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Snjezana Kovjanic Sebastian C. Schuh Klaus Jonas Niels Van Quaquebeke Rolf van Dick 《组织行为杂志》2012,33(8):1031-1052
Although followers' needs are a central aspect of transformational leadership theory, little is known about their role as mediating mechanisms for this leadership style. The present research thus seeks to integrate and extend theorizing on transformational leadership and self‐determination. In particular, we propose that the satisfaction of followers' basic needs (autonomy, competence, and relatedness) mediates the relationship between transformational leadership and employee outcomes (job satisfaction, self‐efficacy, and commitment to the leader). We tested this model in two studies involving employees from a broad spectrum of organizations in Germany (N = 410) and in Switzerland (N = 442). Results revealed largely consistent patterns across both studies. The need for competence fulfillment solely mediated the link between transformational leadership and occupational self‐efficacy; the need for relatedness fulfillment solely mediated the link between transformational leadership and commitment to the leader. The mediating pattern for the link between transformational leadership and job satisfaction varied slightly across studies. In Study 1, only the need for autonomy fulfillment was a significant mediator, whereas in Study 2, all three needs mediated this relationship. Taken together, our study integrates theorizing on transformational leadership and self‐determination by corroborating that need fulfillment indeed is a central mechanism behind transformational leadership. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Association of extinction risk of saproxylic beetles with ecological degradation of forests in Europe 下载免费PDF全文
Sebastian Seibold Roland Brandl Jörn Buse Torsten Hothorn Jürgen Schmidl Simon Thorn Jörg Müller 《Conservation biology》2015,29(2):382-390
To reduce future loss of biodiversity and to allocate conservation funds effectively, the major drivers behind large‐scale extinction processes must be identified. A promising approach is to link the red‐list status of species and specific traits that connect species of functionally important taxa or guilds to resources they rely on. Such traits can be used to detect the influence of anthropogenic ecosystem changes and conservation efforts on species, which allows for practical recommendations for conservation. We modeled the German Red List categories as an ordinal index of extinction risk of 1025 saproxylic beetles with a proportional‐odds linear mixed‐effects model for ordered categorical responses. In this model, we estimated fixed effects for intrinsic traits characterizing species biology, required resources, and distribution with phylogenetically correlated random intercepts. The model also allowed predictions of extinction risk for species with no red‐list category. Our model revealed a higher extinction risk for lowland and large species as well as for species that rely on wood of large diameter, broad‐leaved trees, or open canopy. These results mirror well the ecological degradation of European forests over the last centuries caused by modern forestry, that is the conversion of natural broad‐leaved forests to dense conifer‐dominated forests and the loss of old growth and dead wood. Therefore, conservation activities aimed at saproxylic beetles in all types of forests in Central and Western Europe should focus on lowlands, and habitat management of forest stands should aim at increasing the amount of dead wood of large diameter, dead wood of broad‐leaved trees, and dead wood in sunny areas. 相似文献
36.
Antimicrobial activities of extracts from tropical Atlantic marine plants against marine pathogens and saprophytes 总被引:1,自引:0,他引:1
Sebastian Engel Melany P. Puglisi Paul R. Jensen William Fenical 《Marine Biology》2006,149(5):991-1002
Studies investigating disease resistance in marine plants have indicated that secondary metabolites may have important defensive functions against harmful marine microorganisms. The goal of this study was to systematically screen extracts from marine plants for antimicrobial effects against marine pathogens and saprophytes. Lipophilic and hydrophilic extracts from species of 49 marine algae and 3 seagrasses collected in the tropical Atlantic were screened for antimicrobial activity against five ecologically relevant marine microorganisms from three separate kingdoms. These assay microbes consisted of the pathogenic fungus Lindra thalassiae, the saprophytic fungus Dendryphiella salina, the saprophytic stramenopiles, Halophytophthora spinosa and Schizochytrium aggregatum, and the pathogenic bacterium Pseudoaltermonas bacteriolytica. Overall, 90% of all species surveyed yielded extracts that were active against one or more, and 77% yielded extracts that were active against two or more assay microorganisms. Broad-spectrum activity against three or four assay microorganisms was observed in the extracts from 48 and 27% of all species, respectively. The green algae Halimeda copiosa and Penicillus capitatus (Chlorophyta) were the only species to yield extracts active against all assay microorganisms. Among all assay microorganisms, both fungi were the most resistant to the extracts tested, with less than 21% of all extracts inhibiting the growth of either L. thalassiae or D. salina. In contrast, over half of all lipophylic extracts were active against the stramenopiles H. spinosa and S. aggregatum, and the bacterium P. bacteriolytica. Growth sensitivity to hydrophilic extracts varied considerably between individual assay microorganisms. While 48% of all hydrophilic extracts were active against H. spinosa, 27% were active against P. bacteriolytica, and only 14% were active against S. aggregatum. Overall, more lipophilic extracts inhibited microbial growth than hydrophilic extracts. The variability observed in the antimicrobial effects of individual extracts against each assay microorganism reflects the importance of choosing appropriate test microbes in assays from which ecologically relevant information is sought. Results from this survey demonstrate that antimicrobial activities are prevalent among extracts from marine algae and seagrasses, suggesting that antimicrobial chemical defenses are widespread among marine plants. 相似文献
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Feiler U Ahlf W Hoess S Hollert H Neumann-Hensel H Meller M Weber J Heininger P 《Environmental science and pollution research international》2005,12(5):257-258
- In current biotest approaches, intact organisms or in vitro systems are exposed to sediments using different exposure scenarios.
