This project addresses a fundamental and unanswered question in the origin of biological complexity and asks how entirely new genes are fabricated de novo. Bacteria are the most ancient and diverse life forms, and the presence of large numbers of novel genes in contemporary strains indicates both that gene formation is an on-going process and also that the complexity of bacterial gene repertoires originates from a novel and unknown source. The plan for the proposed research is to apply both computational and experimental methods that will determine if the viruses and phage that infect and interact with bacteria serve as the creative source for the production of novel genes. Our approach will assess the broad genomic diversity within bacteria and their associated phage, and establish the functional significance of this diversity by assessing the function of new gene and their affects on organismal fitness. The proposed research has the potential to change the way that we think about the origins of biological complexity , will provide direct evidence of a new evolutionary process, and will contribute significantly to other fields of biology, including co-evolutionary processes and synthetic biology.