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Author |
Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J. |
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Title |
Horses damp the spring in their step |
Type |
Journal Article |
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Year |
2001 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
414 |
Issue |
6866 |
Pages |
895-899 |
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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 |
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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. |
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Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk |
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0028-0836 |
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PMID:11780059 |
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Equine Behaviour @ team @ |
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2300 |
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Author |
Dubois, F.; Giraldeau, L.-A. |
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Title |
The forager's dilemma: food sharing and food defense as risk-sensitive foraging options |
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Journal Article |
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Year |
2003 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
162 |
Issue |
6 |
Pages |
768-779 |
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Keywords |
Animals; Competitive Behavior/*physiology; *Environment; Feeding Behavior/*physiology; *Game Theory; *Models, Biological; Population Density; Population Dynamics |
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Abstract |
Although many variants of the hawk-dove game predict the frequency at which group foraging animals should compete aggressively, none of them can explain why a large number of group foraging animals share food clumps without any overt aggression. One reason for this shortcoming is that hawk-dove games typically consider only a single contest, while most group foraging situations involve opponents that interact repeatedly over discovered food clumps. The present iterated hawk-dove game predicts that in situations that are analogous to a prisoner's dilemma, animals should share the resources without aggression, provided that the number of simultaneously available food clumps is sufficiently large and the number of competitors is relatively small. However, given that the expected gain of an aggressive animal is more variable than the gain expected by nonaggressive individuals, the predicted effect of the number of food items in a clump-clump richness-depends on whether only the mean or both the mean and variability associated with payoffs are considered. More precisely, the deterministic game predicts that aggression should increase with clump richness, whereas the stochastic risk-sensitive game predicts that the frequency of encounters resulting in aggression should peak at intermediate clump richnesses or decrease with increasing clump richness if animals show sensitivity to the variance or coefficient of variation, respectively. |
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Departement des Sciences Biologiques, Universite du Quebec a Montreal, Case postale 8888, Succursale Centre-Ville, Montreal, Quebec H3C 3P8, Canada. fdubois@u-bourgogne.fr |
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0003-0147 |
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PMID:14737714 |
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2132 |
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Author |
Flack, J.C.; de Waal, F.B.M.; Krakauer, D.C. |
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Title |
Social structure, robustness, and policing cost in a cognitively sophisticated species |
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Journal Article |
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Year |
2005 |
Publication |
The American Naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
165 |
Issue |
5 |
Pages |
E126-139 |
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Keywords |
Animals; *Behavior, Animal; Cognition; Conflict (Psychology); Female; Macaca nemestrina/*physiology; Male; Models, Biological; *Social Behavior |
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Abstract |
Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power. |
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Address |
Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu |
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1537-5323 |
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PMID:15795848 |
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no |
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Call Number |
refbase @ user @ |
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168 |
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Author |
Munoz-Sanz, A. |
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Title |
[Christopher Columbus flu. A hypothesis for an ecological catastrophe] |
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Journal Article |
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Year |
2006 |
Publication |
Enfermedades Infecciosas y Microbiologia Clinica |
Abbreviated Journal |
Enferm Infecc Microbiol Clin |
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Volume |
24 |
Issue |
5 |
Pages |
326-334 |
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Keywords |
Animals; Atlantic Islands; Birds; Chickens; Disease Outbreaks/*history; Disease Reservoirs; Disease Susceptibility; Ecology; Europe/ethnology; History, 15th Century; Horses; Humans; Indians, South American; Influenza A virus/classification/genetics/pathogenicity; Influenza in Birds/epidemiology/history/transmission/virology; Influenza, Human/epidemiology/*history/mortality/transmission; Models, Biological; Orthomyxoviridae Infections/epidemiology/history/veterinary/virology; Poultry Diseases/epidemiology/history/transmission/virology; Reassortant Viruses/genetics/pathogenicity; Species Specificity; Sus scrofa; Swine Diseases/history/transmission/virology; Terminology; West Indies/epidemiology |
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Abstract |
When Christopher Columbus and his men embarked on the second Colombian expedition to the New World (1493), the crew suffered from fever, respiratory symptoms and malaise. It is generally accepted that the disease was influenza. Pigs, horses and hens acquired in Gomera (Canary Islands) traveled in the same ship. The pigs may well have been the origin of the flu and the intermediary hosts for genetic recombination of other viral subtypes. The Caribbean archipelago had a large population of birds, the natural reservoir of the avian influenza virus. In this ecological scenario there was a concurrence of several biological elements that had never before coexisted in the New World: pigs, horses, the influenza virus and humans. We propose that birds are likely to have played an important role in the epidemiology of the flu occurring on the second Colombian trip, which caused a fatal demographic catastrophe, with an estimated mortality of 90% among the natives. |
