Task switching is associated with temporal delays in<i>Temnothorax rugatulus</i>ants

Leighton, Gavin M.; Charbonneau, Daniel; Dornhaus, Anna

doi:10.1093/beheco/arw162

Cited by 29 publications

(21 citation statements)

References 60 publications

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“…Division of colony labor among workers is widely considered the key adaptation of social insects, with the specialization of workers on specific tasks theorized to improve colony performance 2 , for example by reducing the costs of switching between tasks 4 , 5 . However, individual workers generally show flexibility in task performance 6 – 8 , and social insect colonies are able to reallocate workers to different tasks when colony demands change 6 , 9 – 13 .…”

Section: Introductionmentioning

confidence: 99%

Spatial fidelity of workers predicts collective response to disturbance in a social insect

et al. 2018

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Individuals in social insect colonies cooperate to perform collective work. While colonies often respond to changing environmental conditions by flexibly reallocating workers to different tasks, the factors determining which workers switch and why are not well understood. Here, we use an automated tracking system to continuously monitor nest behavior and foraging activity of uniquely identified workers from entire bumble bee (Bombus impatiens) colonies foraging in a natural outdoor environment. We show that most foraging is performed by a small number of workers and that the intensity and distribution of foraging is actively regulated at the colony level in response to forager removal. By analyzing worker nest behavior before and after forager removal, we show that spatial fidelity of workers within the nest generates uneven interaction with relevant localized information sources, and predicts which workers initiate foraging after disturbance. Our results highlight the importance of spatial fidelity for structuring information flow and regulating collective behavior in social insect colonies.

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Section: Introductionmentioning

confidence: 99%

Spatial fidelity of workers predicts collective response to disturbance in a social insect

et al. 2018

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“…We have made the assumption that the relevant measure of how well a task allocation mechanism performs is related to the time to correct allocation, that is the time until workers are matched to tasks that need work. Other performance measures are possible, such as assessing how quickly the task-worker match approaches an ideal allocation, or how good the match can ever get; or entirely different parameters may be under selection, such as how much workers have to switch tasks [ 38 ], how well workers prioritize more important tasks over unimportant ones, or how much information workers need to collect in order to allocate correctly.…”

Section: Discussionmentioning

confidence: 99%

“…Despite this uncertainty about the precise mechanism, the fact that social insects achieve task allocation is well studied. Workers in a colony specialize to a large or small degree on different tasks, and may switch tasks as needed [ 37 ], although this may come at additional cost [ 38 ]. Colonies are typically able to effectively compensate for worker loss ([ 36 ], although see [ 39 ]) or changes in demand for different tasks [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Costs of task allocation with local feedback: Effects of colony size and extra workers in social insects and other multi-agent systems

et al. 2017

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Adaptive collective systems are common in biology and beyond. Typically, such systems require a task allocation algorithm: a mechanism or rule-set by which individuals select particular roles. Here we study the performance of such task allocation mechanisms measured in terms of the time for individuals to allocate to tasks. We ask: (1) Is task allocation fundamentally difficult, and thus costly? (2) Does the performance of task allocation mechanisms depend on the number of individuals? And (3) what other parameters may affect their efficiency? We use techniques from distributed computing theory to develop a model of a social insect colony, where workers have to be allocated to a set of tasks; however, our model is generalizable to other systems. We show, first, that the ability of workers to quickly assess demand for work in tasks they are not currently engaged in crucially affects whether task allocation is quickly achieved or not. This indicates that in social insect tasks such as thermoregulation, where temperature may provide a global and near instantaneous stimulus to measure the need for cooling, for example, it should be easy to match the number of workers to the need for work. In other tasks, such as nest repair, it may be impossible for workers not directly at the work site to know that this task needs more workers. We argue that this affects whether task allocation mechanisms are under strong selection. Second, we show that colony size does not affect task allocation performance under our assumptions. This implies that when effects of colony size are found, they are not inherent in the process of task allocation itself, but due to processes not modeled here, such as higher variation in task demand for smaller colonies, benefits of specialized workers, or constant overhead costs. Third, we show that the ratio of the number of available workers to the workload crucially affects performance. Thus, workers in excess of those needed to complete all tasks improve task allocation performance. This provides a potential explanation for the phenomenon that social insect colonies commonly contain inactive workers: these may be a ‘surplus’ set of workers that improves colony function by speeding up optimal allocation of workers to tasks. Overall our study shows how limitations at the individual level can affect group level outcomes, and suggests new hypotheses that can be explored empirically.

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“…Experiments with marked ants (50) show that most task switching is within the group of ants currently active outside the nest, who do not mix with the inactive ants deeper in the nest (1,51), as in other Pogonomyrmex species (82). By contrast, workers of Temnothorax rugatulus, who are often called upon to respond to drastic changes, such as a move to a new nest, more easily switch tasks (18,81) and make transitions between actively performing some task and being mostly inactive, not performing any task (18,103). An important influence on task switching is age polyethism; workers tend to move from tasks inside the nest, such as brood care, to tasks outside the nest, such as foraging, as they grow older (e.g., 15,50).…”

Section: Task Switchingmentioning

confidence: 99%

The Ecology of Collective Behavior in Ants

Gordon

2019

Annu. Rev. Entomol.

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Nest choice in Temnothorax spp.; task allocation and the regulation of activity in Pheidole dentata, Pogonomyrmex barbatus, and Atta spp.; and trail networks in Monomorium pharaonis and Cephalotes goniodontus all provide examples of correspondences between the dynamics of the environment and the dynamics of collective behavior. Some important aspects of the dynamics of the environment include stability, the threat of rupture or disturbance, the ratio of inflow and outflow of resources or energy, and the distribution of resources. These correspond to the dynamics of collective behavior, including the extent of amplification, how feedback instigates and inhibits activity, and the extent to which the interactions that provide the information to regulate behavior are local or spatially centralized.

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Task switching is associated with temporal delays inTemnothorax rugatulusants

Cited by 29 publications

References 60 publications

Spatial fidelity of workers predicts collective response to disturbance in a social insect

Spatial fidelity of workers predicts collective response to disturbance in a social insect

Costs of task allocation with local feedback: Effects of colony size and extra workers in social insects and other multi-agent systems

The Ecology of Collective Behavior in Ants

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