Colony size predicts division of labour in attine ants

Ferguson-Gow, Henry; Sumner, Seirian; Bourke, Andrew F. G.; Jones, Kate E.

doi:10.1098/rspb.2014.1411

Cited by 91 publications

(108 citation statements)

References 73 publications

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“…There is good evidence for a size-complexity relationship within ant species 6 , but evidence among ant species is mixed 13,27 . We found no relationship between colony size and worker size variation among our 28 species of stingless bees (Fig.…”

Section: Discussionmentioning

confidence: 99%

Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees

Grüter

Segers

Menezes³

et al. 2017

Nat Commun

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The differentiation of workers into morphological castes represents an important evolutionary innovation that is thought to improve division of labor in insect societies. Given the potential benefits of task-related worker differentiation, it is puzzling that physical worker castes, such as soldiers, are extremely rare in social bees and absent in wasps. Following the recent discovery of soldiers in a stingless bee, we studied the occurrence of worker differentiation in 28 stingless bee species from Brazil and found that several species have specialized soldiers for colony defence. Our results reveal that worker differentiation evolved repeatedly during the last ~ 25 million years and coincided with the emergence of parasitic robber bees, a major threat to many stingless bee species. Furthermore, our data suggest that these robbers are a driving force behind the evolution of worker differentiation as targets of robber bees are four times more likely to have nest guards of increased size than non-targets. These findings reveal unexpected diversity in the social organization of stingless bees.

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Section: Discussionmentioning

confidence: 99%

Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees

Grüter

Segers

Menezes³

et al. 2017

Nat Commun

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“…In contrast, in eusocial insects that have evolved a sterile worker caste, social complexity concerns selection pressures fundamentally different from those in vertebrates, particularly in relation to reproductive competition and the fitness of individual group members. Complexity in insect societies is associated not only with an increased group size but also with worker polymorphism, division of labor, and associated colony level processes of task performance and emergent collective behavior [Anderson and McShea, 2001; Thomas and Elgar, 2003;Holbrook et al, 2011;Ferguson-Gow et al, 2014;Feinerman and Korman, 2017]. Worker groups can be more efficient and accurate at decision-making than individuals, thus improving colony level fitness [Sasaki and Pratt, 2018], and task performance efficiency may be enhanced by behavioral specialization [Robinson, 1992].…”

Section: Introductionmentioning

confidence: 99%

Social Complexity and Brain Evolution: Comparative Analysis of Modularity and Integration in Ant Brain Organization

2019

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The behavioral demands of living in social groups have been linked to the evolution of brain size and structure, but how social organization shapes investment and connectivity within and among functionally specialized brain regions remains unclear. To understand the influence of sociality on brain evolution in ants, a premier clade of eusocial insects, we statistically analyzed patterns of brain region size covariation as a proxy for brain region connectivity. We investigated brain structure covariance in young and old workers of two formicine ants, the Australasian weaver ant Oecophylla smaragdina, a pinnacle of social complexity in insects, and its socially basic sister clade Formica subsericea. As previously identified in other ant species, we predicted that our analysis would recognize in both species an olfaction-related brain module underpinning social information processing in the brain, and a second neuroanatomical cluster involved in nonolfactory sensorimotor processes, thus reflecting conservation of compartmental connectivity. Furthermore, we hypothesized that covariance patterns would reflect divergence in social organization and life histories either within this species pair or compared to other ant species. Contrary to our predictions, our covariance analyses revealed a weakly defined visual, rather than olfactory, sensory processing cluster in both species. This pattern may be linked to the reliance on vision for worker behavioral performance outside of the nest and the correlated expansion of the optic lobes to meet navigational demands in both species. Additionally, we found that colony size and social organization, key measures of social complexity, were only weakly correlated with brain modularity in these formicine ants. Worker age also contributed to variance in brain organization, though in different ways in each species. These findings suggest that brain organization may be shaped by the divergent life histories of the two study species. We compare our findings with patterns of brain organization of other eusocial insects.

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“…Moreover, most species that form large societies will cross a phase in their ontogeny where they are composed of only few individuals, during which the division of labour into highly specialized modules may jeopardize the survival of the group as a whole. Hence, small or young societies are expected to rely more on generalists in their work force to absorb fluctuations in the environment, and there is indeed ample empirical evidence supporting the positive association between group size and division of labour [34][35][36]. From an evolutionary perspective, the fitness pay-offs of division of labour in small societies are of particular interest, as social life probably evolved starting with small groups rather than large, complex societies.…”

Section: Discussionmentioning

confidence: 99%

Fitness costs of worker specialization for ant societies

Jongepier¹,

Foitzik

2016

Proc. R. Soc. B.

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Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony's annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.

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Colony size predicts division of labour in attine ants

Cited by 91 publications

References 73 publications

Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees

Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees

Social Complexity and Brain Evolution: Comparative Analysis of Modularity and Integration in Ant Brain Organization

Fitness costs of worker specialization for ant societies

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