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Address |
Unidad de Patologia Infecciosa, Hospital Universitario Infanta Cristina, Servicio Extremeno de Salud, Universidad de Extremadura, Badajoz, Espana. infectio@unex.es |
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Spanish |
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Original Title |
La gripe de Cristobal Colon. Hipotesis sobre una catastrofe ecologica |
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0213-005X |
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PMID:16762260 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2624 |
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Author |
Waite, T.A. |
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Title |
Interruptions improve choice performance in gray jays: prolonged information processing versus minimization of costly errors |
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Journal Article |
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Year |
2002 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
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Volume |
5 |
Issue |
4 |
Pages |
209-214 |
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Keywords |
Animals; *Behavior, Animal; *Choice Behavior; Female; Learning; Male; Models, Biological; Motivation; Reinforcement Schedule; Songbirds/*physiology; Time Factors |
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Abstract |
Under the assumption that selection favors minimization of costly errors, erroneous choice may be common when its fitness cost is low. According to an adaptive-choice model, this cost depends on the rate at which an animal encounters the choice: the higher this rate, the smaller the cost of choosing a less valuable option. Errors should thus be more common when interruptions to foraging are shorter. A previous experiment supported this prediction: gray jays, Perisoreus canadensis, were more error prone when subjected to shorter delays to access to food rewards. This pattern, though, is also predicted by an attentional-constraints model. Because the subjects were able to inspect the rewards during delays, their improved performance when subjected to longer delays could have been a byproduct of the experimentally prolonged opportunity for information processing. To evaluate this possibility, a follow-up experiment manipulated both delay to access and whether rewards could be inspected during delays. Depriving jays of the opportunity to inspect rewards (using opaque lids) induced only a small, nonsignificant increase in error rate. This effect was independent of length of delay and so the jays' improved performance when subjected to longer delays was not simply a byproduct of prolonged information processing. More definitively, even when the jays were prevented from inspecting rewards during delays, their performance improved when subjected to longer delays. The findings are thus consistent with the adaptive-choice model. |
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Department of Evolution, Ecology, and Organismal Biology, Ohio State University, 1735 Neil Avenue, Columbus, OH 43210-1293, USA. waite.1@osu.edu |
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ISSN |
1435-9448 |
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PMID:12461598 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2592 |
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Permanent link to this record |
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Author |
Vallortigara, G.; Rogers, L.J. |
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Title |
Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization |
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Journal Article |
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Year |
2005 |
Publication |
The Behavioral and Brain Sciences |
Abbreviated Journal |
Behav Brain Sci |
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Volume |
28 |
Issue |
4 |
Pages |
575-89; discussion 589-633 |
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Keywords |
Animals; Attention/*physiology; Behavior/*physiology; Behavior, Animal/*physiology; Dominance, Cerebral/*physiology; *Evolution; Humans; Models, Biological; Visual Perception/physiology |
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Abstract |
Recent evidence in natural and semi-natural settings has revealed a variety of left-right perceptual asymmetries among vertebrates. These include preferential use of the left or right visual hemifield during activities such as searching for food, agonistic responses, or escape from predators in animals as different as fish, amphibians, reptiles, birds, and mammals. There are obvious disadvantages in showing such directional asymmetries because relevant stimuli may be located to the animal's left or right at random; there is no a priori association between the meaning of a stimulus (e.g., its being a predator or a food item) and its being located to the animal's left or right. Moreover, other organisms (e.g., predators) could exploit the predictability of behavior that arises from population-level lateral biases. It might be argued that lateralization of function enhances cognitive capacity and efficiency of the brain, thus counteracting the ecological disadvantages of lateral biases in behavior. However, such an increase in brain efficiency could be obtained by each individual being lateralized without any need to align the direction of the asymmetry in the majority of the individuals of the population. Here we argue that the alignment of the direction of behavioral asymmetries at the population level arises as an “evolutionarily stable strategy” under “social” pressures occurring when individually asymmetrical organisms must coordinate their behavior with the behavior of other asymmetrical organisms of the same or different species. |
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Department of Psychology and B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34123 Trieste, Italy. vallorti@univ.trieste.it |
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0140-525X |
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PMID:16209828 |
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no |
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Equine Behaviour @ team @ |
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4622 |
