The Experts below are selected from a list of 280050 Experts worldwide ranked by ideXlab platform
Jonathan Wright - One of the best experts on this subject based on the ideXlab platform.
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rich pickings near large communal roosts favor gang foraging by juvenile common ravens corvus corax
PLOS ONE, 2009Co-Authors: Sasha R X Dall, Jonathan WrightAbstract:Ravens (Corvus corax) feed primarily on rich but ephemeral carcasses of large animals, which are usually defended by territorial pairs of adults. Non-breeding juveniles forage Socially and aggregate in communal winter roosts, and these appear to function as ‘information centers’ regarding the location of the rare food bonanzas: individuals search independently of one another and pool their effort by recruiting each other at roosts. However, at a large raven roost in Newborough on Anglesey, North Wales, some juveniles have been observed recently to forage in ‘gangs’ and to roost separately from other birds. Here we adapt a general model of juvenile common raven foraging behavior where, in addition to the typical co-operative foraging strategy, such gang foraging behavior could be evolutionarily stable near winter raven roosts. We refocus the model on the conditions under which this newly documented, yet theoretically anticipated, gang-based foraging has been observed. In the process, we show formally how the trade off between search efficiency and Social Opportunity can account for the existence of the alternative Social foraging tactics that have been observed in this species. This work serves to highlight a number of fruitful avenues for future research, both from a theoretical and empirical perspective.
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Rich Pickings Near Large Communal Roosts Favor 'Gang' Foraging by Juvenile Common Ravens, Corvus corax
2009Co-Authors: Sasha R X Dall, Jonathan WrightAbstract:TITLE Rich pickings near large communal roosts favor 'gang' foraging by juvenile common ravens, Corvus corax AUTHORS Dall, SR; Wright, J JOURNAL PLoS One DEPOSITED IN ORE May 2016 This version available at http://hdl.handle.net/10871/21722 COPYRIGHT AND REUSE Open Research Exeter makes this work available in accordance with publisher policies. A NOTE ON VERSIONS Abstract Ravens (Corvus corax) feed primarily on rich but ephemeral carcasses of large animals, which are usually defended by territorial pairs of adults. Non-breeding juveniles forage Socially and aggregate in communal winter roosts, and these appear to function as 'information centers' regarding the location of the rare food bonanzas: individuals search independently of one another and pool their effort by recruiting each other at roosts. However, at a large raven roost in Newborough on Anglesey, North Wales, some juveniles have been observed recently to forage in 'gangs' and to roost separately from other birds. Here we adapt a general model of juvenile common raven foraging behavior where, in addition to the typical co-operative foraging strategy, such gang foraging behavior could be evolutionarily stable near winter raven roosts. We refocus the model on the conditions under which this newly documented, yet theoretically anticipated, gangbased foraging has been observed. In the process, we show formally how the trade off between search efficiency and Social Opportunity can account for the existence of the alternative Social foraging tactics that have been observed in this species. This work serves to highlight a number of fruitful avenues for future research, both from a theoretical and empirical perspective
Karen P. Maruska - One of the best experts on this subject based on the ideXlab platform.
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Social Opportunity rapidly regulates expression of CRF and CRF receptors in the brain during Social ascent of a teleost fish, Astatotilapia burtoni.
