Cospeciation between Laboulbeniales microfungi and their arthropod hosts


Laboulbeniales (Ascomycota) are obligate associates of arthropod hosts. Species in this order are microscopic in size and produce 3-dimensional structures—named thalli—instead of hyphae and mycelia. These fungi are dependent on a living host for the entire duration of their life cycle. With about 2370 described species in 146 genera, Laboulbeniales form the most diverse fungal assemblage associated with representatives of the phylum Arthropoda, predominantly insects. Laboulbeniales are a poorly studied group, with most research having focused on alpha taxonomy, which refers to species descriptions solely based on morphology. Our research group at Ghent University studies the Laboulbeniales using an integrative taxonomy approach (meaning that we also use evidence from ecology and molecular phylogeny). In addition, we focus on trophic interactions and community ecology.


The evolutionary history of many parasitic species depends on the evolution of their hosts. This leads to a tight association (congruence) between the phylogenies of host and parasite. However, when host shifts occur between phylogenetic distant hosts, the close evolutionary links may be weakened. In Laboulbeniales, it has been proposed that haustorial taxa – i.e., those that penetrate their hosts for nutrition – maintain close interactions with their hosts. The one-host-one-parasite (1H1P) model was proposed for these taxa, which assumes congruent phylogenies between Laboulbeniales species and their hosts. However, systematic analyses testing this hypothesis have not been performed in this group of fungi.


The goals of this master thesis are to expand on the phylogenetic tree of the Laboulbeniales, and to analyze patterns of cospeciation between Laboulbeniales and their arthropod hosts. The student who takes on this project will learn to extract DNA from thalli, generate sequences of loci that are informative at the species level, perform molecular phylogenetic analyses, and construct co-phylogenetic plots with appropriate packages in R. Analyses will focus on particular sections of the phylogenetic tree of Laboulbeniales: those that are well studied, including the genus Gloeandromyces (with bat fly hosts), the genus Hesperomyces (with ladybird hosts), and the genus Laboulbenia (with ground beetle hosts). The project will involve a component of screening previously collected material from Mozambique. Fieldwork is planned in Norway (with support from the Artsdatabanken Project 2023/25, iNoLa – Inventory of the Norwegian species of thallus-forming Laboulbeniales associated with beetles, with particular focus on the superfamily Staphylinoidea).


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