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Positive Relationships (positive + relationships)
Kinds of Positive Relationships Selected AbstractsPositive diversity,stability relationships in forest herb populations during four decades of community assemblyECOLOGY LETTERS, Issue 10 2010Martin Dov Ecology Letters (2010) Abstract It is suggested that diversity destabilizes individual populations within communities; however, generalizations are problematic because effects of diversity can be confounded by variation attributable to community type, life history or successional stage. We examined these complexities using a 40-year record of reassembly in forest herb communities in two clearcut watersheds in the Andrews Long-term Ecological Research Site (Oregon, USA). Population stability was higher among forest than colonizing species and increased with successional stage. Thus, life history and successional stage may explain some of the variability in diversity,stability relationships found previously. However, population stability was positively related to diversity and this relationship held for different forest communities, for species with contrasting life histories, and for different successional stages. Positive relationships between diversity and population stability can arise if diversity has facilitative effects, or if stability is a precursor, rather than a response, to diversity. [source] The silver spoon effect and habitat selection by natal dispersersECOLOGY LETTERS, Issue 11 2006Judy A. Stamps Abstract The silver spoon effect in the context of habitat selection occurs when dispersers in good condition are more likely to settle in high-quality habitats than dispersers in poor condition. Positive relationships between disperser condition and the quality of post-dispersal habitats are predicted by at least two non-exclusive ultimate hypotheses. The competition hypothesis assumes that a disperser's condition affects its chances of competing for space or joining an established group after arriving at a high-quality habitat, while the search hypothesis assumes that a disperser's condition affects its selectivity, and hence its chances of accepting a lower-quality habitat when it is searching for a new habitat. Thus far, silver spoon effects in the context of habitat selection have been reported in only a handful of species (several birds and marine invertebrates), but this study suggests that they may be relatively common in particular species and situations. [source] Attachment styles, personality, and Dutch emigrants' intercultural adjustmentEUROPEAN JOURNAL OF PERSONALITY, Issue 5 2004Winny Bakker The present study examines the relationship of adult attachment styles with personality and psychological and sociocultural adjustment. A sample of 847 first-generation Dutch emigrants filled out measures for attachment styles, the Big Five, and indicators of psychological and sociocultural adjustment. Positive relationships were found between Secure attachment on the one hand and psychological and sociocultural adjustment on the other. Ambivalent attachment was strongly negatively associated with psychological adjustment. Dismissive attachment was mildly negatively related to sociocultural adjustment. Significant relations were found between attachment styles and the Big Five dimensions, particularly Extraversion and Emotional Stability. The attachment scales were able to explain variance in sociocultural adjustment beyond that explained by the Big Five dimensions. Intercultural adjustment is discussed from a transactional view of personality. Copyright © 2004 John Wiley & Sons, Ltd. [source] Relationship between plasma leptin concentrations and carcass composition in fattening mutton: a comparison with ultrasound resultsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2005M. Altmann Summary Positive relationships between circulating leptin concentrations and body fat content have been established in sheep when covering a rather broad range of age and/or body weight. The usefulness of leptin measurements for predicting carcass fat has yet to be evaluated specifically in fattening lambs. We therefore measured plasma leptin concentrations in 56 male lambs half and half Merino Mutton and Blackheaded Mutton. Subcutaneous fat thickness was measured by ultrasound 1 day before the lambs were slaughtered at 35 or 45 kg live weight. Carcass composition was determined by tissue dissection. The coefficients of correlations between leptin and the different amounts in fat depots ranged from 0.40 to 0.56 within the two live weight groups, and from 0.53 to 0.64 when taking the two groups together. Carcass fat percentage was estimated by leptin concentrations with the same accuracy (R2 = 0.34) as with ultrasound fat thickness. The accuracy was higher for leptin in the 35 kg-group whereas the accuracy was higher for ultrasound fat thickness in the 45 kg-group (R2 = 0.26 vs. 0.31). A combination of leptin and ultrasound fat thickness clearly enhanced the precision of estimation in all groups. Further investigations on the influence of factors such as breed, gender, duration of feed withdrawal or photoperiod on the association between leptin and carcass composition are necessary before the suitability of plasma leptin concentration for practical application can be evaluated. [source] Relationships between partner's support during labour and maternal outcomesJOURNAL OF CLINICAL NURSING, Issue 2 2000MPhil, Wan Yim Ip BN ,,The objective of this study was to measure the relationship between women's ratings of partners' participation during labour and maternal outcomes as measured by anxiety level, pain perception, dosage of pain-relieving drug used and length of labour. ,,A convenience sample of 45 primigravid women was selected from the postpartum unit of a public hospital in Hong Kong. They were all first-time Chinese mothers, aged 18 or over, who had attended antenatal classes and had their partners present during labour. ,,The State Scale of the State-Trait Anxiety Inventory was used to measure maternal anxiety during labour. Labour pain was measured by the Visual Analogue Scale. A series of scales were developed to measure partners' participation during labour. ,,Women's ratings of partners' practical support were significantly lower than their ratings of partners' emotional support. There were no significant associations between level of emotional support and maternal