Social systems (or sociality) in all living organisms are rooted in the evolution from single-celled organisms to multicellular and colonial forms. Extant cyanobacteria such as the marine dinitrogen fixing filamentous Trichodesmium spp. represent a window to the past enabling us to investigate the drivers of sociality in the ocean. Trichodesmium spp, which form massive surface blooms across the tropical oceans, are found as free-living single filaments (trichomes) and colonies comprised of aggregated trichomes in spherical (“puff”) or fusiform (“tuft”) morphologies. Substantial investigations into the physiology and ecology of this organism in its two forms show several adaptive benefits to the colonies. However, the drivers and mechanisms prompting transformation from single trichomes to colonies have not yet been elucidated.
We are studying the mechanistic of transformation from single filaments to colonies and the biogeochemical implications of the different morphologies (see schematic)