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Spatial characteristics of alarm recruitment. Variation in unalarmed ants b AS during the time of approaching their alarmed neighbours. Each point indicates one unalarmed ant. The y-axis shows the variation in b AS during the time the two ants were near each other, and the x-axis shows the minimum distance between the two ants during that time. Unalarmed ants which came closer to alarmed neighbours varied more in their b AS (7.3 pixel = 1 mm). Circles represent observations; curve represents expectations in exponential decay model equation (3.1).
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Alarm signal propagation through ant colonies provides an empirically tractable context for analysing information flow through a natural system, with useful insights for network dynamics in other social animals. Here, we develop a methodological approach to track alarm spread within a group of harvester ants, Pogonomyrmex californicus. We initially...
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... For instance, ants have been shown to exhibit lower levels of aggression when alone versus in a group owing to the need for colony defence [62] or the presence of social cues [60,63]. In a colony setting, the social environment can amplify individual defence based on the social information individuals perceive (e.g. via alarm pheromones [64,65] or non-nestmate cues [66]). Additionally, past work on social insects involved colonies containing individuals of varying ages, genetic backgrounds and/or morphology. ...
Division of labour (DOL) plays a key role across all scales of biological organization, but how its expression varies across contexts is still poorly understood. Here, we measure DOL in a crucial task, colony defence, in a social insect that affords precise experimental control over individual and colony traits, the clonal raider ant (Ooceraea biroi). We find that DOL in defence behaviour emerges within colonies of near-identical workers, likely reflecting variation in individual response thresholds, and that it increases with colony size. Additionally, colonies with pupae show higher defence levels than those without brood. However, we do not find evidence for a behavioural syndrome linking defence with exploration and activity, as previously reported in other systems. By showing how colony composition and size affect group response to potential threats, our findings highlight the role of the social context in shaping DOL.
This article is part of the theme issue ‘Division of labour as key driver of social evolution’.
... Also of interest is the higher level of undecane. This organic compound (an alkane) has been found to be a mild sex attractant for various types of insects, such as moths and cockroaches [64], and an alert signal for a variety of ants [60,65]. During this study, undecane was seen to have the highest concentration in females with a lower concentration of xylose and arabinose metabolites in their feces. ...
Background/Objectives: This study provides the first insights to the fecal metabolome of the giraffe (Giraffa camelopardalis). By using untargeted metabolomics via gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS), this study primarily aims to provide results of the impact that external stimuli, such as supplemental feeding (SF) practices, seasonal variation and sex, might have on the fecal metabolome composition of healthy, free-roaming giraffes. Methods: Untargeted GCxGC/TOF-MS analysis was applied to the feces collected from thirteen giraffes (six males and seven females) from six different locations within the central Free State Province of South Africa over a period of two years. Statistical analysis of the generated data was used to identify the metabolites that were significantly different between the giraffes located in environments that provided SF and others where the giraffes only fed on the natural available vegetation. The same metabolomics analysis was used to investigate metabolite concentrations that were significantly different between the wet and dry seasons for a single giraffe male provided with SF over the two-year period, as well as for age and sex differences. Results: A total of 2042 features were detected from 26 giraffe fecal samples. Clear variations between fecal metabolome profiles were confirmed, with higher levels of amino acid-related and carbohydrate-related metabolites for giraffes receiving SF. In addition, a separation between the obtained profiles of samples collected from a single adult male giraffe during the wet and dry seasons was identified. Differences, such as higher levels of carbohydrate-related metabolites and organic compounds during the wet season were noted. Distinct variations in profiles were also identified for the metabolites from fecal samples collected from the six males and seven females, with higher concentrations in carbohydrate-related metabolites and alkanes for female giraffes comparatively. Conclusions: This is the first study to investigate the composition of the fecal metabolome of free-roaming giraffes, as well as the effects that external factors, such as environmental exposures, feeding practices, seasonal variations, age and sex, have on it. This novel use of fecal metabolomics assists in developing non-invasive techniques to determine giraffe populations’ health that do not require additional stressors such as capture, restraint and blood collection. Ultimately, such non-invasive advances are beneficial towards the conservation of wildlife species on a larger scale.
... (1) Speeding up is a common behaviour of ants during a state of alarm (e.g. Guo et al., 2022;Lalor & Hughes, 2011). The ants in the present study sped up immediately after touching the fungus treatment, which indicates that the differences in odour or taste between the plant fibres and rhizomorphs were enough to trigger the alarm after encountering the rhizomorph. ...
