Evolutionary genomic of sociality in beetles

DFG STE 1874/11-1; SPP 2349 GEvol

From 06/2022 to 04/2025

Principal Investigator: Prof. Dr. Sandra Steiger

Although sociality is rare in insects, various types of social lifestyles have evolved sporadically across a broad range of taxa. Sociality ranges from parental care of offspring in subsocial species to complex colonies with division of reproductive labour in eusocial insects, such as in ants, as well as some bees, wasps and termites. Several comparative studies have revealed a broad range of genomic signatures related to the evolution of eusociality, especially in Hymenoptera (mainly ants and bees) and termites. However, little is known about the genomic origins of sociality in beetles or on the early transitions from solitary living to subsociality.This is an important omission since subsociality, which occurs in at least 11 beetle families, is recognised as an important first step towards eusociality. With our project we aim to close this gap by investigating the genomic signatures related to the evolution of sociality in beetles. We put a particular focus on genomic mechanisms linked to the early stages of social evolution and aim to distinguish these molecular signals from those related to later elaborations towards eusociality. We propose to study several species from two beetle families (carrion beetles and weevils) that cover several levels of subsociality, two origins of facultative and one origin of obligate eusociality. With a broad range of genomic and transcriptomic analyses, we plan to infer detailed changes in genomic content, transcriptional regulation, protein evolution, and expression patterns, that are related to the transitions from solitary to subsocial living and then the further elaborations towards obligate eusociality. We will support these inferences with investigations into the influence of purifying and positive selection, as well as genomic and transcriptomic upheavals caused, for instance, by transposable element activity. In the early stages of social evolution, we expect to find regulatory changes leading to the emergence of expression patterns associated with parental care. Greater adaptive changes, especially those affecting communication, nutrition, and immunity, are expected to occur along the progression towards obligate eusociality in wood-boring weevils. With genomic comparisons across all origins of insect eusociality (Hymenoptera, Isoptera and Coleoptera), we aim to identify molecular mechanisms that are universally associated with the rare evolutionary progressions from solitary to eusocial species. Moreover, by combining these genomic and transcriptomic analyses with lab-based manipulations and RNAi experiments we aim to identify candidate gene families and networks that are integral to social behaviour. This project can bring us closer to understanding the genomic and regulatory mechanisms associated with the emergence of subsociality from solitary ancestors, and its rare advancement along the ultimate transition towards eusociality.