outcome measures. However, perceived practical support was positively related to the dosage of pain-relieving drug used and total length of labour. Positive relationships between the duration of partners' presence and women's ratings of perceived support provided by partners during labour were also found. [source] Relationship between soil nutrient availability and plant species richness in a tropical semi-arid environmentJOURNAL OF VEGETATION SCIENCE, Issue 6 2006Yareni Perroni-Ventura Abstract Question: What is the relationship between soil fertility and plant species richness in the ,fertile islands' occurring beneath two species of legume (Cercidium praecox and Prosopis laevigata)? Location: Tehuacán-Cuicatlán region, central Mexico. Methods: Plant richness was measured in three micro-environments (below canopies of C. praecox, below canopies of P. laevigata and in areas without canopies). The concentration of soil nutrients (C, N and P), C and N in the microbiota, and processes of ecosystem functioning (net C mineralization rate and N mineralization) were measured. The relationship between soil variables and plant richness were assessed with ANCOVAs. Results: Soil nutrients and species richness increases markedly under fertility islands. There were higher concentrations of C and N in the soil, faster rates of C mineralization, and higher species richness under P. laevigata canopies. The relationship between soil fertility and species richness was always positive except for total N, ammonium and net C mineralization rate under C. praecox, and for available P under P. laevigata. Conclusions: The sign of the relationship between soil fertility and species richness varies according to the nutrient and the micro-environment. Positive relationships could result from between species complementarity and facilitation. Negative relationships could be explained by a specific limitation threshold for some soil resources (P and N for plants and C for the soil microbiota) which eliminate the possibilities of between species complementarity and facilitation above that threshold. As in all observational studies, these relationships should be considered only correlational. [source] Inbreeding, outbreeding and environmental effects on genetic diversity in 46 walleye (Sander vitreus) populationsMOLECULAR ECOLOGY, Issue 2 2006CHRISTOPHER J. CENA Abstract Genetic diversity is recognized as an important population attribute for both conservation and evolutionary purposes; however, the functional relationships between the environment, genetic diversity, and fitness-related traits are poorly understood. We examined relationships between selected lake parameters and population genetic diversity measures in 46 walleye (Sander vitreus) populations across the province of Ontario, Canada, and then tested for relationships between six life history traits (in three categories: growth, reproductive investment, and mortality) that are closely related to fitness, and genetic diversity measures (heterozygosity, d2, and Wright's inbreeding coefficient). Positive relationships were observed between lake surface area, growing degree days, number of species, and hatchery supplementation versus genetic diversity. Walleye early growth rate was the only life history trait significantly correlated with population heterozygosity in both males and females. The relationship between FIS and male early growth rate was negative and significant (P < 0.01) and marginally nonsignificant for females (P = 0.06), consistent with inbreeding depression effects. Only one significant relationship was observed for d2: female early growth rate (P < 0.05). Stepwise regression models showed that surface area and heterozygosity had a significant effect on female early growth rate, while hatchery supplementation, surface area and heterozygosity had a significant effect on male early growth rate. The strong relationship between lake parameters, such as surface area, and hatchery supplementation, versus genetic diversity suggests inbreeding and outbreeding in some of the populations; however, the weak relationships between genetic diversity and life history traits indicate that inbreeding and outbreeding depression are not yet seriously impacting Ontario walleye populations. [source] Cross-sectional study of allergic disorders associated with breastfeeding in Japan: The Ryukyus Child Health StudyPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 5 2007Yoshihiro Miyake Uncertainties remain as to whether breastfeeding is protective against childhood allergic disorders. Positive relationships of breastfeeding with asthma and atopic eczema were observed in two previous Japanese studies. This cross-sectional study investigated the association between the feeding pattern after birth and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 24,077 children aged 6,15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Allowance was made for age, sex, number of siblings, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Breastfeeding, regardless of exclusivity, for 13 months or longer and exclusive breastfeeding for 4,11 months were independently associated with a higher prevalence of atopic eczema, particularly among children without a parental allergic history. A clear positive dose,response relationship was observed between prolonged duration of breastfeeding, regardless of exclusivity, but not exclusive breastfeeding, and the prevalence of atopic eczema. We found a significant positive trend for atopic eczema across the three categories (formula milk, partial and exclusive breastfeeding) in the first 4 months of life although the odds ratio for exclusive breastfeeding was not statistically significant. No material association was found between the feeding pattern after birth and the prevalence of wheeze or allergic rhinoconjunctivitis. Prolonged breastfeeding may be associated with a higher prevalence of atopic eczema in Japanese children. [source] Microbial and nutrient pollution in the coastal bathing waters of Dar es SalaamAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009Thomas J. Lyimo Abstract 1.The objective of the present study was to assess the microbial and nutrient quality of coastal beach waters used for bathing in the city of Dar es Salaam, Tanzania. Concentrations of traditional and alternative microbial indicators of faecal pollution and nutrients were assessed over a 1 year period (August 2005 to August 2006) using standard methods and the results were compared with the WHO water quality guidelines. 