bluuebunny/crossref_metadata_2025 huggingface dataset:
Building a required, virtual, voice‐supported library skills course: an Israeli experience
Authors: Asner Haya , Polani Tsviya
Published: September 2004

New students at Ben‐Gurion University of the Negev, Be'er Sheva, Israel, are required to take a completely virtual library skills course that utilizes new voice technology developed in Israel. The course, which the student may take from any computer at his/her convenience, is made up of lessons (PowerPoint screens and accompanying spoken explanations), hands‐on exercises and a final exam. This article explains why and how the course was designed and suggests further improvements of the system.
Collaboration for point‐of‐need library instruction
Authors: Malenfant Chuck , Egan Demers Nora
Published: September 2004

Beginning in the spring of 2001, a librarian and a member of the teaching faculty collaborated on an advanced information literacy instructional experience through the teaching faculty's “Issues in Science and Technology” classes. They collected data from the students both before and after the advanced information literacy instructional sessions that included the students' own attitudes about, and perceived level of, information literacy. Additionally, the instructor assigned point values to assignments directly related to the information literacy instruction her students received, thereby encouraging participation. The collaborators found that increasing the point values of the related assignments also increased student participation and performance. They also found strong indications that offering advanced library instruction to upper‐division students at their point of need, as they are facing more challenging research assignments in their regular coursework, also increases student interest and participation in the program.
Assessing library instruction in the freshman seminar: a citation analysis study
Authors: Ursin Lara , Blakesley Lindsay Elizabeth , Johnson Corey M.
Published: September 2004

In light of the general emerging focus on assessment, it is imperative that librarians develop effective methods for evaluating their instructional endeavors. This study involved analyzing the frequency with which Washington State University Freshman Seminar students used items from librarian‐constructed resource guides. In addition, the researchers evaluated the quality of Web sites used in the freshman seminar final projects. Regardless of the information format and special treatment to place resource guide items at their fingertips, students largely did not use the librarian‐recommended resources. Citation analysis of the student Web sites exhibited a broad spectrum of quality levels and raised key questions about Web site evaluation. Ideas for improving student resource selection are discussed.
Getting down to business: library staff training
Authors: Cory Tucker James
Published: September 2004

Develops a model for a library staff training program for business reference. The program identifies core business reference competencies for library staff and uses performance measure standards to meet Reference and User Services Association guidelines. Provides a training program that offers insight into the information‐seeking habits of business students, general knowledge of the business discipline and assistance in identifying appropriate library resources. Covers all aspects of establishing a training program including planning, implementation and assessment. Effective training programs covering business and other disciplines provide library staff with an opportunity for professional development and give the library an avenue to improve the quality of reference assistance.
Researching specific non‐profit organizations: a selective bibliography
Authors: Hines Todd M.
Published: September 2004

The non‐profit sector is a large, vital part of the US economy. Many researchers and librarians face research questions dealing with non‐profit organizations, especially questions about the fundraising, lobbying, and administrative expenses of specific non‐profits. This selective bibliography identifies sources to assist both librarians and researchers in locating information on specific not‐for‐profit organizations. It focuses principally on three main types of non‐profits: charities, foundations, and associations.
Government information education and training: a selected annotated bibliography
Authors: Cox Jennifer L. , Skarl Susie A.
Published: September 2004

An urgent topic of conversation among government documents librarians today is the need for training, in both the use of federal depository collections and the provision of reference services for these collections. Two trends that have pushed this issue to the forefront in recent years are the proliferation of electronic resources and the fact that, in many institutions, government documents reference services are being integrated into general reference service points. This selective bibliography focuses on recent articles that present a substantially detailed account of training and educational programs for everything from ongoing professional development training for staff to course‐integrated instruction for students, and will serve as a resource for librarians involved in these educational efforts.
Canadian guide to gaming industry resources
Authors: Stevens Rhys , Beristain Maureen
Published: September 2004

The rapid expansion of the Canadian gambling industry since 1969 has generated substantial profits for provincial governments and industry operators. As gambling expands its reach and regulatory structures evolve, a growing body of researchers is starting to scrutinize the industry and its socio‐economic impacts on Canadians. This article provides background information on Canada's gambling industry and presents an overview of essential information resources.
Should we worry about an “academic‐practitioner divide” in marketing?
Authors: Brennan Ross
Published: September 2004

In marketing, as in other areas of management studies, there is a feeling abroad that lines of communication need to be improved between those who work largely in the academic sphere and the practitioner community. Introduces the papers presented in this special issue, which explore the nature of the “academic‐practitioner divide”, investigates the reasons for it and the barriers to communication that exist, and put forward ideas for improving the effectiveness of academic‐practitioner collaboration. However, members of the academic community should carefully avoid a headlong and uncritical rush for managerial relevance, since their claim to a unique position in the knowledge production process relies on maintaining objectivity and a certain distance from the day‐to‐day pressures of marketing management.
Business‐to‐business marketing
Authors: Reed Gary , Story Vicky , Saker Jim
Published: September 2004

