Foraging vibration signals attract foragers and identify food size in the drywood termite, <Emphasis Type="Italic">Cryptotermes secundus</Emphasis>

Information gathering and communication behaviour has evolved within constraints of size, physiology and ecology of the animal. Due to these constraints, small herbivorous insects are likely to use substrate borne vibrations for information gathering and communication. Although such signals have been characterised in many types of insects, including group-living insects, they are poorly known in termites.We showed that the Australian drywood termite Cryptotermes secundus could determine the size of wooden blocks by using the vibrations generated during foraging. The termites behaved differently in choice experiments when artificially generated vibration signals were played compared with natural recordings, indicating that these termites can discriminate the source of the vibration as well. AT-maze experiment showed that the termites were attracted to the natural recordings of feeding termites, suggesting that vibrations are important in communication during foraging as well as food resource assessment. Combining the effects of food size preference and attraction to other termites explained differences in behaviour between artificially generated vibration signals compared with natural recordings. This study demonstrates that termites use substrate borne vibrations for information gathering and communication as predicted. Received 21 March 2007; revised 19 June and 7 August 2007; accepted 20 August 2007.     

Know thine enemy: fighting fish gather information from observing conspecific interactions

Many of the signals that animals use to communicate transmit relatively large distances and therefore encompass several potential signallers and receivers. This observation challenges the common characterization of animal communication systems as consisting of one signaller and one receiver. Furthermore, it suggests that the evolution of communication behaviour must be considered as occurring in the context of communication networks rather than dyads. Although considerations of selection pressures acting upon signallers in the context of communication networks have rarely been expressed in such terms, it has been noted that many signals exchanged during aggressive interactions will transmit far further than required for information transfer between the individuals directly involved, suggesting that these signals have been designed to be received by other, more distant, individuals. Here we consider the potential for receivers in communication networks to gather information, one aspect of which has been termed eavesdropping. We show that male Betta splendens monitor aggressive interactions between neighbouring conspecifics and use the information on relative fighting ability in subsequent aggressive interactions with the males they have observed.     

Directionality in the mechanical response to substrate vibration in a treehopper (Hemiptera: Membracidae: Umbonia crassicornis)

The use of substrate vibrations in communication and predator-prey interactions is widespread in arthropods. In many contexts, localization of the vibration source plays an important role. For small species on solid substrates, time and amplitude differences between receptors in different legs may be extremely small, and the mechanisms of vibration localization are unclear. Here we ask whether directional information is contained in the mechanical response of an insect's body to substrate vibration. Our study species was a membracid treehopper (Umbonia crassicornis) that communicates using bending waves in plant stems. We used a bending-wave simulator that allows precise control of the frequency, intensity and direction of the vibrational stimulus. With laser-Doppler vibrometry, we measured points on the substrate and on the insect's thorax and middle leg. Transfer functions showing the response of the body relative to the substrate revealed resonance at lower frequencies and attenuation at higher frequencies. There were two modes of vibration along the body's long axis, a translational and a rotational mode. Furthermore, the transfer functions measured on the body differed substantially depending on whether the stimulus originated in front of or behind the insect. Directional information is thus available in the mechanical response of the body of these insects to substrate vibration. These results suggest a vibration localization mechanism that could function at very small spatial scales.     

Food-Offering Calls in Wild Golden Lion Tamarins (<Emphasis Type="Italic">Leontopithecus rosalia</Emphasis>): Evidence for Teaching Behavior?

Many animals emit calls in the presence of food, but researchers do not always know the function of these calls. Evidence suggests that adult golden lion tamarins (Leontopithecus rosalia) use food-offering calls to teach juveniles which substrate (i.e., microhabitat) to forage on, or in, for food. However, we do not yet know whether juveniles learn from this aspect of the adults’ behavior. Here we examine whether juveniles learn to associate food-offering calls with a foraging substrate, as a step toward assessing whether these calls qualify as teaching behavior. We compared the performance of four wild juvenile golden lion tamarins that were introduced to a novel substrate while exposed to playbacks of food-offering calls (experimental condition) to the performance of three juveniles that were exposed to the novel substrate without the presence of food-offering playbacks (control condition). We varied the location of the novel substrate between trials. We found that food-offering calls had an immediate effect on juveniles’ interactions with the novel substrate, whether they inserted their hands into the substrate and their eating behavior, and a long-term effect on eating behavior at the substrate. The findings imply that juvenile golden lion tamarins can learn through food-offering calls about the availability of food at a substrate, which is consistent with (but does not prove) teaching in golden lion tamarins through stimulus enhancement. Our findings support the hypothesis that teaching might be more likely to evolve in cooperatively breeding species with complex ecological niches.     

