Mycoplasma gallisepticum is a bacterial pathogen that causes respiratory diseases in domestic poultry. Recently, especially over the last 12 years, this bacterial infection has jumped species and emerged as a disease and spread to a wild songbird host, the house finch. This disease was first spotted in house finch populations in Washington, D. C. in 1994 and quickly spread to house finch populations in several other mid-Atlantic and eastern states and then quickly crossed the continental U.S. The disease in house finches was different than in domestic poultry in that the house finches developed severe eye infections. The objective of this project is to sequence and analyse the genomes of five key Mycoplasma strains from the 1994 outbreak to the present and of isolates from different disease outbreak locations across the U.S. The goal is to track the molecular evolution of this rapidly evolving disease agent as a consequence of its emergence and spread in a new host population. Further, this study plans to determine what factors permitted this bacterial pathogen to jump host species and to exhibit a new disease in the new host population. This study is rare in that samples of the disease agents are available for all the points from which it emerged in the new host population. This permits an unprecedented epidemiological study of a wild disease event. The study has important broader impacts for the public since many are birders and are interested in songbirds. Many are concerned about the decline in song birds and the PI will provide a website for the general findings of the research for the birding public.