The Evolution of Morphogenetic Signalling in Social Amoebae

Abstract

Multicellular organisms have evolved several times from unicellular protists giving rise to the familiar forms of animals, plants and fungi. An important question in biology is how such transitions occurred. Multicellular life is typically dependent on complex communication between cells, whereas unicellular organisms respond mainly to environmental signals. Social amoebae are eminently suited to study the evolution of multicellularity, since they still combine a unicellular feeding stage with a stage where thousands of cells aggregate to form motile slugs and fruiting structures. In this chapter we summarize the signalling mechanisms that coordinate multicellular development in social amoebae and we discuss how these signalling mechanisms evolved from a response to environmental stress in solitary amoebae.