R-ant

with an inflexible transition state.

Abstract

Three homologous spectrin domains have remarkably different folding characteristics. We have previously shown that the slow-folding R16 and R17 spectrin domains can be altered to resemble the fast folding R15, in terms of speed of folding (and unfolding), landscape roughness and folding mechanism, simply by substituting five residues in the core. Here we show that, by contrast, R15 cannot be engineered to resemble R16 and R17. It is possible to engineer a slow-folding version of R15, but our analysis shows that this protein neither has a rougher energy landscape nor does change its folding mechanism. Quite remarkably, R15 appears to be a rare example of a protein with a folding nucleus that does not change in position or in size when its folding nucleus is disrupted. Thus, while two members of this protein family are remarkably plastic, the third has apparently a restricted

Formicidae

The ants of the Formicidae family have a true sting apparatus. Ants of the genus Solenopsis are widespread in the southeastern US, and stings occur so frequently that in many areas, as much as 50% of the population is stung each year.4 In most cases, multiple ants each administer multiple stings, although they are not painful. The unique lesions form sterile pustules that can become infected if excoriated or opened.

Other genera of the formicid ants include the harvester ants (Pogonomyrmex spp.) found in western areas of the US Canada, and Mexico; the Australian jack jumper ants (Myrmecia spp.); and Asian ants (Pachycondyla spp.), which have been reported to cause allergic reactions.Ants are among the most advanced social insects and are characterized by a very efficient recognition system allowing discrimination between group members and strangers, thus protecting colonies from competitors and parasites. Nestmate recognition cues are encoded in the complex hydrocarbon profile present on the cuticle of each ant. The neural mechanisms allowing ants to distinguish between friends and enemies are still not completely understood, and it is unclear whether learning plays a crucial role in this process. However, learning does play an important role when distinguishing individual identity is beneficial, as in the case of co-founding associations of ant queens that establish a dominance hierarchy. Recently, a set of experimental tools has been developed to study learning and memory in ants. This will allow exploring cognitive abilities and their underlying mechanisms in this very diverse taxon.

Ant

Ants are often abundant in mangroves, including the aggressive nest-building weaver ants (Oecophylla) of the Indo-Pacific and leaf-cutter ants (Atta) of South America.

From: Reference Module in Life Sciences, 2017

Related terms:

Venom

Protein

Insect

Raptor

Hymenoptera

Columbidae

Isoptera

Bee

Wasp

Honeybee

View all Topics

Insect Allergy

David B.K. Golden, in Middleton's Allergy Essentials, 2017

Formicidae

View chapterPurchase book

Invertebrate Learning and Memory

Patrizia d'Ettorre, in Handbook of Behavioral Neuroscience, 2013

Ants are among the most advanced social insects and are characterized by a very efficient recognition system allowing discrimination between group members and strangers, thus protecting colonies from competitors and parasites. Nestmate recognition cues are encoded in the complex hydrocarbon profile present on the cuticle of each ant. The neural mechanisms allowing ants to distinguish between friends and enemies are still not completely understood, and it is unclear whether learning plays a crucial role in this process. However, learning does play an important role when distinguishing individual identity is beneficial, as in the case of co-founding associations of ant queens that establish a dominance hierarchy. Recently, a set of experimental tools has been developed to study learning and memory in ants. This will allow exploring cognitive abilities and their underlying mechanisms in this very diverse taxon.

View chapterPurchase book

Plant–Animal Interactions

Ellen L. Simms, in Encyclopedia of Biodiversity (Second Edition), 2013

Benefits to Plants – What Motivates Ants to Patrol?

Ants have frequently been observed killing and removing insect herbivores, and numerous experiments demonstrate the efficacy of this defense. Fonseca (1994) observed more than four times as many herbivores on Tachigali myrmecophila plants from which he removed Pseduomyrmex concolor ants as on plants with intact ant colonies. Further, the daily rate of herbivory was about 10 times lower when ants were present, resulting in experimental plants without ants exhibiting about twice as much cumulative herbivore damage during the 18-month experiment. Leaf longevity was also substantially higher on plants with ants. It is interesting to note that these ants do not eat the herbivores they kill. Instead, they feed exclusively on catenococcid insects they tend inside the domatium, which is the hollow rachis of the compound leaf.

Ants are also effective deterrents of mammalian herbivory. For example, the African myrmecophyte, Acacia drepanolobium, possesses two kinds of thorns. The swollen thorns are domatia in which Crematogaster ants live and rear their broods. The unswollen thorns slow plant damage by browsing mammals, but browsers may compensate by feeding longer. Ants provided far more effective defenses (Stapley, 1998). When a browsing mammal was encountered and stung by ants, it stopped feeding immediately and could not be induced to feed further on that tree.

