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Genes and the environment jointly shape individual traits, but the influence of indirect genetic effects (IGEs), arising from the genetic composition of interacting conspecific individuals, is often ignored or underemphasized. Moreover, because of practical challenges in characterizing IGEs, empirical research has fallen behind theoretical advancement. The fire antSolenopsis invictaoffers a uniquely suitable study system due to its distinct colony-level phenotypic variation (monogyne and polygyne social forms) attributed to IGEs of a social-supergene variant (ballele). A minority ofb-carrying workers (Bbgenotype) can trigger colony-level conversion from monogyne (single queen per colony) to polygyne (multiple queens per colony) behavior. This study investigated the mechanisms underlying this process via 400-ant microcolonies. We first showed that assimilatedBbworkers reduce aggression by hostBBworkers towardBbqueens, thus inducing polygyny, at rates observed earlier in experiments that used full-size (>20,000 ants) colonies. We then demonstrated that social conversion is facilitated by cuticular contact between the worker types, and verified the presence of nonvolatile cuticular pheromones that are necessary but not sufficient components underpinning this process. Follow-up experiments suggested that a second, polygyne worker-produced pheromone that is only released once such workers detect aBbqueen is also necessary but again insufficient, for full expression of the conversion phenomenon. Thus, multiple pheromonal components linked to presence of thebsupergene allele in colony workers appear to be involved in shaping social environments and thereby inducing, via IGEs, the transformation from monogyne to polygyne fire ant societies.
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Bumble bee workers adopt novel behavioral roles and reshape their social networks in the absence of a queen
Summary Dominant individuals often structure group organization, but less is known about how social networks differ in their absence or how variation among subordinates contributes to collective outcomes. Bumble bees (Bombus impatiens) provide an ideal system to study how individual behavior shapes colony organization: queens typically monopolize reproduction, but in some contexts individual workers can adopt queen-like social roles. We asked how this process shapes the collective phenotype. Using multi-animal pose tracking to quantify social behaviors, we compared matched queenright and queenless partitions from the same source colonies. Queenless colonies were more interactive and contained a subset of behaviorally extreme queen-like workers with higher movement, spatial centrality, and reproductive potential. Such variation, absent in queenright colonies, coincided with a shift to decentralized, efficient network structures. These results demonstrate how social context shapes the expression of individual phenotypes, revealing a mechanism by which seemingly hierarchical societies can retain latent social flexibility and underscoring the link between individual variation and collective organization.
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- Award ID(s):
- 1734030
- PAR ID:
- 10672182
- Publisher / Repository:
- bioRxiv
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript
- Posted Content:
- https://doi.org/10.1101/2025.01.07.630106
