scholarly journals Sources of intraspecific variation in the collective tempo and synchrony of ant societies

2019 ◽  
Vol 30 (6) ◽  
pp. 1682-1690
Author(s):  
Grant Navid Doering ◽  
Kirsten A Sheehy ◽  
James L L Lichtenstein ◽  
Brian Drawert ◽  
Linda R Petzold ◽  
...  
Keyword(s):  
Intraspecific Variation ◽  
Social Insects ◽  
Activity Cycle ◽  
Behavioral Differences ◽  
Short Term ◽  
Ant Colonies ◽  
Collective Activity ◽  
Worker Activity ◽  
Animal Societies

Abstract Populations of independently oscillating agents can sometimes synchronize. In the context of animal societies, conspicuous synchronization of activity is known in some social insects. However, the causes of variation in synchrony within and between species have received little attention. We repeatedly assessed the short-term activity cycle of ant colonies (Temnothorax rugatulus) and monitored the movements of individual workers and queens within nests. We detected persistent differences between colonies in the waveform properties of their collective activity oscillations, with some colonies consistently oscillating much more erratically than others. We further demonstrate that colony crowding reduces the rhythmicity (i.e., the consistent timing) of oscillations. Workers in both erratic and rhythmic colonies spend less time active than completely isolated workers, but workers in erratic colonies oscillate out of phase with one another. We further show that the queen’s absence can impair the ability of colonies to synchronize worker activity and that behavioral differences between queens are linked with the waveform properties of their societies.

scholarly journals Discovery of short-term activity cycles in F-type stars

2019 ◽  
Vol 621 ◽  
pp. A136 ◽  
Author(s):  
M. Mittag ◽  
J. H. M. M. Schmitt ◽  
A. Hempelmann ◽  
K.-P. Schröder
Keyword(s):  
Activity Cycle ◽  
Total Activity ◽  
Short Term ◽  
Cyclic Activity ◽  
Solar Type ◽  
Cyclic Variations ◽  
Activity Cycles ◽  
F Stars ◽  
One Year ◽  
Index Time Series

Previous studies have revealed a 120 day activity cycle in the F-type star τ Boo, which represents the shortest activity cycle discovered until now. The question arises as to whether or not short-term activity cycles are a common phenomenon in F-type stars. To address this question, we analyse S-index time series of F-type stars taken with the TIGRE telescope to search for periodic variations with a maximal length of 2 years using the generalised Lomb-Scargle periodogram method. In our sample, we find four F-type stars showing periodic variations shorter than one year. However, the amplitude of these variations in our sample of F-star type stars appears to be smaller than that of solar-type stars with well-developed cyclic activity, and apparently represents only a part of the total activity. We conclude that among F-stars, the time-behaviour of activity differs from that of the Sun and cooler main sequence stars, as short-term cyclic variations with shallow amplitude of the cycle seem to prevail, rather than cycles with 10+ years periods and a larger cycle amplitude.

scholarly journals A Summary of the Joint Discussion at Patras on Solar Luminosity Variations

1983 ◽  
Vol 6 ◽  
pp. 75-94
Author(s):  
J. Eddy ◽  
P. Foukal
Keyword(s):  
Storage Time ◽  
Activity Cycle ◽  
Thermal Storage ◽  
Solar Activity Cycle ◽  
Solar Constant ◽  
Short Term ◽  
Solar Luminosity ◽  
The Past ◽  
Direct Observations ◽  
Total Irradiance

The most interesting result in solar luminosity studies in the past decade has been the detection of significant variations in the total irradiance by precision radiometers on the NIMBUS-7 and SMM spacecraft. A substantial fraction of the observed variation can be attributed to sunspot blocking. Thermal storage models indicate that the blocked flux can be stored in a slight increase of the thermal and potential energy of the convective zone. The thermal storage time is likely to far exceed one solar activity cycle, implying an 11-year modulation of the solar constant at a level of about 0.1%. Direct observations of the 11-year or longer variations are more difficult but there is some evidence for secular trends below about 0.4% amplitude over the 14-year period of modern sampling. Ongoing stellar photometric programs suggest that luminosity changes exceeding 1% may have been detected in young, chromospherically active stars.H. S. Hudson (University of California, San Diego) reviewed observations of short-term solar irradiance variations from spacecraft, commenting principally on the precision measurements of the solar constant (S) made by the Active Cavity Radiometer (ACRIM) on the Solar Maximum Mission (SMM) spacecraft (Willson et al., 1981).

