Effect of temperature on phytochrome—mediated anthocyanin synthesis in red cabbage

Abstract. A brief high temperature treatment (45 C) promoted anthocyanin synthesis in 2-d-old dark-grown red cabbage seedlings. The increased effectiveness of a temperature/red light treatment as opposed to the reverse sequence suggests that an elevated temperature 'induces' some component which facilitates the phytochrome response.     

Population genomics of wild and laboratory zebrafish (Danio rerio)

Understanding a wider range of genotype–phenotype associations can be achieved through ecological and evolutionary studies of traditional laboratory models. Here, we conducted the first large‐scale geographic analysis of genetic variation within and among wild zebrafish (Danio rerio) populations occurring in Nepal, India, and Bangladesh, and we genetically compared wild populations to several commonly used lab strains. We examined genetic variation at 1832 polymorphic EST‐based single nucleotide polymorphisms (SNPs) and the cytb mitochondrial gene in 13 wild populations and three lab strains. Natural populations were subdivided into three major mitochondrial DNA clades with an average among‐clade sequence divergence of 5.8%. SNPs revealed five major evolutionarily and genetically distinct groups with an overall F_ST of 0.170 (95% CI 0.105–0.254). These genetic groups corresponded to discrete geographic regions and appear to reflect isolation in refugia during past climate cycles. We detected 71 significantly divergent outlier loci (3.4%) and nine loci (0.5%) with significantly low F_ST values. Valleys of reduced heterozygosity, consistent with selective sweeps, surrounded six of the 71 outliers (8.5%). The lab strains formed two additional groups that were genetically distinct from all wild populations. An additional subset of outlier loci was consistent with domestication selection within lab strains. Substantial genetic variation that exists in zebrafish as a whole is missing from lab strains that we analysed. A combination of laboratory and field studies that incorporates genetic variation from divergent wild populations along with the wealth of molecular information available for this model organism provides an opportunity to advance our understanding of genetic influences on phenotypic variation for a vertebrate species.     

FLUXNET and modelling the global carbon cycle

Measurements of the net CO₂ flux between terrestrial ecosystems and the atmosphere using the eddy covariance technique have the potential to underpin our interpretation of regional CO₂ source–sink patterns, CO₂ flux responses to forcings, and predictions of the future terrestrial C balance. Information contained in FLUXNET eddy covariance data has multiple uses for the development and application of global carbon models, including evaluation/validation, calibration, process parameterization, and data assimilation. This paper reviews examples of these uses, compares global estimates of the dynamics of the global carbon cycle, and suggests ways of improving the utility of such data for global carbon modelling. Net ecosystem exchange of CO₂ (NEE) predicted by different terrestrial biosphere models compares favourably with FLUXNET observations at diurnal and seasonal timescales. However, complete model validation, particularly over the full annual cycle, requires information on the balance between assimilation and decomposition processes, information not readily available for most FLUXNET sites. Site history, when known, can greatly help constrain the model‐data comparison. Flux measurements made over four vegetation types were used to calibrate the land‐surface scheme of the Goddard Institute for Space Studies global climate model, significantly improving simulated climate and demonstrating the utility of diurnal FLUXNET data for climate modelling. Land‐surface temperatures in many regions cool due to higher canopy conductances and latent heat fluxes, and the spatial distribution of CO₂ uptake provides a significant additional constraint on the realism of simulated surface fluxes. FLUXNET data are used to calibrate a global production efficiency model (PEM). This model is forced by satellite‐measured absorbed radiation and suggests that global net primary production (NPP) increased 6.2% over 1982–1999. Good agreement is found between global trends in NPP estimated by the PEM and a dynamic global vegetation model (DGVM), and between the DGVM and estimates of global NEE derived from a global inversion of atmospheric CO₂ measurements. Combining the PEM, DGVM, and inversion results suggests that CO₂ fertilization is playing a major role in current increases in NPP, with lesser impacts from increasing N deposition and growing season length. Both the PEM and the inversion identify the Amazon basin as a key region for the current net terrestrial CO₂ uptake (i.e. 33% of global NEE), as well as its interannual variability. The inversion's global NEE estimate of −1.2 Pg [C] yr⁻¹ for 1982–1995 is compatible with the PEM‐ and DGVM‐predicted trends in NPP. There is, thus, a convergence in understanding derived from process‐based models, remote‐sensing‐based observations, and inversion of atmospheric data. Future advances in field measurement techniques, including eddy covariance (particularly concerning the problem of night‐time fluxes in dense canopies and of advection or flow distortion over complex terrain), will result in improved constraints on land‐atmosphere CO₂ fluxes and the rigorous attribution of mechanisms to the current terrestrial net CO₂ uptake and its spatial and temporal heterogeneity. Global ecosystem models play a fundamental role in linking information derived from FLUXNET measurements to atmospheric CO₂ variability. A number of recommendations concerning FLUXNET data are made, including a request for more comprehensive site data (particularly historical information), more measurements in undisturbed ecosystems, and the systematic provision of error estimates. The greatest value of current FLUXNET data for global carbon cycle modelling is in evaluating process representations, rather than in providing an unbiased estimate of net CO₂ exchange.     

