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191.
Marc H. Anderson 《组织行为杂志》2008,29(1):51-78
Information gathering is central to a variety of organizational behavior theories, but researchers have suggested that our understanding of the actual information gathering behaviors of managers is underdeveloped. Social network characteristics are theorized to be a key determinant of information gathering behaviors, but social network research has been criticized for: (1) not measuring the intervening mechanisms by which network characteristics are theorized to have their effects and (2) not considering how actors' motivation affects what network benefits are realized. This article addresses these concerns through an empirical study of the actual information gathering behaviors of managers. It posits that individual differences in a personality variable called need for cognition capture differences in actors' cognitive motivation to realize the potential information benefits that exist in their social networks. Results show that network characteristics do affect information benefits, but these effects are stronger for managers motivated to take advantage of them. These findings both support social capital theory and suggest the important role that personality can play in augmenting social network analyses. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Cadotte MW 《Ecology》2007,88(4):823-829
The competition-colonization trade-off has long been a mechanism explaining patterns of species coexistence and diversity in nonequilibrium systems. It forms one explanation of the intermediate disturbance hypothesis (IDH) for local communities--specifically that diversity should be maximized at intermediate disturbance frequencies, yet only a fraction of empirical studies support IDH predictions. Similarly, this trade-off is also a powerful explanation of coexistence at larger spatial scales. I show, with a microbial experimental system, that the diversity-disturbance relationship is dependent on the relative distribution of species along this trade-off. Here I show that, when species are skewed toward late-successional habits, local diversity declines with disturbance. Yet, despite this trait skew, diversity at scales larger than the patch appears insensitive to the trade-off distribution. Intermediate disturbance frequencies produce the greatest diversity in patch successional stage, thus benefiting the maximum number of species at larger scales. 相似文献
195.
Whether sexual selection and species recognition involve distinct preferences and signals is still debated. Earlier work showed that traits under sexual selection can reduce the efficiency of species recognition but remains uncertain on how frequently such a conflict occurs. We can, however, hypothesise that overlapping distributions of sexual signals may enhance the hybridization risk in many species. We tested this hypothesis in a newt, Lissotriton vulgaris, which hybridises with Lissotriton helveticus. The two species also share an ultraviolet (UV) colour trait, which influences male attractiveness in L. vulgaris, though this trait is probably not functional for sexual communication in L. helveticus. We predicted that the shared trait would affect species recognition when UV radiation is present in the environment. We staged binary choice preference tests under UV+ and UV? conditions. In the UV+ treatment, female preference depended on the values of the shared UV trait and total brightness, regardless of male species identity. Thus, species recognition was enhanced or reversed depending on the difference in the male trait. Females preferred no male type in the UV? treatment, likely explained by our design, which alternated different sensory environments, and the limited prior exposure of subjects to the other species’ morph. We conclude that the presence of this shared trait used in sexual communication contributes to the production of hybrids in syntopic ponds. To our knowledge, this is the first experimental evidence of the influence of an UV sexual signal modulating species recognition. 相似文献
196.
Theo C. M. Bakker Michael Hollmann Marion Mehlis Marc Zbinden 《Behavioral ecology and sociobiology》2014,68(4):617-627
Some theoretical models of sperm competition make the assumption that in fish species with external fertilisation, sperm length relates positively to swimming speed at the expense of sperm longevity. Few studies have tested this assumption. We used the three-spined stickleback, Gasterosteus aculeatus L., to study functional sperm morphology. In this study, the relationship between males’ mean sperm length and fertilisation rate was investigated in vitro in a non-competitive situation. Fertilisation at different time points after sperm release was taken into account, and sperm morphology was quantified from scanning electron microscopy images. The time series of artificial fertilisations demonstrated that males which produced sperm with a longer tail fertilised faster, but their sperm had a shorter lifespan (or activity period). It was further suggested that males that produced sperm with a larger midpiece had greater fertilisation chances later on in the fertilisation process. Thus, in sticklebacks, there exists functional variation in sperm morphology, and sperm tail length is traded off against sperm longevity (or activity). 相似文献
197.
Laura Bouriaud Mariella Marzano Manfred Lexer Liviu Nichiforel Christopher Reyer Christian Temperli Heli Peltola Ché Elkin Gabriel Duduman Philip Taylor Stephen Bathgate Jose G. Borges Sandra Clerkx Jordi Garcia-Gonzalo Carlos Gracia Geerten Hengeveld Seppo Kellomäki Georgi Kostov Michael Maroschek Bart Muys Gert-Jan Nabuurs Bruce Nicoll Marc Palahí Werner Rammer Duncan Ray Mart-Jan Schelhaas Louise Sing Margarida Tomé Juergen Zell Marc Hanewinkel 《Regional Environmental Change》2015,15(8):1595-1609
198.
Habitat Loss and Changes in the Species-Area Relationship 总被引:4,自引:0,他引:4
Abstract: The species-area relationship (SAR) has been used successfully to predict extinction from extent of habitat reduction. These extinction estimates assume that species have uniformly distributed range requirements and a minimum abundance level required for persistence; how many species are lost depends solely on how much habitat is removed, not on where it is removed. We consider another limiting case in which range requirements, rather than abundances, determine extinctions. We used a new method for constructing SARs based on assumptions about geographic ranges of species. Our results show that habitat destruction can change the SAR and consequently the number of species predicted to be lost due to habitat destruction. Our method generates SARs that vary in shape according to the specific distributions of geographic range and occupancy but that have the common feature of being described by a power law with an exponent of <1. When the geographic range of species was included in the SAR, the way habitat was lost became important. Although the SAR before habitat destruction is often used to predict species loss after habitat destruction, assumptions must be clearly stated. To predict the damage caused by habitat loss with our model, it is necessary to know the fraction of aggregated species, the distribution of geographic ranges, the form of habitat destruction, and the sampling protocol. The remaining theoretical challenge is to develop a full theory that links abundance and range. 相似文献
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D. Marc. Kilgour Liping Fang Keith W. Hipel 《Journal of the American Water Resources Association》1992,28(1):141-153
ABSTRACT: Game-theoretic models are developed for describing and analyzing the inspection and enforcement process, especially as it relates to environmental laws and regulations in North America. Based on these models, systems using irrevocable control orders can be compared to those relying on court determination of guilt and punishment. The cost-effectiveness of environmental enforcement can be systematically assessed in terms of factors such as the private gains for violators, the costs of inspection, penalties, and the social value of deterring violations. The policy implications of the analysis, especially with reference to environmental protection, are emphasized. 相似文献