Phylogeny and ecology of ciliated protozoa

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I study the ciliated protozoa, common unicellular microorganisms found in lakes and oceans, in soils and forest litter, and in small ponds. Ciliates feed on bacteria and smaller protists. Ciliates are eaten by larval fish and small crustaceans that may then be eaten by larger fish. Thus, ciliates are trophic links in food webs, and it is important to understand their roles in these ecosystems. One aspect of my research program is experimental ecology. We have built a research facility called the Limnotron in which we will be able to assemble ecosystems of varying complexity, some of them with ciliates and other unicellular organisms. In this way, we can begin to understand their ecological importance in, for example, maintaining ecosystem stability. There may be over 30,000 species of ciliates, but the state of our knowledge of their species diversity and geographic distributions presents a barrier to understanding their ecological role. For example, different species may have very different ecological roles so correct species identification is a critical first step in any ecological study. Thus, a second major goal of my research is to develop molecular methods, such as DNA barcodes, to enable us to operationally assess biodiversity and distribution. An understanding of ciliate diversity leads to a third major goal: construction of both the evolutionary history or phylogeny of the group and establishment of a modern classification. Today phylogenetic analyses use gene sequences, such as ribosomal genes, which are highly conserved across all life forms. Species are related to each other by comparing these gene sequences, which are more similar to each other than the microscopic morphology of ciliates. Ribosomal genes however are not providing us with sufficient information, and so I will use multiple genes to increase the character information and provide more robust conclusions. Since I am the only expert on these organisms in Canada and one of the few in the world, I often collaborate with colleagues around the world to describe new species.