Clonal-aggregative multicellularity tuned by salinity in a choanoflagellate

Nature

by Núria Ros-Rocher

February 26, 2026

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A groundbreaking study reveals that the choanoflagellate *Choanoeca flexa* exhibits a unique form of multicellularity, combining both clonal growth and aggregation to adapt to its dynamic environment. Unlike previously thought, this organism can form colonies through pure clonality, pure aggregation, or a mix of both processes, depending on conditions. This flexible strategy allows *C. flexa* to thrive in ephemeral splash pools, where salinity fluctuates dramatically during evaporation and refilling cycles. The study challenges earlier assumptions that choanoflagellates exclusively rely on clonal multicellularity, expanding our understanding of how multicellularity can evolve. Multicellularity has evolved independently across eukaryotes, with two main mechanisms: clonality (serial cell division without separation) and aggregation (independent cells assembling into a group). While animals are known for clonal multicellularity, the study shows that *C. flexa* employs a more versatile approach. It forms motile and contractile cell monolayers, transitioning between unicellularity and multicellularity as needed. This behavior is influenced by environmental factors like salinity, which affects colony formation strategies. The research highlights how *C. flexa* uses clonal-aggregative multicellularity to establish colonies robustly in its variable habitat. In genetically distinct populations, aggregation is constrained by kin recognition, ensuring that only related cells come together. This finding underscores the adaptability of multicellular systems and their ability to evolve diverse strategies for survival in fluctuating environments. This discovery not only advances our knowledge of choanoflagellate biology but also provides new insights into the origins of multicellularity in early eukaryotes. By revealing a more flexible approach to colony formation, the study enriches our understanding of how complex life forms may have emerged and adapted to challenging conditions during evolution. The findings challenge previous generalizations about choanoflagellates and

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Originally published on Nature on 2/26/2026