2.Faecal indicator bacteria values varied in a consistent fashion and correlated significantly with eachother, reflecting the presumed human faecal pollution. 3.The maximum counts (MPN per 100,mL) were observed on the site close to the city centre (Ocean Road) throughout the sampling period where values ranged from 1700 to>240 000 total coliform (TC), 200 to 92000 faecal coliform (FC) and 11 to 4900 enterococci (ENT). Other sites showed less predictable results with a range of values from 0,920, 0,540 and 0,46 for TC, FC and ENT, respectively. Furthermore, the faecal indicator bacteria concentration varied significantly with sampling time (P<0.05) and between sampling points (P<0.05). 4.Similarly, nutrients were significantly higher (P<0.05) at Ocean Road where concentration (µmolL,1) ranges were 0.2,54 (NO3), 0.0,20 (NO2) and 0.3,45 (PO4). 5.The levels of faecal indicator bacteria and nutrients were higher during the rainy seasons than the dry seasons, showing the inclusion of rain run-off as a source of contamination. The faecal indicator bacteria correlated positively with nutrients in both 1 year and daily data sets (P<0.01). Positive relationships were also observed among faecal indicators. This strongly suggests that an important role is played by sewage contamination in the extent of microbial pollution at the studied urbanized coastal beaches. Copyright © 2009 John Wiley & Sons, Ltd. [source] How Attitudes of Leaders May Enhance Organizational Creativity: Evidence from a Chinese StudyCREATIVITY AND INNOVATION MANAGEMENT, Issue 3 2007Karen Yuan Wang It has been argued that a key factor in the development of competitive advantage is the provision of an environment that encourages employees to be creative. Leaders play a crucial role in cultivating an environment that encourages subordinates to be creative. Based on a survey of 219 managers in privately owned enterprises in China, this study investigates how trust in subordinates in terms of their reliability and their loyalty to the leader is related to leaders encouraging subordinates to be creative. The findings reveal positive relationships between these two types of trust in subordinates and leaders encouraging subordinates to be creative. The findings also reveal that attitude to formalization moderated the relationship between trust in subordinates and encouraging them to be creative. [source] Local Food, Local Engagement: Community-Supported Agriculture in Eastern IowaCULTURE, AGRICULTURE, FOOD & ENVIRONMENT, Issue 1 2010Brandi Janssen Abstract This paper examines some of the daily realities of operating a Community-Supported Agriculture (CSA) farm in eastern Iowa and addresses the concept of community among growers. Popular depictions of local foods systems often emphasize the close relationships that develop between producers and consumers. This picture, however, may gloss over the necessary complexities of a healthy local food system. CSA has been promoted as a direct marketing strategy for small-scale growers and touted as a way of developing positive relationships between producers and consumers. Nevertheless, it is also important to understand that successful CSA initiatives are often reliant on a broad network of support that includes more than just growers and eaters. Ethnographic descriptions of CSA farms presented here show how involvement by media and other organizations contribute to successful CSAs as well as an overall concept of "civic agriculture." These descriptions also show that access to affordable, reliable labor tends to be among the greatest challenges for CSA growers. [source] An Exploratory Analysis of the Value of the Skills of IT Personnel: Their Relationship to IS Infrastructure and Competitive AdvantageDECISION SCIENCES, Issue 1 2001Terry Anthony Byrd Abstract Determining and assessing the requisite skills of information technology (IT) personnel have become critical as the value of IT has risen in modern organizations. In addition to technical skills traditionally expected of IT personnel, softer skills like managerial, business, and interpersonal skills have been increasingly cited in previous studies as mandatory for these employees. This paper uses a typology of IT personnel skills,technology management skills, business functional skills, interpersonal skills, and technical skills,and investigates their relationships to two information systems (IS) success variables, IS infrastructure flexibility and the competitive advantage provided by IS. The study investigates these relationships using the perceptions of chief information officers (CIOs) from mostly Fortune 2000 companies. The contributions of this study are: IT personnel skills do affect IS success, technical skills are viewed as the most important skill set in affecting IS infrastructure flexibility and competitive advantage, and modularity is viewed as more valuable to competitive advantage than integration. Several explanations are offered for the lack of positive relationships between the softer IT personnel skills and the dimensions of IS success used in this study. [source] The role of fruit traits of bird-dispersed plants in invasiveness and weed risk assessmentDIVERSITY AND DISTRIBUTIONS, Issue 6 2009Carl R. Gosper Abstract Aim, Birds play a major role in the dispersal of seeds of many fleshy-fruited invasive plants. The fruits that birds choose to consume are influenced by fruit traits. However, little is known of how the traits of invasive plant fruits contribute to invasiveness or to their use by frugivores. We aim to gain a greater understanding of these relationships to improve invasive plant management. Location, South-east Queensland, Australia. Methods, We measure a variety of fruit morphology, pulp nutrient and phenology traits of a suite of bird-dispersed alien plants. Frugivore richness of these aliens was derived from the literature. Using regressions and multivariate methods, we investigate relationships between fruit traits, frugivore richness and invasiveness. Results, Plant invasiveness was negatively correlated to fruit size, and all highly invasive species had quite similar fruit morphology [smaller fruits, seeds of intermediate size and few (< 10) seeds per fruit]. Lower pulp water was the only pulp nutrient trait associated with invasiveness. There were strong positive relationships between