... The specific information and resources acquired by workers can, in turn, influence individual spatial preferences and, in doing so, assist the whole colony to re-establish the spatial distribution of workers to cope with various challenges (Theraulaz et al. 2003). This interplay between information acquisition and worker spatial movement patterns has been widely studied in various ant species, for example, nest-site choice and famine relief of T. albipennis (Pratt et al. 2002a;Sendova-Franks et al. 2010), alarm propagation of P. californicus (Guo et al. 2022), social immunity of L. niger (Stroeymeyt et al. 2018) and nutritional balance of C. sanctus (Baltiansky et al. 2021). Although an ideal model for studying this interplay, the processes and mechanisms by which task-related information and social contact mediate workforce re-allocation within colonies are still understudied. ...
Models of social interaction dynamics have been powerful tools for understanding the efficiency of information spread and the robustness of task allocation in social insect colonies. How workers spatially distribute within the colony, or spatial heterogeneity degree (SHD), plays a vital role in contact dynamics, influencing information spread and task allocation. We used agent-based models to explore factors affecting spatial heterogeneity and information flow, including the number of task groups, variation in spatial arrangements, and levels of task switching, to study: (1) the impact of multiple task groups on SHD, contact dynamics, and information spread, and (2) the impact of task switching on SHD and contact dynamics. Both models show a strong linear relationship between the dynamics of SHD and contact dynamics, which exists for different initial conditions. The multiple-task-group model without task switching reveals the impacts of the number and spatial arrangements of task locations on information transmission. The task-switching model allows task-switching with a probability through contact between individuals. The model indicates that the task-switching mechanism enables a dynamical state of task-related spatial fidelity at the individual level. This spatial fidelity can assist the colony in redistributing their workforce, with consequent effects on the dynamics of spatial heterogeneity degree. The spatial fidelity of a task group is the proportion of workers who perform that task and have preferential walking styles toward their task location. Our analysis shows that the task switching rate between two tasks is an exponentially decreasing function of the spatial fidelity and contact rate. Higher spatial fidelity leads to more agents aggregating to task location, reducing contact between groups, thus making task switching more difficult. Our results provide important insights into the mechanisms that generate spatial heterogeneity and deepen our understanding of how spatial heterogeneity impacts task allocation, social interaction, and information spread.
... Through a combination of modeling, simulation, and empirical observations of alarm spread and damping patterns, we identified the behavioral rules governing this adaptive response. Experimental trials involving alarmed ant workers (Pogonomyrmex californicus) released into a tranquil group of nestmates revealed a consistent pattern of rapid alarm propagation followed by a comparatively extended decay period [1]. The experiments in [1] showed that individual ants exhibiting alarm behavior increased their movement speed, with variations in response to alarm stimuli, particularly during the peak of the reaction. ...
... Experimental trials involving alarmed ant workers (Pogonomyrmex californicus) released into a tranquil group of nestmates revealed a consistent pattern of rapid alarm propagation followed by a comparatively extended decay period [1]. The experiments in [1] showed that individual ants exhibiting alarm behavior increased their movement speed, with variations in response to alarm stimuli, particularly during the peak of the reaction. We used the data in [1] to investigate whether these observed characteristics alone could account for the swift mobility increase and gradual decay of alarm excitement. ...
... At its peak, the alarm response can trigger a qualitative shift in colony behavior, leading to attacks on invaders or the abandonment of the nest space. However, when the threat is unfounded, the alarm response quickly subsides to pre-alarm activity levels [1]. The physical contacts associated with the diffusion-modulated pattern of alarm information contribute to the amplification, flow, and dampening of the alarm response, making it a valuable model for understanding transmission and infection processes at various scales. ...
Ant colonies demonstrate a finely tuned alarm response to potential threats, offering a uniquely manageable empirical setting for exploring adaptive information diffusion within groups. To effectively address potential dangers, a social group must swiftly communicate the threat throughout the collective while conserving energy in the event that the threat is unfounded. Through a combination of modeling, simulation, and empirical observations of alarm spread and damping patterns, we identified the behavioral rules governing this adaptive response. Experimental trials involving alarmed ant workers (Pogonomyrmex californicus) released into a tranquil group of nestmates revealed a consistent pattern of rapid alarm propagation followed by a comparatively extended decay period [1]. The experiments in [1] showed that individual ants exhibiting alarm behavior increased their movement speed, with variations in response to alarm stimuli, particularly during the peak of the reaction. We used the data in [1] to investigate whether these observed characteristics alone could account for the swift mobility increase and gradual decay of alarm excitement. Our self-propelled particle model incorporated a switch-like mechanism for ants' response to alarm signals and individual variations in the intensity of speed increased after encountering these signals. This study aligned with the established hypothesis that individual ants possess cognitive abilities to process and disseminate information, contributing to collective cognition within the colony (see [2] and the references therein). The elements examined in this research support this hypothesis by reproducing statistical features of the empirical speed distribution across various parameter values.
