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Recruitment Process (recruitment + process)
Selected AbstractsCold-Induced Recruitment of Brown Adipose Tissue ThermogenesisEXPERIMENTAL PHYSIOLOGY, Issue 1 2003Martin Klingenspor Non-shivering thermogenesis in brown adipose tissue is the main mechanism for thermoregulatory heat production in small mammals and newborns. During cold acclimation the sympathetic innervation triggers the recruitment of brown adipose tissue by hyperplasia, which involves the proliferation and differentiation of precursor cells, and by hypertrophy of mature brown adipocytes. Mitochondrial biogenesis and increased synthesis of the uncoupling protein 1 (UCP-1) are hallmarks of the thermogenic recruitment process. The severalfold increase of mitochondrial protein content during cold acclimation recruits a large capacity for oxidative phosphorylation. However, UCP-1 increases proton leakage across the inner membrane of brown adipocyte mitochondria and thereby dissipates proton motive force as heat instead of ATP synthesis. During recent years considerable progress has been achieved in the analysis of transcriptional mechanisms controlling Ucp1 gene expression. However, so far only little is known about the molecular basis of cold-induced mitochondrial biogenesis in brown adipose tissue. [source] Emergence of larval yellow perch, Perca flavescens, in South Dakota lakes: potential implications for recruitmentFISHERIES MANAGEMENT & ECOLOGY, Issue 4 2008D. A. ISERMANN Abstract, Temporal patterns in length frequency distributions and hatch dates were described for larval yellow perch, Perca flavescens (Mitchill), captured in surface ichthyoplankton trawls from late April to mid-June 2000 to 2002 in six South Dakota, USA lakes. Fewer than 15 larval yellow perch were collected in four of six lakes during 2002, suggesting that in some cases factors prior to, during or immediately after hatching likely play a critical role in the perch recruitment process. When larval yellow perch were encountered in larger numbers, temporal trends in total length (TL) frequencies indicated that only a single cohort was produced annually in each lake. Most yellow perch in these lakes hatched between 29 April and 17 May, and most hatching occurred during 5,11 days each year. Larval TL was not related to hatch date. The apparent prevalence of relatively short hatch periods in these yellow perch populations probably increases the risk of catastrophic losses resulting from periods of poor environmental conditions. [source] The influence of environment and spawning distribution on the survival of anchovy (Engraulis encrasicolus) larvae in the Bay of Biscay (NE Atlantic) investigated by biophysical simulationsFISHERIES OCEANOGRAPHY, Issue 6 2007GWENHAEL ALLAIN Abstract A growth and survival model of the early life stages was run along virtual drift trajectories tracked in a hydrodynamic model to simulate the annual recruitment process of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). These biophysical simulations concerning three different years were analysed in order to investigate the influence of environment and spawning dynamics on the survival of larvae and juveniles. The location of space,time survival windows suggested major environmental mechanisms involved in simulated recruitment variability at the different scales , retention of larvae and juveniles in favourable habitats over the shelf margins and turbulence effects. These small-scale and meso-scale mechanisms were related to the variations in wind direction and intensity during spring and summer. Survival was also variable according to the origin of the drift trajectories, that is spawning distribution in space and time. The observed spawning distribution (according to field surveys) was compared with the spawning distribution that would maximize survival (according to the biophysical model) on a seasonal scale, which revealed factors not considered in the biophysical model (e.g. spawning behaviour of the different age classes). The variation of simulated survival according to spawning distribution was examined on a multi-annual scale and showed a coherent pattern with past and present stock structures. The interaction processes between the population (influence on spawning) and its environment (influence on survival) and its implications on recruitment and stock dynamics are discussed. [source] A middle-class global mobility?GLOBAL NETWORKS, Issue 1 2008The working lives of Indian men in a west London hotel Abstract In this article we examine the working lives of young, single, middle-class Indian men employed in the increasingly global hospitality sector in London, UK. Using a case study of a single hotel, we investigate a particular form of Indian middle-class global mobility that differs from both the well-documented ,low