The social brain: allowing humans to boldly go where no other species has been

The biological basis of complex human social interaction and communication has been illuminated through a coming together of various methods and disciplines. Among these are comparative studies of other species, studies of disorders of social cognition and developmental psychology. The use of neuroimaging and computational models has given weight to speculations about the evolution of social behaviour and culture in human societies. We highlight some networks of the social brain relevant to two-person interactions and consider the social signals between interacting partners that activate these networks. We make a case for distinguishing between signals that automatically trigger interaction and cooperation and ostensive signals that are used deliberately. We suggest that this ostensive signalling is needed for ‘closing the loop’ in two-person interactions, where the partners each know that they have the intention to communicate. The use of deliberate social signals can serve to increase reputation and trust and facilitates teaching. This is likely to be a critical factor in the steep cultural ascent of mankind.     

Computer-generated animal model stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In particular, understanding the constraints on visual signal design for communication has been of great interest. Traditional methods for investigating animal interactions have used basic observational techniques, staged encounters, or physical manipulation of morphology. Less intrusive methods have tried to simulate conspecifics using crude playback tools, such as mirrors, still images, or models. As technology has become more advanced, video playback has emerged as another tool in which to examine visual communication (Rosenthal, 2000). However, to move one step further, the application of computer-animation now allows researchers to specifically isolate critical components necessary to elicit social responses from conspecifics, and manipulate these features to control interactions. Here, I provide detail on how to create an animation using the Jacky dragon as a model, but this process may be adaptable for other species. In building the animation, I elected to use Lightwave 3D to alter object morphology, add texture, install bones, and provide comparable weight shading that prevents exaggerated movement. The animation is then matched to select motor patterns to replicate critical movement features. Finally, the sequence must rendered into an individual clip for presentation. Although there are other adaptable techniques, this particular method had been demonstrated to be effective in eliciting both conspicuous and social responses in staged interactions.     

Mechanical feeding aids for patients with ataxia: design considerations

A mechanism has been designed which transforms steady, vertical hand motion into the scooping motion of a spoon. The mechanism incorporates vibration isolation through a spring-damper system to attenuate the transmission of low frequency (2–8Hz) hand tremor to the spoon. A series arrangement of spring and damper has produced spoon amplitudes of between 5 and 12% of the hand amplitude at the lowest ataxic tremor frequencies. A prototype has been tested by four ataxic patients. The degree of vibration isolation and the ability to pick up food were adequate but the mechanism was felt to be unacceptable as a feeder for social reasons. Two other mechanisms have also been considered.     

The public world of insect vibrational communication

Food webs involving plants, herbivorous insects and their predators account for 75% of terrestrial biodiversity (Price 2002). Within the abundant arthropod community on plants, myriad ecological and social interactions depend on the perception and production of plant-borne mechanical vibrations (Hill 2008). Study of ecological relationships has shown, for example, that termites monitor the vibrations produced by competing colonies in the same tree trunk (Evans et al. 2009), that stink bugs and spiders attend to the incidental vibrations produced by insects feeding or walking on plants (Pfannenstiel et al. 1995, Barth 1998) and that caterpillars can distinguish among the foraging-related vibrations produced by their invertebrate predators (Castellanos & Barbosa 2006). Study of social interactions has revealed that many insects and spiders have evolved the ability to generate intricate patterns of substrate vibration, allowing them to communicate with potential mates or members of their social group (Cokl & Virant-Doberlet 2003; Hill 2008). Surprisingly, research on the role of substrate vibrations in social and ecological interactions has for the most part proceeded independently, in spite of evidence from other communication modalities – acoustic, visual, chemical and electrical – that predators attend to the signals of their prey (Zuk & Kolluru 1998; Stoddard 1999). The study by Virant-Doberlet et al. (2011) in this issue of Molecular Ecology now helps bring these two areas of vibration research together, showing that the foraging behaviour of a spider is influenced by the vibrational mating signals of its leafhopper prey.     

