Perspective: The Size-Complexity Rule

Bonner, John Tyler

doi:10.1111/j.0014-3820.2004.tb00476.x

Cited by 111 publications

(51 citation statements)

References 16 publications

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“…It has been repeatedly reported that over the tree of life organismal complexity is positively correlated with size, in particular with cell number (5,62) and colony size (15,63). Our model shows that a priori module number has no influence on the strength of selection for functional specialization because condition Eq.…”

Section: Discussionmentioning

confidence: 63%

Evolution of functional specialization and division of labor

Rueffler

Hermisson²,

Wagner³

2012

Proc. Natl. Acad. Sci. U.S.A.

156

170

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Division of labor among functionally specialized modules occurs at all levels of biological organization in both animals and plants. Well-known examples include the evolution of specialized enzymes after gene duplication, the evolution of specialized cell types, limb diversification in arthropods, and the evolution of specialized colony members in many taxa of marine invertebrates and social insects. Here, we identify conditions favoring the evolution of division of labor by means of a general mathematical model. Our starting point is the assumption that modules contribute to two different biological tasks and that the potential of modules to contribute to these tasks is traded off. Our results are phrased in terms of properties of performance functions that map the phenotype of modules to measures of performance. We show that division of labor is favored by three factors: positional effects that predispose modules for one of the tasks, accelerating performance functions, and synergistic interactions between modules. If modules can be lost or damaged, selection for robustness can counteract selection for functional specialization. To illustrate our theory we apply it to the evolution of specialized enzymes coded by duplicated genes.complexity | fitness landscape | saddle point

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Section: Discussionmentioning

confidence: 63%

Evolution of functional specialization and division of labor

Rueffler

Hermisson²,

Wagner³

2012

Proc. Natl. Acad. Sci. U.S.A.

156

170

View full text Add to dashboard Cite

show abstract

“…Group size is positively correlated with the degree of reproductive and non-reproductive division of labour in multicellular organisms (e.g. volvocine algae [3] and ants [4,5]). Individuals in a group can specialize on a set of tasks required for the efficient functioning of the group, leading to division of labour.…”

Section: Introductionmentioning

confidence: 99%

Specialization and group size: brain and behavioural correlates of colony size in ants lacking morphological castes

et al. 2015

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Group size in both multicellular organisms and animal societies can correlate with the degree of division of labour. For ants, the task specialization hypothesis (TSH) proposes that increased behavioural specialization enabled by larger group size corresponds to anatomical specialization of worker brains. Alternatively, the social brain hypothesis proposes that increased levels of social stimuli in larger colonies lead to enlarged brain regions in all workers, regardless of their task specialization. We tested these hypotheses in acacia ants (Pseudomyrmex spinicola), which exhibit behavioural but not morphological task specialization. In wild colonies, we marked, followed and tested ant workers involved in foraging tasks on the leaves (leaf-ants) and in defensive tasks on the host tree trunk (trunk-ants). Task specialization increased with colony size, especially in defensive tasks. The relationship between colony size and brain region volume was task-dependent, supporting the TSH. Specifically, as colony size increased, the relative size of regions within the mushroom bodies of the brain decreased in trunk-ants but increased in leaf-ants; those regions play important roles in learning and memory. Our findings suggest that workers specialized in defence may have reduced learning abilities relative to leaf-ants; these inferences remain to be tested. In societies with monomorphic workers, brain polymorphism enhanced by group size could be a mechanism by which division of labour is achieved.

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“…Living organisms have generally become increasingly large, complex, and diverse over nearly 4 billion years of evolutionary history (Maynard Smith and Szathmáry 1995;Bonner 2004;DeLong et al 2010). At critical transitions, these increases occurred when existing entities formed collectives-genes into genomes, cells into metazoans, indi-viduals into eusocial societies, and species into mutualisms (Bourke 2011).…”

Section: Introductionmentioning

confidence: 99%

Metabolism and the Rise of Fungus Cultivation by Ants

Shik

Santos

Seal

et al. 2014

The American Naturalist

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. abstract: Most ant colonies are comprised of workers that cooperate to harvest resources and feed developing larvae. Around 50 million years ago (MYA), ants of the attine lineage adopted an alternative strategy, harvesting resources used as compost to produce fungal gardens. While fungus cultivation is considered a major breakthrough in ant evolution, the associated ecological consequences remain poorly understood. Here, we compare the energetics of attine colony-farms and ancestral hunter-gatherer colonies using metabolic scaling principles within a phylogenetic context. We find two major energetic transitions. First, the earliest lower-attine farmers transitioned to lower mass-specific metabolic rates while shifting significant fractions of biomass from ant tissue to fungus gardens. Second, a transition 20 MYA to specialized cultivars in the higher-attine clade was associated with increased colony metabolism (without changes in garden fungal content) and with metabolic scaling nearly identical to hypometry observed in hunter-gatherer ants, although only the hunter-gatherer slope was distinguishable from isometry. Based on these evolutionary transitions, we propose that shifting living-tissue storage from ants to fungal mutualists provided energetic storage advantages contributing to attine diversification and outline critical assumptions that, when tested, will help link metabolism, farming efficiency, and colony fitness.

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Perspective: The Size-Complexity Rule

Cited by 111 publications

References 16 publications

Evolution of functional specialization and division of labor

Evolution of functional specialization and division of labor

Specialization and group size: brain and behavioural correlates of colony size in ants lacking morphological castes

Metabolism and the Rise of Fungus Cultivation by Ants

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