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Author |
Scheffer, M.; van Nes, E.H. |
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Title |
Self-organized similarity, the evolutionary emergence of groups of similar species |
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Journal Article |
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Year |
2006 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
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Volume |
103 |
Issue |
16 |
Pages |
6230-6235 |
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Keywords |
Animals; *Competitive Behavior; *Ecosystem; *Evolution; *Models, Biological |
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Abstract |
Ecologists have long been puzzled by the fact that there are so many similar species in nature. Here we show that self-organized clusters of look-a-likes may emerge spontaneously from coevolution of competitors. The explanation is that there are two alternative ways to survive together: being sufficiently different or being sufficiently similar. Using a model based on classical competition theory, we demonstrate a tendency for evolutionary emergence of regularly spaced lumps of similar species along a niche axis. Indeed, such lumpy patterns are commonly observed in size distributions of organisms ranging from algae, zooplankton, and beetles to birds and mammals, and could not be well explained by earlier theory. Our results suggest that these patterns may represent self-constructed niches emerging from competitive interactions. A corollary of our findings is that, whereas in species-poor communities sympatric speciation and invasion of open niches is possible, species-saturated communities may be characterized by convergent evolution and invasion by look-a-likes. |
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Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 8080, 6700 DD, Wageningen, The Netherlands. marten.scheffer@wur.nl |
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0027-8424 |
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PMID:16585519 |
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no |
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refbase @ user @ |
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510 |
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Author |
Wolf, M.; van Doorn, G.S.; Leimar, O.; Weissing, F.J. |
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Title |
Life-history trade-offs favour the evolution of animal personalities |
Type |
Journal Article |
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Year |
2007 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
447 |
Issue |
7144 |
Pages |
581-584 |
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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) |
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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. |
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Theoretical Biology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands |
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1476-4687 |
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PMID:17538618 |
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no |
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Equine Behaviour @ team @ |
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4098 |
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Author |
Grosenick, L.; Clement, T.S.; Fernald, R.D. |
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Title |
Fish can infer social rank by observation alone |
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Journal Article |
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Year |
2007 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
445 |
Issue |
7126 |
Pages |
429-432 |
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Aggression/physiology; Animals; Cognition/*physiology; Female; Fishes/*physiology; Learning/*physiology; Male; Models, Biological; *Social Dominance; Territoriality |
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Transitive inference (TI) involves using known relationships to deduce unknown ones (for example, using A > B and B > C to infer A > C), and is thus essential to logical reasoning. First described as a developmental milestone in children, TI has since been reported in nonhuman primates, rats and birds. Still, how animals acquire and represent transitive relationships and why such abilities might have evolved remain open problems. Here we show that male fish (Astatotilapia burtoni) can successfully make inferences on a hierarchy implied by pairwise fights between rival males. These fish learned the implied hierarchy vicariously (as 'bystanders'), by watching fights between rivals arranged around them in separate tank units. Our findings show that fish use TI when trained on socially relevant stimuli, and that they can make such inferences by using indirect information alone. Further, these bystanders seem to have both spatial and featural representations related to rival abilities, which they can use to make correct inferences depending on what kind of information is available to them. Beyond extending TI to fish and experimentally demonstrating indirect TI learning in animals, these results indicate that a universal mechanism underlying TI is unlikely. Rather, animals probably use multiple domain-specific representations adapted to different social and ecological pressures that they encounter during the course of their natural lives. |
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Department of Biological Sciences, Stanford University, Stanford, California, 94305, USA. logang@stanford.edu |
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1476-4687 |
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PMID:17251980 |
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no |
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refbase @ user @ |
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600 |
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Author |
Gentner, T.Q.; Fenn, K.M.; Margoliash, D.; Nusbaum, H.C. |
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Title |
Recursive syntactic pattern learning by songbirds |
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Journal Article |
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Year |
2006 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
440 |
Issue |
7088 |
Pages |
1204-1207 |
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Keywords |
Acoustic Stimulation; *Animal Communication; Animals; Auditory Perception/*physiology; Humans; *Language; Learning/*physiology; Linguistics; Models, Neurological; Semantics; Starlings/*physiology; Stochastic Processes |
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Abstract |
Humans regularly produce new utterances that are understood by other members of the same language community. Linguistic theories account for this ability through the use of syntactic rules (or generative grammars) that describe the acceptable structure of utterances. The recursive, hierarchical embedding of language units (for example, words or phrases within shorter sentences) that is part of the ability to construct new utterances minimally requires a 'context-free' grammar that is more complex than the 'finite-state' grammars thought sufficient to specify the structure of all non-human communication signals. Recent hypotheses make the central claim that the capacity for syntactic recursion forms the computational core of a uniquely human language faculty. Here we show that European starlings (Sturnus vulgaris) accurately recognize acoustic patterns defined by a recursive, self-embedding, context-free grammar. They are also able to classify new patterns defined by the grammar and reliably exclude agrammatical patterns. Thus, the capacity to classify sequences from recursive, centre-embedded grammars is not uniquely human. This finding opens a new range of complex syntactic processing mechanisms to physiological investigation. |
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Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois 60637, USA. tgentner@ucsd.edu |
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1476-4687 |
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PMID:16641998 |
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no |
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refbase @ user @ |
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353 |
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Author |
Flack, J.C.; Girvan, M.; de Waal, F.B.M.; Krakauer, D.C. |
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Title |
Policing stabilizes construction of social niches in primates |
Type |
Journal Article |
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Year |
2006 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
439 |
Issue |
7075 |
Pages |
426-429 |
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Keywords |
Animals; Conflict (Psychology); Female; Macaca nemestrina/*physiology/*psychology; Male; Models, Biological; *Social Behavior |
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Abstract |