the diversity of bird frugivores and plant invasiveness, and in the diversity of bird frugivores in the study region and another part of the plants' alien range. Main conclusions, Our results suggest that weed risk assessments (WRA) and predictions of invasive success for bird-dispersed plants can be improved. Scoring criteria for WRA regarding fruit size would need to be system-specific, depending on the fruit-processing capabilities of local frugivores. Frugivore richness could be quantified in the plant's natural range, its invasive range elsewhere, or predictions made based on functionally similar fruits. [source] Overstorey tree species regulate colonization by native and exotic plants: a source of positive relationships between understorey diversity and invasibilityDIVERSITY AND DISTRIBUTIONS, Issue 4 2008Kathleen S. Knight ABSTRACT The North American woody species, Prunus serotina Ehrh., is an aggressive invader of forest understories in Europe. To better understand the plant invasion process, we assessed understorey plants and Prunus serotina seedlings that have colonized a 35-year-old replicated common-garden experiment of 14 tree species in south-western Poland. The density and size of established (> 1 year old) P. serotina seedlings varied among overstorey species and were related to variation in light availability and attributes of the understorey layer. In a multiple regression analysis, the density of established P. serotina seedlings was positively correlated with light availability and understorey species richness and negatively correlated with understorey species cover. These results suggest that woody invader success is adversely affected by overstorey shading and understorey competition for resources. Simultaneously, however, invader success may generally be positively associated with understorey species richness because both native and invasive plant colonization respond similarly to environmental conditions, including those influenced by overstorey tree species. Identification of characteristics of forests that increase their susceptibility to invasion may allow managers to target efforts to detect invasives and to restore forests to states that may be less invasible. [source] Restoring landscapes: the authenticity problemEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2006Isis Brook Abstract Philosophical concerns about restoring landscapes often revolve around two, connected, issues. First is the idea that a restored landscape, even if it is a perfect replica, has lost some of its value. The claim might appeal to a break in the continuity of the landscape and that continuity is part of what is valuable. Alternatively, often in the case of natural landscapes, the appeal is that any human manipulation is inauthentic; here the analogy is sometimes made with the art world and the restoration is deemed a fake. The second problem highlighted in philosophical debates is that the greater the success of restoration projects, the more threatened natural landscapes become: any claim that something must be preserved in its pristine or historically layered state is undermined by the claim that it could be put back again. Initially I discuss two opposing potential responses to these claims: (1) that humans are part of nature and thus cannot be an alien dominating force outside of nature; and (2) that nature is itself a social construct. Neither of these positions is entirely satisfactory, but what they jointly reveal is the reality of our fluid and multifaceted relationship with the world. I then show that Elliot's claim of the additional value of pristine nature is actually not based on an inherent value, but is dependent on the human valuation of it. I propose an alternative that places the source of value in the thing itself and thus arrive at a positive role for restoration as the setting in train and guiding of positive relationships above and beyond their social or public amenity value to us. Copyright © 2006 John Wiley & Sons, Ltd. [source] Post-gall induction performance of Adelges Abietis (L.) (Homoptera: Adelgidae) is influenced by clone, shoot length, and density of colonising gallicolaeECOLOGICAL ENTOMOLOGY, Issue 1 2010LEAH FLAHERTY 1. We evaluated the effect of clone (one susceptible and one resistant clone), shoot length, crown level, and gallicola density on post-gall induction performance of Adelges abietis. Galls that had been successfully induced by one fundatrix on a range of shoot sizes were selected, and the number of gallicolae that could colonise the gall was manipulated. 2. Post-induction gall development success was inversely related to shoot length and was higher on the susceptible clone than on the resistant clone. As gallicola density did not influence the proportion of galls that successfully completed development, reduced post-induction gall development on large shoots was not likely to be result of an insufficient stimulus from gallicolae. 3. Clone was the only factor that significantly influenced gall volume and galls were larger on the susceptible clone than on the resistant clone. As gall volume did not increase when more gallicolae attempted to colonise a gall, competition within a gall increased. Gallicola survival was inversely related to the number of colonising gallicolae. Our results suggest that gall size may be limiting at natural densities. 4. Previous studies report positive relationships between gall induction success and fundatrix density, and between gall size and fundatrix density. As each fundatrix produces one egg mass of gallicolae, this study suggests that there may be a trade-off between the successful induction of a large gall and subsequent survival of gallicolae. 5. In the present study, clone influenced all measures of post-gall induction performance. Performance was always higher on the susceptible than on the resistant clone. [source] Cascading effects of variation in plant vigour on the relative performance of insect herbivores and their parasitoidsECOLOGICAL ENTOMOLOGY, Issue 1 2002Tiit Teder Abstract 1. Consequences of variation in food plant quality were estimated for a system consisting of two monophagous noctuid herbivores and three ichneumonid parasitoids. 