The paper reports on research sponsored by the Chartered Institute of Marketing as part of its Canon of Knowledge initiative. The paper addresses the issue of what areas currently being taught as part of the discipline of marketing are considered important by business‐to‐business marketing practitioners. It also examines how these differ between the private and public sectors and identifies the tools and techniques felt to be most useful to practitioners.
In search of relevance
Authors: Brennan Ross , Ankers Paul
Published: September 2004

This article reports on three related empirical studies of the relevance of academic research to management practice in the field of business‐to‐business marketing. These studies comprise a survey of 58 academic researchers, a qualitative study of ten marketing practitioners, and a qualitative study of eight academic researchers. Academic researchers in the field of business‐to‐business marketing believe that their work is of interest, potential value, and relevance to practitioners, and aspire to make a contribution to management practice. Practitioners claim not to be interested in academic research, and are more favourably disposed towards consultants, who they see as more responsive to, and understanding of, business pressures. It seems clear that although academics would like to get closer to practitioners, they are inhibited by institutional factors, such as academic reward systems and the “publish or perish” culture. Mechanisms for improving the degree of cooperation between researchers and practitioners are explored.
Barriers to practical use of academic marketing knowledge
Authors: Grundvåg Ottesen Geir , Grønhaug Kjell
Published: September 2004

It is commonly assumed that a prime purpose of developing research‐based marketing knowledge is that it should be useful to marketing managers and other practitioners. However, evidence suggests that academic marketing knowledge is only to a limited degree utilised in practical life. It is thus important to understand why this is the case, as well as how use of academic knowledge can be enhanced. This paper focuses on scientific knowledge about market orientation and explores a range of factors, which might impair its practical application. More specifically, it examines what types of knowledge marketing practitioners might perceive as useful and discusses a range of potential barriers to successful transfer of market orientation knowledge from academia to practitioners. Substantial barriers are identified which relate to attributes of market orientation knowledge itself and characteristics of both academics and practitioners. Findings are discussed and implications highlighted.
Refocusing marketing to reflect practice
Authors: McCole Patrick
Published: September 2004

Presents a conceptual discussion concerning the academic/practitioner divide in marketing. States that the marketing concept and the way we teach marketing needs to be refocused to reflect practice. Presents two new developments in marketing that are ideal candidates for narrowing the gap between academia and practice. These are retro‐marketing and experiential marketing.
Making marketers accountable:a failure of marketing education?
Authors: Baker Susan , Holt Sue
Published: September 2004

The academic/practitioner divide in marketing is very evident in marketers’ real world problems of accountability. Empirical research reported in this paper reveals senior non‐marketers perceive marketers to be “unaccountable, untouchable, slippery and expensive” and this is further reflected in the domain literature. Exploration of the issues raises questions about whether marketing educators have failed to deliver the theory and frameworks that could address this problem. Since the 1960s, many tools have been developed and used by marketing educators, academic researchers and consultants that should have helped practitioners to become more accountable; yet something appears to have gone wrong. This paper synthesizes the most recent literature in these areas, contends that accountability is imperative to avoid the marginalization of marketers and proposes an agenda for further research to close the academic/practitioner divide.
In search of relevance and rigour for research in marketing
Authors: Katsikeas Constantine S. , Robson Matthew J. , Hulbert James M.
Published: September 2004

There is concern that academic research in marketing does not sufficiently support firms confronting today's hostile business conditions. This paper offers a perspective on enhancing the relevance and rigour of research in marketing. It takes the view that rigorous research conducted on issues relevant to practising managers is especially valuable for the marketing discipline's future development and status. Emphasis is placed on identifying a number of “hot” topics worthy of future investigation, accomplished by a brainstorming workshop involving a large number of distinguished marketing professors. Areas identified were global marketing strategy, consumer behaviour and marketing strategy. It is hoped that the identification and discussion of these topics will spark greater research on fundamental marketing issues, and that the allied explication of research rigour will likewise enhance the efficacy of research in marketing.
A call to arms for applied marketing academics
Authors: Tapp Alan
Published: September 2004

“Research has a value that does not depend on how true it is” is a quote from Griseri's call for management researchers to concern themselves less with scientific validity and more with relevance, striking a chord within the marketing academy in the light of criticism of the lack of progress in building a body of theory in marketing and creating more links with practice. Some have warned of the dangers of too closely following practitioners’ agendas. This paper debates these issues and proposes that the academic marketing community should recognise the value of getting closer to practitioners. After reviewing literature on the issue, the paper makes the case for an overtly recognised applied researcher culture to sit alongside pure research colleagues. A theoretical framework is developed and applied to a “template” for research design that will allow researchers to generate and communicate knowledge more effectively.
The dimensions that construct the evaluation of service quality in academic libraries
Authors: Nagata Haruki , Satoh Yoshinori , Gerrard Sarah , Kytömäki Päivi
Published: September 2004