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Author |
Seyfarth, R.M. |
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Title |
A model of social grooming among adult female monkeys |
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Journal Article |
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Year |
1977 |
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Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
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65 |
Issue |
4 |
Pages |
671-698 |
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Animals; Behavior, Animal; Female; *Grooming; Haplorhini/*physiology; *Models, Biological; Reproduction; Social Dominance; Time Factors |
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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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0022-5193 |
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PMID:406485 |
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Equine Behaviour @ team @ |
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5259 |
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Author |
Viscido, S.V.; Miller, M.; Wethey, D.S. |
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Title |
The response of a selfish herd to an attack from outside the group perimeter |
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Journal Article |
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Year |
2001 |
Publication |
Journal of theoretical biology |
Abbreviated Journal |
J. Theor. Biol. |
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Volume |
208 |
Issue |
3 |
Pages |
315-328 |
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Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior |
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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. |
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Address |
Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu |
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0022-5193 |
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PMID:11207093 |
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no |
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Call Number |
refbase @ user @ |
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555 |
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Permanent link to this record |
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Author |
Uehara, T.; Yokomizo, H.; Iwasa, Y. |
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Title |
Mate-choice copying as Bayesian decision making |
Type |
Journal Article |
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Year |
2005 |
Publication |
The American naturalist |
Abbreviated Journal |
Am Nat |
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Volume |
165 |
Issue |
3 |
Pages |
403-410 |
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Keywords |
Animals; *Bayes Theorem; *Choice Behavior; Female; Male; *Models, Biological; *Sexual Behavior, Animal |
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Abstract |
Mate-choice copying by females has been reported in fishes (e.g., guppies) and lekking birds. Presumably, females assess males' quality using both information from direct observation of males and information acquired by observing other females' choices. Here, we study mathematically the conditions under which mate-choice copying is advantageous on the basis of Bayesian decision theory. A female may observe the mate choice of another female, called the model female, who has performed an optimal choice based on her own judgment. The conditions required for the focal female to choose the same mate as that chosen by the model female should depend on the male's appearance to her, the reliability of her own judgment of male quality, and the reliability of the model females. When three or more females are involved, the optimal mate choice critically depends on whether multiple model females make decisions independently or they themselves copy the choices of others. If two equally reliable females choose different males, the choice of the second female, made knowing the choice of the first, should have a stronger effect on the choice of the third (focal) female. This “last-choice precedence” should be tested experimentally. |
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Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan. uehara@bio-math.biology.kyushu-u.ac.jp |
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1537-5323 |
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Notes |
PMID:15729669 |
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no |
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Call Number |
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1821 |
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Permanent link to this record |
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Author |
Kaplan, A.I.; Borodovskii, M.I. |
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Title |
[Alternative animal behavior: a model and its statistical characteristics] |
Type |
Journal Article |
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Year |
1989 |
Publication |
Nauchnye Doklady Vysshei Shkoly. Biologicheskie Nauki |
Abbreviated Journal |
Nauchnye Doki Vyss Shkoly Biol Nauki |
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Volume |
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Issue |
3 |
Pages |
29-32 |
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Keywords |
Animals; *Behavior, Animal; Cognition; Male; Mathematics; *Models, Biological; *Models, Statistical; Rats; Reinforcement (Psychology) |
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Abstract |
The rats' alternative behaviour in T-maze at simultaneous two-sided food refreshment in 13 trials a day during 6 days has been studied. It has been found that in the first testing days the indexes of alternative behaviour of animals correspond to the characteristics of the random alternation. However, on the 5-6th day of testing in the overwhelming majority of rats the true deviation of alternation index above or below than the theoretical values has been revealed. A question on the existence of two strategies of cognitive behaviour alteration and perseveration in rat population is under discussion. |
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Russian |
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Original Title |
Al'ternativnoe povedenie zhivotnykh: model' i statisticheskie kharakteristiki |
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ISSN |
0470-4606 |
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Notes |
PMID:2742929 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2799 |
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