Arthropods are one of the most abundant and diverse groups of animals on the planet. A key feature that has been modified during evolution to produce this diversity is the number and types of body segments. Most arthropods develop their segments in the same way: they add them one by one from the posterior, from a region commonly called the 'growth zone'. In spite of being the most common mode of arthropod segmentation, the growth zone is mostly unstudied. This project will analyze cell dynamics and genetic regulation of the growth zone in two species - a crustacean, Artemia, and a beetle, Tribolium - both of which add segments one by one from the posterior. It will focus on a common set of genes that recently have been hypothesized to control the growth zone and segmental patterning in diverse arthropods. The fusion of cellular dynamics and genetic regulation provides the strongest vantage point for developing hypotheses about the evolution of segmentation. In the long term, this research will provide additional data to evaluate the growing speculation that segmentation throughout all animals shares a common evolutionary origin and that indeed segmentation is akin to the much broader phenomena of reiteration. This work is a collaborative effort between one PI at a teaching institution and one PI at a research institution. This project is aimed at both institutions to promote participation of undergraduates in research and includes a plan for students from the teaching institution to do summer research at the research institution. Both PIs are active in recruiting under-represented minorities and women to a supportive environment of scientific discovery.