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| Author | Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J. | ||||
| Title | Horses damp the spring in their step | Type | Journal Article | ||
| Year | 2001 | Publication | Nature | Abbreviated Journal  |
Nature |
| Volume | 414 | Issue | 6866 | Pages | 895-899 |
| Keywords | Animals; Biomechanics; Elasticity; Forelimb; Gait; Horses/anatomy & histology/*physiology; Leg Bones/*physiology; Locomotion; Models, Biological; Muscle Fibers/physiology; Muscle, Skeletal/anatomy & histology/*physiology; Tendons/anatomy & histology/*physiology; Vibration | ||||
| Abstract | The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb. | ||||
| Address | Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0028-0836 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:11780059 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 2300 | ||
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| Author | Wolf, M.; van Doorn, G.S.; Leimar, O.; Weissing, F.J. | ||||
| Title | Life-history trade-offs favour the evolution of animal personalities | Type | Journal Article | ||
| Year | 2007 | Publication | Nature | Abbreviated Journal |
Nature |
| Volume | 447 | Issue | 7144 | Pages | 581-584 |
| Keywords | Aggression/physiology/psychology; Animals; Behavior, Animal/*physiology; *Evolution; Exploratory Behavior/physiology; Models, Biological; Personality/*physiology; Predatory Behavior/physiology; Reproduction/physiology; Risk-Taking; Selection (Genetics) | ||||
| Abstract | In recent years evidence has been accumulating that personalities are not only found in humans but also in a wide range of other animal species. Individuals differ consistently in their behavioural tendencies and the behaviour in one context is correlated with the behaviour in multiple other contexts. From an adaptive perspective, the evolution of animal personalities is still a mystery, because a more flexible structure of behaviour should provide a selective advantage. Accordingly, many researchers view personalities as resulting from constraints imposed by the architecture of behaviour (but see ref. 12). In contrast, we show here that animal personalities can be given an adaptive explanation. Our argument is based on the insight that the trade-off between current and future reproduction often results in polymorphic populations in which some individuals put more emphasis on future fitness returns than others. Life-history theory predicts that such differences in fitness expectations should result in systematic differences in risk-taking behaviour. Individuals with high future expectations (who have much to lose) should be more risk-averse than individuals with low expectations. This applies to all kinds of risky situations, so individuals should consistently differ in their behaviour. By means of an evolutionary model we demonstrate that this basic principle results in the evolution of animal personalities. It simultaneously explains the coexistence of behavioural types, the consistency of behaviour through time and the structure of behavioural correlations across contexts. Moreover, it explains the common finding that explorative behaviour and risk-related traits like boldness and aggressiveness are common characteristics of animal personalities. | ||||
| Address | Theoretical Biology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1476-4687 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:17538618 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 4098 | ||
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| Author | Bell, A.M. | ||||
| Title | Evolutionary biology: animal personalities | Type | |||
| Year | 2007 | Publication | Nature | Abbreviated Journal |
Nature |
| Volume | 447 | Issue | 7144 | Pages | 539-540 |
| Keywords | Aggression/physiology/psychology; Animals; Behavior, Animal/*physiology; *Evolution; Humans; *Models, Biological; Personality/genetics/*physiology; Reproduction/genetics/physiology; Risk-Taking; Selection (Genetics) | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1476-4687 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:17538607 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 4099 | ||
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| Author | Conradt, L.; Roper, T.J. | ||||
| Title | Group decision-making in animals | Type | Journal Article | ||
| Year | 2003 | Publication | Nature | Abbreviated Journal |
Nature |
| Volume | 421 | Issue | 6919 | Pages | 155-158 |
| Keywords | Animals; Behavior, Animal/*physiology; *Decision Making; Democracy; Group Processes; *Models, Biological; Population Density; Social Behavior | ||||
| Abstract | Groups of animals often need to make communal decisions, for example about which activities to perform, when to perform them and which direction to travel in; however, little is known about how they do so. Here, we model the fitness consequences of two possible decision-making mechanisms: 'despotism' and 'democracy'. We show that under most conditions, the costs to subordinate group members, and to the group as a whole, are considerably higher for despotic than for democratic decisions. Even when the despot is the most experienced group member, it only pays other members to accept its decision when group size is small and the difference in information is large. Democratic decisions are more beneficial primarily because they tend to produce less extreme decisions, rather than because each individual has an influence on the decision per se. Our model suggests that democracy should be widespread and makes quantitative, testable predictions about group decision-making in non-humans. | ||||