The most important issue in sediment toxicity testing protocols is the question which test phase (solid or liquid) should
be used. Whole-sediment exposure protocols represent the most realistic scenario to simulate in situ exposure conditions in
the laboratory. However, until now there is no agreement in how to acquire and to evaluate the data of the various available
sediment contact assays. The SeKT joint research project was initiated with the aim to compare recently developed sediment
contact assays by addressing reference conditions, control sediments and toxicity thresholds for limnic sediment contact tests. 相似文献
38.
Sebastian U. Senger 《Umweltwissenschaften und Schadstoff-Forschung》2000,12(4):221-223
Zusammenfassung Die durch die Fernstra?en versiegelte Fl?che in Deutschland betr?gt 0,47% der Oberfl?che, ohne die Seitenstreifen und Gemeindestra?en.
Z?hlt man diese hinzu, so erh?ht sich der Wert auf 1,3%. In den dicht besiedelten Bundesl?ndern Hessen und Nordrhein-Westfalen
erh?hen sich die Werte in Hessen auf 0,59 bzw. 1,59% und in NRW auf 0,68 bzw. 1,82%. In anderen OECD-L?ndern betragen die
Prozents?tze des durch Fernstra?en versiegelten Bodens zwischen 0,2 und 3,0%. Bei diesem Vergleich liegt Deutschland an 5.
Stelle hinter den Benelux-L?ndern und Japan. In der Verkehrsdichte (zugelassene Kraftfahrzeuge pro Stra?enkilometer) liegt
Deutschland an 3. Stelle hinter Italien und Gro?britannien. Die Bodenversiegelung durch Stra?endecken sch?digt die Umwelt
durch die Einbringung verkehrsbedingter Schadstoffe und St?rung des Grundwasserspiegels, aber noch mehr durch die Zerteilung
und Zerst?rung von Biotopen.
Online-First: 19. Mai 2000 相似文献
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Isabel Mück Sebastian Wacker Lise Cats Myhre Trond Amundsen 《Behavioral ecology and sociobiology》2013,67(4):609-619
The distribution of breeding resources, such as nest sites, can have a pronounced impact on a population by affecting the proportion of individuals that succeed to breed and hence, the variation in reproductive success. Aggregation of important resources can lead to resource monopolisation by a limited number of individuals and thus affect the intensity of sexual selection. In this study, we tested, by contrasting two experimental treatments (dispersed vs. aggregated), how nest distribution affects: (1) mating behaviour, (2) male nest occupation and mating success, and (3) reproductive success and the opportunity for selection. We used the two-spotted goby (Gobiusculus flavescens), a small marine fish with a resource-based mating system, as our model species. When nests were aggregated, a larger proportion of the males behaved aggressively, fewer males succeeded in occupying a nest, fewer males became mated, and those males that mated received fewer eggs from spawning females. These effects resulted in a higher variance in reproductive success and hence, a higher opportunity for selection (I rs ), in the aggregated treatment. We suggest that the results are a direct consequence of males defending a territory around their nest, preventing competitively inferior males from breeding. However, we found no significant selection differentials for body length or condition of males in either treatment. Our results support the hypothesis that aggregation of essential resources like nests promotes resource monopolisation. In species facing highly clumped nesting resources in the wild, monopolisation may negatively impact population productivity but could lead to strong selection on traits that promote male competitive ability. 相似文献