PloS one, 2014Co-Authors: Russ E. Carpenter, Karen P. Maruska, Lisa BeckerAbstract:In Social animals, hierarchical rank governs food availability, territorial rights and breeding access. Rank order can change rapidly and typically depends on dynamic aggressive interactions. Since the neuromodulator corticotrophin releasing factor (CRF) integrates internal and external cues to regulate the hypothalamic-pituitary adrenal (HPA) axis, we analyzed the CRF system during Social encounters related to status. We used a particularly suitable animal model, African cichlid fish, Astatotilapia burtoni, whose Social status regulates reproduction. When presented with an Opportunity to rise in rank, subordinate A. burtoni males rapidly change coloration, behavior, and their physiology to support a new role as dominant, reproductively active fish. Although changes in gonadotropin-releasing hormone (GnRH1), the key reproductive molecular actor, have been analyzed during Social ascent, little is known about the roles of CRF and the HPA axis during transitions. Experimentally enabling males to ascend in Social rank, we measured changes in plasma cortisol and the CRF system in specific brain regions 15 minutes after onset of Social ascent. Plasma cortisol levels in ascending fish were lower than subordinate conspecifics, but similar to levels in dominant animals. In the preoptic area (POA), where GnRH1 cells are located, and in the pituitary gland, CRF and CRF1 receptor mRNA levels are rapidly down regulated in ascending males compared to subordinates. In the Vc/Vl, a forebrain region where CRF cell bodies are located, mRNA coding for both CRFR1 and CRFR2 receptors is lower in ascending fish compared to stable subordinate conspecifics. The rapid time course of these changes (within minutes) suggests that the CRF system is involved in the physiological changes associated with shifts in Social status. Since CRF typically has inhibitory effects on the neuroendocrine reproductive axis in vertebrates, this attenuation of CRF activity may allow rapid activation of the reproductive axis and facilitate the transition to dominance.
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Social Opportunity causes rapid transcriptional changes in the Social behaviour network of the brain in an african cichlid fish
Journal of Neuroendocrinology, 2013Co-Authors: Karen P. Maruska, April Zhang, Anoop Neboori, Russell D. FernaldAbstract:Animals constantly integrate external stimuli with their own internal physiological state to make appropriate behavioural decisions. Little is known, however, about where in the brain the salience of these signals is evaluated, or which neural and transcriptional mechanisms link this integration to adaptive behaviours. We used an African cichlid fish Astatotilapia burtoni to test the hypothesis that a new Social Opportunity activates the conserved ‘Social behaviour network’ (SBN), a collection of brain nuclei known to regulate Social behaviours across vertebrates. We measured mRNA levels of immediate early genes (IEGs) in microdissected brain regions as a proxy for neuronal activation, and discovered that IEGs were higher in all SBN nuclei in males that were given an Opportunity to rise in Social rank compared to control stable subordinate and dominant individuals. Furthermore, because the presence of sex-steroid receptors is one defining criteria of SBN nuclei, we also tested whether Social Opportunity or status influenced androgen and oestrogen receptor mRNA levels within these same regions. There were several rapid region-specific changes in receptor mRNA levels induced by Social Opportunity, most notably in oestrogen receptor subtypes in areas that regulate Social aggression and reproduction, suggesting that oestrogenic signalling pathways play an important role in regulating male status. Several receptor mRNA changes occurred in regions with putative homologies to the mammalian septum and extended amygdala, two regions shared by SBN and reward circuits, suggesting an important role in the integration of Social salience, stressors, hormonal state and adaptive behaviours. We also demonstrated increases in plasma sex- and stress-steroids at 30 min after a rise in Social rank. This rapid endocrine and transcriptional response suggests that the SBN is involved in the integration of Social inputs with internal hormonal state to facilitate the transition to dominant status, which ultimately leads to improved fitness for the previously reproductively-suppressed individual.
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Behavioral and physiological plasticity: rapid changes during Social ascent in an African cichlid fish.
Hormones and Behavior, 2010Co-Authors: Karen P. MaruskaAbstract:Abstract In many vertebrates, reproduction is regulated by Social interactions in which dominant males control access to females and food. Subordinate males that displace dominant individuals must rapidly adopt behavioral and physiological traits of the higher rank to gain reproductive success. To understand the process of phenotypic plasticity during Social ascent, we analyzed the temporal expression pattern of dominance behaviors and circulating androgen levels when Socially-suppressed males of an African cichlid fish Astatotilapia burtoni ascended in status. These experiments tested a prediction of the ‘challenge hypothesis’ that, during periods of Social instability, male androgen levels are higher than during Socially stable times. We found that Socially and reproductively suppressed males perform territorial and reproductive behaviors within minutes of an Opportunity to ascend in status, and that animals switch from initial expression of territorial behaviors to more reproductive behaviors during territory establishment. Following this rapid response, Social stability may be achieved within 1–3 days of Social ascent. Consistent with predictions of the ‘challenge hypothesis’, circulating 11-ketotestosterone (11-KT) levels were elevated within 30 min following Social Opportunity, coincident with increased aggressive behavior. However, territorial behaviors and serum 11-KT levels were then dissociated by 72 h after Social ascent, suggesting either rapid Social stability and/or increased physiological potential for androgen production. This behavioral and physiological plasticity in male A. burtoni suggests that perception of Social Opportunity triggers a suite of quick changes to facilitate rapid transition towards reproductive success, and reveals important features of Social ascent not previously recognized.
