Foraminifera ("forams") are structurally complex, abundant, and widely distributed protists. Allogromiid forams often dominate deep-sea and high-latitude assemblages, and are believed to aggressively rework sediments in these habitats. Allogromiids are also common in continental slope systems, which are important for the recycling of organic matter and hence for global biogeochemical cycles. Most studies of foram biology have focused on species from shallow tropical/temperate settings, where they have been shown to employ diverse trophic strategies ranging from osmotrophy to metazoan carnivory. As a major meio- and macrofaunal component in deeper settings, a better understanding of the in situ behavior and feeding biology of basal allogromiids is of major importance to the ocean sciences. Explorers Cove, Antarctica, is currently the only place on Earth where biologists can use scuba to directly access a "deep-sea-like" ecosystem and collect basal allogromiids in bulk; it is therefore a site of profound scientific interest. Explorers Cove forams, which may normally have bathymetric ranges to >3,000 m, are ideal for field and laboratory experimentation, and serve as useful model systems for studying the ecology and evolution of deep-sea assemblages.
Just as a firm understanding of the protists is vital to developing a clear picture of early eukaryotic evolution, the key to the origin of Foraminifera lies in the study of the early branching allogromiids. An improved understanding of the relationships between early forams through multigene based molecular phylogenies is a goal of this project. Additionally, a more careful study of the "crown allogromiids" will illuminate the evolutionary steps that lead to the rotaliids, which dominate many shallow-water temperate environments and pelagic foram assemblages. Extant protists represent the modern products of ancient predatory (phagotrophic) prokaryotes. Protists are well known as consumers of microbiota, but the consumption of metazoans by protists, one focus of our studies on allogromiids, is not widely appreciated. As a result, the consequences of ancient predatory protists are rarely considered a major factor in the diversification of animals during the late Proterozoic/early Cambrian . This project will test hypothesis that predation on metazoans is widespread among basal forams, and if supported by analyses of the new protein-coding sequence data, then the role of these protists in Neoproterozoic ecosystems will need to be reevaluated.
The objectives of the research are to: test the validity of the foram phylogenetic hypotheses currently based solely on single gene sequence data; examine the ultrastructure of representative members of allogromiid clades; explore the origin of polar forams using the new molecular phylogenetic and structural data; further examine the trophic strategies of allogromiids; and to determine if carnivory is a fundamental nutritional mode for basal forams, or a special derived character. Additional broader impacts of this research include training of underrepresented groups through both grass-roots efforts and formal participation in national federally funded education programs.
