Morphological differences between extranidal and intranidal workers in the ant Temnothorax rugatulus, but no effect of body size on foraging distance

Westling, J. N.; Harrington, K.C.; Bengston, Sarah; Dornhaus, Anna

doi:10.1007/s00040-014-0363-5

Cited by 21 publications

(30 citation statements)

References 29 publications

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“…One observation that could indicate a strategy to reduce the risk of breakups is that extranidal workers were larger than intranidal workers. This is consistent with findings in two other Temnothorax species (Herbers & Cunningham 1983; Westling et al 2014). Allocating larger workers to outside tasks is likely to decrease the probability that very large ants perform tandem runs with very small ants.…”

Section: Discussionsupporting

confidence: 93%

Large body size variation is linked to low communication success in tandem running ants

Wagner

Bachenberg

Simone

et al. 2019

Preprint

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Large body size variation is linked to low communication 1 success in tandem running ants 2 3 4 Abstract 22Diversity in animal groups is often assumed to increase group performance. In insect colonies, 23 genetic, behavioral and morphological variation among workers can improve colony 24 functioning and resilience. However, it has been hypothesized that during communication 25 processes, differences between workers, e.g. in body size, could also have negative effects. 26Tandem running is a common recruitment strategy in ants and allows a leader to guide a 27 nestmate follower to resources. A substantial proportion of tandem runs fail because leader and 28 follower loose contact. Using the ant Temnothorax nylanderi as a model system, we tested the 29 hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, 30 we found that the success rate of tandem pairs drops considerably as size variation increases: 31 only ~7% of tandem runs were successful when the leader-follower size difference exceeded 32 10%, whereas 80% of tandem runs were successful when ants differed less than 5% in body 33 length. One possible explanation is that ant size is linked to the preferred walking speed. Ants 34 did not choose partners of similar size, but extranidal workers were larger than intranidal 35 workers, which could reduce recruitment mistakes because it reduced the chance that very large 36 and very small ants perform tandem runs together. Our results suggest that phenotypic 37 differences between interacting workers can have negative effects on the efficiency of 38 communication processes. Whether phenotypic variation has positive or negative effects is 39 likely to depend on the task and the phenotypic trait that shows variation. 40 41 42 Social groups consist of individuals that differ from each other in a number of ways. For 43 instance, people working in a company may differ in experience, training, gender, ethnicity or 44 skills and this diversity can affect group performance and success. Scientists interested in 45 organizational theory have found that group diversity often has positive effects on group 46 performance, most likely because diverse groups possess a broader range of knowledge, 47

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Section: Discussionsupporting

confidence: 93%

Large body size variation is linked to low communication success in tandem running ants

Wagner

Bachenberg

Simone

et al. 2019

Preprint

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“…Only foraging has been assessed, in two studies, and larger workers were more likely to forage than smaller workers (Herbers and Curningham 1983;Westling et al 2014). In our study, the only task that was affected by the treatment (through a significant interaction between colony size and treatment) was foraging for liquid food.…”

Section: Temnothoraxmentioning

confidence: 99%

“…To study the effects of continuous diversity on colony fitness and efficiency for particular tasks, researchers often focused on the function of larger and smaller workers in the colonies without manipulating worker diversity (e.g. Goulson et al 2002;Spaethe and Weidenmüller 2002;Peat et al 2005;Couvillon and Dornhaus 2010;Westling et al 2014). In order to test whether colony fitness is affected by colony-level worker size diversity, including the colony-level emerging properties of worker size diversity and not only the functions of large and small workers, we manipulated colonies to reduce worker size diversity in test colonies while natural diversity was retained in control colonies.…”

Section: Introductionmentioning

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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“…T. rugatulus colonies show behavioral specialization and their behavior is similar between the lab and the field . T. rugatulus has medium-sized colonies (typically ~50 to 250 workers [Bengston and Dornhaus 2013]) and monomorphic workers (though, see Westling et al [2014]), both of which are typical for most ant species . T. rugatulus colonies live in rock crevices in the field, while in the lab the colonies are housed between 2 glass slides and cardboard siding on 1 or 3 sides (Pinter-Wollman et al 2012;.…”

Section: Study Speciesmentioning

confidence: 99%

Task switching is associated with temporal delays inTemnothorax rugatulusants

Leighton

Charbonneau

Dornhaus

2016

BEHECO

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The major evolutionary transitions often result in reorganization of biological systems, and a component of such reorganization is that individuals within the system specialize on performing certain tasks, resulting in a division of labor. Although the traditional benefit of division of labor is thought to be a gain in work efficiency, one alternative benefit of specialization is avoiding temporal delays associated with switching tasks. While models have demonstrated that costs of task switching can drive the evolution of division of labor, little empirical support exists for this hypothesis. We tested whether there were task-switching costs in Temnothorax rugatulus. We recorded the behavior of every individual in 44 colonies and used this dataset to identify each instance where an individual performed a task, spent time in the interval (i.e., inactive, wandering inside, and self-grooming), and then performed a task again. We compared the interval time where an individual switched task type between that first and second bout of work to instances where an individual performed the same type of work in both bouts. In certain cases, we find that the interval time was significantly shorter if individuals repeated the same task. We find this time cost for switching to a new behavior in all active worker groups, that is, independently of worker specialization. These results suggest that task-switching costs may select for behavioral specialization.

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Morphological differences between extranidal and intranidal workers in the ant Temnothorax rugatulus, but no effect of body size on foraging distance

Cited by 21 publications

References 29 publications

Large body size variation is linked to low communication success in tandem running ants

Large body size variation is linked to low communication success in tandem running ants

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

Task switching is associated with temporal delays inTemnothorax rugatulusants

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