Aggregative multicellularity evolved independently in the eukaryotic supergroup Rhizaria

Area of Science:

• Eukaryotic evolution
• Protistan biology
• Developmental biology

Background:

• Multicellularity has evolved independently multiple times in eukaryotes, leading to diverse lineages like animals, plants, and fungi.
• A common form of eukaryotic multicellularity involves social aggregative fruiting, forming sorocarps, famously studied in Dictyostelium discoideum.
• Sorocarpic protists have been identified across five major eukaryote groups, but Guttulinopsis vulgaris remained unclassified.

Purpose of the Study:

• To classify the globally distributed species Guttulinopsis vulgaris.
• To investigate the evolutionary origins of aggregative multicellularity in protists.
• To determine if Guttulinopsis vulgaris exhibits social aggregative fruiting behavior.

Main Methods:

• Phylogenomic analyses were conducted using a dataset comprising 159 proteins.
• The evolutionary placement of Guttulinopsis vulgaris within the eukaryotic tree of life was determined.

Main Results:

• Phylogenomic analyses placed Guttulinopsis vulgaris within the Rhizaria supergroup.
• This finding represents the first known instance of aggregative multicellularity in the Rhizaria.
• Guttulinopsis vulgaris demonstrates a complex, coordinated developmental process involving thousands of cells.

Conclusions:

• Guttulinopsis vulgaris is a member of the Rhizaria supergroup.
• The discovery of aggregative multicellularity in Rhizaria expands the known diversity of this complex trait.
• This finding highlights the independent evolution of multicellularity across major eukaryotic lineages.