Consequences of Colony Size and Configuration on Susceptibility of Choanoflagellates to Predation by Ciliates
Microbial eukaryotes are important components of aquatic food webs, with many microbial eukaryotes able to exist in both unicellular and multicellular forms. However, the effects of the size and configuration of such colonies on susceptibility to predation are not yet well understood. This summer, I will be continuing an investigation using the choanoflagellate, Choanoeca flexa (which can form cup-shaped colonies with flagella lining the cavity and which can turn themselves inside-out so that the flagella point outwards), to study the consequences of colony configuration on susceptibility to predation by the ciliate, Euplotes sp. I am using micro videography to record the interactions of C.flexa and Euplotes sp., and am analyzing those videos to measure which aspects of the morphology and behavior of these predators and prey affect Euplotes sp. feeding rates on colonies of different configurations and sizes. Choanoflagellates share a common ancestor with sponges (primitive animals) and are used as model systems to identify selective factors that might have affected the evolution of multicellularity and colony form in the ancestors of animals. Thus, my study may not only shed light on mechanisms affecting ecological interactions of aquatic protozoans, but also provide insights about whether predation might have been one of the selective pressures on colony configuration in the choanoflagellate-like ancestors of animals.