status', unskilled migrant as well as the highly-skilled, science oriented migrants. We explore how their jobs both reinforce and challenge middle-class Indian notions of masculinity, as well as how the recruitment process is both gendered and economically selective. We suggest that the transnational formation of Indian middle-class identity is drawn from four main categories: a middle-class lifestyle in India, class-based motivations, the gendered and class based recruitment process of the UK hospitality industry, and the performance of class-based gender identities. [source] Applicant Attraction: The role of recruiter function, work,life balance policies and career salienceINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 4 2007Sally A. Carless This study examined the impact of salient identity, career path and recruiter functional area [internal human resource (HR) personnel vs external recruitment company] on perceptions of organizational attraction with a sample of young, inexperienced job seekers. Two hundred and one participants responded to a questionnaire and rated their attraction to two different job advertisements. The results partially supported the first hypothesis; applicants perceived a job opportunity in an organization that offered either a flexible career path or a dual career path as significantly more attractive than a position in an organization that offered a traditional career path. There was no support for the second hypothesis that identity salience would interact with career path. The results showed that recruiter functional area had no impact on attraction to the organization. It was concluded that flexible HR policies increase applicants' perceptions of organizational attraction during the initial stages of the recruitment process. Practical and research applications are discussed. [source] Patterns of reproductive effort and success in birds: path analyses of long-term data from European ducksJOURNAL OF ANIMAL ECOLOGY, Issue 2 2002Peter Blums Summary 1We tested ecological hypotheses about timing of breeding and reproductive effort in birds, by analysing > 15-year data sets for individually marked females in three species of Latvian ducks (northern shoveler, tufted duck, common pochard). 2Duckling survival and recruitment declined with advancing hatch date in pochard and tufted duck, after controlling for effects of female age and other factors with path analysis, a novel finding which indicates that fitness advantages associated with early hatching extended beyond the prefledging period. Logistic regression analysis suggested further that individual duckling prefledging survival was moderate in the earliest phase of the breeding season, greatest in mid-season and lowest later on. 3However, selection acting against early hatched ducklings was surpassed by strong directional selection favouring recruitment of the earliest hatching females. The absolute and relative numbers of female recruits produced by a breeding female declined sharply with advancing hatch date in all species. 4Unlike previous studies, an hypothesized intraspecific trade-off between duckling mass and brood size was detected, being very robust in two of three species. 5Unexpectedly, female age effects on recruitment were manifested only indirectly by several pathways, the most important being the earlier hatching dates of older females. Size-adjusted body mass (i.e. condition index) was positively related to reproductive success, and was 2,8-fold more influential than female size (indexed by wing length). 6Overall, fecundity-independent variables (e.g. hatching date, weather, indices of duckling production and habitat quality) generally had 2,10 times greater influence on recruitment rates than did fecundity-dependent variables such as female size or condition, duckling mass and brood size, suggesting a critical role for external environmental factors vs. individual female-specific traits in the recruitment process. [source] Costs and Strategies in Minority Recruitment for Osteoporosis Research,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2003Miriam A Marquez Abstract To meet expectations for the participation of minority populations in research, we committed to enroll 140 minority subjects in addition to a random sample of Olmsted County, Minnesota residents (90% white) for a study of risk factors for age-related bone loss and fractures. We successfully enrolled 597 additional minority subjects but encountered specific problems with respect to identification of potential subjects, recruitment, obtaining informed consent, transportation to the study site, and collecting study data. These problems were resolved by observing the tenets of outreach to a diverse study population, namely (1) understand the target population; (2) establish explicit recruitment goals; (3) agree on research plans between