I am very excited to announce that our latest paper in Scientific Reports, on the Nesobasis damselflies in Fiji is available online as of today! In this paper we explore the relationship between these endemic island damselflies and a group of alpha-protobacteria called Wolbachia. These bacteria are intracellular (living inside the cells of their hosts), and are fairly common in insects and other arthropods. As these bacteria are intracellular, they are passed on in eggs but not in sperm, and so male hosts represent a reproductive dead-end for the bacteria, as they cannot infect the next generation of hosts.
This has led to a number of strange relationships between the hosts and their Wolbachia parasites, with Wolbachia sometimes killing male hosts, or feminizing them, to improve their own chances at reproduction. Wolbachia can also cause cytoplasmic incopatability (CI) in their hosts, with males and females of a particular host species only being able to successfully mate with other individuals that carry compatible strains of Wolbachia. CI can sometimes drive speciation in host species by limiting mating opportunities within host populations.
We found a large number of Neosbasis species to be infected with Wolbachia, —a total of 25 different Wolbachia strains were detected across these damselfly species, and another genus of Fijian damselfly, Melanesobasis, was also infected. Many of the damselflies carry multiple strains of Wolbachia. We also found different rates of infection across different islands; about half of the species on Viti Levu, the largest island in Fiji, were infected with Wolbachia, while all of the species on Vanua Levu (the second largest island) were infected.
In previous work we had shown that for some species of Nesobasis, males are much less common than females at reproductive sites, causing us to suspect that Wolbachia might be killing males, but Wolbachia were found to be common in these species as well as in species where males are abundant, and so they are not likely to be skewing host sex ratios. The possibility that CI might have something to do with helping to create all of these species of Nesobasis is an intriguing idea, and one that these results suggest would be worthwhile to explore!
Please check out the paper here at Scientific Reports!