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Uehara, T., Yokomizo, H., & Iwasa, Y. (2005). Mate-choice copying as Bayesian decision making. Am Nat, 165(3), 403–410.
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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Parrish, J. K., & Viscido, S. V. (2005). Traffic rules of fish schools: A review of agent-based approaches. In C. K. Hemelrijk (Ed.), Self-organisation and the evolution of social behaviour. (pp. 50–80). Cambridge: Cambridge University Press.
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de Waal, F. B. M. (2005). How animals do business. Sci Am, 292(4), 54–61.
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Moehlman, P. D. (2005). Endangered wild equids. Sci Am, 292(3), 74–81.
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Macfadden, B. J. (2005). Evolution. Fossil horses--evidence for evolution. Science, 307(5716), 1728–1730.
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Landaeta-Hernández, A. J., Chenoweth, P. J., Randles, R., Littell, R., Rae, O., & Chase, C. C. (2005). Identifying the social dominance order in a mixed breed herd: a practical methodology. Revista Científica, 15(2), 148–154.
Abstract: The major objective of this study was to identify a simple and accurate method of assessing differences in female social status. Three methods of estimating dominance value (DV) were compared in beef cows of three breed-types; Angus (A; n=10), Brahman (B; n=10), and Senepol (S; n=10). Cows were equitably assigned to two groups of fifteen each, allocated into separate pastures and containing equal number of animals by breed. Agonistic interactions were recorded for 45 d of study, in two 1 h periods during concentrate feeding using the method of competitive orders winner/loser. Methods of estimating DV included: I) Ratio between individuals dominated and total encountered, II) Ratio between encounters won to total encounters, III) Proportion of individuals dominated to total herdmates. Due to the different level of interactivity evidenced among animals as well as between and within social orders, method III with subsequent arc-sin transformation was considered as the most practical and accurate method for estimating DV and subsequent allocation of cows into a social dominance order. In addition, a breed effect was found on social dominance. Senepol cows obtained greater DV`s (1.24 ± 0.08) than Angus (0.97 ± 0.08; P<0.03) and Brahman cows (0.76 ± 0.08; P<0.005).
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Bigiani, A., Mucignat-Caretta, C., Montani, G., & Tirindelli, R. (2005). Pheromone reception in mammals. Reviews of Physiology, Biochemistry and Pharmacology, 154, 1–35.
Abstract: Pheromonal communication is the most convenient way to transfer information regarding gender and social status in animals of the same species with the holistic goal of sustaining reproduction. This type of information exchange is based on pheromones, molecules often chemically unrelated, that are contained in body fluids like urine, sweat, specialized exocrine glands, and mucous secretions of genitals. So profound is the relevance of pheromones over the evolutionary process that a specific peripheral organ devoted to their recognition, namely the vomeronasal organ of Jacobson, and a related central pathway arose in most vertebrate species. Although the vomeronasal system is well developed in reptiles and amphibians, most mammals strongly rely on pheromonal communication. Humans use pheromones too; evidence on the existence of a specialized organ for their detection, however, is very elusive indeed. In the present review, we will focus our attention on the behavioral, physiological, and molecular aspects of pheromone detection in mammals. We will discuss the responses to pheromonal stimulation in different animal species, emphasizing the complicacy of this type of communication. In the light of the most recent results, we will also discuss the complex organization of the transduction molecules that underlie pheromone detection and signal transmission from vomeronasal neurons to the higher centers of the brain. Communication is a primary feature of living organisms, allowing the coordination of different behavioral paradigms among individuals. Communication has evolved through a variety of different strategies, and each species refined its own preferred communication medium. From a phylogenetic point of view, the most widespread and ancient way of communication is through chemical signals named pheromones: it occurs in all taxa, from prokaryotes to eukaryotes. The release of specific pheromones into the environment is a sensitive and definite way to send messages to other members of the same species. Therefore, the action of an organism can alter the behavior of another organism, thereby increasing the fitness of either or both. Albeit slow in transmission and not easily modulated, pheromones can travel around objects in the dark and over long distances. In addition, they are emitted when necessary and their biosynthesis is usually economic. In essence, they represent the most efficient tool to refine the pattern of social behaviors and reproductive strategies. © Springer-Verlag 2005.
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Hedberg, Y., Dalin, A. - M., Ohagen, P., Holm, K. R., & Kindahl, H. (2005). Effect of oestrous-cycle stage on the response of mares in a novel object test and isolation test. Reprod Domest Anim, 40(5), 480–488.
Abstract: In various species, sex, hormonal treatments and oestrous-cycle stage have been shown to affect the animal's response in behavioural tests. Few such studies have been performed in the horse. The main aim of the present study was to investigate whether oestrous-cycle stage affects mares' response to a novel object test and isolation test and, in part, to study whether mares, assumed to suffer from oestrous-related behavioural problems, respond differently in these tests when compared with controls. Twelve mares were tested twice, in oestrus and dioestrus, in a crossover design. Seven behavioural and two heart rate variables were measured for the novel object test and two heart rate variables for the isolation test. Oestrous-cycle stage and whether a mare was classified as a 'problem' mare did not affect the mare's response. However, test order, i.e. the cycle stage a mare was tested in first, affected its reaction. This effect could partly be explained by significant differences between test occasions 1 and 2 in three behavioural variables and one heart rate variable (p < 0.05) in the novel object test. The mares explored the novel object more and had a higher mean heart rate in the first test. Exploring the novel object more could largely be attributed to those mares tested in dioestrus first, perhaps indicating that the mares in oestrus were less receptive to the novel object. The reason for the differences between test occasions could be an effect of learning or habituation.
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Bates, D. (2005). Fitting linear mixed models in R. R News, 5.
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Mehlem M. (2005). Angst und Pferd – Wege zur Bewältigung und Integration von Ängsten mit Hilfe der Pferde. In DKThR (Ed.), Psychotherapie mit dem Pferd – Beiträge aus der Praxis (pp. 20–37). Warendorf: FN-Verlag.
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