Odorant and gustatory receptor diversity and evolution in the stinging wasps, ants, and bees (Hymenoptera: Aculeata)

• Applicants: Dr. Ewald Große-Wilde; Professor Dr. Oliver Niehuis
• Subject Area: Evolution, Anthropology ; Sensory and Behavioural Biology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 328103412

Information about the chemical composition of the environment is of critical importance for any organism. Chemical senses enable, for example, localizing and assessing the quality of food sources, oviposition sites, and reproductive partners. Social insects, such as ants, further utilize chemical factors (pheromones) to establish their social behaviors. Insects rely on three types of chemosensory receptors to perceive their chemical environment: olfactory (Ors), gustatory (Grs), and ionotropic receptors. While the latter are typically conserved in both their copy number and amino acid sequence, some insects feature remarkable Or and Gr repertoire expansions, most notably ants and bees. These expansions have been linked with the ants' and bees' eusocial life and the associated necessity to discriminate between various different chemical factors (e.g., trail pheromones). The characterization of the chemoreceptors in some non-eusocial wasps revealed, however, that species with a parasitoid lifestyle can also exhibit large chemoreceptor repertoires. Since chemoreceptors have not been studied in any lineage of Hymenoptera comparatively closely related to eusocial ants and bees, it remains unclear whether or not the extraordinary diversity of chemoreceptors in ants and bees is a derived feature of these two groups at all. Our research project aims at comprehensively inferring for the first time the evolution of Or and Gr diversity in the group of Hymenoptera from within which ants and bees arose: the stinging wasps (Aculeata). The expected results will inform both about when and in what context of lifestyle changes Or and Gr repertoire expansions occurred. Furthermore, they will provide new insights into whether or not Ors of the 9-exon subgroup are likely involved in the perception of cuticular hydrocarbons. We will study the chemoreceptors in a total of 23 stinging wasps (representing all major lineages of Aculeata, incl. those with parasitoid lifestyles) and in a wasp species closely related to the aculeates. To answer our research questions, we will compare gene transcript data from studying chemosensory tissues with genomic data. The foundation for our comparisons will be, among others, draft genome assemblies of eleven species of solitary wasps that we sequenced in preparation for this project. To compile corresponding genomic sequence data of Or- and Gr-coding genes also in species whose genomes have not been sequenced so far, we will apply a target DNA enrichment approach. The approach promises to foster future comparative analyses of gene repertoires in species whose genomes cannot be sequenced economically due to the huge size of the genomes. The insights gained from our research project will thus not only be of major interest for evolutionary biologists as well as evolutionary and chemical ecologists, but also for scientists working in various areas in the field of comparative genomics.

• DFG Programme: Research Grants