Biological Sciences

Events and seminars

Rapid turnover of pathogen-blocking Wolbachia and their host-manipulating loci

Michael Turelli

5th October 2022 at 2:00pm [Download iCalendar / .ics file]

Ashworth, Hybrid: LT3 and Zoom

Associations between hosts and endosymbionts are widespread and represent the most intimate of interspecific interactions. Among known endosymbionts, maternally inherited Wolbachia alphaproteobacteria are the most common, infecting about half of all insect species and many other arthropods. Roughly half of Wolbachia cause cytoplasmic incompatibility (CI), a sperm modification that kills uninfected eggs and drives Wolbachia to high frequencies in host populations. CI-inducing Wolbachia variant wMel, discovered in Drosophila melanogaster, is being used to control dengue fever and other human diseases spread by the mosquito Aedes aegypti, as well as to suppress insect pests. Wolbachia’s ability to infect and cause CI in distantly related host species is critical to these applications. I provide an overview of the rapid spread of Wolbachia within and among host species. Although Wolbachia are pervasive across insect species, many of those Wolbachia have been acquired recently by their host species. Our latest finding is that wMel-related variants (“wMel-like” Wolbachia), which diverged over less than about 200,000 years, have naturally invaded insect hosts that diverged about 350 million years ago. These Wolbachia harbor CI-determining loci (cifs) and phage types that span all known cif variants found in insect-infecting Wolbachia. Thus, the cifs rapidly turn over across wMel-like lineages, just as Wolbachia rapidly turn over across insect hosts. As predicted, some of these Wolbachia have non-functional cifs, despite CI’s central role in Wolbachia prevalence. Our results reveal the timescales of Wolbachia, phage, and cif evolution –– and demonstrate why algebra is our friend.

Host Brian Charlesworth

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