Predatory bug <Emphasis Type="Italic">Picromerus bidens</Emphasis> communicates at different frequency levels

The Asopinae (Heteroptera: Pentatomidae) are a subfamily of stinkbugs with predaceous feeding habits and poorly understood communication systems. In this study we recorded vibratory signals emitted by Picromerus bidens L. on a non-resonant substrate and investigated their frequency characteristics. Males and females produced signals by vibration of the abdomen and tremulation. The female and male songs produced by abdominal vibrations showed gender-specific time structure. There were no differences in the temporal patterns of male or female tremulatory signals. The signals produced by abdominal vibrations were emitted below 600 Hz whereas tremulatory signals had frequency ranges extending up to 4 kHz. Spectra of male vibratory signals produced by abdominal vibrations contained different peaks, each of which may be dominant within the same song sequence. Males alternated with each other during production of rivalry signals, using different dominant frequency levels. We show that the vibratory song repertoire of P. bidens is broader than those of other predatory stinkbugs that have been investigated. The emission of vibrational signals with different dominant frequencies but the same production mechanism has not yet been described in heteropteran insects, and may facilitate location of individual sources of vibration within a group.     

Communication during aggressive interactions with particular reference to variation in choice of behaviour

Communication during aggressive interactions is discussed and defined primarily on the basis of functional considerations. A distinction is made between communication due to choice of action and communication due to performance of a given choice of action. Most attention is directed to choice of behaviour. Two models are developed to show that there are no arguments of general validity against communication through choice of behaviour or signalling as has been claimed. The first model is built on variation in fighting ability only and shows that choice of signal can carry information both about intentions (use of local strategy) and fighting ability. The second model which is based on the war of attrition with random rewards instead considers variation in subjective resource value. It shows that signalling of local strategy can be stable. It is concluded that evolutionary stability of communication through choice of behaviour is due to variation among animals in the utility of showing different behaviour patterns whereas communication by performance is due to a not easily removed relationship between the performance of a certain behaviour pattern and the factor communicated.     

Wild Western Lowland Gorillas Signal Selectively Using Odor

Mammals communicate socially through visual, auditory and chemical signals. The chemical sense is the oldest sense and is shared by all organisms including bacteria. Despite mounting evidence for social chemo-signaling in humans, the extent to which it modulates behavior is debated and can benefit from comparative models of closely related hominoids. The use of odor cues in wild ape social communication has been only rarely explored. Apart from one study on wild chimpanzee sniffing, our understanding is limited to anecdotes. We present the first study of wild gorilla chemo-communication and the first analysis of olfactory signaling in relation to arousal levels and odor strength in wild apes. If gorilla scent is used as a signaling mechanism instead of only a sign of arousal or stress, odor emission should be context specific and capable of variation as a function of the relationships between the emitter and perceiver(s). Measured through a human pungency scale, we determined the factors that predicted extreme levels of silverback odor for one wild western lowland gorilla (Gorilla gorilla gorilla) group silverback. Extreme silverback odor was predicted by the presence and intensity of inter-unit interactions, silverback anger, distress and long-calling auditory rates, and the absence of close proximity between the silverback and mother of the youngest infant. Odor strength also varied according to the focal silverback''s strategic responses during high intensity inter-unit interactions. Silverbacks appear to use odor as a modifiable form of communication; where odor acts as a highly flexible, context dependent signaling mechanism to group members and extra-group units. The importance of olfaction to ape social communication may be especially pertinent in Central African forests where limited visibility may necessitate increased reliance on other senses.     