study staff and minority communities; (4) continuously evaluate the recruitment process; and (5) maintain lines of communication. Success depended especially on the recruitment of cultural advisors from the different ethnic groups. These special efforts increased the recruitment cost substantially; the total expense of $122,000 for recruiting 550 Asian, Hispanic, and Somali subjects was almost 5-fold higher than the $26,000 required to recruit 699 mostly white study subjects from the population who were contacted by mail. Although it is not impossible to recruit minority subjects, investigators (and grant reviewers) should recognize that significant resources are required to gain access to ethnic communities for research. These results should contribute to more realistic budgets for recruiting minority subjects into clinical research studies. [source] Who joins a preventive intervention?JOURNAL OF COMMUNITY PSYCHOLOGY, Issue 4 2001How risk status predicts enrollment The objective of this study was to identify social, psychological, and health-related variables that predict mothers' refusals to join a prevention program for families of children with chronic illnesses. A two-step recruitment process was used with 193 families of children with chronic illnesses. First, families were recruited for a longitudinal research survey. Then, mothers were given the opportunity to randomly receive one of two programs. Mothers who refused the opportunity to participate in either program continued in the research project. Data were collected through structured interviews at baseline and 12 months later. Compared to mothers who agreed to participate in one of the programs, those who refused reported more confidence, more support, and less depression and higher functional status and better adjustment in their child. Mothers who agree to participate in a longitudinal research effort but refuse to participate in an intervention program are likely to be functioning well, and may perceive no need for a program designed to prevent mental health problems. © 2001 John Wiley & Sons, Inc. [source] Spatial patterns of recruitment in Mediterranean plant species: linking the fate of seeds, seedlings and saplings in heterogeneous landscapes at different scalesJOURNAL OF ECOLOGY, Issue 6 2008Lorena Gómez-Aparicio Summary 1Plant recruitment is a multiphase process that takes place in environments that are heterogeneous in space and time. In this work, I analyse how environmental heterogeneity in Mediterranean forests affects dynamics of early recruitment at different scales, using the wind-dispersed tree Acer opalus subsp. granatense as a case study. 2Seed dispersal and viability, post-dispersal predation, seedling emergence and seedling and sapling survival were evaluated in different habitats (regional scale) and microhabitats (local scale). Simultaneously, a review of the literature on spatial dynamics of plant recruitment in Mediterranean systems was conducted to look for general patterns and investigate their fit to the Acer system. Nineteen woody and herbaceous species were included in the review. 3At the regional scale, Acer recruitment dynamics strongly converged among sites of the same habitat. This was mainly due to large seedling emergence and survival differences among habitats. Although most of the studies reviewed analyzed only one site per habitat type, they also support strong regional variation (either site- or habitat-specific) in recruitment patterns. 4At the local scale, Acer recruitment was microhabitat-specific, a result shared by almost all the reviewed species independently of their life form and dispersal syndrome. This was mostly due to spatial differences in seed arrival (higher under conspecifics) and seedling survival (higher under nurse shrubs). 5Spatial discordance among seed rain and recruitment was found in 60% of the reviewed species at the regional scale, and in 67% at the local scale. Acer results supported this predominant lack of concordance. Discordance among seed rain and recruitment suggests that regeneration is largely limited by safe sites than by seed availability. Because seedling survival was the limiting process with a larger impact on the magnitude and spatial pattern of recruitment, safe sites might be defined as those where seedlings have a higher survival probability. 