Phylogenomics and eDNA to study interaction networks of insects across tropical rainforests

Tropical rainforest ecosystems are generally recognised as top biodiversity hotspots, but there are huge differences in the total species richness among biogeographic and ecographic settings. We only have minimal understanding of these differences and their causes, mostly because the great diversity prohibits strict comparisons among sites, except perhaps for the most well studied groups of vertebrates.

Even less well known are the complex interactions within these ecosystems, e.g. between herbivorous insects and their host plants.

This project will tackle the challenge of global comparisons through a novel approach that combines ecosystem-wide genomics with phylogenetics. We will use the specific case of Coleoptera (beetles), the arguably largest radiation of Earth,

in a comparison of primary forests across three continents, representing the Oriental, Neotropical, and Afrotropical regions. We will ask: what is the phylogenetic diversity of these communities and is diversity recent or ancient (i.e. are rainforests 'cradles' or 'museums' of diversity)? Where on Earth is the highest endemicity of lineages, and are there hotspots of lineage origin?

At the population level, we will ask if the most phylogenetically diverse communities also hold high genetic diversity within the species, using population size as a measure of age of species in different continents. Finally, eDNA methods allow to study interactions: between herbivores and hostplants, bark beetles and tree-pathogenic fungi, and dung beetles and their mammalian dung resource.

The student will be part of the SITE-100 project (www.site100.org) for the study of global arthropod diversity, which provides a large unpublished database of genomic and imaging data that can be exploited for this project. Progress in the field of high-throughput taxonomy is rapid, but at this stage they rarely go beyond issues of method development.

Its application to tropical beetle assemblages across continents allows the taxonomic characterisation of a largely unknown realm of biodiversity and the study of global patterns and conservation priorities, on an ecosystem scale.