2. In a natural population, pupal weights of the herbivores in this system, Nonagria typhae and Archanara sparganii, were found to be highly variable. Pupal weights increased strongly and consistently with the increase in the vigour of the host plant, Typha latifolia, providing support for the plant vigour hypothesis. Correspondingly, as the moths do not feed as adults, a strong, positive correlation between host vigour and fecundity of the herbivores would be expected. 3. There were strong and positive relationships between adult body sizes of the parasitoids and the sizes of their lepidopteran hosts. Moreover, a direct, positive link between plant quality and parasitoid size was documented. 4. For all three parasitoids, cascading effects of plant quality on body size were weaker than for the herbivores. Differences in the importance of adult feeding and oviposition behaviour suggest that dependence of fitness on body size is also weaker in the parasitoids than in the moths. It is therefore concluded that the numerical response of the herbivore population to a change in plant quality should exceed the corresponding response in the parasitoids. 5. The results of this work imply that variation in plant variables may affect performance of different trophic levels to a different extent. It is suggested that the importance of adult feeding for the reproductive success (capital vs. income breeding strategies) in both herbivores and parasitoids is an essential aspect to consider when predicting responses of such a system to changes in plant quality. [source] Effects of size and morphology on swimming performance in juvenile brown trout (Salmo trutta L.)ECOLOGY OF FRESHWATER FISH, Issue 4 2003A. F. Ojanguren Abstract,,, Our study assesses swimming capacity (speed and stamina) and possible morphometric determinants of locomotor performance of juvenile brown trout (Salmo trutta L.). We addressed these issues at the individual level to have an approach of the functional significance of intraspecific variation in morphological design. Both swimming speed and endurance time showed significant positive relationships with fish length. Size-corrected values of speed and endurance time were negatively correlated suggesting a phenotypic trade-off between burst and prolonged swimming. Size was also highly correlated with all the morphological variables measured. Therefore, we used the residuals of the regressions of those variables on fish length to remove the effect of body size. A principal components analysis (PCA) summarised the 12 morphological variables into two factors, which accounted for 44.3% of the variance. PC1 combined several measures of body depth and width, whereas PC2 represented mainly postanal length relative to abdomen length. Relationships between the scores of the two factors and size-corrected values of maximum swimming speed and endurance time were weak. PC2 showed a significant positive relationship with endurance time; that is, individuals with longer caudal regions were able to swim against water flow for longer periods of time. Stoutness (PC1) showed a marginally significant negative correlation with endurance time. The lack of stronger relationships could be because of the low morphometric variability among the test individuals, all proceeding from the same population, reared in a common environment, and measured at the same ontogenetic stage. [source] Male Mate Choice in the Guppy (Poecilia reticulata): Do Males Prefer Larger Females as Mates?ETHOLOGY, Issue 2 2004Emily J. E. Herdman Although females are the choosier sex in most species, male mate choice is expected to occur under certain conditions. Theoretically, males should prefer larger females as mates in species where female fecundity increases with body size. However, any fecundity-related benefits accruing to a male that has mated with a large female may be offset by an associated fitness cost of shared paternity if large females are more likely to be multiply mated than smaller females in nature. We tested the above hypothesis and assumption using the Trinidadian guppy (Poecilia reticulata) by behaviourally testing for male mate choice in the laboratory and by ascertaining (with the use of microsatellite DNA genotyping) patterns of male paternity in wild-caught females. We observed significant positive relationships between female body length and fecundity (brood size) and between body length and level of multiple paternity in the broods of females collected in the Quaré River, Trinidad. In laboratory tests, a preference for the larger of two simultaneously-presented virgin females was clearly expressed only when males were exposed to the full range of natural stimuli from the females, but not when they were limited to visual stimuli alone. However, as suggested by our multiple paternity data, males that choose to mate with large females may incur a larger potential cost of sperm competition and shared paternity compared with males that mate with smaller females on average. Our results thus suggest that male guppies originating from the Quaré River possess mating preferences for relatively large females, but that such preferences are expressed only when males can accurately assess the mating status of encountered females that differ in body size. [source] Corporate Governance, Board Diversity, and Firm ValueFINANCIAL REVIEW, Issue 1 2003David A. Carter This study examines the relationship between board diversity and firm value for Fortune 1000 firms. Board diversity is defined as the percentage of women, African Americans, Asians, and Hispanics on the board of directors. This research is important because it presents the first empirical evidence examining whether board diversity is associated with improved financial value. After controlling for size, industry, and other corporate governance measures, we find significant positive relationships between the fraction of women or minorities on the board and firm value. We also find that the proportion of women and minorities on boards increases with firm size and board size, but decreases as the number of insiders increases. [source] Day,night changes in the spatial distribution and habitat preferences of freshwater shrimps, Gammarus pulex, in a stony streamFRESHWATER BIOLOGY, Issue 4 2005J. M. ELLIOTT Summary 1. As many invertebrates are nocturnal, their spatial distribution and habitat preferences may change from day to night. Both aspects are examined for Gammarus pulex by testing the hypotheses: (i) a power function was a suitable model for the spatial distribution of the shrimps in both day and night; (ii) diurnal and nocturnal spatial distributions were significantly different; (iii) diurnal and nocturnal habitat preferences were significantly different. Five different life-stages were treated separately. To ensure that the conclusions were consistent, large samples were taken near midday and midnight in April, June and November over 4 years at two sites about 3 km apart in a stony stream: downstream (n = 30) and upstream (n = 50). 