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731.
732.
Despite the efforts to enhance knowledge transfer in organizations, success has been elusive. It is becoming clear that in many instances employees are unwilling to share their knowledge even when organizational practices are designed to facilitate transfer. Consequently, this paper develops and investigates a novel construct, knowledge hiding. We establish that knowledge hiding exists, we distinguish knowledge hiding from related concepts (knowledge hoarding and knowledge sharing), and we develop a multidimensional measure of this construct. We also identify several predictors of knowledge hiding in organizations. The results of three studies, using different methods, suggest that knowledge hiding is comprised of three related factors: evasive hiding, rationalized hiding, and playing dumb. Each of these hiding behaviors is predicted by distrust, yet each also has a different set of interpersonal and organizational predictors. We draw implications for future research on knowledge management. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
733.
Zakia Parveen Richard Smart Catherine White Shimna Gammack Claire Deacon Malcolm Cresser 《Chemistry and Ecology》2013,29(4):293-314
Calluna vulgaris/peat microcosms have been used in an outdoor simulated acid rain experiment to test a series of hypotheses about sulphuric acid deposition effects upon the growth of Calluna on peat soil, namely: (1) Initially, enhanced acid input will enhance base cation and ammonium concentrations in soil solution. This may enhance uptake of these species, increasing foliar concentrations of base cations and nitrogen, and possibly foliar chlorophyll a and b concentrations. (2) If changes are induced in nutritional status, they may influence plant growth. (3) in the longer term, enhanced ammonium and base cation solubility occurring as a consequence of cation exchange reactions will lead, especially in winter months, to enhanced leaching losses. Hence any positive effects upon plant nutrition will not be sustainable. (4) the peat will acidify significantly over two years, in the shorter term primarily as a consequence of an enhanced mobile anion effect. (5) Acidification may reduce the rate of mineralisation of organic phosphorus and, in a phosphorus-deficient peat soil, this may lead to reduced foliar phosphate concentration and possibly induce phosphorus deficiency. Most of these hypotheses were supported to some extent by the experimental results. the peat soil solution pH fell immediately in response to the acid treatments, and longer-term acidification continued progressively over the two years of the experiment. in the first year, the treatments significantly influenced the calcium, magnesium, phosphorus and nitrogen status of the leaves from Calluna new shoots, whereas in the second year calcium, potassium and phosphorus were influenced. However, in both years foliar phosphate concentration was enhanced, rather than reduced, in response to increased acid load. Foliar carbon and nitrogen concentrations fell with increasing acidity of 相似文献
734.
Jeremy?FieldEmail author Robert?Paxton Antonella?Soro Paul?Craze Catherine?Bridge 《Behavioral ecology and sociobiology》2012,66(5):743-756
Phenotypic plasticity may evolve when conditions vary temporally or spatially on a small enough scale. Plasticity is thought
to play a central role in the early stages of evolutionary transitions, including major transitions such as those between
non-sociality and sociality. The sweat bee Halictus rubicundus is of special interest in this respect, because it is socially plastic in the British Isles: Nests are social or non-social
depending on the environment. However, sociality comprises a complex suite of inter-related traits. To further investigate
social plasticity in H. rubicundus, we measured traits that are potentially integral to social phenotype at a northern site, where nests are non-social, and
a southern site where nests can be social. We found that foundresses at non-social sites were smaller, produced offspring
of a size more similar to themselves, initiated nesting later, and took longer to produce their first female offspring. They
began provisioning earlier in the day, finished earlier, and collected more pollen loads. Common garden experiments suggested
that these differences represent mainly plasticity, as expected for traits involved in the overall plastic social phenotype,
with only limited evidence for fixed genetic differences in foraging. Conditions during overwintering did not have major effects
on a foundress' subsequent behaviour. 相似文献
735.
Plants are expected to differentially allocate resources to reproduction, growth, and survival in order to maximize overall fitness. Life history theory predicts that the allocation of resources to reproduction should occur at the expense of vegetative growth. Although it is known that both organism size and resource availability can influence life history traits, few studies have addressed how size dependencies of growth and reproduction and variation in resource supply jointly affect the coupling between growth and reproduction. In order to understand the relationship between growth and reproduction in the context of resource variability, we utilize a long-term observational data set consisting of 670 individual trees over a 10-year period within a local population of Bursera simaruba (L.) Sarg. We (1) quantify the functional form and variability in the growth-reproduction relationship at the population and individual-tree level and (2) develop a theoretical framework to understand the allometric dependence of growth and reproduction. Our findings suggest that the differential responses of allometric growth and reproduction to resource availability, both between years and between microsites, underlie the apparent relationship between growth and reproduction. Finally, we offer an alternative approach for quantifying the relationship between growth and reproduction that accounts for variation in allometries. 相似文献
736.