The objective of this study is to identify the dimensions that determine the customers' evaluation of service quality in academic libraries. One university library each in England and Finland and two in Japan were selected to conduct a questionnaire survey based on the GAP theory of SERVQUAL that has led discussions on the assessment of service quality in marketing theory and practice. Since the actual delivery of information as a service outcome is as important as the service process in libraries, attributes inherent to libraries were incorporated into the survey. Subjecting data obtained to exploratory and confirmatory factor analysis showed that library service quality consists of four dimensions: effect of service (personal), library as ba (place), collections and access, and effect of service (organizational), which are different from the five SERVQUAL dimensions: tangibles, reliability, responsiveness, assurance, and empathy.
Utilizing points of differentiation to enhance competitiveness and growth: some thoughts for consideration
Authors: Dwyer Rocky J.
Published: September 2004

One of the hallmarks of a leading‐edge organization – be it public or private sector – has been the ability to differentiate itself from third parties by gaining insight into and making judgments about its product and customer (constituent) and the ability of the organization to effect positive change. Leading private and public organizations use evaluation inquiry reports and their subsequent recommendations to drive improvements and successfully translate policy and programs into action. Grace Hopper once said: “One accurate measurement is worth more than 1,000 expert opinions.” When evaluation staff consult and maintain frequent interaction with persons or organizations affected by evaluations, directly or indirectly, a differentiated evaluation process can, in fact, be a lever for change.
The Singapore River thematic zone: sustainable tourism in an urban context
Authors: Savage Victor R , Huang Shirlena , Chang T C
Published: September 2004

This paper explores the concept of sustainable tourism and how it applies to urban destinations such as Singapore. As tourism is an important industry in Singapore, in terms of employment, business activity and an income generator, the Singapore Tourism Board is continuously looking at potential avenues to make Singapore a competitive destination. We examine the use of thematic zones in Singapore as a strategy to achieve its ambition of becoming a tourism capital of the world. By focusing on a case study of the Singapore River thematic zone (one of the 11 thematic zones identified by the Singapore Tourism Board), we assess the viability of thematic zones in ensuring sustainable urban tourism. The paper closes with some theoretical reflections and policy implications arising from our key findings.
Accessibility and land‐use patterns at the forest fringe in the northeastern part of the Philippines
Authors: Verburg Peter H , Overmars Koen P , Witte Nol
Published: September 2004

Accessibility is considered to be one of the most important determinants of use and land‐cover change. In rural land‐use change studies, the accessibility situation is often described by simple measures of the distance to a location of interest. In this paper, different measures of access are tested for a rural area at the forest fringe in the northeastern Philippines. The accessibility measures addressed range from simple distance measures to land‐use type specific transport costs and a population potential measure. The different measures are tested based on their capacity to explain the spatial pattern of different land‐use types. A comparison of the findings based on a spatial analysis and an analysis of household level data is made. It is concluded that the relation between land use and accessibility is dependent on the specific characteristics of the different land‐use types. The (dis‐)advantages of the use of the different accessibility measures are discussed.
Dispersal phenology of hydrochorous plants in relation to discharge, seed release time and buoyancy of seeds: the flood pulse concept supported
Authors: BOEDELTJE GER , BAKKER JAN P. , TEN BRINKE ALBERT , VAN GROENENDAEL JAN M. , SOESBERGEN MARTIN
Published: September 2004

Restored floodplains and backwaters lacking a viable propagule bank, may need flood pulses to facilitate inward dispersal of diaspores. Temporal patterns of hydrochorous plant dispersal are, however, not well known.

Diversity and abundance of diaspores dispersed in a water body over 12 months were quantified using a 200 µm net in order to: (i) test for a relationship between discharge and the number of species and diaspores dispersed; (ii) examine the effect of seed buoyancy and seed release period on the length of the dispersal period; and (iii) test whether diaspores of species that disperse during a similar period of the year are characterized by similar dispersal and dormancy traits.

A total 359 188 individuals of 174 vascular species developed from 144 samples, with most (90%) from vegetative diaspores and only 10% from seeds. Mean number of species and diaspores varied between months in parallel with discharge levels. Stepwise multiple regression analysis showed that both seed buoyancy and seed release influenced dispersal periods.