6Synthesis: This study indicates that the influence of seed dispersal on the spatial patterns and demography of plant species could be limited in heterogeneous and stressful environments (as are found in the Mediterranean), where recruitment is restricted to a small fraction of the landscape. If we are to preserve the distribution and abundance of Mediterranean species in the face of environmental changes, we need to explicitly consider the strong patch-specificity that characterizes their recruitment process at all scales. [source] Voluntary turnover among nurses working in Kuwaiti hospitalsJOURNAL OF NURSING MANAGEMENT, Issue 3 2008MUHAMMAD ALOTAIBI BSN Background, Voluntary turnover rates are high among staff nurses working in Kuwaiti hospitals. It is a major problem, costly and it is presumed to impact on the quality of nursing care delivered. Aims, The two aims of this study were to (1) find out if nurses' resignations in Kuwaiti hospitals could be ascribed to failure in the recruitment process and (2) examine the feelings of nurses who resigned. Methods, Two sets of exit interviews with 60 nurses who had resigned were conducted. Results, No evidence emerged that any false information or misleading information was provided except for the salary adjustments. The real insight lay in what might not have been said in the recruitment interviews. While feelings of discontent emerged in the interviews relating to the loss of income, the greatest source of complaint related to the failure of managers to solve the evident problems. Conclusions, High rates of voluntary turnover require more attention from administrators and policy makers because of its potential consequences in terms of the quality of nursing care delivered. Implications for nursing management, This paper identifies many causes of nurses' voluntary turnover. It also shows the need for nursing managers to explore these causes and suggests successful strategies for recruitment and retention practices and policies. [source] Different expression of adhesion molecules and tetraspanins of monocytes of patients with atopic eczemaALLERGY, Issue 12 2006J. J. Jockers Background:, Atopic eczema (AE) and psoriasis vulgaris (Pso) represent the most frequent chronic inflammatory skin diseases, which have a high number of characteristics in common but differ in their clinical picture and immunological background. A shared feature of both AE and Pso is a high recruitment of distinct proinflammatory cells from the blood into the skin at the initiation of the disease. A multistep adhesion cascade via different adhesion receptors consisting of ,tethering' and ,rolling' mediated by selectins, , -integrins and , -integrins and the ,arrest' of the cells is initiated during this process. Aims of the study:, To evaluate the expression of adhesion molecules and tetraspanins of monocytes of patients with AE and Pso in comparison with healthy controls. Methods:, We analysed the expression of adhesion molecules and tetraspanins on monocytes freshly isolated from the peripheral blood of patients with AE (n = 40) and Pso (n = 65) during exacerbation of their disease in comparison with healthy, non-atopic controls (n = 50). Results:, A high number of similarities between monocytes of patients with AE and patients with Pso, and disease-related differences in the expression of CD62L, CD62P, CD11a, CD11b, CD11c, CD49b, CD49d, CD49e and CD18 and the tetraspanins CD9, CD53, CD63 and CD151, which were elevated on monocytes of patients with AE could be observed. Conclusion:, A distinct expression pattern of adhesion molecules and tetraspanins on monocytes of patients with AE and Pso might influence the recruitment process of inflammatory precursor cells and facilitate new approaches for therapeutic strategies aimed at interrupting the very earliest steps of the fateful recruitment process. [source] The Lingering Effects of the Recruitment Experience on the Long-Term Employment RelationshipNEGOTIATION AND CONFLICT MANAGEMENT RESEARCH, Issue 3 2008Merideth Ferguson Abstract Two studies (one cross-sectional and one longitudinal) examine the effects that job negotiation interactional justice perceptions created in the recruitment process have on an employee's turnover intentions. The findings indicate a long-term impact of the interactional justice perceptions experienced in the recruitment negotiation on employees' intent to leave their organization. Specifically, job negotiation interactional justice perceptions have a lingering effect on an individual's turnover intentions beyond the effects of distributive justice and supportive human resource practices. [source] High school profiles: Application of HTML for recruitment decision makingNEW DIRECTIONS FOR INSTITUTIONAL RESEARCH, Issue 137 2008Iryna Y. JohnsonArticle first published online: 25 MAR 200 Because high school graduates are many colleges' primary target population, information on high school students' performance and sociodemographic characteristics becomes important for the recruitment process. [source] THE RELATION OF INSTRUMENTAL and SYMBOLIC ATTRIBUTES TO A COMPANY'S ATTRACTIVENESS AS AN EMPLOYERPERSONNEL PSYCHOLOGY, Issue 1 2003FILIP LIEVENS This study adds a new marketing-based angle to the study of the attractiveness of organizations in the early stages of the recruitment process. Drawing on the instrumental-symbolic