Sasha R X Dall - One of the best experts on this subject based on the ideXlab platform.
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rich pickings near large communal roosts favor gang foraging by juvenile common ravens corvus corax
PLOS ONE, 2009Co-Authors: Sasha R X Dall, Jonathan WrightAbstract:Ravens (Corvus corax) feed primarily on rich but ephemeral carcasses of large animals, which are usually defended by territorial pairs of adults. Non-breeding juveniles forage Socially and aggregate in communal winter roosts, and these appear to function as ‘information centers’ regarding the location of the rare food bonanzas: individuals search independently of one another and pool their effort by recruiting each other at roosts. However, at a large raven roost in Newborough on Anglesey, North Wales, some juveniles have been observed recently to forage in ‘gangs’ and to roost separately from other birds. Here we adapt a general model of juvenile common raven foraging behavior where, in addition to the typical co-operative foraging strategy, such gang foraging behavior could be evolutionarily stable near winter raven roosts. We refocus the model on the conditions under which this newly documented, yet theoretically anticipated, gang-based foraging has been observed. In the process, we show formally how the trade off between search efficiency and Social Opportunity can account for the existence of the alternative Social foraging tactics that have been observed in this species. This work serves to highlight a number of fruitful avenues for future research, both from a theoretical and empirical perspective.
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Rich Pickings Near Large Communal Roosts Favor 'Gang' Foraging by Juvenile Common Ravens, Corvus corax
2009Co-Authors: Sasha R X Dall, Jonathan WrightAbstract:TITLE Rich pickings near large communal roosts favor 'gang' foraging by juvenile common ravens, Corvus corax AUTHORS Dall, SR; Wright, J JOURNAL PLoS One DEPOSITED IN ORE May 2016 This version available at http://hdl.handle.net/10871/21722 COPYRIGHT AND REUSE Open Research Exeter makes this work available in accordance with publisher policies. A NOTE ON VERSIONS Abstract Ravens (Corvus corax) feed primarily on rich but ephemeral carcasses of large animals, which are usually defended by territorial pairs of adults. Non-breeding juveniles forage Socially and aggregate in communal winter roosts, and these appear to function as 'information centers' regarding the location of the rare food bonanzas: individuals search independently of one another and pool their effort by recruiting each other at roosts. However, at a large raven roost in Newborough on Anglesey, North Wales, some juveniles have been observed recently to forage in 'gangs' and to roost separately from other birds. Here we adapt a general model of juvenile common raven foraging behavior where, in addition to the typical co-operative foraging strategy, such gang foraging behavior could be evolutionarily stable near winter raven roosts. We refocus the model on the conditions under which this newly documented, yet theoretically anticipated, gangbased foraging has been observed. In the process, we show formally how the trade off between search efficiency and Social Opportunity can account for the existence of the alternative Social foraging tactics that have been observed in this species. This work serves to highlight a number of fruitful avenues for future research, both from a theoretical and empirical perspective
Russell D. Fernald - One of the best experts on this subject based on the ideXlab platform.
