A reproductive heir has a central position in multilayer social networks of paper wasps

The effect of social structure on vocal flexibility in monk parakeets

The social complexity hypothesis argues that communicative complexity arises as a result of social complexity, with this occurring through mechanisms including plasticity and selection. Most research to date has focused on ultimate drivers of repertoire size, for example finding that cooperative breeding species exhibit larger repertoires. Until this date, to our knowledge, no study has focused on individual-level drivers of vocal diversity. Here, we examine social networks and vocalizations in wild colonial-nesting monk parakeets (Myiopsitta monachus). We recorded social networks for 337 individuals, relatedness for 100 individuals and matched these with 5599 vocalizations from 229 individuals over 2 years. Overall, we found that all individuals exhibited high contact-call diversity; however, individual-level diversity increased with age in 2020 and with number of nest mates in 2021. Call similarity was not predicted by relatedness, but individuals with stronger affiliative bonds had more dissimilar calls, suggesting an active process to sound unique among close associates. Finally, females had more diverse repertoires, producing relatively fewer contact calls across years and individuals living in larger groups had more diverse repertoires in 2021. Our results demonstrate a multi-faceted social influence on call content, diversity and repertoire diversity, exhibiting how fine-scale variation in social structure can influence expressed vocal complexity.

Transcriptomic correlates of nutritional manipulation in a facultatively social bee

Subsocial behaviour in insects consists of extended parental care and may set the stage for the evolution of cooperation through manipulation of offspring. Manipulation of brood nutrition may produce differences in developmental or adult gene regulation, but it also produces smaller offspring which may be coerced into cooperation. The eastern small carpenter bee Ceratina calcarata frequently produces a smaller under-provisioned dwarf eldest daughter (DED). These DEDs are the only offspring to forage and feed siblings. To test whether nutritional manipulation of DEDs alters gene expression, inducing cooperative sibling care, we conducted a transcriptomic study, using whole heads, to assess differences in brain gene expression among naturally provisioned regular daughters and DEDs, experimentally under-provisioned regular daughters, and experimentally supplemented DEDs, prior to social interaction. Differences in gene expression were minimal among groups but were dramatic as a function of body size as a continuous variable, suggesting that differences in gene expression are more associated with absolute differences in body size, not discrete castes or order of eclosion. Enrichment for GO terms related to hormonal regulation in small bees points to hormonal regulation of transcription factors in behavioural differences that emerge in DEDs. Subordinate behaviours thus likely involve experience and social environment, though other developmental mechanisms, such as parental care, and later adult social interactions after eclosion, may act on differences in body size and gene expression to produce the distinct behaviour of DEDs.

The origin and maintenance of division of labour in an Indian paper wasp

Division of labour (DoL) is of prime importance in the success of social insects in various ecosystems and benefits their colonies by increasing efficiency and productivity. This review summarizes more than three decades of experimental evidence collected towards understanding the emergence and maintenance of division of labour in the Indian tropical paper wasp Ropalidia marginata. This primitively eusocial species provides an interesting variation between newly founded colonies and mature colonies in terms of the behavioural mechanisms regulating division of labour. Newly founded colonies rely on physical dominance behaviour for establishing division of labour. Workers in mature post-emergence colonies continue to implement physical dominance as a way to regulate non-reproductive division of labour in a decentralized manner, while the queens switch to chemical regulation of worker reproduction. We discuss experiments that build evidence toward establishing R. marginata as an important model for understanding the origin and maintenance of division of labour.This article is part of the theme issue 'Division of labour as key driver of social evolution'.

Exploring animal behaviour multilayer networks in immersive environments - a conceptual framework

Animal behaviour is often modelled as networks, where, for example, the nodes are individuals of a group and the edges represent behaviour within this group. Different types of behaviours or behavioural categories are then modelled as different yet connected networks which form a multilayer network. Recent developments show the potential and benefit of multilayer networks for animal behaviour research as well as the potential benefit of stereoscopic 3D immersive environments for the interactive visualisation, exploration and analysis of animal behaviour multilayer networks. However, so far animal behaviour research is mainly supported by libraries or software on 2D desktops. Here, we explore the domain-specific requirements for (stereoscopic) 3D environments. Based on those requirements, we provide a proof of concept to visualise, explore and analyse animal behaviour multilayer networks in immersive environments.

Social situations differ in their contribution to population-level social structure in griffon vultures

Social relationships among animals emerge from interactions in multiple ecological and social situations. However, we seldom ask how each situation contributes to the global structure of a population, and whether different situations contribute different information about social relationships and the position of individuals within the social fabric. Griffon vultures (Gyps fulvus) interact socially in multiple situations, including communal roosting, joint flights, and co-feeding. These social interactions can influence population-level outcomes, such as disease transmission and information sharing that determine survival and response to changes. We examined the unique contribution of each social and ecological situation to the social structure of the population and individuals' positions within the overall social network using high-resolution GPS tracking. We found that the number of individuals each vulture interacted with (degree) was best predicted by diurnal interactions-both during flights and on the ground (such as when feeding). However, the strength of social bonds, that is, the number of interactions an individual had (strength), was best predicted by interactions on the ground-both during the day (e.g., while feeding) and at night (e.g., while roosting) but not by interactions while flying. Thus, social situations differ in their impact on the relationships that individuals form. By incorporating the ecological situations in which social interactions occur we gain a more complete view of how social relationships are formed and which situations are important for different types of interactions.

Catalogue of the Australian social wasps (Hymenoptera: Vespidae)

A catalogue of the social wasps occurring in Australia is presented. New synonymies include Vespa cohabitatrix Curtiss, 1938 (= Polistes olivaceus (DeGeer, 1773)) and Vespula vulgaris vetus Eck, 1999 (= Vespula vulgaris (Linnaeus, 1758)).