The Experts below are selected from a list of 163596 Experts worldwide ranked by ideXlab platform
John C. Wingfield - One of the best experts on this subject based on the ideXlab platform.
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A blurring of life-history lines: Immune function, molt and reproduction in a highly Stable Environment.
General and comparative endocrinology, 2015Co-Authors: Loren Merrill, Paulina L. González-gómez, Vincenzo A. Ellis, Iris I. Levin, Rodrigo A. Vásquez, John C. WingfieldAbstract:Rufous-collared sparrows (Zonotrichia capensis peruviensis) from valleys in the Atacama Desert of Chile, live in an extremely Stable Environment, and exhibit overlap in molt and reproduction, with valley-specific differences in the proportion of birds engaged in both. To better understand the mechanistic pathways underlying the timing of life-history transitions, we examined the relationships among baseline and stress-induced levels of corticosterone (CORT), testosterone, and bacteria-killing ability of the blood plasma (BKA), as well as haemosporidian parasite infections and the genetic structure of two groups of sparrows from separate valleys over the course of a year. Birds neither molting nor breeding had the lowest BKA, but there were no differences among the other three categories of molt-reproductive stage. BKA varied over the year, with birds in May/June exhibiting significantly lower levels of BKA than the rest of the year. We also documented differences in the direction of the relationship between CORT and BKA at different times during the year. The direction of these relationships coincides with some trends in molt and reproductive stage, but differs enough to indicate that these birds exhibit individual-level plasticity, or population-level variability, in coordinating hypothalamo-pituitary-adrenal axis activity with life-history stage. We found weak preliminary evidence for genetic differentiation between the two populations, but not enough to indicate genetic isolation. No birds were infected with haemosporidia, which may be indicative of reduced parasite pressure in deserts. The data suggest that these birds may not trade off among different life-history components, but rather are able to invest in multiple life-history components based on their condition.
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Breaking down seasonality: Androgen modulation and stress response in a highly Stable Environment
General and comparative endocrinology, 2013Co-Authors: Paulina L. González-gómez, Loren Merrill, Vincenzo A. Ellis, Rodrigo A. Vásquez, Cristóbal I. Venegas, Javiera I. Pantoja, John C. WingfieldAbstract:Previous studies show that most birds inhabiting temperate regions have well defined life history stages, and they modulate the production of testosterone (T) and corticosterone (CORT) in response to changes in seasonality. In this study we aimed to examine baseline and stress-induced levels of CORT and circulating T in relation with life history stages in the rufous-collared sparrow, Zonotrichia capensis. We carried out this study for a year in a population inhabiting riparian habitats in the Atacama Desert in Chile, one of the most climatically Stable and driest places in the world. This Environment shows minimal yearly change in average temperature and precipitation is virtually zero. We found individuals breeding, molting and overlapping breeding and molt year round, although most individuals were molting during March and in breeding condition during October. T levels were not related to individual breeding condition, and at population level they were not significantly different across sampling months. Baseline levels of CORT did not vary across the year. Stress-induced levels of CORT were suppressed during March when most of the birds were molting. This phenomenon was also observed in birds not molting during this period suggesting a mechanism other than molt in determining the stress-response suppression. Our results strongly suggest that in this study site, long-term extremely Stable conditions could have relaxed the selective pressures over the timing of life history stages which was evidenced by the breeding and molt schedules, its overlap and endocrine profiles.
Gerard P Hodgkinson - One of the best experts on this subject based on the ideXlab platform.
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the role of intuition in strategic decision making
Human Relations, 2000Co-Authors: Marta Sinclair, Eugene Sadlersmith, Gerard P HodgkinsonAbstract:Although intuitive processes are critical for effective strategic decision making, there is little in the way of applied research on the topic. Apart from many popularized treatments of intuition in the literature today, there are only a handful of serious scholarly works on the subject. The majority of them are essentially theoretical in nature; field research in management settings is virtually nonexistent. This study examined this neglected but important process in strategic decision making. We surveyed senior managers of companies representing computer, banking, and utility industries in the United States and found that intuitive processes are used often in organizational decision making. Use of intuitive synthesis was found to be positively associated with organizational performance in an unStable Environment, but negatively so in a Stable Environment.
Paul S Kemp - One of the best experts on this subject based on the ideXlab platform.
