The Intracellular Symbiont Enhances Recombination in a Dose-Dependent Manner.

is an intracellular alphaproteobacterium that infects 40%-60% of insect species and is well known for host reproductive manipulations. Although are primarily maternally transmitted, evidence of horizontal transmission can be found in incongruent host-symbiont phylogenies and recent acquisitions of the same strain by distantly related species. Parasitoids and predator-prey interactions may indeed facilitate the transfer of between insect lineages, but it is likely that are acquired via introgression in many cases. Many hypotheses exist to explain prevalence and penetrance, such as nutritional supplementation, protection from parasites, protection from viruses, or direct reproductive parasitism. Using classical genetics, we show that increase recombination in infected lineages across two genomic intervals. This increase in recombination is titer-dependent as the MelPop variant, which infects at higher load in , increases recombination 5% more than the Mel variant. In addition, we also show that another bacterial intracellular symbiont of , does not induce an increase in recombination. Our results suggest that infection specifically alters its host's recombination landscape in a dose-dependent manner.