Larger colonies do not have more specialized workers in the ant Temnothorax albipennis

Dornhaus, Anna; Holley, Jo Anne; Franks, Nigel R.

doi:10.1093/beheco/arp070

Cited by 68 publications

(43 citation statements)

References 81 publications

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“…The degree to which this may enhance decision accuracy in small colonies remains unclear but any compensation for the lack of numbers is likely to be partial, as currently available data suggest that smaller colonies of M. nipponica suffer from reduced decision accuracy relative to larger colonies (AL Cronin 2014, unpublished data). Evidence that workers vary effort with colony size in other species is contradictory: Dornhaus et al [49] show that the most active individual performed proportionately more work in smaller colonies of Temnothorax albipennis over a range of tasks, whereas honeybee foragers in large colonies work harder than those in small colonies [56]. However, in many cases, workload is likely to scale with colony size; foraging effort, for example will depend on the number of brood, which in turn is correlated with colony size.…”

Section: Discussionmentioning

confidence: 99%

“…The former two categories were natural colonies of varying size (34 ants for large colonies and 15 -18 ants for small colonies; table 1). Because natural colonies of different sizes can differ in other size-correlated attributes such as experience [49] we also performed relocations with manipulated (split) colonies. Split colonies were the same colonies as those used in large relocations, but were halved in size (17 ants), such that small and split colonies were of equivalent size.…”

Section: Experimental Approachmentioning

confidence: 99%

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Ants work harder during consensus decision-making in small groups

Cronin

Stumpe²

2014

J. R. Soc. Interface.

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Individuals derive many benefits from being social, one of which is improved accuracy of decision-making, the so-called 'wisdom of the crowds' effect. This advantage arises because larger groups can pool information from more individuals. At present, limited empirical data indicate that larger groups outperform smaller ones during consensus decision-making in human and non-human animals. Inaccurate decisions can lead to significant costs, and we might therefore expect individuals in small groups to employ mechanisms to compensate for the lack of numbers. Small groups may be able to maintain decision accuracy if individuals are better informed than those in larger groups and/or by increasing the proportion of the group involved in collective decision-making relative to larger groups. In this study, we use interactive computer vision software to investigate individual contributions to consensus decision-making during house-hunting in different sized groups of the ant Myrmecina nipponica. We show that individuals in small colonies invest greater effort in the consensus decision process than those in large colonies and should be better informed as a result. This may act to ameliorate the limitations of group size, but could leave smaller groups more susceptible to additional stresses.

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Section: Discussionmentioning

confidence: 99%

Section: Experimental Approachmentioning

confidence: 99%

Ants work harder during consensus decision-making in small groups

Cronin

Stumpe²

2014

J. R. Soc. Interface.

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“…Dornhaus et al 2009;Pinter-Wollman et al 2012) and behavioral diversity in brood care and exploration has been shown to positively correlate with colony productivity (Modlmeier et al 2012). However, little is known about the link between division of labor and worker size in…”

Section: Onmentioning

confidence: 99%

Decreasing worker size diversity does not affect colony performance during laboratory challenges in the ant Temnothorax nylanderi

Colin

Doums

Péronnet

et al. 2017

Behav Ecol Sociobiol

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Authors' contributions TC collected colonies, reared them, performed the experiments and statistical analyses, and wrote the manuscript. CD designed the study, contributed to statistical analysis and wrote the manuscript. RP collected colonies, and assisted in rearing and experiments. MM designed the study, wrote the manuscript, and supervised the project. All authors read and approved the final manuscript. Within-colony phenotypic diversity can play an essential role in some eusocial insect taxa by increasing the performance of division of labor, thereby increasing colony fitness. Empirical studies of the effect of phenotypic diversity on colony fitness mostly focused on species with discrete castes (workers, soldiers) or with continuously and highly morphologically variable workers, which is not the most common case. Indeed, most species exhibit continuous but limited worker morphological variation. It is still unclear whether this variation impacts colony fitness. To test this, we reduced the worker size diversity in 25 colonies of the ant Temnothorax nylanderi and compared their performances to 25 control colonies. We reared these colonies in the laboratory and measured the effect of treatment (reduced diversity or control) and colony size (number of workers) on colony performance at six challenges, as well as on worker mortality and brood production. The reduction of worker size diversity did not affect colony performance nor mortality and brood production. As expected, colony performance and brood production increased with colony size. These results suggest that worker size diversity may not be under positive selection in this species, but rather the product of a lack of developmental canalization. We propose that social life could decrease the selective pressures maintaining developmental canalization, subsequently leading to higher size diversity without necessarily increasing colony performance. 4 Significance statementIn social insects, nestmate size diversity is commonly thought to improve division of labour and colony performance. This has been clearly demonstrated in species with high size diversity, either discrete or continuous, but this is unclear in most of the social insects that exhibit low size diversity. We experimentally decreased worker size diversity in the ant Temnothorax nylanderi, a species with low worker size diversity. Reducing worker size diversity had no effect on colony performance, worker mortality or brood production. Our findings support the hypothesis that low size diversity is merely the product of developmental noise and is not necessarily adaptive. We propose that social life could relax the selective pressures maintaining developmental and social canalizations, subsequently leading to size diversity.5

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“…This might not always be the case in nature, as the presence of idle workers may be beneficial for the colony, for example, because of energy constraints (Gordon 1989;Robinson 1992;Krieger et al 2000) or to serve as reserve force that can be mobilized when needed (Wilson 1983;Gordon 1989;Robinson 1992). It would be possible to include such effects in more complex foraging scenarios and to study, for example, the expected relationship between the proportion of idle workers and colony size (Jeanson et al 2007;Dornhaus et al 2009). Finally, we assumed that the task stimuli are available to all workers in the colony.…”

Section: Discussionmentioning

confidence: 99%

Neural Networks as Mechanisms to Regulate Division of Labor

Lichocki

Tarapore

Keller

et al. 2012

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. 26, 2011; Accepted October 27, 2011; Electronically published January 26, 2012 Online enhancements: appendixes abstract: In social insects, workers perform a multitude of tasks, such as foraging, nest construction, and brood rearing, without central control of how work is allocated among individuals. It has been suggested that workers choose a task by responding to stimuli gathered from the environment. Response-threshold models assume that individuals in a colony vary in the stimulus intensity (response threshold) at which they begin to perform the corresponding task. Here we highlight the limitations of these models with respect to colony performance in task allocation. First, we show with analysis and quantitative simulations that the deterministic response-threshold model constrains the workers' behavioral flexibility under some stimulus conditions. Next, we show that the probabilistic responsethreshold model fails to explain precise colony responses to varying stimuli. Both of these limitations would be detrimental to colony performance when dynamic and precise task allocation is needed. The University of Chicago Press andTo address these problems, we propose extensions of the responsethreshold model by adding variables that weigh stimuli. We test the extended response-threshold model in a foraging scenario and show in simulations that it results in an efficient task allocation. Finally, we show that response-threshold models can be formulated as artificial neural networks, which consequently provide a comprehensive framework for modeling task allocation in social insects.

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Larger colonies do not have more specialized workers in the ant Temnothorax albipennis

Cited by 68 publications

References 81 publications

Ants work harder during consensus decision-making in small groups

Ants work harder during consensus decision-making in small groups

Decreasing worker size diversity does not affect colony performance during laboratory challenges in the ant Temnothorax nylanderi

Neural Networks as Mechanisms to Regulate Division of Labor

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