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| Author |
Creel, S. |
| Title |
Social dominance and stress hormones |
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Journal Article |
| Year |
2001 |
Publication |
Trends in Ecology & Evolution |
Abbreviated Journal |
Trends. Ecol. Evol |
| Volume |
16 |
Issue |
9 |
Pages |
491-497 |
| Keywords |
Dominance; rank; stress; glucocorticoids; cooperative breeding; sociality; behavioural endocrinology; mammals |
| Abstract |
In most cooperatively breeding birds and mammals, reproductive rates are lower for social subordinates than for dominants, and it is common for reproduction in subordinates to be completely suppressed. Early research conducted in captivity showed that losing fights can increase glucocorticoid (GC) secretion, a general response to stress. Because GCs can suppress reproduction, it has been widely argued that chronic stress might underlie reproductive suppression of social subordinates in cooperative breeders. Contradicting this hypothesis, recent studies of cooperative breeders in the wild show that dominant individuals have elevated GCs more often than do subordinates. The findings that elevated GCs can be a consequence of subordination or a cost of dominance complicate the conventional view of social stress, with broad ramifications for the evolution of dominance and reproductive suppression. |
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Equine Behaviour @ team @ |
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4072 |
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Doutrelant, C.; McGregor, P. K.; Oliveira, R. F. |
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The effect of an audience on intrasexual communication in male Siamese fighting fish, Betta splendens |
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Journal Article |
| Year |
2001 |
Publication |
Behavioral Ecology |
Abbreviated Journal |
Behav. Ecol. |
| Volume |
12 |
Issue |
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Pages |
283-286 |
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Equine Behaviour @ team @ |
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4224 |
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| Author |
Fleurance,Géraldine; Duncan ,Patrick; Mallevaud, Bruno |
| Title |
Daily intake and the selection of feeding sites by horses in heterogeneous wet grasslands |
Type |
Journal Article |
| Year |
2001 |
Publication |
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Abbreviated Journal |
Anim. Res. |
| Volume |
50 |
Issue |
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Pages |
149-156 |
| Keywords |
horse / intake / grassland / heterogeneity / wetland cheval / ingestion / prairie / hétérogénéité / zone humide |
| Abstract |
In spite of the importance of grazed forage in horse nutrition, little information is available on their daily intake at pasture. We determined the intake of 4 non-breeding mares of a heavy breed (average body weight = 674 kg), grazing during the summer in heterogeneous natural grasslands of the Marais Poitevin (France), an internationally important wetland where grazing is an essential process which maintains biodiversity. The mares ate large quantities of forage (21.9 $pm$ 2.4 kg of organic matter per day, i.e. 166.2 $pm$ 20.8 g of organic matter per kg LW0.75 per day) in comparison with previous published values and with the estimated requirements of these horses. The use of the vegetation was very selective, the mares spent about 70% of their feeding time on short grass lawns (sward surface $leq$ 4 cm, biomass < 100 g$cdot$m-2), that represented only 10% of the area. This behaviour maintained the plants at young growing stages which are of better quality than ungrazed plants. These results are discussed in relation to the dynamics of the plant communities. |
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horse / intake / grassland / heterogeneity / wetland |
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Equine Behaviour @ team @ |
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4238 |
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van der Kolk, J.H.; Nachreiner, R.F.; Schott, H.C.; Refsal, K.R.; Zanella, A.J. |
| Title |
Salivary and plasma concentration of cortisol in normal horses and horses with Cushing's disease |
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Journal Article |
| Year |
2001 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
Equine Vet J |
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33 |
Issue |
2 |
Pages |
211-213 |
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Adrenal Cortex Function Tests/standards/veterinary; Animals; Cushing Syndrome/diagnosis/metabolism/*veterinary; Female; Horse Diseases/blood/*diagnosis/metabolism; Horses/blood/*metabolism; Hydrocortisone/blood/*metabolism; Male; Predictive Value of Tests; Reference Values; Saliva/*metabolism |
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Department of Large Animal Medicine and Nutrition, Veterinary Faculty, Utrecht University, The Netherlands |
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English |
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0425-1644 |
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PMID:11266074 |
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no |
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Equine Behaviour @ team @ |
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4281 |
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Schaefer, M.L.; Young, D.A.; Restrepo, D. |
| Title |
Olfactory Fingerprints for Major Histocompatibility Complex-Determined Body Odors |
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Journal Article |
| Year |
2001 |
Publication |
J. Neurosci. |
Abbreviated Journal |
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21 |
Issue |
7 |
Pages |
2481-2487 |
