The arthropods comprise the most species-rich animal phylum, filling a broad range of distinct ecological niches and comprising about 80% of all animal species. Central to the arthropods' diversity is a variety of modular, segmented body forms, as well as modular, segmented appendage forms. Features such as these are central to major animal body plans. How such features arise and diversify by the evolution of specific developmental patterning mechanisms is a fundamental issue that is not yet well understood. Water bears (tardigrades) can serve as uniquely valuable research subjects for addressing how modular, segmented body forms and appendages diversified among ancestors of the arthropods. In this project, tardigrades will be used as an outgroup to address this issue, using genomics, gene expression analysis, and reverse genetic methods. A tardigrade genome project will be completed and used to generate a publicly shared database. Diversification of body regions along the anteroposterior axis and along the proximodistal axis of the limbs will be studied using water bear gene expression and gene function studies. The project outcomes will include infrastructure for future studies of this animal phylum and will answer fundamental questions about the evolution of major animal body plans. The work will also train students and postdoctoral trainees in scientific research.