| Address | School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK. l.conradt@sussex.ac.uk | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0028-0836 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:12520299 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 5136 | ||
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| Author | Rands, S.A.; Cowlishaw, G.; Pettifor, R.A.; Rowcliffe, J.M.; Johnstone, R.A. | ||||
| Title | Spontaneous emergence of leaders and followers in foraging pairs | Type | Journal Article | ||
| Year | 2003 | Publication | Nature | Abbreviated Journal |
Nature |
| Volume | 423 | Issue | 6938 | Pages | 432-434 |
| Keywords | Animals; *Energy Metabolism; Food; *Food Chain; *Models, Biological; Motor Activity; *Social Behavior; Time Factors | ||||
| Abstract | Animals that forage socially often stand to gain from coordination of their behaviour. Yet it is not known how group members reach a consensus on the timing of foraging bouts. Here we demonstrate a simple process by which this may occur. We develop a state-dependent, dynamic game model of foraging by a pair of animals, in which each individual chooses between resting or foraging during a series of consecutive periods, so as to maximize its own individual chances of survival. We find that, if there is an advantage to foraging together, the equilibrium behaviour of both individuals becomes highly synchronized. As a result of this synchronization, differences in the energetic reserves of the two players spontaneously develop, leading them to adopt different behavioural roles. The individual with lower reserves emerges as the 'pace-maker' who determines when the pair should forage, providing a straightforward resolution to the problem of group coordination. Moreover, the strategy that gives rise to this behaviour can be implemented by a simple 'rule of thumb' that requires no detailed knowledge of the state of other individuals. | ||||
| Address | Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. s.rands@zoo.cam.ac.uk | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0028-0836 | ISBN | Medium | ||
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| Notes | PMID:12761547 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 5138 | ||
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| Author | Kiltie, R.A.; Fan, J.; Laine, A.F. | ||||
| Title | A wavelet-based metric for visual texture discrimination with applications in evolutionary ecology | Type | Journal Article | ||
| Year | 1995 | Publication | Mathematical Biosciences | Abbreviated Journal |
Math Biosci |
| Volume | 126 | Issue | 1 | Pages | 21-39 |
| Keywords | Animals; Carnivora; *Ecology; Equidae; *Evolution; Humans; Mathematics; Models, Biological; Moths; *Pattern Recognition, Visual; Pigmentation | ||||
| Abstract | Much work on natural and sexual selection is concerned with the conspicuousness of visual patterns (textures) on animal and plant surfaces. Previous attempts by evolutionary biologists to quantify apparency of such textures have involved subjective estimates of conspicuousness or statistical analyses based on transect samples. We present a method based on wavelet analysis that avoids subjectivity and that uses more of the information in image textures than transects do. Like the human visual system for texture discrimination, and probably like that of other vertebrates, this method is based on localized analysis of orientation and frequency components of the patterns composing visual textures. As examples of the metric's utility, we present analyses of crypsis for tigers, zebras, and peppered moth morphs. | ||||
| Address | Department of Zoology, University of Florida, Gainesville | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0025-5564 | ISBN | Medium | ||
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| Notes | PMID:7696817 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 2660 | ||
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| Author | Viscido, S.V.; Miller, M.; Wethey, D.S. | ||||
| Title | The dilemma of the selfish herd: the search for a realistic movement rule | Type | Journal Article | ||
| Year | 2002 | Publication | Journal of theoretical biology | Abbreviated Journal |
J. Theor. Biol. |
| Volume | 217 | Issue | 2 | Pages | 183-194 |
| Keywords | Animals; *Behavior, Animal; *Mass Behavior; Models, Biological; *Motor Activity; Predatory Behavior | ||||
