How marine are Marine Stramenopiles (MAST)? A cross-system evaluation

Area of Science:

• * Marine microbial ecology
• * Protist diversity and evolution
• * Molecular phylogenetics

Background:

• * Marine Stramenopiles (MAST) are ancient microbial eukaryotes identified via ribosomal RNA (rRNA) gene sequences.
• * Most MAST diversity remains uncultured, with prior research focusing on marine habitats.
• * Limited knowledge exists regarding MAST presence outside marine environments.

Purpose of the Study:

• * To assess the extent to which MAST can be classified as marine protists.
• * To update Stramenopiles phylogeny and identify novel MAST lineages.
• * To investigate MAST distribution across various habitats.

Main Methods:

• * Analysis of the extensive EukBank dataset.
• * Incorporation of newly available rRNA gene sequences.
• * Phylogenetic analysis of Stramenopiles.

Main Results:

• * MAST are primarily marine, with exceptions in MAST-2 and MAST-12 found in freshwater and soil.
• * Three novel MAST lineages were identified.
• * Specific MAST clades (-1, -3, -4, -7) dominate marine water columns with distinct latitudinal patterns.

Conclusions:

• * The study confirms and expands the known diversity of MAST groups.
• * MAST are predominantly marine, but some lineages inhabit freshwater and soil.
• * MAST distribution patterns in marine environments are significant.