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Social Opportunity Rapidly Regulates Expression of CRF and CRF Receptors in the Brain during Social Ascent of a
2016Co-Authors: Teleost Fish, Lisa Becker, Astatotilapia Burtoni, Russ E. Carpenter*¤a, Karen P. Maruska¤b, Russell D. FernaldAbstract:In Social animals, hierarchical rank governs food availability, territorial rights and breeding access. Rank order can change rapidly and typically depends on dynamic aggressive interactions. Since the neuromodulator corticotrophin releasing factor (CRF) integrates internal and external cues to regulate the hypothalamic-pituitary adrenal (HPA) axis, we analyzed the CRF system during Social encounters related to status. We used a particularly suitable animal model, African cichlid fish, Astatotilapia burtoni, whose Social status regulates reproduction. When presented with an Opportunity to rise in rank, subordinate A. burtoni males rapidly change coloration, behavior, and their physiology to support a new role as dominant, reproductively active fish. Although changes in gonadotropin-releasing hormone (GnRH1), the key reproductive molecular actor, have been analyzed during Social ascent, little is known about the roles of CRF and the HPA axis during transitions. Experimentally enabling males to ascend in Social rank, we measured changes in plasma cortisol and the CRF system in specific brain regions 15 minutes after onset of Social ascent. Plasma cortisol levels in ascending fish were lower than subordinate conspecifics, but similar to levels in dominant animals. In the preoptic area (POA), where GnRH1 cells are located, and in the pituitary gland, CRF and CRF1 receptor mRNA levels are rapidly down regulated in ascending males compared to subordinates. In the Vc/Vl, a forebrain region where CRF cell bodies are located, mRNA coding for both CRFR1 and CRFR2 receptors is lower in ascending fish compared to stable subordinate conspecifics. The rapid time course of thes
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Social Opportunity causes rapid transcriptional changes in the Social behaviour network of the brain in an african cichlid fish
Journal of Neuroendocrinology, 2013Co-Authors: Karen P. Maruska, April Zhang, Anoop Neboori, Russell D. FernaldAbstract:Animals constantly integrate external stimuli with their own internal physiological state to make appropriate behavioural decisions. Little is known, however, about where in the brain the salience of these signals is evaluated, or which neural and transcriptional mechanisms link this integration to adaptive behaviours. We used an African cichlid fish Astatotilapia burtoni to test the hypothesis that a new Social Opportunity activates the conserved ‘Social behaviour network’ (SBN), a collection of brain nuclei known to regulate Social behaviours across vertebrates. We measured mRNA levels of immediate early genes (IEGs) in microdissected brain regions as a proxy for neuronal activation, and discovered that IEGs were higher in all SBN nuclei in males that were given an Opportunity to rise in Social rank compared to control stable subordinate and dominant individuals. Furthermore, because the presence of sex-steroid receptors is one defining criteria of SBN nuclei, we also tested whether Social Opportunity or status influenced androgen and oestrogen receptor mRNA levels within these same regions. There were several rapid region-specific changes in receptor mRNA levels induced by Social Opportunity, most notably in oestrogen receptor subtypes in areas that regulate Social aggression and reproduction, suggesting that oestrogenic signalling pathways play an important role in regulating male status. Several receptor mRNA changes occurred in regions with putative homologies to the mammalian septum and extended amygdala, two regions shared by SBN and reward circuits, suggesting an important role in the integration of Social salience, stressors, hormonal state and adaptive behaviours. We also demonstrated increases in plasma sex- and stress-steroids at 30 min after a rise in Social rank. This rapid endocrine and transcriptional response suggests that the SBN is involved in the integration of Social inputs with internal hormonal state to facilitate the transition to dominant status, which ultimately leads to improved fitness for the previously reproductively-suppressed individual.