In general, species that dispersed most diaspores in spring and summer had non‐dormant seeds, a shorter seed release period and a shorter seed dispersal period than species whose dormant seeds dispersed in autumn and winter. Vegetative diaspores were dispersed on average over 8 months, indicating their importance to long‐distance dispersal. Several species dispersed both generative and vegetative diaspores, often in different seasons.

Our results may assist the planning of regenerative processes in riverine wetlands at landscape scales, as dispersal phenology, and discharge rates must be taken into consideration. Vegetative diaspores may be more important than seeds, although the latter may extend the species dispersal period into other seasons. Temporal heterogeneity in diaspore dispersal influences the identity of diaspores reaching restored habitats.
How far can a hawk's beard fly? Measuring and modelling the dispersal of Crepis praemorsa
Authors: SKARPAAS OLAV , STABBETORP ODD E. , RØNNING INGEBORG , SVENNUNGSEN THOMAS O.
Published: September 2004

We measured and modelled the dispersal of a wind‐dispersed herb, the leafless hawk's beard (Crepis praemorsa, Asteraceae), using a combination of measurement techniques, selected empirical models and mechanistic models originally developed for trees.

Dispersal was measured by releasing individual seeds and by placing seed traps around an experimentally created point source of seeding plants. Dispersal distances varied considerably between the experiments. In the seed releases, dispersal distances were positively related to horizontal wind speed (linear regression, P < 0.001) and, under favourable conditions, many seeds dispersed over several metres, with a few at > 30 m.

Four empirical models (the inverse power (IP), the negative exponential (NE), Bullock & Clarke's mixed model (MIX) and Clark et al.'s 2Dt model) were fitted to the data. IP and NE models often failed to accommodate the shape of the empirical distribution of dispersal distances, and the MIX model, although extremely flexible, tended to overfit the data. The 2Dt model was, however, flexible and realistic in each experiment. Nevertheless, the parameter values for all of the empirical models varied dramatically between experiments; no set of parameter values predicted the observed dispersal distances under all conditions.

Two mechanistic models (Greene & Johnson's analytical model (GJ) and Nathan et al.'s individual‐based simulation model (NSN)), originally developed for trees, were parameterized using independent data and parameter values from the literature. Although the NSN model provided a poor fit for the seed trap experiment, it performed almost as well as the best empirical models in the seed release experiments. Its predictions were further improved by including convection, and predicted dispersal > 30 m corresponded closely with our observations. The prediction of low (< 1%) dispersal > 200 m requires further validation.

We conclude that dispersal models for wind‐dispersed trees can be adapted for herbs with different dimensions and diaspore characteristics. Mechanistic simulations are superior because they are robust to environmental heterogeneity, as well as being informative in terms of understanding and predicting the effects of species characteristics and ecological factors on dispersal distances. Future empirical studies are needed at a wide range of environmental conditions, with careful measurement of conditions such as the strength and variability of horizontal and vertical wind speeds.
Effect of photosynthetic efficiency and water availability on tolerance of leaf removal inAmaranthus hybridus
Authors: GASSMANN AARON J.
Published: September 2004

Although substantial genetic variation in photosynthetic rate exists within natural populations, it is unclear how such variation might affect the capacity of plants to tolerate herbivore damage.

I tested if decreased efficiency of electron transport, caused by a mutation that confers resistance to the herbicide triazine, affected the ability ofAmaranthus hybridusto tolerate leaf removal, and if this genotypic effect interacted with water availability.

Tolerance levels were compared with the root‐to‐shoot ratio and with compensatory photosynthesis, to investigate the mechanisms of tolerance.

Triazine‐resistantA. hybriduswas found to have lower tolerance to herbivory suggesting that herbivores should drive selection for higher photosynthetic capacity.

Although interactive effects between water availability and photosynthetic genotype were not detected, reduced water availability did cause an overall increase in the ability of plants to tolerate damage.

Greater tolerance of plants under low water availability and of the TS genotype was associated positively with root‐to‐shoot ratios, but there was a negative association between greater tolerance under low water availability and compensatory photosynthesis.

These results suggest that photosynthetic variation is more likely to alter tolerance indirectly though changes in resource allocation, and that direct associations between physiological variables and tolerance may be uncommon in natural systems.
Location and Pricing Decisions of a MultiStore Monopoly in a Spatial Market
Authors: Dasci Abdullah , Laporte Gilbert
Published: September 2004

Abstract.  This article presents an analysis of location and pricing decisions of a monopolist about to open several stores in a compact geographical space. The number of stores is made endogenous by the introduction of fixed costs. A novel methodology is developed, by which the firm's location and price decisions are represented as continuous functions defined over the geographical space. This modeling artifact generates a negligible error but simplifies the solution considerably and allows the derivation of several intuitive results. Although the focus is on one‐dimensional markets, it is shown that the method can easily be adapted to two‐dimensional markets.
Regional Labor Market Dynamics, Housing, and Migration
Authors: Hämäläinen Kari , Böckerman Petri
Published: September 2004