... We first isolated workers in a foraging arena (11 × 17 × 5 cm) coated with INSECT-a-SLIP (BioQuip Products Inc., Rancho Dominguez, CA) for 5 min to acclimate. We then prodded individuals on their back legs with soft forceps to illicit a defense response (similar to methods in Guo et al., 2022). We recorded reactions according to the behavioral scale of 1-6 modified from Kamhi et al. (2015): (1) Nondefensive behavior, such as reversing direction or running away, ...
Human disturbance including rapid urbanization and increased temperatures can have profound effects on the ecology of local populations. Eusocial insects, such as ants, have adapted to stressors of increasing temperature and urbanization; however, these evolutionary responses are not consistent among populations across geographic space. Here we asked how urbanization and incubation temperature influence critical thermal maximum (CT max) and various ecologically relevant behaviors in three ant species in urban and rural locations in Worcester, MA, USA. We did this by incubating colonies of three species of cavity dwelling ant (Aphaenogaster picea, Tapinoma sessile, and Temnothorax longispinosus) from 2 habitat types (Rural and Urban), for 60-days at multiple temperatures. We found that incubation temperature, urbanization, and species of ant all significantly affected overall colony critical thermal maximum. We also found that recruitment time, colonization time, and defense response were significantly affected by incubation temperature and varied between species of ant, while recruitment and colonization time were additionally affected by urbanization. These variable changes in performance and competitive traits across species suggest that responses to urbanization and shifting temperatures are not universal across species. Changes in behavioral responses caused by urbanization may disrupt biodiversity, creating unusual competitive environments as a consequence of natural adaptations and cause both direct and indirect mechanisms for which human disturbance can lead to local species extinction.
... Within an insect colony, frequent communication among workers (Fig. 2b) means that the effects of an error made by one individual can potentially propagate throughout the colony. For example, ants alert nestmates when the colony is under attack to mount a collective colony defense, but false alarms can occur (Guo et al. 2022). What keeps these false alarm signals from propagating and leading to costly colony-level responses that pull workers away from essential tasks to a non-existent threat? ...
... What keeps these false alarm signals from propagating and leading to costly colony-level responses that pull workers away from essential tasks to a non-existent threat? In the harvester ant (Pogonomyrmex californicus), a combination of physical interactions and short-lived individual responses acts to rapidly curtail the propagation of false alarms (Guo et al. 2022). The widespread mobilization of unalarmed ants through interaction requires sustained efforts by alarmed ants. ...
Supporting the Earth’s human population without destabilizing planetary processes is the central challenge of sustainability science. Key to achieving this goal is designing systems that are robust and resilient to dynamic and unpredictable conditions. Bioinspiration leverages naturally evolved solutions to address such challenges, yet a solution derived from one-to-one correspondence between a natural and artificial challenge can be limited in its broader application. Here we advocate for an approach to nature-inspired design that forgoes mimicking specific solutions in favor of identifying general design features that enable natural systems to function. These features are not specific to any naturally evolved solution and so have the potential to be broadly applied across human-engineered systems to enhance resiliency in ways that do not compromise ecosystem functioning, thereby contributing to sustainable development. As an illustrative example, we show how a well-known bioinspired algorithm that mimics the collective action of ant colonies can be understood in terms of fundamental design features and how these features can in turn be better harnessed to benefit diverse sustainable design initiatives.
The ecological success of social insects makes their colony organization fascinating to scientists studying collective systems. In recent years, the combination of automated behavioural tracking and social network analysis has deepened our understanding of many aspects of colony organization. However, because studies have typically worked with single species, we know little about interspecific variation in network structure. Here, we conduct a comparative network analysis across five ant species from five subfamilies, separated by more than 100 Myr of evolution. We find that social network structure is highly conserved across subfamilies. All species studied form modular networks, with two social communities, a similar distribution of individuals between the two communities, and equivalent mapping of task performance onto the communities. Against this backdrop of organizational similarity, queens of the different species occupied qualitatively distinct network positions. The deep conservation of the two community structure implies that the most fundamental behavioural division of labour in social insects is between workers that stay in the nest to rear brood, and those that leave the nest to forage. This division has parallels across the animal kingdom in systems of biparental care and probably represents the most readily evolvable form of behavioural division of labour.
