Population differentiation and structural variation in the Manduca sexta genome across the United States

"Many species that are extensively studied in the laboratory are less well characterized in their natural habitat, and laboratory strains represent only a small fraction of the variation in a species’ genome. Here we investigate genomic variation in three natural populations of an agricultural pest and a model insect for many scientific disciplines, the tobacco hornworm (Manduca sexta). We show that hornworms from Arizona, Kansas, and North Carolina are genetically distinct, with Arizona being particularly differentiated from the other two populations. Specifically, two segregating inversions and a potential pseudogene are found only in the Arizona population. One inversion on the Z chromosome may enhance adaptive evolution of the sex chromosome, while the significance of the other, autosomal inversion remains unclear. The pseudogene may be involved in the exploitation of a novel hostplant in Arizona, but functional genetic assays will be required to confirm this hypothesis. Nevertheless, our results reveal undiscovered natural variation and provide useful genomic data for a model insect species."