A second benefit that patrolling ants may provide is in competition with neighboring plants. Ants will prune vines (lianas) and branches of neighboring trees, effectively preventing their host tree from being overgrown (Janzen, 1966). The result of this vigilance is that the host tree might occupy a dramatically open cylinder of space amid otherwise densely packed tree canopies. Although such pruning of neighbors clearly benefits the host tree, it also benefits the ant colony by reducing the number of directions from which it may be attacked by competing or predatory ants (Davidson et al., 1988).

However, ants sometimes harm their own host by pruning it rather than its neighbors. For example, Crematogaster nigriceps so severely prunes its host tree, A. drepanolobium, that the tree cannot flower and is sterilized (Stanton et al., 1999). In the habitat studied, four species of ants compete strongly for hosts, and C. nigriceps fares poorly in the violent conflicts over nest space. Instead of pruning neighboring trees, C. nigriceps prunes its own tree, apparently because it cannot prune neighboring trees occupied by competitively dominant ants. Indeed, careful observation of a large number of trees occupied by C. nigriceps revealed that these trees were always pruned in such a way as to avoid canopy contact with adjacent trees occupied by competing ant colonies. Canopy pruning of its own tree appears to be a defensive response by a C. nigriceps colony to competition with dominant ants which prevent it from pruning their trees.

View chapterPurchase book

Comparative Social Behavior

Michael D. Breed, Janice Moore, in Animal Behavior (Second Edition), 2016

Ants

Ants are all highly eusocial and, in many ways, are the most diverse group of eusocial animals. This diversity is especially apparent in caste structure and in diet. Ant diets range from strictly carnivorous (army ants) to strictly herbivorous (leafcutter ants). The evolutionary ability of ants to exploit this wide range of diets has led to their ubiquity in terrestrial habitats.75

In castes, ants range from species such as the common wood ants, Formica sp., that show very little size variation in workers and no noticeable differences among workers in form, to species such as leafcutter ants, Atta sp., and members of the genus Pheidole, which have extreme physical worker castes (Figure 14.28). As discussed in the section on castes, caste differentiation allows task specialization, a key element in gaining efficiency for the social unit. The high level of eusociality in ants is established by the major morphological differences between ant queens and workers and the lack of reproductive potential (beyond laying male eggs) in workers of most ant species.

Figure 14.28. Ants: (A) Worker ants with brood. (B) Worker ants tending eggs. (C) An ant colony filled with plaster and then excavated (next to scientist Walter Tschinkel. (D) An ant tending aphids.

Photos: (A) USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org; (B) Susan Ellis, Bugwood.org; (C) Charles F. Badland, with permission from Walter Tschinkel; (D) David Cappaert, Michigan State University, Bugwood.org.

Ant queens exhibit two different patterns of nest founding, depending on the species. In some less-advanced species, the queen mates and then finds a nest site, to be used as a base for her foraging activities. Her first batch of eggs, which are all female, develop into workers, but to feed them she needs to actively forage and bring food back to the nest. This style of nest establishment is exemplified by the giant tropical ant, Paraponera clavata, in which the queens, during the initial stages of nest foundation, forage on insect prey. The obvious downsides to this strategy are that the queen must retain morphological adaptations for foraging and that she is exposed to predators while foraging.

Alternatively, ant queens may begin nests claustrally or semiclaustrally.76 In claustral species, the queen relies solely on her metabolic resources, including digestion of her now-unnecessary wing muscles, to feed her first batch of larvae. Semiclaustral species rely largely on the queen's metabolic resources, but the queen occasionally forages. Claustral founding avoids the risk of exposure to predation, but the queen is limited by how much fat and muscle she can use as nutritional resources for her offspring. Semiclaustral founding, which is seen in leafcutter and harvester ants, bridges the gap between the two extremes, allowing the queen to collect some critical nutrients while she avoids the risks involved in full-time foraging.

View chapterPurchase book

Butterflies

Philip J. DeVries, in Encyclopedia of Biodiversity (Second Edition), 2001

Butterfly–Ant Symbioses

The ability to form symbiotic associations with ants (myrmecophily) occurs only within the Lycaenidae. Here, caterpillars provide food secretions to ants in exchange for protection against insect predators such as social and parasitic wasps. To form these symbioses, caterpillars have a suite of unique adaptations that may include organs (collectively known as ant-organs) to produce food secretions, volatile chemicals, and sound, all of which work in concert to modify ant behavior and enhance the protective attitude of ants toward caterpillars. Recent studies on ant-organs indicate that myrmecophily evolved at least twice in the butterflies: once in the Riodininae and independently in other lycaenid subfamilies.