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Challenging convention: the winter ecology of brown trout (Salmo trutta) in a productive and Stable Environment
Freshwater Biology, 2016Co-Authors: Paul S Kemp, Andrew S. Vowles, Nick Sotherton, Dylan E. Roberts, Mike Acreman, Perikles KarageorgopoulosAbstract:1. Understanding of the winter ecology of stream salmonids is biased by research conducted in northern temperate and boreal regions dominated by hard rock geology. Such systems are driven by highly dynamic surface-flow regimes and tend to be physically diverse, nutrient poor and influenced by ice. This study investigated how the behaviour of brown trout, Salmo trutta, inhabiting a Stable groundwater-fed, productive and comparatively warm southern English chalk stream differs from that described for other systems, and how this is translated to performance, measured as growth. 2. Physical characteristics were mapped, and high-resolution temperature data collected using a spatial array of data loggers installed throughout the study reach during the winter. A combination of passive integrated transponder and radio telemetry was used to monitor distribution, density, and movement of trout. Micro-archival data storage tags inserted in some individuals provided information on temperature regimes experienced. Growth performance was calculated for recaptured fish. 3. Trout density was positively related to depth and there was no evidence that temperature influenced microhabitat selection. Three patterns of movement were observed. Over three-quarters of tracked fish exhibited high site fidelity and tended to remain in a single focal position throughout the study. Fourteen per cent of trout exploited more than one distinct location, while the remainder were detected at multiple locations and showed no preference for any one. 4. Trout exhibited regular daily activity patterns and highly periodic local movements at dusk and dawn and tended to experience positive growth performance during periods that included winter. 5. This study challenges the conventional view of salmonid winter ecology, which is biased towards populations that inhabit hard rock surface-flow dominated rivers that experience the influence of ice. Despite inhabiting a distinctly different winter habitat template than more commonly studied populations, trout occupying a hydrologically Stable and productive chalk stream exhibited behaviours similar to those described for elsewhere, yet performed considerably better.
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Dataset for 'Challenging convention: the winter ecology of a stream salmonid in a productive and Stable Environment'
2016Co-Authors: Paul S KempAbstract:Data to support: Kemp, Paul et al (2016) Challenging convention: the winter ecology of brown trout (Salmo trutta) in a productive and Stable Environment. Freshwater Biology
Perikles Karageorgopoulos - One of the best experts on this subject based on the ideXlab platform.
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Challenging convention: the winter ecology of brown trout (Salmo trutta) in a productive and Stable Environment
Freshwater Biology, 2016Co-Authors: Paul S Kemp, Andrew S. Vowles, Nick Sotherton, Dylan E. Roberts, Mike Acreman, Perikles KarageorgopoulosAbstract:1. Understanding of the winter ecology of stream salmonids is biased by research conducted in northern temperate and boreal regions dominated by hard rock geology. Such systems are driven by highly dynamic surface-flow regimes and tend to be physically diverse, nutrient poor and influenced by ice. This study investigated how the behaviour of brown trout, Salmo trutta, inhabiting a Stable groundwater-fed, productive and comparatively warm southern English chalk stream differs from that described for other systems, and how this is translated to performance, measured as growth. 2. Physical characteristics were mapped, and high-resolution temperature data collected using a spatial array of data loggers installed throughout the study reach during the winter. A combination of passive integrated transponder and radio telemetry was used to monitor distribution, density, and movement of trout. Micro-archival data storage tags inserted in some individuals provided information on temperature regimes experienced. Growth performance was calculated for recaptured fish. 3. Trout density was positively related to depth and there was no evidence that temperature influenced microhabitat selection. Three patterns of movement were observed. Over three-quarters of tracked fish exhibited high site fidelity and tended to remain in a single focal position throughout the study. Fourteen per cent of trout exploited more than one distinct location, while the remainder were detected at multiple locations and showed no preference for any one. 4. Trout exhibited regular daily activity patterns and highly periodic local movements at dusk and dawn and tended to experience positive growth performance during periods that included winter. 5. This study challenges the conventional view of salmonid winter ecology, which is biased towards populations that inhabit hard rock surface-flow dominated rivers that experience the influence of ice. Despite inhabiting a distinctly different winter habitat template than more commonly studied populations, trout occupying a hydrologically Stable and productive chalk stream exhibited behaviours similar to those described for elsewhere, yet performed considerably better.
Marta Sinclair - One of the best experts on this subject based on the ideXlab platform.
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the role of intuition in strategic decision making
Human Relations, 2000Co-Authors: Marta Sinclair, Eugene Sadlersmith, Gerard P HodgkinsonAbstract:Although intuitive processes are critical for effective strategic decision making, there is little in the way of applied research on the topic. Apart from many popularized treatments of intuition in the literature today, there are only a handful of serious scholarly works on the subject. The majority of them are essentially theoretical in nature; field research in management settings is virtually nonexistent. This study examined this neglected but important process in strategic decision making. We surveyed senior managers of companies representing computer, banking, and utility industries in the United States and found that intuitive processes are used often in organizational decision making. Use of intuitive synthesis was found to be positively associated with organizational performance in an unStable Environment, but negatively so in a Stable Environment.
