scholarly journals Colony expansions underlie the evolution of army ant mass raiding

2021 ◽  
Vol 118 (22) ◽  
pp. e2026534118
Author(s):  
Vikram Chandra ◽  
Asaf Gal ◽  
Daniel J. C. Kronauer
Keyword(s):  
Collective Behavior ◽  
Colony Size ◽  
Cooperative Behavior ◽  
Close Relative ◽  
Army Ants ◽  
Army Ant ◽  
Cooperative Hunting ◽  
Behavioral Rules ◽  
Behavioral Interaction ◽  
Collective Phenomenon

The mass raids of army ants are an iconic collective phenomenon, in which many thousands of ants spontaneously leave their nest to hunt for food, mostly other arthropods. While the structure and ecology of these raids have been relatively well studied, how army ants evolved such complex cooperative behavior is not understood. Here, we show that army ant mass raiding has evolved from a different form of cooperative hunting called group raiding, in which a scout directs a small group of ants to a specific target through chemical communication. We describe the structure of group raids in the clonal raider ant, a close relative of army ants in the subfamily Dorylinae. We find evidence that the coarse structure of group raids and mass raids is highly conserved and that all doryline ants likely follow similar behavioral rules for raiding. We also find that the evolution of army ant mass raiding occurred concurrently with expansions in colony size. By experimentally increasing colony size in the clonal raider ant, we show that mass raiding gradually emerges from group raiding without altering individual behavioral rules. This suggests that increasing colony size can explain the evolution of army ant mass raids and supports the idea that complex social behaviors may evolve via mechanisms that need not alter the behavioral interaction rules that immediately underlie the collective behavior of interest.

scholarly journals Colony expansions underlie the evolution of army ant mass raiding

2020 ◽  
Author(s):  
Vikram Chandra ◽  
Asaf Gal ◽  
Daniel J. C. Kronauer
Keyword(s):  
Collective Behavior ◽  
Close Relative ◽  
Alternative Mechanism ◽  
Scaling Effects ◽  
Army Ants ◽  
Evolutionary Transitions ◽  
Army Ant ◽  
Behavioral Rules ◽  
Group Members ◽  
Fine Tune

ABSTRACTCollective behavior emerges from local interactions between group members, and natural selection can fine-tune these interactions to achieve different collective outcomes. However, at least in principle, collective behavior can also evolve via changes in group-level parameters. Here, we show that army ant mass raiding, an iconic collective behavior in which many thousands of ants spontaneously leave the nest to go hunting, has evolved from group raiding, in which a scout directs a much smaller group of ants to a specific target. We describe the structure of group raids in the clonal raider ant, a close relative of army ants. We find that the coarse structure of group raids and mass raids is highly conserved, and that army ants and their relatives likely follow similar behavioral rules, despite the fact that their raids differ strikingly in overall appearance. By experimentally increasing colony size in the clonal raider ant, we show that mass raiding gradually emerges from group raiding without altering individual behavioral rules. This suggests a simple mechanism for the evolution of army ant mass raids, and more generally that scaling effects may provide an alternative mechanism for evolutionary transitions in complex collective behavior.

Cooperation between Species

2017 ◽  
Author(s):  
Raymond Pierotti ◽  
Brandy R. Fogg
Keyword(s):  
Cooperative Behavior ◽  
Natural World ◽  
Western Science ◽  
Ecological Communities ◽  
Cooperative Hunting ◽  
Wide Range

This chapter reviews the study of cooperative behavior between species, with emphasis on examples of cooperative hunting found in a wide range of species. Seen in this context, the idea of cooperative hunting between humans and wolves that evolved into present relationships with dogs does not seem unusual or surprising. The chapter then critiques the proposal that competition between species is more important than cooperation in structuring ecological communities, discussing how this notion leads to a suite of ideas philosophically separating humans from the rest of the natural world. In many ways Western science is unintentionally complicit in such thinking. The chapter concludes by discussing complex cooperation, including long-term relationships between members of different species.

scholarly journals Deep-time parallel evolution of myrmecoid syndrome in rove beetle symbionts of army ants

2016 ◽  
Author(s):  
Munetoshi Maruyama ◽  
Joseph Parker
Keyword(s):  
Parallel Evolution ◽  
Army Ants ◽  
Deep Time ◽  
Rove Beetles ◽  
Army Ant ◽  
Rove Beetle ◽  
Arthropod Predators ◽  
Adaptive Radiations ◽  
Ecological Dominance ◽  
Temporary Nest

