The origins of multicellularity and its ecological consequences

Multicellularity dramatically changed life on earth.

Cellular cooperation gave rise to novel functions that facilitated the evolution of several major branches of the tree of life, including animals, fungi, plants and algae.

While we know a lot about how multicellular organisms function, we lack fundamental knowledge of the natural conditions that foster its evolution and the consequences it has for ecosystems.This project will study a radiation of green algae to address:1) What the advantages of multicellularity are: Surveys of algae communities across Sweden will be used to model the ecological niches of unicellular and multicellular species (year 1).2) How multicellular groups arise: Experiments will test how environmental changes influence unicellular processes that promote cellular associations (years 1-2). 3) How multicellular organisms evolve: Experimental evolution of unicellular species will be used to study multicellular evolution in real-time (years 2-3).4) How multicellularity changes ecosystems: The resources unicellular species use and produce regulate global nutrient cycles.

Such resources are predicted to change with multicellular evolution.

Mesocosm experiments will be used to test how (years 3-4).Together, this project will help explain how complex life has evolved and how microbial communities will respond to environmental change.