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Gasser, R. B., Hung, G. - C., Chilton, N. B., & Beveridge, I. (2004). Advances in developing molecular-diagnostic tools for strongyloid nematodes of equids: fundamental and applied implications. Mol Cell Probes, 18(1), 3–16.
Abstract: Infections of equids with parasitic nematodes of the order Strongylida (subfamilies Strongylinae and Cyathostominae) are of major veterinary importance. In last decades, the widespread use of drugs against these parasites has led to problems of resistance within the Cyathostominae, and to an increase in their prevalence and intensity of infection. Novel control strategies, based on improved knowledge of parasite biology and epidemiology, have thus become important. However, there are substantial limitations in the understanding of fundamental biological and systematic aspects of these parasites, which have been due largely to limitations in their specific identification and diagnosis using traditional, morphological approaches. Recently, there has been progress in the development of DNA-based approaches for the specific identification of strongyloids of equids for systematic studies and disease diagnosis. The present article briefly reviews information on the classification, biology, pathogenesis, epidemiology of equine strongyloids and the diagnosis of infections, highlights knowledge gaps in these areas, describes recent advances in the use of molecular techniques for the genetic characterisation, specific identification and differentiation of strongyloids of equids as a basis for fundamental investigations of the systematics, population biology and ecology.
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Gardner, A., West, S. A. (2004). Cooperation and Punishment, Especially in Humans. Americ. Natur., 164(6), 753–764.
Abstract: Explaining altruistic cooperation is one of the greatest
challenges faced by sociologists, economists, and evolutionary biologists. The problem is determining why an individual would carry out a costly behavior that benefits another. Possible solutions to this problem include kinship, repeated interactions, and policing. Another solution that has recently received much attention is the threat of punishment. However, punishing behavior is often costly for the punisher, and so it is not immediately clear how costly punishment could evolve. We use a direct (neighbor-modulated) fitness approach to analyze when punishment is favored. This methodology reveals that, contrary to previous suggestions, relatedness between interacting individuals is not crucial to explaining cooperation through punishment. In fact, increasing relatedness directly disfavors punishing behavior. Instead, the crucial factor is a positive correlation between the punishment strategy of an individual and the cooperation it receives. This could arise in several ways, such as when facultative adjustment of behavior leads individuals to cooperate more when interacting with individuals who are more likely to punish. More generally, our results provide a clear example of how the fundamental factor driving the evolution of social traits is a correlation between social partners and how this can arise for reasons other than genealogical kinship. |
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Galef, J., Bennett G., & Whiskin, E. E. (2004). Effects of environmental stability and demonstrator age on social learning of food preferences by young Norway rats. Anim. Behav., 68(4), 897–902.
Abstract: We used socially learned food preferences of Norway rats, Rattus norvegicus, to examine two common predictions of formal models of social learning in animals: (1) that animals living in relatively stable environments should be more attentive to socially acquired information than animals living in highly variable environments, and (2) that older demonstrators should have greater influence than younger demonstrators on the behaviour of young observers. Old and young demonstrators were equally effective in modifying the food preferences of juveniles that interacted with them. However, food choices of rats that were moved daily from one cage to another and fed at unpredictable times for unpredictable periods were less affected by demonstrators than were rats maintained in stable environments. Our results thus provided experimental support for the first, but not the second, prediction from theory.
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Galef Jr B.G.,. (2004). Approaches to the study of traditional behaviors of free-living animals. Learn. Behav., 32, 53–61.
Abstract: I review literature on four different approaches to the study of traditions in animals: observation of free-living animals, laboratory experiment, armchair analysis, and field experiment. Because, by definition, a tradition entails social learning of some kind, it is difficult, perhaps impossible, to establish that a behavior is in fact traditional without knowledge of how it develops. Observations of free-living animals often provide strong circumstantial evidence of a tradition. However, even in the view of several researchers who have studied possibly traditional behaviors in natural populations, observation alone has not proven sufficient to show that social learning contributes to development of behaviors of interest. The relevance of laboratory experiments to the understanding of the development of behaviors in free-living animals is always open to challenge. Armchair analyses of field data can produce interesting hypotheses but cannot test them. Field experiments to determine how behaviors of interest develop in population members provide a promising way forward.