Recent adaptive radiations provide striking examples of convergence, but the predictability of evolution over much deeper timescales is controversial, due to a scarcity of ancient clades exhibiting repetitive patterns of phenotypic evolution. Army ants are ecologically dominant arthropod predators of the world's tropics, with large nomadic colonies housing diverse communities of socially parasitic myrmecophiles. Remarkable among these are many species of rove beetle (Staphylinidae) that exhibit ant-mimicking “myrmecoid” body forms and are behaviorally accepted into their aggressive hosts' societies: emigrating with colonies and inhabiting temporary nest bivouacs, grooming and feeding with workers, but also consuming the brood. Here we demonstrate that myrmecoid rove beetles are strongly polyphyletic, with this novel adaptive morphological and behavioral syndrome having evolved at least twelve times during the evolution of a single staphylinid subfamily, Aleocharinae. Each independent myrmecoid clade is restricted to one zoogeographic region and highly host-specific on a single army ant genus. Dating estimates reveal that myrmecoid clades are separated by substantial phylogenetic distances—as much as 105 million years (My). All such groups arose in parallel during the Cenozoic, as army ants are proposed to have risen to ecological dominance. This work uncovers a rare example of an ancient system of complex morphological and behavioral convergence, with replicate beetle lineages following a predictable phenotypic trajectory during their parasitic coevolution with army ants.

scholarly journals Comparative chemical analysis of army ant mandibular gland volatiles (Formicidae: Dorylinae)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5319 ◽  
Author(s):  
Adrian Brückner ◽  
Philipp O. Hoenle ◽  
Christoph von Beeren
Keyword(s):  
Solid Phase ◽  
Keystone Species ◽  
Chemical Compounds ◽  
Mandibular Gland ◽  
Army Ants ◽  
Army Ant ◽  
Alarm Communication ◽  
Gland Volatiles ◽  
Precise Role ◽  
Mandibular Gland Secretions

Army ants are keystone species in many tropical ecosystems. Yet, little is known about the chemical compounds involved in army ant communication. In the present study, we analyzed the volatile mandibular gland secretions—triggers of ant alarm responses—of six Neotropical army ant species of the genus Eciton (outgroup: Nomamyrmex esenbeckii). Using solid-phase microextraction, we identified 12 chemical compounds, primarily ketones with associated alcohols, one ester and skatole. Most compounds were shared among species, but their relative composition was significantly different. By comparing chemical distances of mandibular gland secretions to species divergence times, we showed that the secretions’ compositions are not strictly determined by phylogeny. By identifying chemical bouquets of seven army ant species, our study provides a valuable comparative resource for future studies aiming to unveil the chemicals’ precise role in army ant alarm communication.

scholarly journals The adaptive significance of phasic colony cycles in army ants

2016 ◽  
Author(s):  
Simon Garnier ◽  
Daniel J. C. Kronauer
Keyword(s):  
Resource Depletion ◽  
Adaptive Significance ◽  
Brood Care ◽  
Army Ants ◽  
Army Ant ◽  
Arthropod Predators ◽  
Per Capita ◽  
Resource Exhaustion ◽  
Reproductive Cycles ◽  
Reproductive Phases

AbstractArmy ants are top arthropod predators in tropical forests around the world. The colonies of many army ant species undergo stereotypical behavioral and reproductive cycles, alternating between brood care and reproductive phases. In the brood care phase, colonies contain a cohort of larvae that are synchronized in their development and have to be fed. In the reproductive phase larvae are absent and oviposition takes place. Despite these colony cycles being a striking feature of army ant biology, their adaptive significance is unclear. Here we use a modelling approach to show that cyclic reproduction is favored under conditions where per capita foraging costs decrease with the number of larvae in a colony ("High Cost of Entry" scenario), while continuous reproduction is favored under conditions where per capita foraging costs increase with the number of larvae ("Resource Exhaustion" scenario). We argue that the former scenario specifically applies to army ants, because large raiding parties are required to overpower prey colonies. However, once raiding is successful it provides abundant food for a large cohort of larvae. The latter scenario, on the other hand, will apply to non-army ants, because in those species local resource depletion will force workers to forage over larger distances to feed large larval cohorts. Our model provides the first quantitative framework for understanding the adaptive value of phasic colony cycles in ants.