framework from the marketing literature, we expected that the meanings (in terms of inferred traits) that prospective applicants associate with employing organizations would play an important role in applicants' attractiveness to these organizations. Two groups of prospective applicants (275 final-year students and 124 bank employees) were drawn from the applicant population targeted by the bank industry. These applicants were asked to rate a randomly assigned bank in terms of job/organizational factors and to ascribe traits to this bank. In both samples, trait inferences about organizations accounted for incremental variance over job and organizational attributes in predicting an organization's perceived attractiveness as an employer. Moreover, it was easier to differentiate among organizations on the basis of trait inferences versus traditional job and organizational attributes. Practical implications for image audit and image management are discussed. [source] Flooding and grazing promote germination and seedling establishment in the perennial grass Paspalum dilatatumAUSTRAL ECOLOGY, Issue 3 2009PATRICIA S. CORNAGLIA Abstract Seed germination and seedling emergence are key processes for population recruitment. Flooding and grazing are disturbances forming gaps that may strongly influence recruitment patterns in space and time, but their combined effects and action mechanisms have rarely been addressed. In this study we analysed the effects of microhabitat conditions associated with winter flooding and spring-summer defoliation on seed germination and seedling establishment of Paspalum dilatatum, a dominant perennial C4 grass in native grasslands of the Flooding Pampa, Argentina. The dynamics of seedling emergence from natural seed banks and buried seeds was studied in a factorial experiment with flooding and defoliation treatments applied to soil monoliths (mesocosms) collected from natural grassland. Additional laboratory experiments were applied to investigate seed germination under different combinations of temperature, light quality and simulated flooding. Seed germination and seedling emergence of P. dilatatum were promoted by flooding and high intensity defoliation. Gaps generated by flooding were maintained by high intensity defoliation exercising a synergistic effect on survival seedlings. Flooding resulted in the breaking of seed dormancy and higher germination rates associated with alternating temperature and the activation of the phytochrome system. Our results indicate that microhabitat conditions associated with the disturbances forming gaps, such as flooding and heavy grazing, synergistically promote the recruitment process of this dominant grass species. [source] Obtaining active parental consent for school-based research: a guide for researchersAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 3 2009Luke Wolfenden Abstract Objective: Schools increasingly require researchers to obtain active parental consent for students to participate in health research. We sought to identify effective strategies for the recruitment of child research participants through schools. Method: A search of Medline, PsycINFO, Educational Resources Information Center, ProQuest 5000 and the Cochrane Library electronic databases was conducted for the period 1988 to 2008. Results: The review found evidence that the following strategies may be effective in enhancing participation rates: 1) promotion of the research to school principals, teachers, parents and students; 2) dissemination of study information using methods allowing direct contact with parents (i.e. telephone or face-to-face); 3) provision of incentives to teachers, students and at a class level; 4) making reminder contacts; and 5) having a member of the research team co-ordinate and closely monitor the recruitment process. Conclusion and Implications: Application of these strategies should reduce the risk of non-response and other biases that result from selective non-participation. Further randomised controlled trials of these and other strategies are required to strengthen the evidence base. [source] Local perspective of the impact of the HIPAA privacy rule on researchCANCER, Issue 2 2006M.P.H., Michael S. Wolf Ph.D. Abstract BACKGROUND The operational and economic impact of the Health Insurance Portability and Accountability Act (HIPAA) of 1996 was evaluated. The setting was a natural experiment which involved a single-site, clinical research study that was initiated before the enactment of HIPAA and subsequently modified to be compliant with the new policy. METHODS A formative assessment was conducted of the recruitment process to a clinical trial evaluating the efficacy of an educational strategy to inform Veterans about the National Cancer Institute/Department of Veterans Affairs cosponsored Selenium and Vitamin E Cancer Prevention