Showing papers by "Macquarie University published in 2004"

The social identity theory of intergroup behavior

Abstract: This chapter presents an outline of a theory of intergroup conflict and some preliminary data relating to the theory. Much of the work on the social psychology of intergroup relations has focused on patterns of individual prejudices and discrimination and on the motivational sequences of interpersonal interaction. The intensity of explicit intergroup conflicts of interests is closely related in human cultures to the degree of opprobrium attached to the notion of "renegade" or "traitor." The basic and highly reliable finding is that the trivial, ad hoc intergroup categorization leads to in-group favoritism and discrimination against the out-group. Many orthodox definitions of "social groups" are unduly restrictive when applied to the context of intergroup relations. The equation of social competition and intergroup conflict rests on the assumptions concerning an "ideal type" of social stratification in which the salient dimensions of intergroup differentiation are those involving scarce resources.

Extinction risk from climate change

Abstract: Climate change over the past approximately 30 years has produced numerous shifts in the distributions and abundances of species and has been implicated in one species-level extinction. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15-37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction ( approximately 18%) than mid-range ( approximately 24%) and maximum-change ( approximately 35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.

The worldwide leaf economics spectrum

Abstract: Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

Regions of Strong Coupling Between Soil Moisture and Precipitation

Abstract: Previous estimates of land-atmosphere interaction (the impact of soil moisture on precipitation) have been limited by a lack of observational data and by the model dependence of computational estimates. To counter the second limitation, a dozen climate-modeling groups have recently performed the same highly controlled numerical experiment as part of a coordinated comparison project. This allows a multimodel estimation of the regions on Earth where precipitation is affected by soil moisture anomalies during Northern Hemisphere summer. Potential benefits of this estimation may include improved seasonal rainfall forecasts.

Using content analysis as a research method to inquire into intellectual capital reporting

Abstract: Increasingly, researchers in the field of intellectual capital (IC) need to be able to justify the specific research methods they use to collect the empirical data that they examine to support and test opinions regarding the merit of different approaches to managing and reporting IC. Of the various methods available to researchers seeking to understand intellectual capital reporting (ICR), content analysis is the most popular. The aim of this paper is to review the use of content analysis as a research method in understanding ICR and to offer some observations on the practical utility of the method. Further, the paper examines several research method issues relating to the use of content analysis that have been discussed in the social environmental accounting literature, but not as yet in the IC literature, which we believe are relevant to investigations underway in the field of ICR. This paper reports on several developmental issues we have confronted when using content analysis to examine the voluntary disclosure of IC in annual reports by various organisations. The paper also suggests two theoretical foundations for further investigation into the voluntary disclosure of IC by organisations, and suggests why content analysis is well matched to both these theories as a means to collect empirical data to test research propositions.

Most species are not driven to extinction before genetic factors impact them

Abstract: There is controversy concerning the role of genetic factors in species extinctions. Many authors have asserted that species are usually driven to extinction before genetic factors have time to impact them, but few studies have seriously addressed this issue. If this assertion is true, there will be little difference in genetic diversity between threatened and taxonomically related nonthreatened species. We compared average heterozygosities in 170 threatened taxa with those in taxonomically related nonthreatened taxa in a comprehensive metaanalysis. Heterozygosity was lower in threatened taxa in 77% of comparisons, a highly significant departure from the predictions of the no genetic impact hypothesis. Heterozygosity was on average 35% lower (median 40%) in threatened taxa than in related nonthreatened ones. These differences in heterozygosity indicate lowered evolutionary potential, compromised reproductive fitness, and elevated extinction risk in the wild. Independent evidence from stochastic computer projections has demonstrated that inbreeding depression elevates extinction risk for threatened species in natural habitats when all other threatening processes are included in the models. Thus, most taxa are not driven to extinction before genetic factors affect them adversely.

Seedling survival and seed size: a synthesis of the literature

Abstract: Summary 1Large-seeded species have long been known to have higher survivorship during establishment than small-seeded species. Here, we assessed the size of this advantage by compiling published data on survival through seedling emergence, seedling establishment and sapling establishment. 2We found no relationship between seed mass and survival through the transition from viable seed in or on the soil to newly emerged seedlings (P = 0.47, n = 33 species). 3Synthesis of data from experimental studies on the advantages of large-seeded species establishing under particular hazards (such as shade, drought or herbivory) confirmed that seedlings of large-seeded species perform better than those of small-seeded species in most situations. However, the magnitude of this advantage was not sufficient to counterbalance the greater number of seeds produced by small-seeded species m−2 of canopy outline year−1. 4Synthesis of data from field studies of populations under natural conditions also showed that large-seeded species have higher survival through early seedling establishment than small-seeded species (P = 0.006, n = 112 species). However, the magnitude of this advantage would only be sufficient to counterbalance the greater number of seeds produced by small-seeded species m−2 of canopy outline year−1 if mortality continued at the same rate for some time. 5The time required for a species with 10-fold larger seeds to recoup the advantage gained by a smaller-seeded species during seed production ranged from 8.8 weeks for the smallest seeded species in the data set, up to an implausible 4.2 years for the largest-seeded species. Thus, while large-seeded species do have a survival advantage over small-seeded species during seedling establishment, the available evidence suggests that advantages must also accrue during other stages in the life cycle. One possibility is that the greater seed production of small-seeded species (m−2 of canopy outline year−1) is partly offset by larger canopies and longer reproductive life spans in large-seeded species.