scholarly journals Constructing social identity? Potential non-nutritional functions of chimpanzee insectivory

2016 ◽  
Author(s):  
Umaru Buba ◽  
Volker Sommer ◽  
Goncalo Jesus ◽  
Alejandra Pascual-Garrido
Keyword(s):  
Social Identity ◽  
Army Ants ◽  
Army Ant ◽  
Dietary Choices ◽  
Faecal Samples ◽  
Identity Based ◽  
Ant Eating ◽  
Principal Method ◽  
Term Data

Many animals, including humans and chimpanzees (Pan troglodytes), eat insects, although frequencies vary greatly between populations. Insects are traditionally either seen as desired nourishment or a fallback fare compensating a shortage of preferred foods. We test these explanations against long-term data on chimpanzees at Gashaka, Nigeria. Here, chimpanzees harvest army ants much more frequently than elsewhere, while termite eating is completely absent. We report a pattern of strict seasonality in terms of rainfall and pronounced peaks in the abundance of fruit, the chimpanzees’ preferred staple food. Even so, evidence based on recovered ant-dipping wands and chimpanzee faecal samples indicates that myrmecophagy does not decrease when fruit becomes more abundant. Instead, ant-eating is virtually constant year round and chimpanzees eat them every other day or so. This contradicts the fallback hypothesis and supports the hypothesis of ants as preferred food. Army ants may thus serve as a supplement or complement in terms of macro - or micronutrients to the chimpanzees. Nevertheless, it remains puzzling why termites are not eaten at Gashaka, despite apparent availability and technological skills to extract insects. We therefore propose that dietary choices are also likely to contain a social element. The non-consumption of a perfectly edible food-item may reflect a "taboo" that comes at some cost. Similarly, army ant gathering is associated with painful bites, and self-experiments suggest that the highly chitinous insects do not taste well, compared to smaller arboreal ants and termites. We speculate that, in this way, mental concepts of identity versus otherness may develop that strengthen group cohesion. We do not have sufficient data for Nigeria, but speculations about social identity based on community-dependent behavioural uniformity are open to empirical testing. The principal method would be to document natural instances of “acculturation”, when female chimpanzees transfer from their natal into a neighbouring community.

scholarly journals Bivouac Checking, A Novel Behavior Distinguishing Obligate from Opportunistic Species of Army-Ant-Following Birds

The Condor ◽  
2001 ◽  
Vol 103 (3) ◽  
pp. 629-633 ◽  
Author(s):  
Monica Beth Swartz
Keyword(s):  
Food Supply ◽  
New Method ◽  
Army Ants ◽  
Ant Colonies ◽  
Opportunistic Species ◽  
Army Ant ◽  
Checking Behavior ◽  
Novel Behavior ◽  
Forest Floors ◽  
The Many

Abstract As swarms of the army ant Eciton burchelli forage across forest floors of the lowland Neotropics, birds gather to eat arthropods flushed by the advancing ants. Past efforts to distinguish members of the obligate ant-following bird guild from the many species that forage opportunistically with army ants have been inadequate. Obligate ant-followers track the locations of multiple nomadic ant colonies in order to maintain a consistent food supply. Each morning, they visit the bivouac site of each colony they are monitoring to assess the ants' activity. Only species dependent upon foraging with army ants exhibit this specialized bivouac checking behavior. This paper proposes a new method for distinguishing between obligate and opportunistic ant-following birds by observing which species check bivouacs. Verificación de Vivaques, un Comportamiento Nuevo que Distingue a Especies Obligatorias de Especies Oportunistas Rastreadores de Hormigas-Ejército Resumen. Cuando enjambres de la hormiga ejército Eciton burchelli forrajean en los suelos de los bosques bajos Neotropicales, algunas aves se aglomeran para ingerir artrópodos espantados por las hormigas que avanzan. Esfuerzos pasados para distinguir entre aquellos miembros del gremio de aves que rastrean las hormigas obligatoriamente de las muchas especies que forrajean de manera oportunista con hormigas ejército han sido inadecuados. Seguidores obligatorios de las hormigas rastrean los sitios de varias colonias nómadas de hormigas a fin de mantener un suministro consistente de alimentos. Cada mañana, estas aves visitan el sitio de vivaque de cada una de las colonias que controlan con fin de evaluar las actividades de las hormigas. Sólo aquellas especies que dependen del forrajeo de las hormigas ejército manifiestan este comportamiento especializado de verificar los vivaques. Este artículo propone un nuevo método para distinguir entre las aves oportunistas y las aves obligatorias rastreadoras de hormigas mediante la observación de aquellas especies que verifican los vivaques.