scholarly journals Optimality in a partitioned task performed by social insects

2008 ◽  
Vol 4 (6) ◽  
pp. 627-629 ◽  
Author(s):  
Martin Burd ◽  
Jerome J Howard
Keyword(s):  
Social Insects ◽  
Social Insect ◽  
Leaf Tissue ◽  
Leaf Fragment ◽  
Ant Colonies ◽  
Tissue Processing ◽  
Leaf Cutting ◽  
Laboratory Colonies ◽  
Atta Colombica ◽  
Behavioural Adaptations

Biologists have long been aware that adaptations should not be analysed in isolation from the function of the whole organism. Here, we address the equivalent issue at the scale of a social insect colony: the optimality of component behaviours in a partitioned sequence of tasks. In colonies of Atta colombica , a leaf-cutting ant, harvested leaf tissue is passed from foragers to nest workers that distribute, clean, shred and implant the tissue in fungal gardens. In four laboratory colonies of A. colombica , we found that the highest colony-wide rate of leaf tissue processing in the nest was achieved when leaf fragment sizes were suboptimal for individual delivery rate by foragers. Leaf-cutting ant colonies appear to compromise the efficiency of collecting leaf tissue in order to increase their ability to handle the material when it arrives in the nest. Such compromise reinforces the idea that behavioural adaptations, like adaptations in general, must be considered within the context of the larger entity of which they are a part.

scholarly journals Nest Entrances, Spatial Fidelity, and Foraging Patterns in the Red Ant Myrmica rubra: A Field and Theoretical Study

Insects ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 317 ◽  
Author(s):  
Marine Lehue ◽  
Claire Detrain ◽  
Bertrand Collignon
Keyword(s):  
Spatial Distribution ◽  
Social Insects ◽  
Theoretical Study ◽  
High Fidelity ◽  
Nest Architecture ◽  
Myrmica Rubra ◽  
Foraging Patterns ◽  
Ant Colonies ◽  
Agent Model ◽  
Multi Agent

The nest architecture of social insects deeply impacts the spatial distribution of nestmates their interactions, information exchanges and collective responses. In particular, the number of nest entrances can influence the interactions taking place beyond the nest boundaries and the emergence of collective structures like foraging trails. Here, we investigated in the field how the number of nest entrances impacted the foraging dynamics of Myrmica rubra ant colonies. We located the nest entrances where recruitment occurred towards sugar feeders placed in their surroundings. The nests showed one or multiple entrance(s) aggregated in clusters spaced by at least 15 cm. Foragers from colonies with two clusters of entrances were distributed more homogeneously among the feeders than those of colonies with one cluster. In addition, foragers always returned to the first discovered feeder and demonstrated a high fidelity to their original entrance. Finally, a multi-agent model highlighted that additional entrances and clusters of entrances delayed the mobilisation of workers but favoured the simultaneous exploitation of several sources, which was further enhanced by the spatial fidelity of foragers. Multiple nest entrances seem to be a way for medium-sized colonies to benefit from advantages conferred by polydomy while avoiding associated costs to maintain social cohesion.

scholarly journals Self-assembly, self-organization and division of labour

1999 ◽  
Vol 354 (1388) ◽  
pp. 1395-1405 ◽  
Author(s):  
Ana B. Sendova-Franks ◽  
Nigel R. Franks
Keyword(s):  
Self Assembly ◽  
Division Of Labour ◽  
Self Organization ◽  
Ecological Communities ◽  
Social Resilience ◽  
Biological Organization ◽  
Ant Colonies ◽  
The Social ◽  
Biological Hierarchy ◽  
Animal Societies

The prospect of generic principles of biological organization being uncovered through the increasingly broad use of the concepts of ‘self–assembly’ and ‘self–organization’ in biology will only be fulfilled if students of different levels of biological organization use the same terms with the same meanings. We consider the different ways the terms ‘self–assembly’ and ‘self–organization’ have been used, from studies of molecules to studies of animal societies. By linking ‘self–assembly’ and ‘self–organization’ with division of labour, we not only put forward a distinction between the underlying concepts but we are also able to relate them to the question: Why has a certain structure been favoured by natural selection? Using the particularly instructive case of social resilience in ant colonies, we demonstrate that the principle of self–organizing self–assembly may apply to higher levels of biological organization than previously considered. We predict that at the level of interactions among organisms within the most advanced animal societies, specialization through learning has a crucial role to play in re–assembly processes. This review may also help important commonalities and differences to be recognized between ordering mechanisms up to the social level and those further up the biological hierarchy, at the level of ecological communities.