The 6dF Galaxy Survey: Samples, observational techniques and the first data release

Abstract: The 6dF Galaxy Survey (6dFGS) aims to measure the redshifts of around 150 000 galaxies, and the peculiar velocities of a 15 000-member subsample, over almost the entire southern sky. When complete, it will be the largest redshift survey of the nearby Universe, reaching out to about z similar to 0.15, and more than an order of magnitude larger than any peculiar velocity survey to date. The targets are all galaxies brighter than K-tot = 12.75 in the 2MASS Extended Source Catalog (XSC), supplemented by 2MASS and SuperCOSMOS galaxies that complete the sample to limits of (H, J, r(F), b(J)) = (13.05, 13.75, 15.6, 16.75). Central to the survey is the Six-Degree Field (6dF) multifibre spectrograph, an instrument able to record 150 simultaneous spectra over the 5.7-field of the UK Schmidt Telescope. An adaptive tiling algorithm has been employed to ensure around 95 per cent fibring completeness over the 17 046 deg(2) of the southern sky with \b\ > 10degrees. Spectra are obtained in two observations using separate V and R gratings, that together give R similar to 1000 over at least 4000-7500 Angstrom and signal-to-noise ratio similar to10 per pixel. Redshift measurements are obtained semi-automatically, and are assigned a quality value based on visual inspection. The 6dFGS data base is available at http://www-wfau.roe.ac.uk/6dFGS/, with public data releases occurring after the completion of each third of the survey.

Spatial scaling of microbial eukaryote diversity

Abstract: Patterns in the spatial distribution of organisms provide important information about mechanisms that regulate the diversity of life and the complexity of ecosystems. Although microorganisms may comprise much of the Earth's biodiversity and have critical roles in biogeochemistry and ecosystem functioning, little is known about their spatial diversification. Here we present quantitative estimates of microbial community turnover at local and regional scales using the largest spatially explicit microbial diversity data set available (> 10(6) sample pairs). Turnover rates were small across large geographical distances, of similar magnitude when measured within distinct habitats, and did not increase going from one vegetation type to another. The taxa-area relationship of these terrestrial microbial eukaryotes was relatively flat (slope z = 0.074) and consistent with those reported in aquatic habitats. This suggests that despite high local diversity, microorganisms may have only moderate regional diversity. We show how turnover patterns can be used to project taxa-area relationships up to whole continents. Taxa dissimilarities across continents and between them would strengthen these projections. Such data do not yet exist, but would be feasible to collect.

A Practical Guide to Rock Microstructure

Abstract: Preface 1. Background 2. Microstructures of sedimentary rocks 3. Microstructures of igneous rocks 4. Microstructures of metamorphic rocks 5. Microstructures of deformed rocks Mineral symbols used in this book Glossary of microstructural terms.

Geodynamic evolution of the Pan-African belt in central Africa with special reference to Cameroon

Abstract: The Pan-African belt in central Africa has benefited from the many petrographic, structural, and geochronological studies in the recent years that have improved our understanding of the belt. However, those studies have also produced various and often divergent evolutionary models for the belt, some of which do not even involve well-defined cratons. Following a review of the available data in Cameroon, we propose a model of continent–continent collision that involved the Congo craton and the north-central Cameroon active margin showing Archean to Paleoproterozoic inheritances. This model is based, among others, on (i) the prominent role of the Congo craton as demonstrated by the regional extension of external nappes on its northern edge and the concomitant exhumation of the 620 Ma granulitic rocks believed to have formed at the root of the collision zone, and (ii) the late development of a strike slip fault system in central Cameroon as the result of horizontal movement following the multistage collision....

Impacts of climate change on aeroallergens: past and future.

Abstract: Human activities are resulting in increases in atmospheric greenhouse gases, such as carbon dioxide, and changes in global climate. These, in turn, are likely to have had, and will continue to have, impacts on human health. While such impacts have received increasing attention in recent years, the impacts of climate change on aeroallergens and related allergic diseases have been somewhat neglected. Despite this, a number of studies have revealed potential impacts of climate change on aeroallergens that may have enormous clinical and public health significance. The purpose of this review is to synthesize this work and to outline a number of research challenges in this area. There is now considerable evidence to suggest that climate change will have, and has already had, impacts on aeroallergens. These include impacts on pollen amount, pollen allergenicity, pollen season, plant and pollen distribution, and other plant attributes. There is also some evidence of impacts on other aeroallergens, such as mould spores. There are many research challenges along the road to a more complete understanding of the impacts of climate change on aeroallergens and allergic diseases such as asthma and hayfever. It is important that public health authorities and allergy practitioners be aware of these changes in the environment, and that research scientists embrace the challenges that face further work in this area.