Abstract.  This study explores the impact of plant‐level labor market dynamics and housing markets on gross migration flows. The internal and the external reorganizations of regional labor markets are shown to be related. An increase in internal turnover of jobs and workers in regional labor markets is found to increase net‐migration. This effect arises mainly from a reduction in out‐migration. Housing markets constitute constraints for migration. In particular, an increase in regional housing prices and a large share of owner‐occupancy housing discourages net‐migration to a region by reducing in‐migration. In contrast, the out‐migration rate remains largely unaffected by housing markets.
Can the growth–differentiation balance hypothesis be tested rigorously?
Authors: Stamp Nancy
Published: September 2004

The growth–differentiation balance (GDB) hypothesis (as elaborated by Herms and Mattson) provides a framework for examining the impact of a resource gradient on the constant tradeoff between growth and differentiation in cells and tissues of plants, in particular with the consequences for plant defense. The GDB hypothesis, which is the most mature of the hypotheses of plant defensive levels, has not been tested directly. Examination of the requirements for a rigorous test indicates that, like the other hypotheses of plant defense, it cannot be tested directly. Furthermore, rigorously testing the primary derivative hypotheses, while possible, would require considerable methodological effort, on a scale not previously attempted for tests of plant defense, which is likely to discourage researchers, and understandably so, even though the GDB hypothesis warrants methodical investigation due to its potential explanatory power. Although farther removed from the abstract model (i.e. the GDB framework), other derivative hypotheses can be tested, but doing so will require thoughtful consideration and acknowledgement of that. Study of a few carefully chosen systems (i.e. plant species) may provide considerable insight and potentially useful refinement of the GDB framework.
Inference from plant competition experiments: the effect of spatial covariance
Authors: Damgaard Christian
Published: September 2004

Two‐species plant competition experiments are often drawn on in an attempt to understand and possibly to predict the formation of plant community structures. Frequently, such competition experiments use a non‐random spatial design but is analysed in models where a random spatial design is implicitly assumed. Here, the effect of spatial covariance in plant competition experiments on the inferred ecological conclusions is demonstrated. It is shown that spatial covariance, which is dependent on the competition kernel and the experimental design, may affect the estimation of parameters of interest. Based on the same set of experimental data, the predicted outcome of competition between two Arabidopsis thaliana genotypes can vary between (almost certain) coexistence and (almost certain) exclusion of one genotype, depending on the assumptions made about the spatial scale of competition between the plants. The predicted outcome of competition depended strongly on the mean interaction distance of the competition kernel, whereas the functional shape of the competition kernel was less important. It is suggested that plants in manipulated competition experiments should be placed randomly, such that the design of the competition experiment is in agreement with the model used in the analysis.
Benefits and costs of floral visitors toChilopsis linearis: pollen deposition and stigma closure
Authors: Richardson Sarah C.
Published: September 2004

In pollination mutualisms, nectar‐robbers are usually considered antagonists; visitors that enter flowers (legitimate visitors) are usually considered mutualists. However, nectar‐robbers may provide some benefits to plants, whereas legitimate visitors may inflict some costs. The costs and benefits of floral visitors toChilopsis linearis(desert willow) were compared by number of pollen grains deposited and their effect on stigmas. Because these plants are self‐incompatible and pollen‐limited, they depend on visitors for services by pollinators to reproduce. On a per‐visit basis, only one legitimate visitor,Bombus sonorus(bumblebees) generally benefited plants in terms of pollen deposition. However, no species of visitor was consistently beneficial; every one was at least sometimes ineffective in terms of pollen deposition.Chilopsishad sensitive stigmas that closed immediately upon touch and sometimes reopened later. Whether stigmas remained permanently closed or reopened depended on number of pollen grains deposited and tended also to be affected by source either, outcross or self. Legitimate visitors sometimes cost plants by causing stigma closure without depositing enough pollen to set a fruit. When abundant, a visitor such asApis mellifera(honeybees) that was only occasionally beneficial on a per‐visit basis may have provided a greater benefit to plants as a population than a more effective, but rare visitor. In contrast, nectar‐robbers did not benefit plants by depositing pollen grains, but they also did not inflict costs on plants by causing stigmas to close without adequate pollen. There are two general implications of these results. First, individuals of species that appear to be mutualists can vary greatly in the benefits that they give to their partners. Second, apparent mutualists can inflict costs on plants that apparent exploiters (nectar‐robbers) do not.
Linking habitat structure and orientation in an arboreal species Gehyra variegata (Gekkonidae)
Authors: Gruber Bernd , Henle Klaus
Published: September 2004

