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Protist Diversity in La Union, Philippines Revealed by Metabarcoding: Ecosystem- and Database-Dependent Lineage
Christon Jairus M Racoma1,2,3, Nikki Heherson A Dagamac1,2,4, Priyal Patel3
1The Graduate School, University of Santo Tomas, Manila, Philippines.
Environmental Microbiology
|May 8, 2026
Summary
This study explored protist diversity in Philippine freshwater and marine ecosystems using DNA sequencing. Metabarcoding revealed dominant microbial groups and highlighted the need for better databases to understand global protist biogeography.
Area of Science:
- Microbiology
- Eukaryotic diversity
- Molecular ecology
Background:
- Protists are diverse single-celled eukaryotes with uneven global study distribution.
- Southeast Asia, especially the Philippines, remains understudied for protist communities.
- Molecular techniques increasingly reveal hidden microbial diversity.
Purpose of the Study:
- Investigate protist community diversity, including Amoebozoa, in Philippine freshwater and marine ecosystems.
- Utilize metabarcoding and reference databases to analyze environmental DNA.
- Assess the impact of database selection on ecological pattern inference.
Main Methods:
- Collected environmental DNA from various Philippine ecosystems.
- Amplified and sequenced the V4 region of the 18S rRNA gene using Oxford Nanopore Technologies.
- Employed metabarcoding with two distinct reference databases for analysis.
Main Results:
- The Telonemia, Stramenopiles, Alveolata, and Rhizaria (TSAR) supergroup dominated across ecosystems.
- Freshwater habitats showed higher family-level diversity and taxonomic richness.
- Community composition varied between freshwater and marine environments, influenced by database choice, yet ecological gradients remained consistent.
Conclusions:
- Metabarcoding effectively captures broad ecological patterns in protist biogeography.
- Database selection significantly impacts inferred taxonomic composition.
- Further exploration of microbial diversity in the Philippines and improved reference databases are crucial.
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