2. The first and second hypotheses were supported at both sites. A power function, relating spatial variance (s2) to mean (m), was an excellent fit in all analyses (P < 0.001, r2 > 0.91), i.e. the spatial variance was density-dependent. All five life-stages were aggregated in the day. At night, the degree of aggregation increased for juveniles at higher densities but decreased for juveniles at lower densities, increased for immature females and males, but decreased slightly for mature females and especially mature males, the latter being close to a random distribution. There were no significant differences between sites, in spite of the lower numbers at the downstream site. 3. The third hypothesis was tested at only the upstream site and supported by comparisons between shrimp densities and 13 physical variables (distance from bank, water depth, water velocity, ten particle size-classes), and three non-physical variables (dry weights of bryophytes, leaf material, organic detritus). During the day, densities were strongly related to particle sizes with the following preferences: 0.5,8 mm for juveniles, 8,256 mm for the other life-stages with a weaker relationship for males. There were no significant positive relationships with the other variables, apart from bryophytes for immature shrimps and adults. At night, densities were unrelated to particle size; juveniles and immature shrimps preferred low water velocities near the banks, often where leaf material and organic detritus accumulated, females often preferred medium water velocities slightly away from the banks, and males showed no habitat preferences. 4. Day samples do not provide a complete picture of habitat preferences and probably identify refuge habitats. Day,night changes in spatial distribution and habitat preferences are an essential part of the behavioural dynamics of the shrimps and should be investigated in other species. [source] Rooting depth and soil moisture control Mediterranean woody seedling survival during droughtFUNCTIONAL ECOLOGY, Issue 3 2007F. M. PADILLA Summary 1Seedling survival is one of the most critical stages in a plant's life history, and is often reduced by drought and soil desiccation. It has been hypothesized that root systems accessing moist soil layers are critical for establishment, but very little is known about seedling root growth and traits in the field. 2We related seedling mortality to the presence of deep roots in a field experiment in which we monitored soil moisture, root growth and seedling survival in five Mediterranean woody species from the beginning of the growing season until the end of the drought season. 3We found strong positive relationships between survival and maximum rooting depth, as well as between survival and soil moisture. Species with roots in moist soil layers withstood prolonged drought better, whereas species with shallow roots died more frequently. In contrast, biomass allocation to roots was not related to establishment success. 4Access to moist soil horizons accounted for species-specific survival rates, whereas large root : shoot (R:S) ratios did not. The existence of soil moisture thresholds that control establishment provides insights into plant population dynamics in dry environments. [source] What determines the relationship between plant diversity and habitat productivity?GLOBAL ECOLOGY, Issue 6 2008Martin Zobel ABSTRACT The relationship between biodiversity and habitat productivity has been a fundamental topic in ecology. Although the relationship between these parameters may exhibit different shapes, the unimodal shape has been frequently encountered. The decrease in diversity at high productivity has usually been attributed to competitive exclusion. We suggest that evolutionary history and dispersal limitation may be even more important in shaping the diversity,productivity relationship. On a global scale, unimodal diversity,productivity relationships dominate in temperate regions, whereas positive relationships are more common in the tropics. This difference can be accounted for by contrasting evolutionary history. Temperate regions have smaller species pools for productive habitats since these habitats have been scarce historically for speciation, while the opposite is true for the tropics. In addition, dispersal within a region may limit diversity either due to the lack of dispersal syndromes at low productivity or the low number of diaspores at high productivity. Thereafter, biotic interactions (competition and facilitation) can shape the relationship. All these processes can act independently or concurrently. We recommend that the common approach to examining empirical diversity,environmental relationships should start with the role of large-scale processes such as evolutionary history and dispersal limitation, followed by influences associated with ecological interactions. [source] Does versatility as measured by geographic range, bathymetric range and morphological variability contribute to taxon longevity?GLOBAL ECOLOGY, Issue 1 2007Lee Hsiang Liow ABSTRACT Aim, This paper aims to examine the relationship between versatility as measured by geographic range, bathymetric range and morphological variability (species and subspecies richness and the occurrence of morphologically highly variable populations), and the geologic longevities of trachyleberidid ostracode species and genera, while accounting for sampling biases and other confounding factors. Location, Global. Methods, A large database of occurrence records of species of the family Trachyleberididae s.l. was analysed. The relationships between genus and species longevity and the above mentioned variables were examined singly and in concert. Re-analyses of subsets of data and rarefaction techniques were employed to account for sampling biases, while randomization was used to account for autocorrelation of variables. Results, The mean number of occurrence records, and latitudinal and longitudinal ranges, were strongly and positively correlated with genus and species longevities. The number of bathymetric zones