Browsing by Subject "Wolbachia"

Phylogenetics is the study of the evolutionary history of life on Earth, which has shifted from relying on morphological characteristics to molecular data with the advancements in sequencing technology. Understanding Earth's biodiversity is crucial, as it has important implications for conservation, ecology, and evolution. Speciation occurs when barriers restrict gene flow between previously interbreeding populations. One such barrier may be endosymbiotic bacteria, like Wolbachia, which can manipulate host reproduction and create incompatibilities between host lineages. Wolbachia is widely distributed among arthropods and is the most common endosymbiont of insects. The bacterium is known to alter its hosts' biology, serving as a master manipulator of reproduction. Wolbachia-induced phenotypes can lead to the divergence of host lineages and speciation events. The genus Cotesia (Hymenoptera: Braconidae: Microgastrinae) is a highly diverse group of parasitoid wasps, where several species parasitize Melitaeini butterflies, including two cryptic species complexes. The current phylogenies of these species are 20 years old and need an update, as they were built with few markers and contain unresolved nodes. Wolbachia has been observed in this system, but its role remains largely unexplored. In this study, I aim to reconstruct the phylogeny of Cotesia species parasitizing Melitaeini butterflies, using two mitochondrial markers and eight nuclear markers to update our understanding of the differentiation of the cryptic Cotesia species. Additionally, I screened the specimens for Wolbachia to determine its possible role in shaping the Cotesia host phylogeny. I expect different Cotesia lineages to carry divergent Wolbachia strains or have different infection statuses (infected vs. uninfected). With fresh Cotesia specimens collected from various locations in Europe, I amplified and sequenced two mitochondrial markers (16s, COI) and eight nuclear markers (18s, 28s, CfCN, CfEN, EF1A1, LwRh, SLD5, TCEB) for phylogenetic analysis. The phylogenetic analysis revealed two main clades: Clade A, where Cotesia acuminata forms a polyphyletic group, and Clade B, where Cotesia melitaearum forms a monophyletic group. Wolbachia was detected only in one species, Cotesia melitaearum Sp. G, where the strain has persisted for over 20 years. The strains infecting Cotesia belong to supergroup B and are all closely related. The close relationship and low infection rate suggest that Wolbachia is not responsible for the original divergence but may play an ongoing role in restricting gene flow between species. The updated phylogeny is in concordance with the previous works but also strengthens our understanding of the relationships within Clade B. Further work is required to resolve some relationships within Clade B and understand the cryptic species' divergence.