Review: From human–animal relation practice research to the development of the livestock farmer's activity: an ergonomics–applied ethology interaction

Animal husbandry and working conditions for livestock farmers have changed significantly in recent years as agriculture has been exposed to economic as well as health, environmental and ethical challenges. The idea of interdependent welfare between humans and animals is more relevant now than ever. Here, we innovatively bridge two disciplines—ergonomics and applied ethology—to achieve an in-depth observational understanding of real husbandry practice (by farmers, inseminators, vets) at work. Ergonomics aims to gain a detailed understanding of human activity in its physical, sensitive and cognitive dimensions in relation to a task. It also aims to transform work situations through a systemic approach drawing on multiple levers for change. Here, we examine how this analysis holds up to the inclusion of animals as an integral component of the livestock farmer’s work situation. Applied ethology studies behaviours in animals managed by humans. It aims to understand how these animals perceive their environment, including how they construct their relationship with the livestock farmer. This paper proposes an original conception of the human–animal relationship in animal husbandry that employs core structural concepts from both disciplines. From an ergonomic point of view, we address the human–animal relations by examining the relationship between ‘prescribed’ and real work practices, between work and personal life situation, between professional task and human activity. On the applied ethology side of the equation, the human–animal relationship is a process built through communication and regular interactions between two ‘partners’ who know each other. The goal is to understand how each partner perceives the other according to their multimodal sensory world and their cognitive and emotional capacities, and to predict the outcome of future interactions. We cross-analyse these scientific views to show, based on examples, how and in what way they can intersect to bring better analysis of these human–animal relationships. We reflect on common working hypotheses and situated observational approaches based on indicators (behaviour and animal and human welfare/health). This analysis prompts us to clarify what human–animal relational practice means in animal husbandry work, i.e. a strategy employed by the livestock farmer to work safely and efficiently in a healthy environment, where the animal is treated as a partner in the relationship. In this perspective, the challenge is for the livestock farmer’s activity to co-build a positive relationship and avoid being subject to this one.     

Contrasting catalytic and allosteric mechanisms for phosphoglycerate dehydrogenases

D-3-Phosphoglycerate dehydrogenases (PGDH) exist with at least three different structural motifs and the enzymes from different species display distinctly different mechanisms. In many species, particularly bacteria, the catalytic activity is regulated allosterically through binding of l-serine to a distinct structural domain, termed the ACT domain. Some species, such as Mycobacterium tuberculosis, contain an additional domain, called the "allosteric substrate binding" or ASB domain, that functions as a co-domain in the regulation of catalytic activity. That is, both substrate and effector function synergistically in the regulation of activity to give the enzyme some interesting properties that may have physiological relevance for the persistent state of tuberculosis. Both enzymes function through a V-type regulatory mechanism and, in the Escherichia coli enzyme, it has been demonstrated that this results from a dead-end complex that decreases the concentration of active species rather than a decrease in the velocity of the active species. This review compares and contrasts what we know about these enzymes and provides additional insight into their mechanism of allosteric regulation.     

Examining docking interactions on ERK2 with modular peptide substrates

ERK2 primarily recognizes substrates through two recruitment sites, which lie outside the active site cleft of the kinase. These recruitment sites bind modular-docking sequences called docking sites and are potentially attractive sites for the development of non-ATP competitive inhibitors. The D-recruitment site (DRS) and the F-recruitment site (FRS) bind D-sites and F-sites, respectively. For example, peptides that target the FRS have been proposed to inhibit all ERK2 activity (Galanis, A., Yang, S. H., and Sharrocks, A. D. (2001) J. Biol. Chem. 276, 965-973); however, it has not been established whether this inhibition is steric or allosteric in origin. To facilitate inhibitor design and to examine potential coupling of recruitment sites to other ligand recognition sites within ERK2, energetic coupling within ERK2 was investigated using two new modular peptide substrates for ERK2. Modeling shows that one peptide (Sub-D) recognizes the DRS, while the other peptide (Sub-F) binds the FRS. A steady-state kinetic analysis reveals little evidence of thermodynamic linkage between the peptide substrate and ATP. Both peptides are phosphorylated through a random-order sequential mechanism with a k(cat)/K(m) comparable to Ets-1, a bona fide ERK2 substrate. Occupancy of the FRS with a peptide containing a modular docking sequence has no effect on the intrinsic ability of ERK2 to phosphorylate Sub-D. Occupancy of the DRS with a peptide containing a modular docking sequence has a slight effect (1.3 ± 0.1-fold increase in k(cat)) on the intrinsic ability of ERK2 to phosphorylate Sub-F. These data suggest that while docking interactions at the DRS and the FRS are energetically uncoupled, the DRS can exhibit weak communication to the active site. In addition, they suggest that peptides bound to the FRS inhibit the phosphorylation of protein substrates through a steric mechanism. The modeling and kinetic data suggest that the recruitment of ERK2 to cellular locations via its DRS may facilitate the formation of F-site selective ERK2 signaling complexes, while recruitment via the FRS will likely inhibit ERK2 through a steric mechanism of inhibition. Such recruitment may serve as an additional level of ERK2 regulation.     