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Rapid behavioral and genomic responses to Social Opportunity
2005Co-Authors: Sabrina S. Burmeister, Erich D. Jarvis, Russell D. FernaldAbstract:From primates to bees, Social status regulates reproduction. In the cichlid fish Astatotilapia (Haplochromis) burtoni, subordinate males have reduced fertility and must become dominant to reproduce. This increase in sexual capacity is orchestrated by neurons in the preoptic area, which enlarge in response to dominance and increase expression of gonadotropin-releasing hormone 1 (GnRH1), a peptide critical for reproduction. Using a novel behavioral paradigm, we show for the first time that subordinate males can become dominant within minutes of an Opportunity to do so, displaying dramatic changes in body coloration and behavior. We also found that Social Opportunity induced expression of the immediate-early gene egr-1 in the anterior preoptic area, peaking in regions with high densities of GnRH1 neurons, and not in brain regions that express the related peptides GnRH2 and GnRH3. This genomic response did not occur in stable subordinate or stable dominant males even though stable dominants, like ascending males, displayed dominance behaviors. Moreover, egr-1 in the optic tectum and the cerebellum was similarly induced in all experimental groups, showing that egr-1 induction in the anterior preoptic area of ascending males was specific to this brain region. Because egr-1 codes for a transcription factor important in neural plasticity, induction of egr-1 in the anterior preoptic area by Social Opportunity could be an early trigger in the molecular cascade that culminates in enhanced fertility and other long-term physiological changes associated with dominance. Citation: Burmeister SS, Jarvis ED, Fernald RD (2005) Rapid behavioral and genomic responses to Social Opportunity. PLoS Biol 3(11): e363
Amartya Sen - One of the best experts on this subject based on the ideXlab platform.
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india development and participation
2002Co-Authors: Jean Dreze, Amartya SenAbstract:1. Introduction and Approach 2. Economic Development and Social Opportunity 3. India in Comparative Perspective 4. India and China 5. Basic Education as a Political Issue 6. Population, Health, and the Environment 7. Gender Inequality and Women's Agency 8. Security and Democracy in a Nuclear India 9. Well Beyond Liberalization 10. The Practice of Democracy
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indian development selected regional perspectives
1997Co-Authors: Jean Dreze, Amartya SenAbstract:India is a country of great diversity. The commonly used indicators of `quality of life' (such as life expectancy, infant mortality, and literacy) vary tremendously between the different states, rivalling international contrasts between very low performing countries and very high achieving ones. This volume of essays reflects an attempt to draw lessons from the disparate experiences within India, rather than from contrasts with the experiences of other countries. It supplements Dreze and Sen's India: Economic Development and Social Opportunity, which studies what we can learn from international comparisons of policies, actions, and achievements. The essays challenge exclusively economic judgements of the development process. The first task is to identify the ends of economic and Social development in order to have a basis in which to found the means and strategies. The second task is to understand a wider range of means than those related simply to the use or non-use of markets.The first two overview essays study the issues at the national level, focusing on policy debates and district-by-district demographic indicators, respectively. They are followed by detailed case studies of three very different states: Uttar Pradesh, Kerala, and West Bengal.
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india economic development and Social Opportunity
1996Co-Authors: Jean Dreze, Amartya SenAbstract:This book presents analysis of endemic deprivation in India and the role of public action in addressing the problem. The analysis is based on a broad view of economic development, focusing on human well-being and 'Social Opportunity' rather than the standard indicators of economic growth. India's success in reducing deprivation since Independence has been limited. Recent diagnoses of this failure of policy have concentrated on the counterproductive role of government regulation, and on the need for economic incentives to accelerate the economy. Professors Dreze and Sen argue that an assessment of India's failure to eliminate basic deprivations has to go beyond this limited focus, and to take note of the role played in that failure by inadequate public involvement in the provision of basic education, health care, Social security, and related fields. Even the fostering of fast and participatory economic growth requires some basic Social change, which is not addressed by liberalization and economic incentives. The authors also discuss the historical antecedents of these political and Social neglects, including the distortion of policy priorities arising from inequalities of political power. Following on from this, the book considers the scope for public action to address these earlier biases and achieve a transformation of policy priorities. ` ... a fine account of India's achievements and failures ... written throughout in a fine style ... it will be a starting-point of subsequent discussions on Social life in India.' Partha Dasgupta, Times Higher Education Supplement
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india economic development and Social Opportunity
1996Co-Authors: Jean Dreze, Amartya SenAbstract:1. Introduction 2. Economic Development through Social Opportunity 3. India in Comparative Perspective 4. China and India 5. Public Action and Social Inequality 6. Basic Education as a Political Issue 7. Gender Inequality and Women's Agency 8. Well Beyond Liberalization Statistical Appendix