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Linking Protistan Trophic Indicators to Phylogenetic Identity: From Single-Cell Grazing Evidence to Biogeographic
Luping Bi1,2,3, Ying Wang1,2,3, Fang Shi1,2,3
1Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen, China.
Molecular Ecology
|July 24, 2026
Summary
Researchers developed a new method to identify protist feeding behaviors, revealing mixotrophy in key aquatic species and highlighting challenges in interpreting fluorescence data for accurate ecological assessments.
Area of Science:
- Microbiology
- Marine Ecology
- Protistology
Background:
- Protists are crucial to aquatic ecosystems, but their diverse feeding strategies (photosynthesis, grazing, or both) are poorly understood at the species level.
- Most protists are uncultivable, and traditional community surveys lack the resolution to link species identity with specific trophic traits.
Purpose of the Study:
- To develop a novel framework for high-resolution analysis of protistan trophic diversity in natural environments.
- To link cellular traits, feeding behavior, and phylogenetic identity in individual protistan cells.
Main Methods:
- A field grazing-scPCR (single-cell Polymerase Chain Reaction) framework was developed, integrating short-term grazing assays and single-cell microscopy.
- This method combined morphological analysis, fluorescence indicators, ingestion evidence, and 18S rRNA gene sequencing for 21 isolated protistan cells.
- Phylogenetic analysis was used to classify trophic strategies and link findings to existing genomic databases (MetaPR2, Tara Oceans).
Main Results:
- The study confirmed constitutive mixotrophy in known species like Cryptomonas curvata and Poterioochromonas malhamensis.
- A novel candidate non-constitutive mixotroph was identified within the Katablepharidaceae family.
- Prey-derived fluorescence was found to potentially overestimate mixotrophy in natural samples, and different life stages (e.g., active vs. cyst) of C. curvata showed distinct fluorescence and feeding states.
Conclusions:
- The developed framework enables species-level resolution of protistan trophic diversity, advancing ecological understanding.
- Interpreting fluorescence and ingestion signals requires careful consideration of phylogenetic and ecological context to avoid overestimation of mixotrophy.
- This research provides a robust method for characterizing protistan functional diversity in aquatic ecosystems.
Keywords:
biogeographic occurrencemixotrophyphylogenetic identityprotistan grazingsingle‐cell PCRtrophic indicatorsMore Related Videos
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