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Gajdon G.K.,, Fijn N.,, & Huber L.,. (2004). Testing social learning in a wild mountain parrot, the kea (Nestor notabilis). Learn. Behav., 32, 62–71.
Abstract: Huber, Taborsky, and Rechberger (2001) reported an experiment in which the efficiency with which captive keas opened a complex food container was increased by observation of a skilled conspecific. However, only testing social learning in free-ranging animals can demonstrate social learning in natural conditions. For that purpose, a tube-lifting paradigm was developed and tested on keas both in captivity and in Mount Cook National Park, New Zealand. The task was to remove a tube from an upright pole in order to gain access to a reward inside the tube. The top of the pole was higher than a standing kea, so that, to remove the tube, an individual had to simultaneously climb onto the pole and manipulate the tube up the pole with its bill. Because only 1 naive bird managed to remove a tube twice in 25 halfhour sessions and disappeared after success, another bird was trained to solve the task and to provide demonstrations for others. Even under such conditions, only 2 of at least 15 birds learned to remove the tube in 28 sessions. There was no indication that observer birds' use of bill and feet when exploring the tube changed as the number of observations of tube removal increased in a way that would, in principle, increase the likelihood of tube removal. The results suggest a dissociation of social learning potential as assessed in laboratory animals, and social transmission of foraging techniques in natural populations.
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Gácsi, M., Miklósi, Á., Varga, O., Topál, J., & Csányi, V. (2004). Are readers of our face readers of our minds? Dogs (Canis familiaris) show situation-dependent recognition of human's attention. Anim. Cogn., 7(3), 144–153.
Abstract: The ability of animals to use behavioral/facial cues in detection of human attention has been widely investigated. In this test series we studied the ability of dogs to recognize human attention in different experimental situations (ball-fetching game, fetching objects on command, begging from humans). The attentional state of the humans was varied along two variables: (1) facing versus not facing the dog; (2) visible versus non-visible eyes. In the first set of experiments (fetching) the owners were told to take up different body positions (facing or not facing the dog) and to either cover or not cover their eyes with a blindfold. In the second set of experiments (begging) dogs had to choose between two eating humans based on either the visibility of the eyes or direction of the face. Our results show that the efficiency of dogs to discriminate between “attentive” and “inattentive” humans depended on the context of the test, but they could rely on the orientation of the body, the orientation of the head and the visibility of the eyes. With the exception of the fetching-game situation, they brought the object to the front of the human (even if he/she turned his/her back towards the dog), and preferentially begged from the facing (or seeing) human. There were also indications that dogs were sensitive to the visibility of the eyes because they showed increased hesitative behavior when approaching a blindfolded owner, and they also preferred to beg from the person with visible eyes. We conclude that dogs are able to rely on the same set of human facial cues for detection of attention, which form the behavioral basis of understanding attention in humans. Showing the ability of recognizing human attention across different situations dogs proved to be more flexible than chimpanzees investigated in similar circumstances.
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Fruehwirth, B., Peham, C., Scheidl, M., & Schobesberger, H. (2004). Evaluation of pressure distribution under an English saddle at walk, trot and canter. Equine Vet J, 36(8), 754–757.
