The Windblown: Possible Explanations for Dinophyte DNA in Forest Soils

Area of Science:

• Protistology
• Environmental DNA (eDNA) Metabarcoding
• Terrestrial Ecology

Background:

• Dinoflagellates (dinophytes) are ubiquitous in aquatic ecosystems but their presence in terrestrial environments remains poorly understood.
• Previous studies have not conclusively documented dinophytes in terrestrial habitats.

Purpose of the Study:

• To investigate the presence and ecological role of dinophytes in Neotropical rainforest soils using environmental DNA (eDNA).
• To determine if observed dinophyte DNA sequences represent active terrestrial residents or passive dispersal from aquatic environments.

Main Methods:

• Analysis of an eDNA metabarcoding dataset from Neotropical rainforest soils.
• Phylogenetic placement of sequencing reads against a reference alignment and tree.
• Correlation analysis of dinophyte reads with taxonomic assignment, environmental preference, nutritional mode, and dormancy.

Main Results:

• Numerous sequencing reads were phylogenetically placed as dinophytes.
• These reads did not correlate with any specific taxonomic assignment, environmental preference, nutritional mode, or dormancy state.
• The data indicated passive dispersal rather than active colonization of terrestrial environments.

Conclusions:

• Dinophyte DNA found in Neotropical rainforest soils originates from windblown dispersal units of aquatic species.
• There is no evidence for biologically active, resident dinophyte populations in these terrestrial environments.
• This highlights the importance of distinguishing between passive eDNA deposition and active biological presence.