“This Gig Is Not for Women”: Gender Stereotyping in Online Hiring

2019 ◽  
pp. 089443931989575
Author(s):  
Hernan Galperin
Keyword(s):  
Gender Stereotypes ◽  
Gender Segregation ◽  
Job Applicants ◽  
Limited Information ◽  
Short Term ◽  
Sex Typing ◽  
Female Candidates ◽  
Gig Economy ◽  
Gender Characteristics ◽  
Worker Activity

This study examines gender segregation in the context of the so-called gig economy. In particular, it explores the role that stereotypes about male and female occupations play in sorting men and women into different jobs in an online freelance marketplace. The findings suggest that gender stereotypes are particularly salient in online hiring because employers typically contract for short-term, relatively low-value jobs based on limited information about job applicants. These conditions trigger the use of cognitive shortcuts about intrinsic gender characteristics linked to different skills and occupations. The results corroborate that female candidates are less likely to be hired for male-typed jobs (e.g., software development) but more likely to be hired for female-typed jobs (e.g., writing and translation) than equally qualified male candidates. Further, the study investigates three mechanisms predicted to attenuate the female penalty in male-typed jobs. The penalty is found to be self-reinforcing, as it perpetuates gender imbalances in worker activity across job categories that strengthen the sex typing of occupations.

scholarly journals A Preliminary Study toward a Rapid Assessment of Age-Related Behavioral Differences in Family Dogs

Animals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1222 ◽  
Author(s):  
Eniko Kubinyi ◽  
Ivaylo B. Iotchev
Keyword(s):  
Short Term Memory ◽  
Rapid Assessment ◽  
Memory Task ◽  
Behavioral Differences ◽  
Short Term ◽  
Test Procedures ◽  
Training Requirements ◽  
Age Related ◽  
Preliminary Study ◽  
Physical Capacities

Over the last few years, several efforts have been undertaken to characterize the aging process in dogs. In the present study, we evaluate a short protocol measuring dogs’ cognitive, social, and physical capacities. Our aim was to develop a feasible test battery, with minimal pre-training requirements, no complex devices, and which is set outdoors (i.e., a specific testing room is not needed). As ageing in dogs is usually associated with a decrease in activity, we also assessed the personality trait activity/excitability with a dog personality questionnaire. Four subtests proved sensitive to the dogs’ age. In particular, old dogs displayed less approaching and following behaviors toward an unknown but friendly human, showed both less avoidance and interest toward a novel object, looked less at the owner when faced with an unsolvable problem, and performed worse on the short-term memory task. Previous test procedures for investigating age-related changes involve expensive and/or complicated devices and extensive pre-training. The main advantage of the proposed battery is to reduce costs and efforts in veterinary assessments. Further tests in same-breed, large samples and between dogs with mild and severe cognitive impairments will be needed in order to further validate the battery.

scholarly journals Workers influence royal reproduction

2010 ◽  
Vol 278 (1711) ◽  
pp. 1524-1531 ◽  
Author(s):  
Richard J. Gill ◽  
Robert L. Hammond
Keyword(s):  
Sex Ratio ◽  
Social Insects ◽  
Cooperative Breeding ◽  
Parentage Analysis ◽  
Egg Laying ◽  
Male Production ◽  
Leptothorax Acervorum ◽  
Worker Brood ◽  
Breeding Groups ◽  
Animal Societies

Understanding which parties regulate reproduction is fundamental to understanding conflict resolution in animal societies. In social insects, workers can influence male production and sex ratio. Surprisingly, few studies have investigated worker influence over which queen(s) reproduce(s) in multiple queen (MQ) colonies (skew), despite skew determining worker-brood relatedness and so worker fitness. We provide evidence for worker influence over skew in a functionally monogynous population of the ant Leptothorax acervorum . Observations of MQ colonies leading up to egg laying showed worker aggressive and non-aggressive behaviour towards queens and predicted which queen monopolized reproduction. In contrast, among-queen interactions were rare and did not predict queen reproduction. Furthermore, parentage analysis showed workers favoured their mother when present, ensuring closely related fullsibs (average r = 0.5) were reared instead of less related offspring of other resident queens ( r ≤ 0.375). Discrimination among queens using relatedness-based cues, however, seems unlikely as workers also biased their behaviour in colonies without a mother queen. In other polygynous populations of this species, workers are not aggressive towards queens and MQs reproduce, showing the outcome of social conflicts varies within species. In conclusion, this study supports non-reproductive parties having the power and information to influence skew within cooperative breeding groups.

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