| Abstract | The selfish herd hypothesis predicts that aggregations form because individuals move toward one another to minimize their own predation risk. The “dilemma of the selfish herd” is that movement rules that are easy for individuals to follow, fail to produce true aggregations, while rules that produce aggregations require individual behavior so complex that one may doubt most animals can follow them. If natural selection at the individual level is responsible for herding behavior, a solution to the dilemma must exist. Using computer simulations, we examined four different movement rules. Relative predation risk was different for all four movement rules (p<0.05). We defined three criteria for measuring the quality of a movement rule. A good movement rule should (a) be statistically likely to benefit an individual that follows it, (b) be something we can imagine most animals are capable of following, and (c) result in a centrally compact flock. The local crowded horizon rule, which allowed individuals to take the positions of many flock-mates into account, but decreased the influence of flock-mates with distance, best satisfied these criteria. The local crowded horizon rule was very sensitive to the animal's perceptive ability. Therefore, the animal's ability to detect its neighbors is an important factor in the dynamics of group formation. | ||||
| Address | Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA. viscido@u.washington.edu | ||||
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| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0022-5193 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | PMID:12202112 | Approved | no | ||
| Call Number | refbase @ user @ | Serial | 554 | ||
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| Author | Viscido, S.V.; Miller, M.; Wethey, D.S. | ||||
| Title | The response of a selfish herd to an attack from outside the group perimeter | Type | Journal Article | ||
| Year | 2001 | Publication | Journal of theoretical biology | Abbreviated Journal |
J. Theor. Biol. |
| Volume | 208 | Issue | 3 | Pages | 315-328 |
| Keywords | Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior | ||||
| Abstract | According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation. | ||||
| Address | Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 0022-5193 | ISBN | Medium | ||
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| Notes | PMID:11207093 | Approved | no | ||
| Call Number | refbase @ user @ | Serial | 555 | ||
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| Author | Hamilton, W.D. | ||||
| Title | Geometry for the selfish herd | Type | Journal Article | ||
| Year | 1971 | Publication | Journal of theoretical biology | Abbreviated Journal |
J. Theor. Biol. |
| Volume | 31 | Issue | 2 | Pages | 295-311 |
| Keywords | Animals; Anura; *Behavior, Animal; Breeding; Communication; Evolution; Fear; Metallurgy; *Models, Biological; Probability; Snakes; *Spatial Behavior | ||||
| Abstract | This paper presents an antithesis to the view that gregarious behaviour is evolved through benefits to the population or species. Following Galton (1871) and Williams (1964) gregarious behaviour is considered as a form of cover-seeking in which each animal tries to reduce its chance of being caught by a predator. It is easy to see how pruning of marginal individuals can maintain centripetal instincts in already gregarious species; some evidence that marginal pruning actually occurs is summarized. Besides this, simply defined models are used to show that even in non-gregarious species selection is likely to favour individuals who stay close to others. Although not universal or unipotent, cover-seeking is a widespread and important element in animal aggregation, as the literature shows. Neglect of the idea has probably followed from a general disbelief that evolution can be dysgenic for a species. Nevertheless, selection theory provides no support for such disbelief in the case of species with outbreeding or unsubdivided populations. The model for two dimensions involves a complex problem in geometrical probability which has relevance also in metallurgy and communication science. Some empirical data on this, gathered from random number plots, is presented as of possible heuristic value. |
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| ISSN | 0022-5193 | ISBN | Medium | ||
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| Notes | PMID:5104951 | Approved | no | ||
| Call Number | refbase @ user @ | Serial | 771 | ||
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| Author | Seyfarth, R.M. | ||||
| Title | A model of social grooming among adult female monkeys | Type | Journal Article | ||
| Year | 1977 | Publication | Journal of Theoretical Biology | Abbreviated Journal |
J. Theor. Biol. |
| Volume | 65 | Issue | 4 | Pages | 671-698 |
| Keywords | Animals; Behavior, Animal; Female; *Grooming; Haplorhini/*physiology; *Models, Biological; Reproduction; Social Dominance; Time Factors | ||||
| Abstract | Grooming networks among adult female monkeys exhibit two similar features across a number of different species. High-ranking animals receive more grooming than others, and the majority of grooming occurs between females of adjacent rank. A theoretical model which duplicates these features is presented, and the properties of the model are used to explain the possible causation and function of female grooming behaviour. The model illustrates how relatively simple principles governing the behaviour of individuals may be used to explain more complex aspects of the social structure of non-human primate groups. | ||||
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| ISSN | 0022-5193 | ISBN | Medium | ||
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| Notes | PMID:406485 | Approved | no | ||
| Call Number | Equine Behaviour @ team @ | Serial | 5259 | ||
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