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Recognition of individual body odors is analogous to human face recognition in that it provides information about identity. Individual body odors determined by differences at the major histocompatibility complex (MHC or H-2) have been shown to influence mate choice, pregnancy block, and maternal behavior in mice. Unfortunately, the mechanism and extent of the main olfactory bulb (MOB) and accessory olfactory bulb (AOB) involvement in the discrimination of animals according to H-2-type has remained ambiguous. Here we study the neuronal activation patterns evoked in the MOB in different individuals on exposure to these complex, biologically meaningful sensory stimuli. We demonstrate that body odors from H-2 disparate mice evoke overlapping but distinct maps of neuronal activation in the MOB. The spatial patterns of odor-evoked activity are sufficient to be used like fingerprints to predict H-2 identity using a novel computer algorithm. These results provide functional evidence for discrimination of H-2-determined body odors in the MOB, but do not preclude a role for the AOB. These data further our understanding of the neural strategies used to decode socially relevant odors. N1 - |
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Equine Behaviour @ team @ |
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4419 |
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Baragli, P.; Tedeschi, D.; Masini, A.P.; Magnaghi, N.; Martelli, F.; Sighieri, C. |
| Title |
Estimation of performance in elite endurance horses by means of an exercise test in field conditions |
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Journal Article |
| Year |
2001 |
Publication |
Ippologia |
Abbreviated Journal |
Valutazione della performance in cavalli da endurance di elite mediante test diesercizio in campo |
| Volume |
12 |
Issue |
1 |
Pages |
13-19 |
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In human sports medicine exercise tests are normally used to check training progression. Correlation tests between blood lactate concentration and exercise speed are often used for this purpose. Studies have been done to adjust exercise tests for athletic horses using the same principle. The aim of this work was to verify the practical possibility that the anaerobic threshold in elite endurance horses could be calculated by adjusting a submaximal exercise field test in order to obtain reference parameters for endurance horses. Ten selected horses from the Italian National Endurance Team were used for this study. The tests were conducted on an 800 meters grass oval. Horses performed three steps (800 meters every step), at increasing speed with two minute intervals between each step. Riders were informed of the ideal speed for every step (5, 7.5, 10 m/s) and the real velocity was calculated on the basis of time taken to finish a single step. Blood samples were obtained via venipuncture from the jugular vein, immediately before the beginning of the test and 60 seconds after the end of each step. The following parameters were evaluated for each horse: individual anaerobic threshold (VSI), anaerobic threshold (V4) and exercise velocity corresponding to a lactate concentration of 2 mM/I (V2). Analysis of results indicate that lactate concentration is exponentially related to exercise speed for the entire test. VSI, V4, V2, were (mearttsd): 25.7±5.1; 30.5±2.5; 21.1±2.9 km/h respectively. |
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Dipto. Anat., Biochim. Fisiol. Vet., Univ. degli Studi di Pisa |
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Export Date: 13 November 2008; Source: Scopus |
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Equine Behaviour @ team @ |
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4654 |
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Kudo, H.; Dunbar, R.I.M. |
| Title |
Neocortex size and social network size in primates |
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Journal Article |
| Year |
2001 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
62 |
Issue |
4 |
Pages |
711-722 |
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Primates use social grooming to service coalitions and it has been suggested that these directly affect the fitness of their members by allowing them to reduce the intrinsic costs associated with living in large groups. We tested two hypotheses about the size of grooming cliques that derive from this suggestion: (1) that grooming clique size should correlate with relative neocortex size and (2) that the size of grooming cliques should be proportional to the size of the groups they have to support. Both predictions were confirmed, although we show that, in respect of neocortex size, there are as many as four statistically distinct grades within the primates (including humans). Analysis of the patterns of grooming among males and females suggested that large primate social groups often consist of a set of smaller female subgroups (in some cases, matrilinearly based coalitions) that are linked by individual males. This may be because males insert themselves into the interstices between weakly bonded female subgroups rather than because they actually hold these subunits together. |
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0003-3472 |
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Equine Behaviour @ team @ |
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4726 |
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Bolhuis, J.J.; Macphail, E.M. |
| Title |
A critique of the neuroecology of learning and memory |
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Journal Article |
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2001 |
Publication |
Trends in Cognitive Sciences |
Abbreviated Journal |
Trends. Cognit. Sci. |
| Volume |
5 |
Issue |
10 |
Pages |
426-433 |
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Recent years have seen the emergence of neuroecology, the study of the neural mechanisms of behaviour guided by functional and evolutionary principles. This research has been of enormous value for our understanding of the evolution of brain- and species-specific behaviour. However, we question the validity of the neuroecological approach when applied to the analysis of learning and memory, given its arbitrary assumption that different [`]problems' engage different memory mechanisms. Differences in memory-based performance in [`]natural' tasks do not prove differences in memory capacity; similarly, differences in the use of memory in the natural environment do not provide a sound basis for expecting differences in anatomical structures that subserve learning and memory. This critique is illustrated with examples taken from the study of the neurobiology of food storing and song learning in birds. |