Understanding how organisms move through landscapes is important for predicting the effects of landscape structure on the population dynamics and spatial distribution of organisms. Despite the accepted importance, the ability to orientate when moving is a poorly studied phenomenon. In this study we report on a translocation experiment in which we used fluorescent powder to study the ability of the arboreal gecko Gehyra variegata to orientate successfully between trees. The relocation experiment demonstrated the ability of translocated geckos to return to the tree of initial capture. Further, we investigated the set of rules geckos employ, when travelling through their structured habitat. Computer simulations relating capture‐mark‐recapture data to structural components of the habitat revealed that movement rules taking vision into account showed the best fit to the empirical data. The movement rule: “move randomly to one of the three next neighbouring trees that are visible” described the observed movement best. This movement rule connects all trees in the habitat and lowers the predation risk during movement.
A powdery mildew infection on a shared host plant affects the dynamics of the Glanville fritillary butterfly populations
Authors: Laine Anna‐Liisa
Published: September 2004

While biotrophic fungal pathogens have generally been considered to have negative effects on phytophagous insects sharing the same host plant, very little is known about whether fungal infection may affect the dynamics of natural insect populations. This study was designed to determine the effects of fungal infection byPodosphaera plantaginis, a powdery mildew, of a shared host plant,Plantago lanceolata, on the larvae of the butterflyMelitaea cinxia. Larval responses were assessed in a no‐choice feeding assay involving infected and healthy leaves, as well as in a behavioural experiment in which larvae had an opportunity to move among infected and uninfected plants. In the no‐choice feeding assay larvae developed more slowly and weighed less at diapause when feeding on fungal‐infected than on healthy leaves. In the behavioural experiment larval groups tended to leave the original host plant when it was infected byP. plantaginis. This tendency was associated with splitting of larval groups into smaller subgroups. These effects observed in an experimental setting were also confirmed to act under natural conditions. An analysis of 167M. cinxiapopulations showed that over‐winter survival of larval groups was 26% lower in host populations infected by the mildew than in non‐infected host populations. Smaller, more slowly developing larvae may not be ready to enter diapause at the onset of fall, causing the observed increase in mortality. This is the first study to demonstrate that the negative effects of a biotrophic fungal infection may extend to the dynamics of entire insect populations.
Is tolerance to summer flooding correlated with distribution patterns in river floodplains? A comparative study of 20 terrestrial grassland species
Authors: Van Eck W. H. J. M. , Van De Steeg H. M. , Blom C. W. P. M. , De Kroon H.
Published: September 2004

It is generally assumed that floods during the growing season have a strong impact on the distribution of grassland plant species in river floodplains but this proposition has never been tested. We examined the survival and growth responses of twenty species, originating from mid‐ and high‐level floodplain grasslands along the River Rhine in the Netherlands, to total submergence for a maximum of two months in an outdoor flooding experiment. Plant survival and biomass reduction with flooding duration was determined as well as biomass recovery after de‐submergence.

Our results indicate that species survival is the most prominent factor correlated with species distribution in floodplain areas. Relatively flood tolerant species occurred mainly at low elevations along the floodplain while more flood sensitive species were restricted to high parts of the floodplain gradient. Biomass reduction rates during submergence were only marginally significantly correlated with species lower distribution boundaries along the flooding gradient. Biomass recovery rate was significantly correlated with species distribution patterns in the field only after 2 weeks of complete submergence, but not after 4 and 8 weeks. Our results suggest that the more flood tolerant species can have various ways to survive and recover from flooding, ranging from low rates of biomass loss and low recovery to relatively high rates of biomass loss and quick recovery.

Our results are consistent with the notion that disturbance by floods during the growing season is an important determinant of species lower distribution boundaries in river floodplains. They also suggest that high survival under flooding may be achieved by different physiological mechanisms. Such mechanisms are discussed in this paper.
Defection by plants in the yucca–yucca moth association: a test of the cheater plant hypothesis for Yucca treculeana
Authors: Amadeus Crabb Beau , Pellmyr Olle
Published: September 2004

In mutualisms, an underlying conflict of interests may select for defection from providing benefits. In the obligate mutualism between yuccas and yucca moths, where pollination service and seeds for pollinator larvae are traded, it has been suggested that some individuals in a population of Y. baccata may defect by preventing pollinator egg or larvae from development. We tested this hypothesis in Y. treculeana, another species suggested to contain cheater plants. Five specific predictions were tested during two years of study. A prediction that a surplus of plants without pollinator larvae should be present was met. Predicted existence of two distinct fruit morphs was rejected, and none of several highly variable morphological traits were linked to presence/absence of larvae. Predicted excess of intact seeds in the fruits of plants without larvae was not found; in fact, such plants produced fewer seeds, contrary to the hypothesis. A suggestion that inverse frequency‐dependent fitness could explain the pattern was rejected. Contrary to prediction, distribution of larvae of a closely related cheater yucca moth was positively associated with pollinator larvae, even though it would not be affected by the proposed killing mechanism. The results together provide strong support against the existence of cheater plants in Y. treculeana.
A recently acquired host plant provides an oligophagous insect herbivore with enemy‐free space
Authors: Mulatu Bayeh , Applebaum Shalom W. , Coll Moshe
Published: September 2004