Selecting pseudo-absence data for presence-only distribution modeling: How far should you stray from what you know? 总被引:1,自引:0,他引:1
An important decision in presence-only species distribution modeling is how to select background (or pseudo-absence) localities for model parameterization. The selection of such localities may influence model parameterization and thus, can influence the appropriateness and accuracy of the model prediction when extrapolating the species distribution across time and space. We used 12 species from the Australian Wet Tropics (AWT) to evaluate the relationship between the geographic extent from which pseudo-absences are taken and model performance, and shape and importance of predictor variables using the MAXENT modeling method. Model performance is lower when pseudo-absence points are taken from either a restricted or broad region with respect to species occurrence data than from an intermediate region. Furthermore, variable importance (i.e., contribution to the model) changed such that, models became increasingly simplified, dominated by just two variables, as the area from which pseudo-absence points were drawn increased. Our results suggest that it is important to consider the spatial extent from which pseudo-absence data are taken. We suggest species distribution modeling exercises should begin with exploratory analyses evaluating what extent might provide both the most accurate results and biologically meaningful fit between species occurrence and predictor variables. This is especially important when modeling across space or time—a growing application for species distributional modeling. 相似文献
737.
Life history and reproductive strategies influence population dynamics at the inter- and intra-specific level. Environmental
conditions suitable for gonad development and spawning, the reproductive range, may be a smaller portion of the broader species
distribution. The only known breeding population of veined rapa whelks (Rapana venosa) in North America is in Chesapeake Bay, USA. There is considerable interest in the potential reproductive range of this non-indigenous
species given the rapa whelk’s negative impacts on commercial shellfish species in both its native and introduced ranges.
Weight-specific reproductive output is described for wild caught Chesapeake Bay rapa whelks maintained in flow-through mesocosms
for 2 years. Measured reproductive output within and between egg capsule deposition seasons (years) in relation to water temperature,
salinity, daylength, and female size is used to describe the rapa whelk’s reproductive range. Egg capsule production is influenced
by seasonal and absolute water temperatures as well as seasonal daylength cycles. Egg capsule deposition by Chesapeake Bay
rapa whelks begins at water temperatures of approximately 18°C and continues for 11–15 weeks. Forty to 70% of female whelks
deposited egg capsules in most weeks during this season, producing 150–200 egg capsules female−1 week−1. Water temperatures >28°C caused reduced egg capsule production relative to temperatures of 20–25°C. Egg capsule production
was positively related to seasonal changes in daylength, and two peaks of egg capsule deposition were observed in the 2001
and 2002 deposition seasons. The combination of declining daylength and higher water temperatures in late summer was associated
with the cessation of egg capsule deposition. A lower average weight specific reproductive output in 130–145 mm SL rapa whelks
(average 12 ± 1%) than in 90–106 mm SL rapa whelks (average 22 ± 1% of body weight) may reflect a life history that balances
the physiological costs of maintaining a large body mass with the production of many planktonic larvae from multiple clutches
of egg capsules per breeding season over a 10–15-year lifespan. Estimates of the cumulative day-degree requirements corresponding
to the annual initiation of egg capsule deposition were 238 and 236 for 2001 and 2002, respectively. Reproductive output and
day-degree requirements for Chesapeake Bay rapa whelks were similar to values calculated from previous studies of native muricids
(Eupleura caudata and Urosalpinx cinerea). A latitudinal range of 30–41° (N and S) is predicted as the realized reproductive range for rapa whelk populations on the
basis of the day-degree requirements for native whelks and reproductively active invasive rapa whelk populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
738.
Amélia Viricel Allan E. Strand Patricia E. Rosel Vincent Ridoux Pascale Garcia 《Behavioral ecology and sociobiology》2008,63(2):173-185
Compared to terrestrial mammals, little is known of cetacean social systems as they are generally less accessible to behavioral
investigations due to their aquatic environment. The present study investigates group structure of the pelagic common dolphin,
Delphinus delphis, using genetic markers. Tissue samples from 52 individuals representing a recent live mass-stranding event were compared
to 42 single strandings taken from presumably different groups. The mass-stranding event occurred in 2002 on the French coast
of the English Channel, whereas the single strandings were collected between 1993 and 2003 along the western coast of France
(Bay of Biscay and English Channel). Analysis of mitochondrial DNA control region sequences indicated that genetic variability
within the mass-stranded pod was similar to variability observed in single strandings. The mass-stranded group was composed
of 41 different mitochondrial haplotypes or matrilines while the single strandings revealed 29 different haplotypes. Analysis
of 11 microsatellite loci revealed that average relatedness of the mass-stranded pod was not different from average relatedness
among all single strandings suggesting that individuals within the group had no closer kin relationships than animals taken
from presumably different groups. These results do not support a matriarchal system and suggest that common dolphins constituting
a pod are not necessarily genetically related. 相似文献
739.
The need to look beyond the production and provision of relief seed: experiences from southern Sudan
Free distribution of seeds in selected areas of southern Sudan has been widespread as a way of increasing food security. Field research in areas targeted for seed relief found that farmer seed systems continue to meet the crop and varietal needs of farmers even following the 1998 famine. Donor investments in seed multiplication of improved sorghum have not been sustained due to a lack of effective demand for the improved seed beyond that created by the relief agencies. The article argues that rather than imposing outside solutions, whether through seed provisioning or seed production enterprises, greater attention needs to be given to building on the strengths of existing farmer systems and designing interventions to alleviate the weaknesses. The case is made to support dynamically the process of farmer experimentation through the informed introduction of new crops and varieties that can potentially reinforce the strength and diversity of local cropping systems. 相似文献
740.