Tremulatory and Abdomen Vibration Signals Enable Communication through Air in the Stink Bug Euschistus heros

Communication by substrate-borne mechanical signals is widespread among animals but remains one of their least understood communication channels. Past studies of vibrational communication in insects have been oriented predominantly to communication during mating, showing that species- and sex-specific vibrational signals enable recognition and localization of potential mates on continuous solid substrates. No special attention has been paid to vibrational signals with less obvious specificity as well as to the possibility of vibrational communication across substrates that are not in physical contact. We aimed to reinvestigate emission of the aforementioned vibrational signals transmitted through a plant in the stink bug Euschistus heros (Pentatomidae: Pentatominae) and to check whether individuals are able to communicate across adjecent, physically separated substrates. We used laser vibrometry for registration of substrate-borne vibrational signals on a bean plant. Using two bean plants separated for 3 to 7 cm between two most adjacent leaves, we investigated the possibility of transmission of these signals through air. Our study showed that males and females of E. heros communicate using tremulatory, percussion and buzzing signals in addition to the previously described signals produced by vibrations of the abdomen. Contrary to the latter, the first three signal types did not differ between sexes or between pentatomid species. Experiments with two physically separated plants showed significant searching behaviour and localization of vibrational signals of an E. heros male or a female, in response to abdominal vibration produced signals of a pair duetting on the neighbouring plant, in comparison to control where no animals were on the neighbouring plant. We also confirmed that transmission through air causes amplitude and frequency decay of vibrational signals, which suggests high-amplitude, low-frequency tremulatory signals of these stink bugs their most plausible way of communication across discontinuous substrates.     

The ecological significance of time sense in animals

Time is a fundamental dimension of all biological events and it is often assumed that animals have the capacity to track the duration of experienced events (known as interval timing). Animals can potentially use temporal information as a cue during foraging, communication, predator avoidance, or navigation. Interval timing has been traditionally investigated in controlled laboratory conditions but its ecological relevance in natural environments remains unclear. While animals may time events in artificial and highly controlled conditions, they may not necessarily use temporal information in natural environments where they have access to other cues that may have more relevance than temporal information. Herein we critically evaluate the ecological contexts where interval timing has been suggested to provide adaptive value for animals. We further discuss attributes of interval timing that are rarely considered in controlled laboratory studies. Finally, we encourage consideration of ecological relevance when designing future interval-timing studies and propose future directions for such experiments.     

Glycogen phosphorylase: control by phosphorylation and allosteric effectors.

Structural studies of muscle glycogen phosphorylase during the last two decades have provided a detailed mechanism for the molecular basis of the control by phosphorylation and by allosteric effectors and the catalytic mechanism. Control by phosphorylation is effected by a disorder to order transition of the NH2-terminal residues that promotes localized changes in the structure of the protein at the region of subunit-subunit contacts and larger changes in the quaternary structure. The covalently attached phosphate group acts like an allosteric effector but the full manifestation of the response is also dependent on the NH2-terminal tail residues. The noncovalently bound allosteric effectors produce similar shifts in the structural states although these are bound at sites that are remote from the serine-phosphate site. The communication from these sites to the catalytic site is through long-range interactions that result in activation of the enzyme through opening access to the buried catalytic site and through creation of the substrate phosphate recognition site by an interchange of an acidic group with a basic group. Recent advances in expression systems have opened the way to a study of properties both for the muscle and other isozymes and other species that should illuminate the different regulatory roles of the enzyme in different tissues and organisms. The allosteric mechanism of activation of phosphorylase by phosphorylation may be relevant to other enzymes although it is now known that other mechanisms such as electrostatic steric blocking mechanisms also exist.     

