Symbiotic relationships between microbes and eukaryotes are ubiquitous across habitats and taxa on Earth. In all of these associations, symbionts must transmit faithfully between hosts to establish stable interactions over evolutionary time. Transmission can occur horizontally, between unrelated hosts, and/or vertically, through inheritance, which has enormous consequences for symbiont genome evolution. In my teaching seminar, I will cover the theory and current progress in symbiont evolutionary genomics, which explains why not all obligately intracellular symbionts that co-opt host reproduction for their own transmission have eroded genomes. In my research seminar, I will present my current work that aims to understand how vertically transmitted symbionts interact with host factors without interfering with normal host biology. The naturally-occurring association between the alphaproteobacterium Wolbachia and its fruit fly host, Drosophila melanogaster, presents an ideal genetic and cell biology model to investigate these processes. I will show how Wolbachia uses the host cytoskeleton to localize to the primordial germline without interfering with germline development. Then, I present evidence suggesting that Wolbachia synthesizes a protein that structurally mimics a host motor protein, which may be involved in the symbiont’s subcellular localization or niche construction. This research reveals fundamental bacterial symbiont inheritance mechanisms that will be essential for ensuring that Wolbachia is inherited at high frequencies in biological control applications.