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Smith, J.E.; Van Horn, R.C.; Powning, K.S.; Cole, A.R.; Graham, K.E.; Memenis, S.K.; Holekamp, K.E. |
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Title |
Evolutionary forces favoring intragroup coalitions among spotted hyenas and other animals |
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Journal Article |
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Year |
2010 |
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Behavioral Ecology |
Abbreviated Journal |
Behav. Ecol. |
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21 |
Issue |
2 |
Pages |
284-303 |
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Abstract |
Coalitionary support in agonistic interactions represents cooperation because intervening in a fight is potentially costly to the donor of support but benefits the recipient. Here, we first review the characteristics of, and evolutionary forces favoring, intragroup coalitions in 49 species and find that patterns of intragroup coalition formation are remarkably similar between primates and nonprimates. We then test hypotheses suggesting kin selection, reciprocal altruism, and direct benefits as adaptive explanations for coalitionary interventions among adult female spotted hyenas (Crocuta crocuta) belonging to a large social group in Kenya. As predicted by kin selection theory, females supported close kin most often, and the density (connectedness) of cooperation networks increased with genetic relatedness. Nevertheless, kinship failed to protect females from coalitionary attacks. We found no evidence of enduring alliances based on reciprocal support among unrelated adult females. Instead, donors generally minimized costs to themselves, intervening most often during low-intensity fights and when feeding opportunities were unavailable. Females also gained direct benefits from directing coalitionary attacks toward subordinates. Finally, females monitored the number of dominant bystanders in the “audience” at fights and modified their level of cooperation based on this knowledge. Overall, hyenas made flexible decisions regarding whether or not to intervene in fights, modifying their tendency to cooperate based on multiple types of information about their immediate social and ecological environments. Taken together, these findings indicate that the combined evolutionary forces of kin selection and direct benefits derived from reinforcing the status quo drive coalitionary interventions among adult female spotted hyenas. |
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agonistic support, audience effect, cooperation network, direct benefits, kin selection * reciprocal altruism * review |
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10.1093/beheco/arp181 |
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Equine Behaviour @ team @ |
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5285 |
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Shultz, S.; Finlayson, L.V. |
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Large body and small brain and group sizes are associated with predator preferences for mammalian prey |
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Journal Article |
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Year |
2010 |
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Behavioral Ecology |
Abbreviated Journal |
Behav. Ecol. |
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21 |
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5 |
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1073-1079 |
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Predation is a major force in shaping biological communities, both over ecological and evolutionary timescales. In response to predation pressure, prey have evolved characteristics designed to mitigate predation pressure. We evaluated predator foraging biases in relation to prey characteristics across 16 vertebrate communities. We show that although predator biases vary, some prey traits are consistently associated with predator diet composition. Within their acceptable prey size range, predators show positive bias toward larger bodied prey, small-brained prey (controlling for body size), small group size, and terrestriality. Thus, whether predator foraging decisions are passive or active, predator choice exerts differential pressure on prey species according to prey characteristics. Predator biases also were positively associated with early age at maturity, supporting the role of mortality in driving life-history characteristics. These results support several theoretical models of predation including its role as a selective force driving evolutionary changes in life history, brain size and sociality, optimal diet theory, and antiapostatic predation. |
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10.1093/beheco/arq108 |
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Equine Behaviour @ team @ |
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5262 |
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Bode, N.W.F.; Faria, J.J.; Franks, D.W.; Krause, J.; Wood, A.J. |
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How perceived threat increases synchronization in collectively moving animal groups |
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2010 |
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Proceedings of the Royal Society B: Biological Sciences |
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Proc. Roy. Soc. Lond. B Biol. Sci. |
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277 |
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1697 |
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3065-3070 |
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Nature is rich with many different examples of the cohesive motion of animals. Previous attempts to model collective motion have primarily focused on group behaviours of identical individuals. In contrast, we put our emphasis on modelling the contributions of different individual-level characteristics within such groups by using stochastic asynchronous updating of individual positions and orientations. Our model predicts that higher updating frequency, which we relate to perceived threat, leads to more synchronized group movement, with speed and nearest-neighbour distributions becoming more uniform. Experiments with three-spined sticklebacks (Gasterosteus aculeatus) that were exposed to different threat levels provide strong empirical support for our predictions. Our results suggest that the behaviour of fish (at different states of agitation) can be explained by a single parameter in our model: the updating frequency. We postulate a mechanism for collective behavioural changes in different environment-induced contexts, and explain our findings with reference to confusion and oddity effects. |
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10.1098/rspb.2010.0855 |
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Equine Behaviour @ team @ |
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5188 |
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Author |
Ecker, C.; Marquand, A.; Mourao-Miranda, J.; Johnston, P.; Daly, E.M.; Brammer, M.J.; Maltezos, S.; Murphy, C.M.; Robertson, D.; Williams, S.C.; Murphy, D.G.M. |
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Describing the Brain in Autism in Five Dimensions--Magnetic Resonance Imaging-Assisted Diagnosis of Autism Spectrum Disorder Using a Multiparameter Classification Approach |
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Journal Article |
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2010 |
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J. Neurosci. |
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J. Neurosci. |
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30 |
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32 |
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10612-10623 |