The widespread trait of myrmecophily within the Lycaenidae and the fact that lycaenids account for approximately 50% of all butterfly species led Pierce (1984) to suggest that myrmecophily has amplified speciation rates in this group. Indeed, the diversity of life histories in myrmecophilous butterflies can be exceedingly complex, encompassing herbivores, carnivores, and those that feed as caterpillars only on secretions, and the associations with ants range from mutualistic to completely parasitic or predatory.

Food Secretions

Ants pay close attention to particular abdominal segments bearing ant-organs that produce food secretions, which in some species are known to have high concentrations of amino acids and sugars. In some Riodininae, these consist of a pair of organs (tentacle nectary organs) on the eighth abdominal segment that can be extruded individually or simultaneously. In all other lycaenid subfamilies, this organ is a single dorsal pore on segment 7 (dorsal nectary organ). Ants are so intent on obtaining the secretions that they constantly antennate the caterpillar to solicit more, and in many cases, this is a good example of a general rule among participants in symbiotic associations— "you scratch my back and I'll scratch yours."

Semiochemical Production

Myrmecophilous caterpillars may have extrusible glands that seem to produce volatile chemicals (semiochemicals or pheromones) that alter the behaviors of attending ants. Some Riodininae have a pair of extrusible glands on the third thoracic (anterior tentacle organs), whereas other lycaenids have a pair of glands on the eighth abdominal segment (tentacle organs). In both cases, when extruded from the body these organs do not produce a liquid secretion but rather the tip is modified with spines that gives the appearance of a tiny feather duster. These spines likely provide a larger surface area to disseminate volatile chemicals that may be similar to ant alarm pheromones. Instead of anterior tentacle organs, a small group of Riodininae caterpillars (Theope) possess a corona of inflated setae around the head that appear to disseminate semiochemicals.

Call Production

The idea that caterpillars produce acoustic calls might seem unlikely. We now know, however, that myrmecophilous caterpillars produce substrate-borne calls that function in the formation and enhancement of their symbioses with ants, and these calls bear similarities to those produced by ants for communicating among themselves. In most Riodininae caterpillars calls are produced by a pair of mobile, grooved, rod-like appendages (vibratory papillae) arising from the distal edge of the first thoracic segment. An acoustical signal is produced when the grooves on the vibratory papillae grate against head granulations (Figure 2). In other lycaenid caterpillars the call is produced by thickened bumps located ventrally between abdominal segments. Most concepts of insect communication suggest that acoustical calls evolved in a sexual context. However, caterpillar calls provide an example showing that, by forming symbiotic associations, the call of one species may evolve to attract another, unrelated species.

Ants and Caterpillar Associations

In general, myrmecophily in caterpillars occurs with a particular type of ant. A basic element among myrmecophilous caterpillars is that they typically form symbioses only with ant species that depend heavily on secretions as food—ants that also form symbioses with Homoptera and plants. Therefore, secretion-harvesting ants likely played a key role in the evolution of myrmecophily, whereas those ants that are predators or herbivores did not. An ecological consequence of the evolution with secretion-harvesting ants is that in any suitable contemporary habitat, a suite of caterpillar, plant, and Homoptera species all share the same species of ant symbionts.

Among myrmecophilous caterpillars there are two main categories of ant association. The most widespread category comprises an association in which a particular caterpillar species may be tended by a suite of secretion-harvesting ant species. The other category comprises an association in which a caterpillar has an obligate association with a single species of ant. In this case, female butterflies may require the presence of a particular ant species to lay their eggs since caterpillars are unable to form symbioses with any other ant species. Furthermore, it is in these types of associations in which some caterpillars are adopted by the ants, taken into the nest, and become parasites or predators of their hosts.

View chapterPurchase book

Ant, Bee and Wasp Social Evolution☆

Raghavendra Gadagkar, in Reference Module in Life Sciences, 2017

Abstract

Ants, bees, and wasps belong to the large and diverse insect order Hymenoptera. All ants and some bees and wasps form eusocial colonies consisting of one or a small number of fertile queens and a large number of sterile workers. The evolution of such altruistic sterility in the workers has been a major theme of investigation. Kin selection and Hamilton's rule, though under attack in recent years, constitute the basic theoretical framework of choice for most investigators attempting to unravel the paradox of altruism. In close parallel with the investigation of such ultimate (evolutionary) questions, studies of the proximate causation of social behavior have also yielded many new insights. In recent times, investigations of the ontogeny and the phylogeny of social behavior have been initiated, satisfying Niko Tinbergen's vision of the integrated study of animal behavior.

