological similarities between Euglena and Euglenaria complicate classification.

Conclusions:

  • The classification of Euglenales requires further refinement, particularly for the genus Euglena.
  • Morphological data alone has led to artificial classification systems.
  • Continued research is essential for resolving phylogenetic relationships and improving taxonomic stability in euglenids.