Why study choanoflagellates?

An Evolutionary Perspective.

Multicellularity has arisen several times in the course of evolutionary history each with unique features and attributes. As Leo Buss noted animal multicellularity is unique, compared to plant and fungal multicellularity, because animals have the capacity to move relative to one another, that is they lack a rigid, confining, cell wall. To understand the evolution of animal multicellularity, the reconstruction of the correct evolutionary antecedents is essential. Specifically, understanding of the character evolution prior to the evolution of animals it is critical to understand the biology animals close living relatives. The closest known living relative of animals is a group of collared flagellates called the choanoflagellates. Choanoflagellates are aquatic heterotrophic eukaryotes characterized morphologically by a single apical flagellum that is surrounded by a collar of actin filled microvilli. Many species of choanosflagellates live a solitary life style; however, some species have the capacity to form colonies. This is particularly interesting because it raises the possibility that the last common ancestor of choanoflagellates and animals may have shared this characteristic, thus understanding choanoflagellate colony formation will be inform our understanding about the evolution of animal multicellularity.