Tall trails: ants resolve an asymmetry of information and capacity in collective maintenance of infrastructure

Bruce, A; Czaczkes, Tomer J.; Burd, Martin

doi:10.1016/j.anbehav.2017.03.018

Cited by 11 publications

(10 citation statements)

References 40 publications

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“…Among trail constructing animals, the leafcutter ants (Atta spp.) show the most intricate trail construction behaviour: workers remove vast amounts of vegetation and undergrowth from prospective trails [14], cut passes through overhanging obstructions [15] and shift soil to level trail surfaces [16]. On average, colonies clear 2730 m of trail per year [14], and individual trails can exceed 200 m [17].…”

Section: Introductionmentioning

confidence: 99%

Infrastructure construction without information exchange: the trail clearing mechanism inAttaleafcutter ants

et al. 2019

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A wide range of group-living animals construct tangible infrastructure networks, often of remarkable size and complexity. In ant colonies, infrastructure construction may require tens of thousands of work hours distributed among many thousand individuals. What are the individual behaviours involved in the construction and what level of complexity in inter-individual interaction is required to organize this effort? We investigate this question in one of the most sophisticated trail builders in the animal world: the leafcutter ants, which remove leaf litter, cut through overhangs and shift soil to level the path of trail networks that may cumulatively extend for kilometres. Based on obstruction experiments in the field and the laboratory, we identify and quantify different individual trail clearing behaviours. Via a computational model, we further investigate the presence of recruitment, which—through direct or indirect information transfer between individuals—is one of the main organizing mechanisms of many collective behaviours in ants. We show that large-scale transport networks can emerge purely from the stochastic process of workers encountering obstructions and subsequently engaging in removal behaviour with a fixed probability. In addition to such incidental removal, we describe a dedicated clearing behaviour in which workers remove additional obstructions independent of chance encounters. We show that to explain the dynamics observed in the experiments, no information exchange (e.g. via recruitment) is required, and propose that large-scale infrastructure construction of this type can be achieved without coordination between individuals.

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Section: Introductionmentioning

confidence: 99%

Infrastructure construction without information exchange: the trail clearing mechanism inAttaleafcutter ants

et al. 2019

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“…Reserve lifting capacity is a reflection of the excess mechanical power that an ant has available after it has selected a load to carry (Eqn 1): power that is not used for lifting can be applied to increase walking speed or to overcome obstacles along the trail (Holt and Askew, 2012;Lewis et al, 2008). The fact that smaller ants maintain lower power reserves when selecting leaf fragments to take to the colony means that they may have more difficulty negotiating physical obstacles in the terrain (Bruce et al, 2017), overcoming mass added by raindrops (Farji-Brener et al, 2018), dealing with gusts of wind (Alma et al, 2016) and maintaining an efficient velocity (Holt and Askew, 2012). Meanwhile, larger ants that have higher power reserves choose smaller leaf fragments than their ability suggests they should be able to carry efficiently and effectively.…”

Section: Resultsmentioning

confidence: 99%

“…In other words, the power an ant can generate can be applied to carry heavier loads (force), increase vertical displacement (also force), increase walking speed (velocity), or a combination of the three. But power output is finite, and if an ant selects a load that is too heavy, then it may not be able to walk at its preferred speed or have enough power to overcome challenges, such as inclines (Holt and Askew, 2012;Lewis et al, 2008), obstructions (Bruce et al, 2017), rain (Farji-Brener et al, 2018) or wind (Alma et al, 2016). Instead, if an ant selects a submaximal load, it maintains power reserves that can be tapped into, if needed.…”

Section: Introductionmentioning

confidence: 99%

Large ants don't carry their fair share: Maximal load carrying performance of leaf-cutter ants (Atta cephalotes)

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Taylor

2019

Journal of Experimental Biology

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Although ants are lauded for their strength, little is known about the limits of their load-carrying abilities. We determined the maximal loadcarrying capacity of leaf-cutter ants by incrementally adding mass to the leaves they carried. Maximal load-carrying ability scaled isometrically with body size, indicating that larger ants had the capacity to lift the same proportion of their body mass as smaller ants (8.78 times body mass). However, larger ants were captured carrying leaf fragments that represented a lower proportion of their body mass compared with their smaller counterparts. Therefore, when selecting leaves, larger ants retained a higher proportion of their load-carrying capacity in reserve. This suggests that either larger ants require greater power reserves to overcome challenges they encounter along the trail or leaf-cutter ants do not select loads that maximize the overall leaf transport rate of the colony.

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“…In collaborative removals, ants behave cooperatively or cut the obstacle in pieces before removing it (Alma, Farji‐Brener, & Elizalde, ; Bochynek et al, ; Howard, ). Despite the existence of previous studies analyzing the clearing behavior of leaf‐cutting ants (Alma et al, ; Bochynek et al, , ; Bruce et al, ; Caldato et al, ; Cevallos Dupuis & Harrison, ; Howard, ), as far as we know, none has analyzed which contexts are more advantageous for individual or collaborative removals.…”

Section: Introductionmentioning

confidence: 96%

With a little help from my friends: Individual and collaborative performance during trail clearing in leaf‐cutting ants

2020

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Social organisms express collaborative behaviors, allowing them to solve problems that exceed their individual capabilities. Group coordination and environmental context are some of the factors that may determine the performance of individual and collaborative strategies. Using the trail‐clearing behavior of leaf‐cutting ants, we evaluated experimentally for both strategies whether the success probability and clearing time depend on problem characteristics and context. We placed obstacles of different sizes and shapes (problem characteristics), in trails with different foragers' fluxes and soil roughness (context) in 10 field nests of Atta cephalotes, and compared removal success (i.e., if ants could remove obstacles) and time of individual and collaborative strategies. Very large obstacles could only be removed collaboratively, confirming individual limitations for transporting large objects. For all obstacle shapes, collaborative removals were more successful but took longer, suggesting that coordination among individuals delays these actions. Individual strategies were faster, regardless of ant flux. However, as ant flux increased, removal success was higher for collaborative than for individual removals. Lastly, trail roughness had no effect. This work highlights one advantage of sociality, the option of collaboratively solving problems that exceed the individual abilities. In addition, it reveals the associated costs of joint actions, since they can be time‐consuming presumably due to coordination problems. Abstract in Spanish is available with online material.

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Tall trails: ants resolve an asymmetry of information and capacity in collective maintenance of infrastructure

Cited by 11 publications

References 40 publications

Infrastructure construction without information exchange: the trail clearing mechanism inAttaleafcutter ants

Infrastructure construction without information exchange: the trail clearing mechanism inAttaleafcutter ants

Large ants don't carry their fair share: Maximal load carrying performance of leaf-cutter ants (Atta cephalotes)

With a little help from my friends: Individual and collaborative performance during trail clearing in leaf‐cutting ants

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