All organisms interact with their environment, and in doing so shape it, modifying resource availability. Termed niche construction, this process has been studied primarily at the ecological level with an emphasis on the consequences of construction across generations. We focus on the behavioural process of construction within a single generation, identifying the role a robustness mechanism--conflict management--has in promoting interactions that build social resource networks or social niches. Using 'knockout' experiments on a large, captive group of pigtailed macaques (Macaca nemestrina), we show that a policing function, performed infrequently by a small subset of individuals, significantly contributes to maintaining stable resource networks in the face of chronic perturbations that arise through conflict. When policing is absent, social niches destabilize, with group members building smaller, less diverse, and less integrated grooming, play, proximity and contact-sitting networks. Instability is quantified in terms of reduced mean degree, increased clustering, reduced reach, and increased assortativity. Policing not only controls conflict, we find it significantly influences the structure of networks that constitute essential social resources in gregarious primate societies. The structure of such networks plays a critical role in infant survivorship, emergence and spread of cooperative behaviour, social learning and cultural traditions. |
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Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu |
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1476-4687 |
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PMID:16437106 |
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no |
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refbase @ user @ |
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298 |
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Author |
Bell, A.M. |
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Title |
Evolutionary biology: animal personalities |
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Year |
2007 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
447 |
Issue |
7144 |
Pages |
539-540 |
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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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1476-4687 |
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PMID:17538607 |
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Equine Behaviour @ team @ |
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4099 |
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Author |
Johnson, D.D.P.; Stopka, P.; Knights, S. |
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Title |
Sociology: The puzzle of human cooperation |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
421 |
Issue |
6926 |
Pages |
911-2; discussion 912 |
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Altruism; *Cooperative Behavior; Evolution; Humans; *Models, Biological; Punishment; Reward; Risk |
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Olin Institute for Strategic Studies, Harvard University, Cambridge, Massachusetts 02138, USA. dominic@post.harvard.edu |
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0028-0836 |
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PMID:12606989 |
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refbase @ user @ |
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467 |
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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 |
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Journal Article |
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2001 |
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Nature |
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Nature |
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414 |
Issue |
6866 |
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895-899 |
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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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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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no |
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Equine Behaviour @ team @ |
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2300 |
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Author |
Fazio, E.; Ferlazzo, A. |
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Title |
Evaluation of Stress During Transport |
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Journal Article |
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2003 |
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Veterinary Research Communications |
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27 |
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519-524 |
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hormones – physiological variables – stress – transport procedures |
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Domestic animals are transported for a variety of reasons including breeding, biomedical purposes, slaughter and, in the case of sporting horses, for competitions, pleasure activities or ceremonial proceedings. Studies to determine the amount of stress on farm animals during transport often have highly variable results and are difficult to interpret. The reaction of animals to stressors depends on the duration and intensity of the stressors, the animal's previous experience, its physiological status and the immediate environmental restraints. Behavioural, haematological, haematochemical, physiological and neuro-hormonal (ß-endorphin, ACTH, cortisol, iodothyronines) variables are discussed on the basis of handling, loading and transport procedures of animals. |
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Equine Behaviour @ team @ |
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4391 |
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Author |
Wilson, R.T. |
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Title |
Biodiversity of Domestic Livestock in the Republic of Yemen |
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Journal Article |
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2003 |
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Tropical Animal Health and Production |
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35 |
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1 |
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27-46 |
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Abstract This paper describes the domestic livestock of the Republic of Yemen and aspires to complement earlier sources listing or partially describing `breeds'. It attempts to cover all species and provide indications of production parameters through a literature review and via field observations made by the author in 1999. Information is provided on livestock numbers and the economic importance of animal production. Most animals are kept in sedentary mixed crop-livestock production systems; transhumant systems have the next greatest number of stock; with nomadic systems being of least and declining importance. Yemen's livestock appear to comprise at least 11 breeds of sheep, 5 breeds of goat, 2 breeds of cattle, 4 breeds of camel, 2 breeds of donkey and 1 breed of horse. There are no data on breeds of poultry but domestic fowl (where clearly considerable diversity exists) and pigeons are kept. There is little formal information on the history and relationships of most breeds. Some appear to be of ancient local origin, whereas others show affinities with those of neighbouring and other countries. None of the identified types is considered endangered, so conservation would be premature. A more formal and detailed genetic characterization, to add to the largely morphological and traditional classification, may, however, reveal such a need. |
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Abstract This paper describes the domestic livestock of the Republic of Yemen and aspires to complement earlier sources listing or partially describing `breeds'. It attempts to cover all species and provide indications of production parameters through a literature review and via field observations made by the author in 1999. Information is provided on livestock numbers and the economic importance of animal production. Most animals are kept in sedentary mixed crop-livestock production systems; transhumant systems have the next greatest number of stock; with nomadic systems being of least and declining importance. Yemen's livestock appear to comprise at least 11 breeds of sheep, 5 breeds of goat, 2 breeds of cattle, 4 breeds of camel, 2 breeds of donkey and 1 breed of horse. There are no data on breeds of poultry but domestic fowl (where clearly considerable diversity exists) and pigeons are kept. There is little formal information on the history and relationships of most breeds. Some appear to be of ancient local origin, whereas others show affinities with those of neighbouring and other countries. None of the identified types is considered endangered, so conservation would be premature. A more formal and detailed genetic characterization, to add to the largely morphological and traditional classification, may, however, reveal such a need. |
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Equine Behaviour @ team @ |
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4389 |
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