Trial (SELECT). Personnel time and costs were determined based on weekly accrual for study periods before and after the implementation of HIPAA. Root cause analysis was used to assess the recruitment protocol and to identify areas for improvement. RESULTS The implementation of HIPAA resulted in a 72.9% decrease in patient accrual (7.0 patients/wk vs. 1.9 patients/wk, P < 0.001), and a threefold increase in mean personnel time spent recruiting (4.1 hrs/patient vs. 14.1 hrs/patient, P < 0.001) and mean recruitment costs ($49/patient vs. $169/patient, P < 0.001). Upon review of the modified HIPAA-compliant protocol, revisions in the recruitment procedure were adopted. The revised protocol improved weekly accrual by 73% (1.9 patients/wk vs. 7.1 patients/wk, P < 0.001) and resulted in improvements in personnel time (5.4 hrs/patient) and recruitment costs ($65/patient). CONCLUSION Enactment of HIPAA initially placed a considerable burden on research time and costs. Establishing HIPAA-compliant recruitment policies can overcome some of these obstacles, although recruitment costs and time are likely to be greater than those observed before HIPAA. Cancer 2006. © 2005 American Cancer Society. [source] Wood distribution in neotropical forested headwater streams of La Selva, Costa RicaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2009Daniel Cadol Abstract Surveys of wood along 30 forested headwater stream reaches in La Selva Biological Station in north-eastern Costa Rica represent the first systematic data reported on wood loads in neotropical streams. For streams with drainage areas of 0·1,8·5 km2 and gradients of 0·2,8%, wood load ranged from 3 to 34·7 m3 wood/100 m channel and 41,612 m3 wood/ha channel. These values are within the range reported for temperate streams. The variables wood diameter/flow depth, stream power, the presence of backflooding, and channel width/depth are consistently selected as significant predictors by statistical models for wood load. These variables explain half to two-thirds of the variability in wood load. These results, along with the spatial distribution of wood with respect to the thalweg, suggest that transport processes exert a greater influence on wood loads than recruitment processes. Wood appears to be more geomorphically effective in altering bed elevations in gravel-bed reaches than in reaches with coarser or finer substrate. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synchronicity in southern hemisphere squid stocks and the influence of the Southern Oscillation and Trans Polar IndexFISHERIES OCEANOGRAPHY, Issue 4 2004C. M. Waluda Abstract Squid are short lived, with highly labile populations that respond rapidly to changes in environmental conditions. This makes them a good model for studying the response of recruitment processes to environmental signals. This study examines the influence of the Southern Oscillation Index (SOI) and Trans Polar Index (TPI) on the environment and abundance of six species of commercially important squid from the southern hemisphere, all linked to major current systems connected by the Antarctic Circumpolar Current: Dosidicus gigas (Southeast Pacific), Loligo vulgaris reynaudii (Southeast Atlantic), Nototodarus sloanii, N. gouldi (Southwest Pacific), Illex argentinus and L. gahi (Southwest Atlantic). All fisheries displayed a high level of inter-annual variability and a degree of synchronicity was seen to occur in the abundance of the three Pacific species. The SOI signal was reflected in the environment of each fishery, particularly in Pacific regions. Both indices are correlated with squid abundance, particularly during the early life history stages (SOI) and adult stages (TPI), suggesting some degree of latitudinal separation, with juveniles potentially influenced by environmental variability at lower latitudes and adults at higher latitudes. [source] Recruitment of Heliozoa, rhizopods and rotifers from the sediments of an extremely acidic lake during spring and early summerLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2008Elanor M. Bell Abstract The goal of this study was to investigate the recruitment of zooplankton from the littoral sediment of Lake 111, an acidic lake in north-east Germany, in April (spring) and June (early summer), and its role in coupling the benthos and the pelagic. Maximum heliozoan and rhizopod recruitment occurred in early summer from sediment cores incubated at ambient water temperatures (20°C). Conversely, recruitment of the rotifer Cephalodella sp. was highest in spring at ambient spring temperatures of 12°C. A combination of passive and active recruitment processes is likely responsible. The seasonal abiotic and biotic sediment characteristics were relatively constant and therefore not likely responsible for the observed temporal recruitment pattern. The sediment water and carbon