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The Molecular Diversity of Phagotrophic Euglenids Examined Using Single-cell Methods
Gordon Lax1, Alastair G B Simpson1
1Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada.
Protist
|October 30, 2020
Summary
Phagotrophic euglenids, particularly Spirocuta, are phylogenetically diverse and crucial for understanding euglenid evolution. New SSU rDNA data reveals significant underestimation of their diversity, highlighting the need for further research.
Area of Science:
- * Protistology
- * Molecular Phylogenetics
- * Eukaryotic Evolution
Background:
- * Euglenids are diverse flagellates, including phototrophs, osmotrophs, and phagotrophs.
- * Phagotrophic euglenids, especially within the Spirocuta clade, are understudied despite their phylogenetic significance.
- * Understanding phagotroph diversity is key to tracing the evolutionary origins of phototrophy in euglenids.
Purpose of the Study:
- * To increase phylogenetic sampling of phagotrophic euglenids, particularly Spirocuta, using single-cell SSU rDNA sequencing.
- * To investigate the phylogenetic diversity within key phagotrophic genera like Urceolus, Jenningsia, Chasmostoma, Sphenomonas, Dinema, and Heteronema.
- * To assess the current understanding of phagotrophic diversity relative to known genera.
Main Methods:
- * Single-cell isolation and amplification of Small Subunit ribosomal DNA (SSU rDNA).
- * Phylogenetic analyses based on newly generated SSU rDNA sequences.
- * Comparative analysis with existing euglenid SSU rDNA data.
Main Results:
- * New SSU rDNA sequences were obtained for previously unsequmented genera (Urceolus, Jenningsia, Chasmostoma, Sphenomonas) and expanded coverage for others (Dinema, Heteronema).
- * Phylogenetic analyses revealed distinct clades within Jenningsia and Dinema, and suggested Sphenomonas is monophyletic and the deepest branch in Petalomonadida.
- * The study indicates that current genera significantly underestimate the true phylogenetic diversity of phagotrophic euglenids.
Conclusions:
- * Phylogenetic diversity of phagotrophic spirocutes is greater than currently recognized by existing genera.
- * Further multi-gene phylogenetic analyses are needed to resolve deep evolutionary relationships within Spirocuta.
- * Taxonomic revisions may be necessary as more sequence data becomes available, especially from type species.
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