Molecular basis of exopeptidase activity in the C-terminal domain of human angiotensin I-converting enzyme: insights into the origins of its exopeptidase activity

Proteolytic processing is a primary means of biological control. Exopeptidases use terminal anchoring interactions to restrict cleavage at peptide substrate N or C termini. In contrast, internal peptide bond targeting by endopeptidases is through context-driven recognition. Angiotensin I-converting enzyme (ACE), a zinc metalloproteinase, has tandem duplicate catalytic domains, N- and C-terminal, each of which is a dual specificity enzyme with exo- and endocarboxypeptidase activities. The mechanisms by which ACE evolved from its endopeptidase ancestors as a dual specificity enzyme have not been defined. Based on kinetic studies of wild-type and mutant forms of the C-terminal catalytic domain of human ACE and of the ACE substrates angiotensin I, substance P, and bradykinin, as well as considerations of the ACE x-ray structure, we provide evidence that the acquisition of its exopeptidase activity is due to novel evolutionary specializations. These involve not only interactions between the S(2)' subsite cognate for the C-terminal substrate P(2)' side chain, acting in concert with carboxylate-docking interactions with Lys(1087) and Tyr(1096), but also electrostatic selection against a cationic C-terminal substrate carboxylate. With a blocked C terminus, substrate side chain interactions are dominant in cleavage site selection. In the evolution of obligate exopeptidases from endopeptidase ancestors, mutations that destroy context-driven peptide bond targeting are likely to have followed the acquisition of terminal docking interactions. Evolutionary intermediates between endopeptidases and obligate exopeptidases could therefore have been dual specificity proteinases like ACE.     

Predator identity and consumer behavior: differential effects of fish and crayfish on the habitat use of a freshwater snail

Predators can alter the outcome of ecological interactions among other members of the food web through their effects on prey behavior. While it is well known that animals often alter their behavior with the imposition of predation risk, we know less about how other features of predators may affect prey behavior. For example, relatively few studies have addressed the effects of predator identity on prey behavior, but such knowledge is crucial to understanding food web interactions. This study contrasts the behavioral responses of the freshwater snail Physellagyrina to fish and crayfish predators. Snails were placed in experimental mesocosms containing caged fish and crayfish, so the only communication between experimental snails and their predators was via non-visual cues. The caged fish and crayfish were fed an equal number of snails, thereby simulating equal prey mortality rates. In the presence of fish, the experimental snails moved under cover, which confers safety from fish predators. However, in the presence of crayfish, snails avoided benthic cover and moved to the water surface. Thus, two species of predators, exerting the same level of mortality on prey, induced very different behavioral responses. We predict that these contrasting behavioral responses to predation risk have important consequences for the interactions between snails and their periphyton resources. Received: 1 June 1998 / Accepted: 12 October 1998     

The structure and allosteric regulation of glutamate dehydrogenase

Glutamate dehydrogenase (GDH) has been extensively studied for more than 50 years. Of particular interest is the fact that, while considered by most to be a ‘housekeeping’ enzyme, the animal form of GDH is heavily regulated by a wide array of allosteric effectors and exhibits extensive inter-subunit communication. While the chemical mechanism for GDH has remained unchanged through epochs of evolution, it was not clear how or why animals needed to evolve such a finely tuned form of this enzyme. As reviewed here, recent studies have begun to elucidate these issues. Allosteric regulation first appears in the Ciliates and may have arisen to accommodate evolutionary changes in organelle function. The occurrence of allosteric regulation appears to be coincident with the formation of an ‘antenna’ like feature rising off the tops of the subunits that may be necessary to facilitate regulation. In animals, this regulation further evolved as GDH became integrated into a number of other regulatory pathways. In particular, mutations in GDH that abrogate GTP inhibition result in dangerously high serum levels of insulin and ammonium. Therefore, allosteric regulation of GDH plays an important role in insulin homeostasis. Finally, several compounds have been identified that block GDH-mediated insulin secretion that may be to not only find use in treating these insulin disorders but to kill tumors that require glutamine metabolism for cellular energy.