Abstract
Protists are major actors of soil communities and play key roles in
shaping food webs, community assembly, and ecosystem processes, yet
their functional diversity is understudied. High-throughput sequencing
data have revealed their ubiquity and diversity, but lack of
standardized traits has hampered the integration of functional
information, limiting our understanding of soil ecosystems. Here we
propose a framework for soil protists, identify a set of common traits
to characterize their functional diversity, and apply the framework on a
broad-scale, real-world dataset. We reviewed studies on soil protists to
identify the traits used in the literature, and define a framework based
on 10 key traits that satisfy two criteria: availability of information,
and applicability to most taxa. The framework was tested on a dataset of
environmental DNA metabarcoding data from 1123 soil samples collected in
48 glacier forelands worldwide. Traits were assigned to all the 570
Molecular Operational Taxonomic Units (MOTUs) detected in our dataset,
leading to the production of a global trait-based dataset from glacier
forelands. We estimated the functional space of protist communities and
evaluated if the selected traits were effective in describing protist
diversity. The functional space of protist communities showed that the
MOTUs are clustered in three regions, mainly reflecting different
nutritional and habitat preferences. The proposed framework is
appropriate for multiple applications, including estimation of
functional diversity and food web analyses, and provides a basis for
ecological studies on soil protists, enabling the functional
characterization of this essential but often neglected component of soil
biodiversity.