Dr. Brian S. Leander

Marine protozoology; comparative invertebrate zoology; evolutionary morphology, molecular phylogenetics, and biodiversity of eukaryotes – particularly euglenozoans, dinoflagellates, and marine apicomplexans; macroevolution; systematics

Single-celled organisms dominate the planet in terms of pure abundance and species diversity, yet most lack even a scientific name, and those with names were poorly described over a century ago before the technical revolutions brought on by electron microscopy and molecular biology. Recent advances in our understanding of cellular diversity are beginning to revolutionize traditional taxonomic paradigms and have dramatically altered long-held views on the evolution of eukaryotic cells and their organelles. My research program currently focuses considerable attention on comparative studies of ultrastructural systems in two diverse and ecologically important groups of eukaryotic single-celled predators, namely euglenids and dinoflagellates. Both groups have independently acquired sophisticated feeding apparatuses, complex photoreception apparatuses and photosynthetic organelles. The independent but corresponding patterns of morphological change in these groups represent an ideal comparative system for investigating the constraints and reoccurring innovations in cell evolution. Research on the diversity of these eukaryotic cells is, in essence, exploratory and progresses in four principal phases: (1) collection, isolation and cultivation of the organisms from nature, (2) identification, specimen preparation and description of the organisms using light and electron microscopy, (3) molecular characterization of the organisms and (4) computational analyses associated with digital image processing and molecularphylogenetics. Outcomes of this research will accelerate the discovery and characterization of new and poorly known species of single-cellular eukaryotes from diverse environments (marine sediment interfaces and hydrothermal vent systems), identify novelways in which unicellular predators have solved basic biological problems (cell locomotion, nutrition, and photoreception) and potentially impact a wide range of socioeconomic issues including public health, conservation, and the advancement of nanotechnologies.

The long-term objectives of my research program are to (a) understand major trends and transitions in eukaryotic cell evolution, (b) identify fundamental properties and reoccurring innovations in ultrastructural systems involved in locomotion, feeding and photoreception, (c) address specific hypotheses about ultrastructural character evolution using molecular phylogenetic methods and (d) accelerate the discovery and ultrastructural characterization of new and poorly known species of single-celled eukaryotes from diverse environments (marine sediment interfaces, surface plankton communities and hydrothermal vent communities). More focused student research projects will be motivated by these broad research themes. In the short-term, research will be centered on comparative studies of complex ultrastructural systems in both euglenids and dinoflagellates. Immediate projects will address the ultrastructural diversity, cellular mechanics and evolutionary history of (a) the feeding apparatuses of euglenids, (b)the euglenid cell cortex (pellicle), (c) the feeding apparatuses of heterotrophic dinoflagellates, (d) the cell cortex (amphiesma) of dinoflagellates and (e) the photoreception apparatuses of dinoflagellates.