More information from fewer questions: the factor structure and item properties of the original and brief fear of negative evaluation scale.

Abstract: Statistical methods designed for categorical data were used to perform confirmatory factor analyses and item response theory (IRT) analyses of the Fear of Negative Evaluation scale (FNE; D. Watson & R. Friend, 1969) and the Brief FNE (BFNE; M. R. Leary, 1983). Results suggested that a 2-factor model fit the data better for both the FNE and the BFNE, although the evidence was less strong for the FNE. The IRT analyses indicated that although both measures had items with good discrimination, the FNE items discriminated only at lower levels of the underlying construct, whereas the BFNE items discriminated across a wider range. Convergent validity analyses indicated that the straightforwardly-worded items on each scale had significantly stronger relationships with theoretically related measures than did the reverse-worded items. On the basis of all analyses, usage of the straightforwardly-worded BFNE factor is recommended for the assessment of fear of negative evaluation.

ICE: a statistical approach to identifying endmembers in hyperspectral images

Abstract: Several of the more important endmember-finding algorithms for hyperspectral data are discussed and some of their shortcomings highlighted. A new algorithm - iterated constrained endmembers (ICE) - which attempts to address these shortcomings is introduced. An example of its use is given. There is also a discussion of the advantages and disadvantages of normalizing spectra before the application of ICE or other endmember-finding algorithms.

Does inbreeding and loss of genetic diversity decrease disease resistance

Abstract: Inbreeding and loss of genetic diversity are predicted to decrease the resistance of species to disease. However, this issue is controversial and there is limited rigorous scientific evidence available. To test whether inbreeding and loss of genetic diversity affect a host''s resistance to disease, Drosophila melanogasterpopulations with different levels of inbreeding and genetic diversity were exposed separately to (a) thuringiensin, an insecticidal toxin produced by some strains of Bacillus thuringiensis, and (b) live Serratia marcescensbacteria. Inbreeding and loss of genetic diversity significantly reduced resistance of D. melanogasterto both the thuringiensin toxin and live Serratia marcescens. For both, the best fitting relationships between resistance and inbreeding were curvilinear. As expected, there was wide variation among replicate inbred populations in disease resistance. Lowered resistances to both the toxin and the pathogen in inbred populations were due to specific resistance alleles, rather than generalized inbreeding effects, as correlations between resistance and population fitness were low or negative. Wildlife managers should strive to minimise inbreeding and loss of genetic diversity within threatened populations and to minimise exposure of inbred populations to disease.

The galactic habitable zone and the age distribution of complex life in the Milky Way.

Abstract: We modeled the evolution of the Milky Way Galaxy to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution, and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun.

Sprouting ability across diverse disturbances and vegetation types worldwide

Abstract: 1 A widely used classification of plant response to fire divides species into two groups, sprouters and non-sprouters. In contrast, regeneration responses to catastrophic wind throw and small gap disturbance are more often considered a continuum. 2 We determined general patterns in the distribution of sprouting ability across species with respect to disturbance type and intensity, vegetation type and phylogeny and assessed the adequacy of a dichotomy for describing species' sprouting responses. These are important steps if sprouting is to be adopted widely and consistently as a functional trait. 3 Quantitative data were compiled from the literature and differences in species' sprouting proportions between disturbance classes were assessed using simple sprouting categorizations, visually using histograms and with mixture models. 4 The sprouter/non-sprouter dichotomy effectively characterized intense disturbances, such as fires resulting in stem-kill (peaks at 13%, 79% probability of sprouting). But there was a continuum of responses following less intense disturbances. Where substantial above-ground tissue was retained, as for wind throw, localized gap disturbances and low intensity fires, there were fewer non-sprouters and more intermediate sprouters. 5 Comparisons across diverse vegetation types and disturbances require quantitative records of sprouting, although the simple sprouter/non-sprouter dichotomy was sufficient for comparisons within fire. Patterns appeared consistent across broad vegetation types. Sprouting ability showed little phylogenetic conservatism.

A Primer of Conservation Genetics

Abstract: Preface Take home messages 1. Introduction 2. Genetic diversity 3. Evolutionary genetics of natural populations 4. Genetic consequences of small population size 5. Genetics and extinction 6. Resolving taxonomic uncertainties and defining management units 7. Genetic management of endangered species in the wild 8. Captive breeding and reintroduction 9. Molecular genetics in forensics and understanding species biology Final messages Glossary Sources and copyright acknowledgments Index.