Abstract: REASONS FOR PERFORMING STUDY: Basic information about the influence of a rider on the equine back is currently lacking. HYPOTHESIS: That pressure distribution under a saddle is different between the walk, trot and canter. METHODS: Twelve horses without clinical signs of back pain were ridden. At least 6 motion cycles at walk, trot and canter were measured kinematically. Using a saddle pad, the pressure distribution was recorded. The maximum overall force (MOF) and centre of pressure (COP) were calculated. The range of back movement was determined from a marker placed on the withers. RESULTS: MOF and COP showed a consistent time pattern in each gait. MOF was 12.1 +/- 1.2 and 243 +/- 4.6 N/kg at walk and trot, respectively, in the ridden horse. In the unridden horse MOF was 172.7 +/- 11.8 N (walk) and 302.4 +/- 33.9 N (trot). At ridden canter, MOF was 27.2 +/- 4.4 N/kg. The range of motion of the back of the ridden horse was significantly lower compared to the unridden, saddled horse. CONCLUSIONS AND POTENTIAL RELEVANCE: Analyses may help quantitative and objective evaluation of the interaction between rider and horse as mediated through the saddle. The information presented is therefore of importance to riders, saddlers and equine clinicians. With the technique used in this study, style, skill and training level of different riders can be quantified, which would give the opportunity to detect potentially harmful influences and create opportunities for improvement.
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Friedrich, A. M., & Zentall, T. R. (2004). Pigeons shift their preference toward locations of food that take more effort to obtain. Behav. Process., 67(3), 405–415.
Abstract: Although animals typically prefer to exert less effort rather than more effort to obtain food, the present research shows that requiring greater effort to obtain food at a particular location appears to increase the value of that location. In Experiment 1, pigeons' initial preference for one feeder was significantly reduced by requiring 1 peck to obtain food from that feeder and requiring 30 pecks to obtain food from the other feeder. In Experiment 2, a similar decrease in preference was not found when pigeons received reinforcement from both feeders independently of the amount of effort required. These results are consistent with the within-trial contrast effect proposed by in which the relative hedonic value of a reward depends on the state of the animal immediately prior to the reward. The greater the improvement from that prior state the greater the value of the reinforcer.
Keywords: Animals; *Behavior, Animal; *Choice Behavior; Columbidae; *Exertion; *Feeding Behavior; Reward
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Friedrich, A. M., Clement, T. S., & Zentall, T. R. (2004). Functional equivalence in pigeons involving a four-member class. Behav. Process., 67(3), 395–403.
Abstract: Research suggests that animals are capable of forming functional equivalence relations or stimulus classes of the kind usually demonstrated by humans (e.g., the class defined by an object and the word for that object). In pigeons, such functional equivalences are typically established using many-to-one matching-to-sample in which two samples are associated with one comparison stimulus and two different samples are associated with the other. Evidence for the establishment of functional equivalences between samples associated with the same comparison comes from transfer tests. In Experiment 1, we found that pigeons can form a single class consisting of four members (many-to-one matching) when the alternative class has only one member (one-to-one matching). In Experiment 2, we ruled out the possibility that the pigeons acquired the hybrid one-to-one/many-to-one task by developing a single-code/default coding strategy as earlier research suggested that it might. Thus, pigeons can develop a functional class consisting of as many as four members, with the alternative class consisting of a single member.
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Friederici, A. D., & Alter, K. (2004). Lateralization of auditory language functions: a dynamic dual pathway model. Brain Lang, 89(2), 267–276.
Abstract: Spoken language comprehension requires the coordination of different subprocesses in time. After the initial acoustic analysis the system has to extract segmental information such as phonemes, syntactic elements and lexical-semantic elements as well as suprasegmental information such as accentuation and intonational phrases, i.e., prosody. According to the dynamic dual pathway model of auditory language comprehension syntactic and semantic information are primarily processed in a left hemispheric temporo-frontal pathway including separate circuits for syntactic and semantic information whereas sentence level prosody is processed in a right hemispheric temporo-frontal pathway. The relative lateralization of these functions occurs as a result of stimulus properties and processing demands. The observed interaction between syntactic and prosodic information during auditory sentence comprehension is attributed to dynamic interactions between the two hemispheres.
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