content ranged from 20 to 50% (mean = 29 ± 6% standard deviation) and 2,12% (mean = 5 ± 2% standard deviation), respectively. Similarly, there was little variation in the chlorophyll- a (mean = 0.2 ± 0.2 µg Chl- a g,1 dry weight , 6.1 ± 3.9 mg Chl- a m,2). The in situ sediment bacterial density (0.82 × 109 ± 0.26 × 109 g,1 dry weight , 1.01 × 109 ± 0.34 × 109 cells cm,3) was high. In contrast, the abundance of zoobenthos and their resting stages was low (< 25 individuals cm,3, and mean of 90 ± 75 cysts cm,3, respectively), with no temporal pattern being observed. Temperature was the only abiotic factor influencing recruitment. This study suggests that, even in relatively young, chemically extreme lakes, the benthos can play an important role in whole lake microbial processes and zooplankton community composition. Such benthic repositories of resting stages potentially provide protection against adverse environmental changes. [source] Microsatellite markers reveal shallow genetic differentiation between cohorts of the common sea urchin Paracentrotus lividus (Lamarck) in northwest MediterraneanMOLECULAR ECOLOGY, Issue 14 2009I. CALDERÓN Abstract Temporal variability was studied in the common sea urchin Paracentrotus lividus through the analysis of the genetic composition of three yearly cohorts sampled over two consecutive springs in a locality in northwestern Mediterranean. Individuals were aged using growth ring patterns observed in tests and samples were genotyped for five microsatellite loci. No reduction of genetic diversity was observed relative to a sample of the adult population from the same location or within cohorts across years. FST and amova results indicated that the differentiation between cohorts is rather shallow and not significant, as most variability is found within cohorts and within individuals. This mild differentiation translated into estimates of effective population size of 90,100 individuals. When the observed excess of homozygotes was taken into account, the estimate of the average number of breeders increased to c. 300 individuals. Given our restricted sampling area and the known small-scale heterogeneity in recruitment in this species, our results suggest that at stretches of a few kilometres of shoreline, large numbers of progenitors are likely to contribute to the larval pool at each reproduction event. Intercohort variation in our samples is six times smaller than spatial variation between adults of four localities in the western Mediterranean. Our results indicate that, notwithstanding the stochastic events that take place during the long planktonic phase and during the settlement and recruitment processes, reproductive success in this species is high enough to produce cohorts genetically diverse and with little differentiation between them. Further research is needed before the link between genetic structure and underlying physical and biological processes can be well established. [source] Spatial distribution and prediction of seed production by Eucalyptus microcarpa in a fragmented landscapeAUSTRAL ECOLOGY, Issue 1 2010PETER A. VESK Abstract Woodlands worldwide have been greatly modified by clearing for agriculture, and their conservation and restoration requires understanding of tree recruitment processes. Seed production is one possible point of recruitment failure, and one that the spatial arrangement of trees may affect. We sampled 118 Eucalyptus microcarpa (Myrtaceae) trees to compare and analyse the determinants of seed production in this dominant tree of modified, fragmented temperate grassy woodlands, which extend over much of southeastern Australia. Fecundity was estimated as the seed crop measured on leaf mass and whole tree bases and was compared between categories of tree configuration. We also modelled fecundity using boosted regression trees, a new and flexible tool. Fecundity on a leaf mass basis was predominantly influenced by environmental factors (topographic ,wetness', slope, soil type), rather than by local tree density and configuration. Fewer seed per unit leaf mass were produced on flat and topographically wet sites, reflecting poor tolerance of waterlogging by E. microcarpa. By contrast, whole tree fecundity was little influenced by environmental factors. Local tree density and configuration did influence whole tree fecundity, which was high in solitary and woodland-spaced trees and reduced under high local density. We found little evidence for reduced fecundity of E. microcarpa in solitary trees. This points to the importance of scattered trees as sources of seed for tree recruitment and for natural regeneration of landscape level tree cover. Considerable uncertainty remains in modelled seed supply, and may be reduced with sampling across multiple years and greater environmental and spatial domains. [source] | |||||||||||||||||||||||||