Patterns of rare and abundant marine microbial eukaryotes

Area of Science:

• Marine ecology
• Microbial ecology
• Biodiversity research

Background:

• Biological communities typically feature abundant and rare species, a pattern pronounced in microbial ecosystems.
• Microbiologists often overlook the distinct characteristics of abundant and rare subcommunities, hindering understanding of community dynamics.
• Marine microbial eukaryotes are vital but underexplored components of global biodiversity.

Purpose of the Study:

• To investigate the distinct ecological roles and structuring patterns of abundant versus rare subcommunities in marine microbial eukaryotes.
• To analyze how organismal size and geographic location influence these subcommunities.
• To assess the potential of the rare biosphere as a reservoir for ecosystem response and adaptation.

Main Methods:

• Surveyed surface waters from six European coastal locations.
• Analyzed picoplankton, nanoplankton, and micro/mesoplankton size fractions.
• Employed deep Illumina sequencing of the 18S rRNA gene to identify taxa.

Main Results:

• Abundant subcommunities were primarily structured by organismal size, while rare subcommunities were mainly structured by geographic origin.
• Both abundant and rare subcommunities exhibited regular proportions across samples, suggesting consistent species-abundance distributions.
• The rare biosphere contains numerous metabolically active lineages, indicating its role as a responsive diversity reservoir.

Conclusions:

• Marine planktonic microeukaryote assemblages comprise dynamic, metabolically active abundant and rare subcommunities.
• These subcommunities display contrasting spatial structuring patterns but maintain regular proportions over space and time.
• The rare biosphere is a crucial, active component of marine microbial ecosystems, capable of rapid responses to environmental shifts.