occupied by genera had no consistent bearing on their longevities, but species data subsets tended to indicate significant positive relationships between bathymetric range and longevities. Species richness was significantly and positively correlated with genus longevities. Species and genera with subspecies and species with high morphological variability all had significantly greater longevities. Genus-level characteristics can be explained largely by species-level characteristics, including longevity, latitudinal ranges and bathymetric ranges to a lesser degree. However, genus longevity was best explained by species richness and genus age, even for extinct genera, while species longevity was best explained by species latitudinal range. Main conclusions, In spite of the incompleteness of the fossil record, we can control for biasing factors and still confidently draw the conclusion that both ecological and evolutionary versatility contribute to lineage longevity, beyond the shorter temporal observation windows available to most ecological studies. [source] Worker flexibility and its perceived contribution to performance: The moderating role of task characteristicsHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2007Eric Molleman This study examined the relationship between worker flexibility in team-based work and its perceived contribution to efficiency, work quality, and innovation, and the moderating role of task autonomy, skill utilization, and task monotony. Four-hundred ninety-four employees from 113 teams in 15 organizations completed and returned questionnaires. Skill utilization proved to be positively related to perceived contribution of flexibility to efficiency, work quality, and innovation. Furthermore, skill utilization strengthened the positive relationships between worker flexibility and its perceived contribution to efficiency and work quality and weakened the negative relationship between worker flexibility and its perceived impact on innovation. Task monotony was negatively related to the perceived quality benefits of being flexible. In addition, it weakened the positive relationship between worker flexibility and its perceived contribution to both efficiency and quality and strengthened the negative relationship with the perceived impact of flexibility on innovation. Task autonomy was positively related to the perceived contribution of flexibility to innovation and weakened the negative relationship between worker flexibility and the perceived innovation benefits of being flexible. The authors conclude that skill utilization and lack of monotony are important issues in relation to worker flexibility on all performance objectives that were considered, whereas task autonomy seems especially relevant when innovation is a key issue. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 117,135, 2007. [source] The relevance of organizational subculture for motivation to transfer learningHUMAN RESOURCE DEVELOPMENT QUARTERLY, Issue 4 2008Toby Marshall Egan Although human resource development practitioners and researchers emphasize organizational culture as a major contributor to employee learning and development, results from this study suggest organizational subculture has greater influence on employee-related learning motivation. The relationships among organizational culture, organizational subculture, leadership style, and motivation to transfer learning are examined in this study of 354 randomly selected health care providers from a population of 1,255 employees of three of the largest health care organizations in the United States. Study findings indicate that organizational subculture was highly associated with employee motivation to transfer learning,far higher than organizational culture overall. Supportive and innovative subcultures have clear positive relationships, while bureaucratic subcultures negatively influenced motivation to transfer learning. Findings also support the differences between leadership style types and particular subculture types in relation to motivation to transfer learning. In terms of leadership style, a consideration style had a stronger relationship to motivation to transfer learning than did structuring style. Implications for HRD research and practice are explored. [source] Importance of Perceived Personnel Selection System Fairness Determinants: Relations with Demographic, Personality, and Job CharacteristicsINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 1-2 2004Chockalingam Viswesvaran This study explored the relative importance attached to various perceived personnel selection fairness determinants (e.g., selection system content-based variables, features of selection system administration). We investigated how demographic variables (ethnicity and gender), individual differences characteristics (the Big Five and cognitive ability) and job characteristics (job complexity and domestic/expatriate assignment status) relate to the importance of ratings of perceived personnel selection system determinants. The results, especially for race/ethnicity analyses indicated that there might be differences across demographic groups in importance placed on different aspects of selection system characteristics. The magnitudes of the relationships were small to moderate for Asian,White and Hispanic,White comparisons. Asian,Hispanic and gender differences in importance assessments were small. Few individual differences variables (i.e., personality and cognitive ability) were associated with importance placed on various aspects of selection system characteristics. Notable exceptions were moderate positive relationships between general mental ability and importance of content-based selection system characteristics, and moderate negative relationships between emotional stability, conscientiousness and cognitive ability, and importance of selection system context variables. The complexity levels of the jobs held by respondents did not appreciably affect the importance placed on the different selection system characteristics. There were few notable differences between importance assessments for domestic versus expatriate positions. Implications for practice, especially managing cultural diversity in organizations, and for theory development are discussed. [source] The importance of ,knowing the patient': community nurses' constructions of quality in providing palliative careJOURNAL OF ADVANCED NURSING, Issue 4 2000Karen