Enemy‐free space (EFS) is a potentially important factor affecting host plant use by phytophagous insects. Yet only a few field studies have demonstrated that natural enemy activity is the sole mechanism underlying use of novel host plants by herbivorous insects. This may be due to the fact that in earlier studies, both herbivores and natural enemies had the opportunity to adapt to the new host plant. Here we studied the possibility that EFS underlies the recently recorded increase in Phthorimaea operculella densities on tomato plants in a few areas within its geographical range. Through field experiments in Ethiopia, we show that all three conditions proposed by Berdegue et al. to demonstrate EFS are fulfilled. First, a significantly higher proportion of larvae survive on caged than on exposed potato plants, showing that natural enemies are an important mortality factor on the original host, potato. Second, larval survival was significantly higher on exposed tomato than potato plants, implying greater protection for the herbivore from its natural enemies on tomato than on potato plants. Thus tomato plants provide P. operculella with an EFS. Finally, larval survival was significantly higher on caged potato than on caged tomato plants at the preblossom stage, indicating that, in the absence of natural enemies, there is a fitness cost when larvae feed on the sub‐optimal tomato plants. Fulfillment of this third condition points to the importance of natural enemy activity relative to that of other unidentified factors, such as food quality and competition. An intensive field survey provides further support for this conclusion.
The impact of density‐independent mortality on species coexistence: an experimental test with zooplankton
Authors: Mittelbach Gary G. , Darcy Hall Tara L. , Dorn Nathan J. , Garcia Erica A. , Steiner Christopher F. , Wojdak Jeremy M.
Published: September 2004

Mortality (e.g. predation, disturbance) is often thought to lower the intensity of interspecific competition and thereby promote the coexistence of competing species. However, surprisingly few tests of this idea exist, especially for metazoans feeding on a self‐renewing resource. Here we examined the effect of density‐independent mortality on the coexistence of four species of pond zooplankton (microcrustacean grazers) in a series of laboratory microcosms. Across the experimental mortality gradient, consumer biomass decreased and resource abundance increased with an increase in mortality. Thus, the treatments resulted in an increase in resource availability per consumer (one measure of reduced competitive intensity). There was no significant effect of mortality treatment on species relative abundances or species evenness, and the zooplankterDiaphanosomadominated community biomass at all mortality levels. Mortality rate did have a marginally significant effect on species richness (p<0.07), but richness did not increase monotonically with mortality level. Instead, richness tended to be highest in the low‐ and no‐mortality treatments.
Are the spatial patterns of weeds scale‐invariant?
Authors: Cousens Roger , Wallinga Jacco , Shaw Michael
Published: September 2004

In previous empirical and modelling studies of rare species and weeds, evidence of fractal behaviour has been found. We propose that weeds in modern agricultural systems may be managed close to critical population dynamic thresholds, below which their rates of increase will be negative and where scale‐invariance may be expected as a consequence. We collected detailed spatial data on five contrasting species over a period of three years in a primarily arable field. Counts in 20×20 cm contiguous quadrats, 225,000 in 1998 and 84,375 thereafter, could be re‐structured into a wide range of larger quadrat sizes. These were analysed using three methods based on correlation sum, incidence and conditional incidence. We found non‐trivial scale invariance for species occurring at low mean densities and where they were strongly aggregated. The fact that the scale‐invariance was not found for widespread species occurring at higher densities suggests that the scaling in agricultural weed populations may, indeed, be related to critical phenomena.
Ectoparasitic Argulus coregoni (Crustacea: Branchiura) hedge their bets – studies on egg hatching dynamics
Authors: Hakalahti Teija , Häkkinen Heli , Valtonen E. Tellervo
Published: September 2004

