Experimental evolution of inherited symbionts in novel hosts

Symbiosis is present in almost all animals, and endosymbiotic bacteria, such as Spiroplasma, are commonly found in terrestrial arthropods. These inherited symbionts are not necessary for host survival but are highly prevalent and exhibit various phenotypic traits, including "male killing," "feminization," or provide selective advantages to their hosts. Despite the stability and efficiency of host-symbiont associations passed from mothers to offspring, the lack of co-cladogenesis suggests that many symbiont-host associations are temporary over evolutionary time. Therefore, hereditary symbionts must regularly establish themselves in new hosts, a process known as "host shifting," to survive. Host shifts are significant evolutionary events for both hosts and symbiont. Our study aims to investigate the factors encoded by symbionts that are crucial for host shifts and how environmental interactions impact host shifts. We will use model host-symbiont systems, such as the Drosophila/Spiroplasma system, to conduct host-shifting experiments and characterize the molecular evolution of inherited symbionts in response to experimental host shifts. Furthermore, we plan to incorporate genomic features associated with successful host shifting in natural populations of inherited symbionts. This study will provide insight into how host shifting impacts symbiont evolution in novel hosts and explain the remarkable diversity and abundance of inherited symbionts in arthropods.