A. Luker PhD BNurs RGN RHV NDNCert The importance of ,knowing the patient': community nurses' constructions of quality in providing palliative care This paper reports findings from a study conducted in one community health care trust where 62 members of the district nursing team (grades B,H) were interviewed. An adaptation of the critical incident technique was used to determine factors which contributed or detracted from high quality care for a number of key areas including palliative care. The centrality of knowing the patient and his/her family emerged as an essential antecedent to the provision of high quality palliative care. Factors enabling the formation of positive relationships were given prominence in descriptions of ideal care. Strategies used to achieve this included establishing early contact with the patient and family, ensuring continuity of care, spending time with the patient and providing more than the physical aspects of care. The characteristics described by the community nurses are similar to those advocated in ,new nursing' which identifies the uniqueness of patient needs, and where the nurse,patient relationship is objectified as the vehicle through which therapeutic nursing can be delivered. The link with ,new nursing' emerges at an interesting time for community nurses. The past decade has seen many changes in the way that community nursing services are configured. The work of the district nursing service has been redefined, making the ideals of new nursing, for example holism, less achievable than they were a decade ago. This study reiterates the view that palliative care is one aspect of district nursing work that is universally valued as it lends itself to being an exemplar of excellence in terms of the potential for realizing the ideals of nursing practice. This is of increasing importance in the context of changes that militate against this ideal. [source] Effect of N Fertilization Rate on Sugar Yield and Non-Sugar Impurities of Sugar Beets (Beta vulgaris) Grown Under Mediterranean ConditionsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2005J. T. Tsialtas Abstract For three successive growing seasons (1999,2001), a completely randomized block design experiment was established at the surrounding area of each of four sugar beet processing plants of Hellenic Sugar Industry SA, Greece (a total of 12 experiments). Nitrogen was applied at five rates (0, 60, 120, 180 and 240 kg N ha,1) and six replications per rate. Nitrogen fertilization had site-specific effects on quantitative (fresh root and sugar yields) and qualitative (sucrose content, K, Na, , -amino N) traits. When data were combined over years and sites, fresh root and sugar yields were maximized at high N rates (330.75 and 295 kg N ha,1 respectively), as derived from quadratic functions fitted to data. In three trials, increased N rates had negative effects on root and sugar yield. These sites were characterized by high yield in control plots, light soil texture (sand > 50 %) and low CEC values. When data were converted into relative values (the ratio of the trait values to the control mean of each experiment), root and sugar yield was found to be maximized at higher N rates (350 and 316 kg N ha,1, respectively). Sucrose content was strongly and linearly reduced by the increased N rates when data were combined but a significant reduction with increasing N rates was found in only two sites. Non-sugar impurities (K, Na, , -amino N) were positively related to the increased N rates when data were combined. Sodium and , -amino N showed to be most affected by N fertilization as positive relationships were found in six and eight of 12 locations, respectively. Increased N supply resulted in higher soil NO3 -N concentrations (0,90 cm depth) at harvest which were related with amino N contents in sugar beet roots (in 1999 and 2001). [source] Density effects on life-history traits in a wild population of the great tit Parus major: analyses of long-term data with GIS techniquesJOURNAL OF ANIMAL ECOLOGY, Issue 2 2006TEDDY A. WILKIN Summary 1Population density often has strong effects on the population dynamics and reproductive processes of territorial animals. However, most estimates of density-dependent effects use the number of breeding pairs per unit area in a given season and look for correlations across seasons, a technique that assigns the same density score to each breeding pair, irrespective of local spatial variation. 2In this study, we employed GIS techniques to estimate individual breeding densities for great tits breeding in Wytham Woods UK, between 1965 and 1996. We then used linear mixed modelling to analyse the effect of density on reproductive processes. 3The areas of Thiessen polygons formed around occupied nestboxes were used to approximate territory size (necessarily inverse of breeding density). There were significant, independent and positive relationships between clutch size, fledging mass and the number of offspring recruited to the population, and territory size (all P < 0·001), but no effect of territory size on lay-date or egg mass. 4Thiessen polygons are contiguous and cover all of the available area. Therefore, at low nest densities territory polygons were excessively oversized. Using a novel procedure to address this limitation, territory sizes were systematically capped through a range of maxima, with the greatest effect in the models when territories were capped at 0·9,2·3 ha. This figure approximates to the maximum effective territory size in our population and is in close agreement with several field-based studies. This capping refinement also revealed a significant negative relationship between lay-date and territory size capped at 0·9 ha (P < 0·001). 5These density-dependent effects were also detected when analyses were restricted to changes within individual females, suggesting that density effects do not merely result from either increased proportions of low-quality individuals, or increased occupation of poor sites, when population density is high. 6Overall, these results suggest that, in the current population, great tits with territories smaller than c. 2 ha independently lay smaller and later clutches, have lighter fledglings, and recruit fewer offspring to the breeding population. These analyses thus suggest a pervasive and causal role of local population density in explaining individual reproductive processes. [source] | ||||||||||||||||||||||||||||