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1364-6613 |
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Equine Behaviour @ team @ |
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4742 |
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Biegler, R.; McGregor, A.; Krebs, J.R.; Healy, S.D. |
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A larger hippocampus is associated with longer-lasting spatial memory |
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Journal Article |
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2001 |
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Proceedings of the National Academy of Sciences of the United States of America |
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Proc. Natl. Acad. Sci. U.S.A. |
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98 |
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12 |
Pages |
6941-6944 |
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Volumetric studies in a range of animals (London taxi-drivers, polygynous male voles, nest-parasitic female cowbirds, and a number of food-storing birds) have shown that the size of the hippocampus, a brain region essential to learning and memory, is correlated with tasks involving an extra demand for spatial learning and memory. In this paper, we report the quantitative advantage that food storers gain from such an enlargement. Coal tits () a food-storing species, performed better than great tits (), a nonstoring species, on a task that assessed memory persistence but not on a task that assessed memory resolution or on one that tested memory capacity. These results show that the advantage to the food-storing species associated with an enlarged hippocampus is one of memory persistence. |
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10.1073/pnas.121034798 |
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Equine Behaviour @ team @ |
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4743 |
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Macphail, E.M.; Boldhuis, J.J |
| Title |
The evolution of intelligence: adaptive specializations versusgeneral process |
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Journal Article |
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2001 |
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Biological Reviews |
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76 |
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3 |
Pages |
341-364 |
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biological constraints, corvids, ecology, food-storing birds, hippocampal size, parids, spatial learning, spatial memory, spatial module. |
| Abstract |
Darwin argued that between-species differences in intelligence were differences of degree, not of kind. The contemporary ecological approach to animal cognition argues that animals have evolved species-specific and problem-specific processes to solve problems associated with their particular ecological niches: thus different species use different processes, and within a species, different processes are used to tackle problems involving different inputs. This approach contrasts both with Darwin's view and with the general process view, according to which the same central processes of learning and memory are used across an extensive range of problems involving very different inputs. We review evidence relevant to the claim that the learning and memory performance of non-human animals varies according to the nature of the stimuli involved. We first discuss the resource distribution hypothesis, olfactory learning-set formation, and the 'biological constraints' literature, but find no convincing support from these topics for the ecological account of cognition. We then discuss the claim that the performance of birds in spatial tasks of learning and memory is superior in species that depend heavily upon stored food compared to species that either show less dependence upon stored food or do not store food. If it could be shown that storing species enjoy a superiority specifically in spatial (and not non-spatial) tasks, this would argue that spatial tasks are indeed solved using different processes from those used in non-spatial tasks. Our review of this literature does not find a consistent superiority of storing over non-storing birds in spatial tasks, and, in particular, no evidence of enhanced superiority of storing species when the task demands are increased, by, for example, increasing the number of items to be recalled or the duration of the retention period. We discuss also the observation that the hippocampus of storing birds is larger than that of non-storing birds, and find evidence contrary to the view that hippocampal enlargement is associated with enhanced spatial memory; we are, however, unable to suggest a convincing alternative explanation for hippocampal enlargement. The failure to find solid support for the ecological view supports the view that there are no qualitative differences in cognition between animal species in the processes of learning and memory. We also argue that our review supports our contention that speculation about the phylogenetic development and function of behavioural processes does not provide a solid basis for gaining insight into the nature of those processes. We end by confessing to a belief in one major qualitative difference in cognition in animals: we believe that humans alone are capable of acquiring language, and that it is this capacity that divides our intelligence so sharply from non-human intelligence. |
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Equine Behaviour @ team @ |
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4797 |
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