View chapterPurchase book

Social Nonprimate Animals

Henry R. Hermann Ph.D., in Dominance and Aggression in Humans and Other Animals, 2017

Ants

Ants represent a large group of eusocial insects that are most closely related to wasps (Bolton, 1995; Hölldobler and Wilson, 1998; Ward, 2007). It is a diverse group of insects with a variety of species-specific behaviors. Most exhibit a despotic dominance in which the queen deposits eggs and the workers do not. In species with multiple queens (polygyny), dominance interactions do occur between females vying for the alpha position.

Other than a few groups of ants (which are monomorphic, all workers being of equal size), most ant species show some anatomical differences (polymorphism) that demonstrate not only a reproductive division of labor but an even greater demarcation of a division of labor among the worker force. Small workers may remain in the nest and care for the young, medium (intermediate) workers may be the prime foragers, and the largest workers may function most in colony defense.

These roles may show considerable overlap. Some major workers possess large mandibles, which they use in defense (especially well expressed in certain army ants, Subfamily Dorylinae). While polymorphic species may exhibit these different divisions of labor, their behavioral demarcation may not be as easily discernable as their anatomical features.

Eggs produced by the queen are cared for by workers who continue the care of the young until the completion of pupation and the subsequent emergence of adults. Workers indulge in trophallaxis between them, larvae, and reproductives, a social exchange of substances from the mouth.

Ant intelligence is difficult to discern because much of their behavior centers around chemical communication (e.g., pheromones). However, researchers have found that some determine directional problems by using celestial or other visual cues, as well as having an internal pedometer that allows them to remember the distance they have traveled from the nest.

View chapterPurchase book

A MODULAR APPROACH TO GRAMMATICAL CATEGORIES EVIDENCE FROM LANGUAGE DIVERSITY AND CONTACT

PIETER MUYSKEN, in Handbook of Categorization in Cognitive Science, 2005

Appendix Abbreviations used

ANTanterior1s, 2s, 3sfirst-, second-, third-person singular1p, 2pfirst-, second-person plural3–2pthird-person subject – second-person plural object1exfirst person exclusive plural.BENbenefactiveCAUcausative suffixCIScislocative (toward speaker)COPcopulaDETdeterminerFOCfocalizing particleIMimperativeINSinstrumentalLOC.Qlocative question particleMDirrealis moodNnounNEGnegationplpluralPRprogressivePSTpastQquestion elementREreflexive suffixRECreciprocal suffixREDUPreduplicationssingularTtenseVverb

View chapterPurchase book

Recommended publications:

International Journal of Drug Policy

Journal

Journal of Natural Gas Science and Engineering

Volume 33, July 2016, Pages 624-633

An improved Ant Colony Optimization (ACO) technique for estimation of flow functions (kr and Pc) from core-flood experiments

Author links open overlay panelMuhammadYaralidaraniHamidrezaShahverdi

Outline

Cite

https://doi.org/10.1016/j.jngse.2016.05.067Get rights and content

Highlights

•

Developing a new efficient version of Ant Colony Optimization (ACO) for the continuous inverse problem.

•

Simultaneous estimation of kr and pc using Ant Colony Optimization (ACO) from corefoold experiments.

•

Capability of the ACO technique to be linked to any simulation program for optimizing different engineering processes.

Abstract

Oil and gas production from petroleum reservoirs are significantly affected by rock and fluid properties. Relative permeability (kr) and capillary pressure (Pc) are two key flow functions in the petroleum reservoir that are employed in numerical modeling to predict oil and gas production in future. The history matching (optimization) techniques are generally used to accurately estimate the flow functions from the results of core flood experiments.

In this study, Ant Colony optimization (ACO) method is modified for the application in the continuous inverse problem to adjust some unknown variables by either minimization or maximization of objective function. Then this technique is implemented to estimate oil, water and gas flow functions from coreflood experiments. Some new ideas and innovations are proposed to improve the performance and convergence of ACO algorithm. This algorithm is an automated history matching technique that can estimate relative permeability and capillary pressure simultaneously. Moreover, this feature enables us to incorporate different mechanisms (i.e. viscous force, gravitational force and capillary force) of the core experiments in the estimation of flow functions. Having developed the algorithm, the validity of this method is tested using two sets of coreflood experiments including gas-oil and oil-water systems. The comparison between actual values of flow functions (kr and Pc) and those obtained from ACO method depicted good agreement and adequate accuracy. Furthermore, the investigation of objective function value versus iteration number demonstrated that the algorithm is converging to the optimal value.This paper studies the asymptotic behavior of several continuous-time dynamical systems which are analogs of ant colony optimization algorithms that solve shortest path problems. Local asymptotic stability of the equilibrium corresponding to the shortest path is shown under mild assumptions. A complete study is given for a recently proposed model called EigenAnt: global asymptotic stability is shown, and the speed of convergence is calculated explicitly and shown to be proportional to the difference between the reciprocals of the second shortest and the shortest paths.

Last Chapter Next Chapter