| Records |
Author  |
Creel, S. |
| Title |
Social dominance and stress hormones |
Type |
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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Christensen, J.W.; Ahrendt, L.P.; Lintrup, R.; Gaillard, C.; Palme, R.; Malmkvist, J. |
| Title |
Does learning performance in horses relate to fearfulness, baseline stress hormone, and social rank? |
Type |
Abstract |
| Year |
2012 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
App Anim Behav Sci |
| Volume |
140 |
Issue |
1 |
Pages |
44-52 |
| Keywords |
Horse; Learning; Fearfulness; Stress; Reinforcement; Social rank |
| Abstract |
The ability of horses to learn and remember new tasks is fundamentally important for their use by humans. Fearfulness may, however, interfere with learning, because stimuli in the environment can overshadow signals from the rider or handler. In addition, prolonged high levels of stress hormones can affect neurons within the hippocampus; a brain region central to learning and memory. In a series of experiments, we aimed to investigate the link between performance in two learning tests, the baseline level of stress hormones, measured as faecal cortisol metabolites (FCM), fearfulness, and social rank. Twenty-five geldings (2 or 3 years old) pastured in one group were included in the study. The learning tests were performed by professional trainers and included a number of predefined stages during which the horses were gradually trained to perform exercises, using either negative (NR) or positive reinforcement (PR). Each of the learning tests lasted 3 days; 7min/horse/day. The NR test was repeated in a novel environment. Performance, measured as final stage in the training programme, and heart rate (HR) were recorded. Faeces were collected on four separate days where the horses had been undisturbed at pasture for 48h. Social rank was determined through observations of social interactions during feeding. The fear test was a novel object test during which behaviour and HR were recorded. Performance in the NR and PR learning tests did not correlate. In the NR test, there was a significant, negative correlation between performance and HR in the novel environment (rS=-0.66, P<0.001, i.e. nervous horses had reduced performance), whereas there was no such correlation in the home environment (both NR and PR). Behavioural reactions in the fear test correlated significantly with performance in the NR test in the novel environment (e.g. object alertness and final stage: rS=-0.43, P=0.04), suggesting that performance under unfamiliar, stressful conditions may be predicted by behavioural responses in a fear test. There was a negative correlation between social rank and baseline stress hormones (rS=-0.43, P=0.04), i.e. high rank corresponded to low FCM concentrations, whereas neither rank nor FCM correlated with fearfulness or learning performance. We conclude that performance under stressful conditions is affected by activation of the sympathetic nervous system during training and related to behavioural responses in a standardised fear test. Learning performance in the home environment, however, appears unrelated to fearfulness, social rank and baseline FCM levels. |
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0168-1591 |
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Equine Behaviour @ team @ S0168-1591(12)00168-2 |
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5769 |
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| Author |
Bang, A.; Deshpande, S.; Sumana, A.; Gadagkar, R. |
| Title |
Choosing an appropriate index to construct dominance hierarchies in animal societies: a comparison of three indices |
Type |
Journal Article |
| Year |
2010 |
Publication |
Animal Behaviour |
Abbreviated Journal |
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79 |
Issue |
3 |
Pages |
631-636 |
| Keywords |
dominance behaviour; dominance hierarchy; dominance index; dominance rank; Ropalidia cyathiformis; Ropalidia marginata; social wasp |
| Abstract |
A plethora of indices have been proposed and used to construct dominance hierarchies in a variety of vertebrate and invertebrate societies, although the rationale for choosing a particular index for a particular species is seldom explained. In this study, we analysed and compared three such indices, viz Clutton-Brock et al.'s index (CBI), originally developed for red deer, Cervus elaphus, David's score (DS) originally proposed by the statistician H. A. David and the frequency-based index of dominance (FDI) developed and routinely used by our group for the primitively eusocial wasps Ropalidia marginata and Ropalidia cyathiformis. Dominance ranks attributed by all three indices were strongly and positively correlated for both natural data sets from the wasp colonies and for artificial data sets generated for the purpose. However, the indices differed in their ability to yield unique (untied) ranks in the natural data sets. This appears to be caused by the presence of noninteracting individuals and reversals in the direction of dominance in some of the pairs in the natural data sets. This was confirmed by creating additional artificial data sets with noninteracting individuals and with reversals. Based on the criterion of yielding the largest proportion of unique ranks, we found that FDI is best suited for societies such as the wasps belonging to Ropalidia, DS is best suited for societies with reversals and CBI remains a suitable index for societies such as red deer in which multiple interactions are uncommon. |
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0003-3472 |
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Equine Behaviour @ team @ |
Serial |
5837 |
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| Author |
Amici, F.; Widdig, A.; Lehmann, J.; Majolo, B. |
| Title |
A meta-analysis of interindividual differences in innovation |
Type |
Journal Article |
| Year |
2019 |
Publication |
Animal Behaviour |
Abbreviated Journal |
Anim. Behav. |
| Volume |
155 |
Issue |
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Pages |
257-268 |
| Keywords |
age; bad competitor hypothesis; excess of energy hypothesis; innovation; interindividual differences; intraspecific variation; personality; rank; sex |
| Abstract |
The ability to innovate and the social transmission of innovations have played a central role in human evolution. However, innovation is also crucial for other animals, by allowing them to cope with novel socioecological challenges. Although innovation plays such a central role in animals' lives, we still do not know the conditions required for innovative behaviour to emerge. Here, we focused on interindividual differences in innovation by (1) extensively reviewing existing literature on innovative behaviour in animals and (2) quantitatively testing the different evolutionary hypotheses that have been proposed to explain interindividual variation in innovation propensity during foraging tasks. We ran a series of phylogenetically controlled mixed-effects meta-regression models to determine which hypotheses (if any) are supported by currently available empirical studies. Our analyses show that innovation is more common in individuals that are older and belong to the larger sex, but also in more neophilic and/or explorative individuals. Moreover, these effects change depending on the study setting (i.e. wild versus captive). Our results provide no clear support to the excess of energy or the bad competitor hypotheses and suggest that study setting and interindividual differences in traits related to personality are also important predictors of innovation. |
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0003-3472 |
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| Call Number |
Equine Behaviour @ team @ |
Serial |
6589 |
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