Unpredictability in the temporal availability of susceptible hosts is likely to act as a selection pressure affecting the life history strategies of parasites. In highly variable environments the future of the lineage can be secured by spreading the risk, for example, by producing descendants that differ in their timing of emergence. Counter to this, in predictable environments a single “best‐adapted” phenotype is expected. We asked whether ectoparasitic Argulus coregoni egg hatching pattern can be explained as a genetically canalized individual trait; an instance of phenotypic plasticity or bet‐hedging. We collected egg clutches laid by individual A. coregoni females in early and late reproductive period of the lice population and randomized the clutches within 3 treatments. Intra‐ and inter‐clutch variability in the hatching dynamics of A. coregoni eggs was monitored and the reproductive potential assessed. On average A. coregoni females laid 317 (SD±176.6) eggs. We found that the plasticity in the hatching dynamics among A. coregoni eggs was remarkable. Noticeable peaks in hatching were followed each of the repeated artificial “winter treatments” in 1°C. Repeated 2 weeks cold treatments induced relatively bigger hatching peaks than 2 days cold treatments compared to controls at room temperature. However, in all treatments, egg clutches hatched through an extended period of 7 months on average and the total hatching percentages were similar. We found that intra‐clutch variability in hatching among eggs laid by single A. coregoni females was greater than inter‐clutch variability. Our data support the predictions of the adaptive bet‐hedging strategy in relation to egg‐hatching dynamics. Response to cooling and bet‐hedging may be adaptive for such species like A. coregoni since by synchronizing the life‐cycle with the seasonal environment will assist transmission and parasite fitness.
Some dynamical consequences of parasitoid diapause
Authors: Lalonde R. G.
Published: September 2004

Parasitoid diapause usually serves to synchronize parasitoids with host populations that are undergoing diapause, to avoid some period of unsuitable conditions. Non‐synchronizing diapause can occur, however, in a number of situations. For example, a fraction of the diapausing parasitoids may stay dormant for a number of seasons. Parasitoids attacking each generation of a multivoltine host may enter a “bank” of diapausing individuals that will emerge at the beginning of the next season. Finally, parasitoid diapause initiation may be driven by density‐dependent processes. I examine the effect of these three scenarios on the stability of Nicholson – Bailey type models. I show that in general, non‐synchronizing parasitoids can potentially have a strong de‐stabilizing influence on parasitoid‐host dynamics.
Behavioral linkage of pelagic prey and littoral predators: microhabitat selection by Daphnia induced by damselfly larvae
Authors: Van de Meutter Frank , Stoks Robby , De Meester Luc
Published: September 2004

Only recently ecologists started treating the previously separately considered benthic, littoral and pelagic zones of lake ecosystems as closely connected compartments. Here we study a link between organisms belonging to a different compartment – namely the pelagic and the littoral – through behavior in a series of laboratory experiments. Waterfleas of the genus Daphnia are inhabitants of the pelagic zone and suffer a high predation pressure from syntopic vertebrate predators (mainly fish). Presumably to escape this predation, they sometimes migrate in the day to the littoral to seek refuge within macrophytes and return to the pelagic at night. Zygopterans from the genus Ischnura do commonly co‐occur in ponds with Daphnia and are known as opportunistic predators of Daphnia. In two initial experiments in microcosms in the lab we showed that Ischnura larvae are littoral predators strongly associated with macrophytes. Although we found that predation rates of individual Ischnura larvae on Daphnia are approximately 1.5 fold lower in macrophytes compared to open water, total predation from Ischnura on Daphnia per unit area is tenfold higher within macrophytes than in open water, making the open water a safer place for Daphnia with regard to Ischnura predation. In a third microcosm experiment we monitored horizontal distribution of Daphnia in the absence, presence and odor only of Ischnura larvae. After 2 hours, on average 10% less Daphnia remained within the vegetation when Ischnura larvae or only their odor were present compared to when Ischnura or their odor were absent. We interpret this as a behavioral anti‐predation response of Daphnia to the presence of Ischnura larvae that seems primarily chemically mediated. The observed horizontal migration of the pelagic prey driven by the littoral predator may couple both lake compartments and may interact with the predator–prey relationships within the pelagic.
Rethinking plant community theory
Authors: Lortie Christopher J. , Brooker Rob W. , Choler Phillipe , Kikvidze Zaal , Michalet Richard , Pugnaire Francisco I. , Callaway Ragan M.
Published: September 2004

Plant communities have traditionally been viewed as either a random collection of individuals or as organismal entities. For most ecologists however, neither perspective provides a modern comprehensive view of plant communities, but we have yet to formalize the view that we currently hold. Here, we assert that an explicit re‐consideration of formal community theory must incorporate interactions that have recently been prominent in plant ecology, namely facilitation and indirect effects among competitors. These interactions do not suppport the traditional individualistic perspective. We believe that rejecting strict individualistic theory will allow ecologists to better explain variation occurring at different spatial scales, synthesize more general predictive theories of community dynamics, and develop models for community‐level responses to global change. Here, we introduce the concept of the integrated community (IC) which proposes that natural plant communities range from highly individualistic to highly interdependent depending on synergism among: (i) stochastic processes, (ii) the abiotic tolerances of species, (iii) positive and negative interactions among plants, and (iv) indirect interactions within and between trophic levels. All of these processes are well accepted by plant ecologists, but no single theory has sought to integrate these different processes into our concept of communities.