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A cytostome/cytopharynx in green euglenoid flagellates (Euglenales) and its phylogenetic implications
Bio Systems
|January 1, 1985
Summary
The phototrophic euglenoid Colacium libellae possesses a reduced feeding apparatus, suggesting evolutionary adaptation. This finding supports the origin of photosynthetic euglenoids from ancestral phagotrophic forms.
Area of Science:
- * Protistology
- * Evolutionary biology
- * Cell biology
Background:
- * The green, phototrophic euglenoid Colacium libellae exhibits unique cellular structures.
- * Previous hypotheses suggest phagotrophic euglenoids as ancestors to phototrophic forms.
Purpose of the Study:
- * To investigate the structure and homology of the feeding apparatus in Colacium libellae.
- * To provide evidence supporting the evolutionary transition from phagotrophic to phototrophic euglenoids.
Main Methods:
- * Microscopic examination of Colacium libellae.
- * Comparative analysis of cellular structures with related organisms.
Main Results:
- * Colacium libellae has a vestigial cytostome and cytopharynx.
- * A microfilamentous mesh connects the feeding pocket to homologous microtubules (MTR).
- * The cytostome's position suggests canal formation via invagination from phagotrophic ancestors.
Conclusions:
- * The feeding apparatus in Colacium libellae shows adaptations related to its phototrophic lifestyle.
- * Observations support the hypothesis that phagotrophic euglenoids evolved from a bondonid ancestor.
- * This lineage subsequently gave rise to phototrophic euglenoids through chloroplast acquisition.