Footprints of parental care in weevil genomes

Sociality in animals can be described as a continuum from subsociality, comprising parental care, to eusociality, comprising cooperative brood care, overlapping generations and division of reproductive labour. Research into the molecular evolution of sociality has so far focused on eusociality in Hymenoptera, including bees, wasps and ants, even though eusociality has evolved in multiple animal clades, for example termites, Ambrosia beetles and naked mole-rats. Eusociality is not common, but where it evolved, phenotypic traits are highly convergent, while molecular mechanisms leading to those phenotypes differ strongly. Different pathways have evolved to adapt to sociality in different species groups, whereas the social lifestyle is assumed to have a similar effect on selection efficiency in all of these groups. Generally, eusocial species are assumed to have a smaller effective population size which leads to decreased purifying selection. However, we are interested in the evolution of lower social complexity, namely parental care, as a potential first step in the evolution of more complex social phenotypes.

There is a longstanding hypothesis that social behaviour affects genetic variation. Parental care for example can buffer the effects of mildly deleterious mutations and modulate immunity genes. Generally, subsociality is expected to lead to changes in regulation rather than genomic changes, however, this remains to be tested.

Here, we investigate genomic footprints of parental care in the genomes of beetles, more specifically weevils (Curculionidae). Within weevils, parental care evolved at least twice, and one species is classified as eusocial, making this beetle family a great study system for the evolution of (sub)sociality.

We are applying genomics approaches to investigate changes in gene family size, rearrangements of protein domains and selection regimes across the species tree. We expect to see changes at the two independent origins of parental care within weevils and an accumulation of genetic variation in species with parental care.

In the future, we will broaden this study by adding newly assembled and annotated genomes of weevils of different social complexity, including eusociality, to the dataset.