Swarm Robotic Systems Based on Collective Behavior of Chloroplasts

2017 ◽  
Vol 29 (3) ◽  
pp. 602-612 ◽  
Author(s):  
Satoshi Hoshino ◽  
◽  
Ryo Takisawa ◽  
Yutaka Kodama ◽  
Keyword(s):  
Light Source ◽  
Collective Behavior ◽  
Autonomous Robots ◽  
Cooperative Behavior ◽  
Ground Surface ◽  
Robotic Systems ◽  
Behavioral Models ◽  
System A ◽  
Robot Behavior ◽  
Behavior Models

[abstFig src='/00290003/15.jpg' width='300' text='Swarming chloroplastic robots around light source' ] In this paper, distributed autonomous robots are used to perform area coverage tasks. In order for robots to cover the ground surface of environments, the coordination of a team of robots is a challenge. For this challenge, we present bio-inspired swarm robotic systems. We focus on the collective behavior of chloroplasts toward a light source. On the basis of the mechanism of the chloroplast, we propose robot behavior models that do not use local communication. The emergence of cooperative behavior through the interaction among the swarming robots is a main contribution of this paper. Based on simulation results, the effectiveness of the chloroplastic robots for the coverage task is discussed in terms of flexibility and scalability. Furthermore, the behavioral models are applied to actual mobile robots. Based on the results of experiments, the applicability of the chloroplastic robots to real environments is discussed. As an application of the swarm robotic system, a specific task, sweeping, is given to actual chloroplastic robots.

scholarly journals Antbird Guilds in the Lowland Caribbean Rainforest of Southeast Nicaragua

The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 784-794 ◽  
Author(s):  
Martin L. Cody
Keyword(s):  
Body Size ◽  
Foraging Ecology ◽  
Habitat Preferences ◽  
Logarithmic Scale ◽  
Mixed Species ◽  
Army Ants ◽  
Army Ant ◽  
Body Sizes ◽  
Mixed Species Flocks ◽  
Species Flocks

Abstract Some 20 species of antbirds occur in lowland Caribbean rainforest in southeast Nicaragua where they form five distinct guilds on the basis of habitat preferences, foraging ecology, and foraging behavior. Three guilds are habitat-based, in Edge, Forest, and Gaps within forest; two are behaviorally distinct, with species of army ant followers and those foraging within mixed-species flocks. The guilds each contain 3–6 antbird species. Within guilds, species are segregated by body size differences between member species, and in several guilds are evenly spaced on a logarithmic scale of body mass. Among guilds, the factors by which adjacent body sizes differ vary between 1.25 and 1.75. Body size differences may be related to differences in preferred prey sizes, but are influenced also by the density of the vegetation in which each species customarily forages. Resumen. Unas 20 especies de aves hormigueras viven en el bosque tropical perennifolio, sureste de Nicaragua, donde se forman cinquo gremios distinctos estribando en preferencias de habitat, ecologia y comportamiento de las costumbres de alimentacion. Las diferencias entre las varias especies son cuantificadas por caractaristicas del ambiente vegetal y por la ecologia y comportamiento de la alimentación, y usados para definir cinco grupos o gremios (“guilds”). Tres gremios se designan por las relaciones de habitat: edge (margen), forest (selva), y gaps (aberturas adentro la selva); dos mas por comportamiento, partidarios de army ants (hormigas armadas) y mixed-species flocks (forrejando en bandadas de especies mexcladas). Estos gremios contenien 3–6 especies hormiguera. Dentro de grupos hay diferencias regulares en peso de cuerpo entre las especies; diferencias que igualmente existen entre los gremios diferentes, con razónes medios de 1.25 a 1.75 en peso de cuerpo. Las diferencias en el tamaño de especies individuales probablemente estan relaciónadas con las diferencias entre los tamaños de las presas preferidas, pero quizas son influenciadas por la densidad de la vegetacion en donde se alimentan.

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