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Autism spectrum disorder (ASD) is a neurodevelopmental condition with multiple causes, comorbid conditions, and a wide range in the type and severity of symptoms expressed by different individuals. This makes the neuroanatomy of autism inherently difficult to describe. Here, we demonstrate how a multiparameter classification approach can be used to characterize the complex and subtle structural pattern of gray matter anatomy implicated in adults with ASD, and to reveal spatially distributed patterns of discriminating regions for a variety of parameters describing brain anatomy. A set of five morphological parameters including volumetric and geometric features at each spatial location on the cortical surface was used to discriminate between people with ASD and controls using a support vector machine (SVM) analytic approach, and to find a spatially distributed pattern of regions with maximal classification weights. On the basis of these patterns, SVM was able to identify individuals with ASD at a sensitivity and specificity of up to 90% and 80%, respectively. However, the ability of individual cortical features to discriminate between groups was highly variable, and the discriminating patterns of regions varied across parameters. The classification was specific to ASD rather than neurodevelopmental conditions in general (e.g., attention deficit hyperactivity disorder). Our results confirm the hypothesis that the neuroanatomy of autism is truly multidimensional, and affects multiple and most likely independent cortical features. The spatial patterns detected using SVM may help further exploration of the specific genetic and neuropathological underpinnings of ASD, and provide new insights into the most likely multifactorial etiology of the condition. |
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10.1523/Jneurosci.5413-09.2010 |
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Equine Behaviour @ team @ |
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5191 |
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Sueur, C.; Jacobs, A.; Amblard, F.; Petit, O.; King, A.J. |
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How can social network analysis improve the study of primate behavior? |
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Journal Article |
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2010 |
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American Journal of Primatology |
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Am. J. Primatol. |
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73 |
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8 |
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703-719 |
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interaction; association; social system; social structure; methodology; behavioral sampling |
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Abstract When living in a group, individuals have to make trade-offs, and compromise, in order to balance the advantages and disadvantages of group life. Strategies that enable individuals to achieve this typically affect inter-individual interactions resulting in nonrandom associations. Studying the patterns of this assortativity using social network analyses can allow us to explore how individual behavior influences what happens at the group, or population level. Understanding the consequences of these interactions at multiple scales may allow us to better understand the fitness implications for individuals. Social network analyses offer the tools to achieve this. This special issue aims to highlight the benefits of social network analysis for the study of primate behaviour, assessing it's suitability for analyzing individual social characteristics as well as group/population patterns. In this introduction to the special issue, we first introduce social network theory, then demonstrate with examples how social networks can influence individual and collective behaviors, and finally conclude with some outstanding questions for future primatological research. Am. J. Primatol. 73:703?719, 2011. ? 2011 Wiley-Liss, Inc. |
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Wiley-Blackwell |
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0275-2565 |
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doi: 10.1002/ajp.20915 |
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Equine Behaviour @ team @ |
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6410 |
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McGreevy, P.D.; Harman, A.; McLean, A.; Hawson, L. |
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Over-flexing the horse's neck: A modern equestrian obsession? |
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2010 |
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Journal of Veterinary Behavior: Clinical Applications and Research |
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Journal of Veterinary Behavior: Clinical Applications and Research |
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5 |
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4 |
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180-186 |
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We used an opportunistic review of photographs of different adult and juvenile horses walking, trotting, and cantering (n = 828) to compare the angle of the nasal plane relative to vertical in feral and domestic horses at liberty (n = 450) with ridden horses advertised in a popular Australian horse magazine (n = 378). We assumed that horses in advertisements were shown at, what was perceived by the vendors to be, their best. Of the ridden horses, 68% had their nasal plane behind the vertical. The mean angle of the unridden horses at walk, trot, and canter (30.7 ± 11.5; 27.3 ± 12.0; 25.5 ± 11.0) was significantly greater than those of the ridden horses (1.4 ± 14.1; ?5.1 ± ?11.1; 3.1 ± 15.4, P < 0.001). Surprisingly, unridden domestic horses showed greater angles than feral horses or domestic horses at liberty. We compared adult and juvenile horses in all 3 gaits and found no significant difference. Taken together, these findings demonstrate that the longitudinal neck flexion of the degree desirable by popular opinion in ridden horses is not a common feature of unridden horses moving naturally. Moreover, they suggest that advertised horses in our series are generally being ridden at odds with their natural carriage and contrary to the international rules of dressage (as published by the International Equestrian Federation). These findings are discussed against the backdrop of the established doctrine, which states that carrying a rider necessitates changes in longitudinal flexion, and in the context of the current debate around hyperflexion. |
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Elsevier |
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1558-7878 |
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doi: 10.1016/j.jveb.2010.03.004 |
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Equine Behaviour @ team @ |
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6501 |
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Detto, T.; Jennions, M. D.; Backwell, P. R. Y. |
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When and Why Do Territorial Coalitions Occur? Experimental Evidence from a Fiddler Crab |
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2010 |
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The American Naturalist |
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Am Nat |
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175 |
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5 |
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E119-E125 |
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coalitions, cooperation, dear enemy, fiddler crabs, fighting, territoriality. |
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Neighboring territory owners are often less aggressive toward each other than to strangers (“dear enemy” effect). There is, however, little evidence for territorial defense coalitions whereby a neighbor will temporarily leave his/her own territory, enter that of a neighbor, and cooperate in repelling a conspecific intruder. This is surprising, as theoreticians have long posited the existence of such coalitions and the circumstances under which they should evolve. Here we document territorial defense coalitions in the African fiddler crab Uca annulipes, which lives in large colonies wherein each male defends a burrow and its surrounding area against neighbors and “floaters” (burrowless males). Fights between a resident and a floater sometimes involve another male who has left his territory to fight the floater challenging his neighbor. Using simple experiments, we provide the first evidence of the rules determining when territorial coalitions form. Our results support recent models that suggest that these coalitions arise from by‐product mutualism. |
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doi: 10.1086/651588 |
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Equine Behaviour @ team @ |
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5112 |
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