C/C++ Coding for Matrix Pseudo Inverses in Clinical Near Infrared Spectroscopy

Near infrared spectroscopy is used clinically to investigate patterns of change in cerebral oxygenation. We have shown that differences reported between authors are likely the result of computer encoding errors in the manipulation of matrices. Current methods compute the inverse of a non-square matrix to derive chromophore concentration values, and solution of another non-square matrix to derive polynomial coefficients of a least squares best fit curve from which the first derivative can be used to estimate blood flow values. Encoding of these pseudo inverses involves too many nested looping steps to easily identify encoding errors. We have given C/C++ source code along with sample numerical values at the termination of each loop within the algorithm. This provides counter checking for future software development by other programmers, and also permits other investigators to report whether the software used for their experiments agrees with previously published material.     

Multi‐species distribution modelling highlights the Adelaide Geosyncline,South Australia,as an important continental‐scale arid‐zone refugium

The mainland portion of the Adelaide Geosyncline (Mount Lofty and Flinders Ranges) has been postulated as an important arid‐zone climate refugium for Australia. To test the sensitivity of this putative Australian arid biome refugium to contemporary climate change, we compared Generalized Additive Modelling and MaxEnt distribution models for 20 vascular plant species. We aimed to identify shared patterns to inform priority areas for management. Models based on current climate were projected onto a hypothetical 2050 climate with a 1.5°C increase in temperature and 8% decrease in rainfall. Individual comparisons and combined outputs of logistic models for all 20 species showed range contraction to shared refugia in the Flinders Ranges and southern Mount Lofty Ranges. Modelling suggests the Flinders Ranges will experience species turnover while suitable climatic habitat will be retained in the Mount Lofty Ranges for the current suite of species. Fragmentation of the southern Mount Lofty Ranges poses management challenges for conserving species diversity with warming and drying. Although projected models must be interpreted carefully, they suggest the region will remain an important but threatened refugium for mesic species at a continental scale.     

Muscle Function in vivo: A Comparison of Muscles used for Elastic Energy Savings versus Muscles Used to Generate Mechanical Power1

SYNOPSIS. The function of muscles used to generate force economicallyand facilitate elastic energy savings in their tendons is comparedwith muscles that function to produce mechanical power. Theunderlying architectural design of the muscle and its tendon(if present) dictate much of their functional capacity and rolein animal locomotion. Using methods that allow direct recordingsof muscle force and fiber length change, the functional designof muscle-tendon systems can now be investigated in vivo. Thesestudies reveal that, in the case of wallaby hindleg muscles,the fibers can maintain sufficient stiffness during tendon stretchand recoil to ensure useful elastic energy recovery and savingsof metabolic energy. In the case of the pectoralis muscle ofpigeons, although isometric or active lengthening of the muscle'sfibers may occur late in the upstroke of the wing beat cycleto enhance force development, the fibers shorten extensivelyduring the downstroke (up to 35% of their resting length) toproduce mechanical power for aerodynamic lift and thrust. Oscillatorylength change, with force enhancement during active lengtheningmay be a general feature of muscles that power aerial and aquaticlocomotion. Similarly, force enhancement by active lengtheningis likely to be important to the design and function of musclesthat primarily generate force to minimize energy expenditure/unitforce generated, as well as for elastic energy savings withina long tendon. Architectural features of muscle-tendon unitsfor effective elastic energy savings, however, are likely toconstrain locomotor performance when mechanical work is required,as when an animal accelerates, either limiting performance orrequiring the recruitment of functional agonists with greatermechanical power generating capability (i.e., longer fibers)     

Habitat selection by the swamp wallaby (Wallabia bicolor) in relation to diel period,food and shelter

Patterns of resource selection by animals may be influenced by sex, and often change over a 24‐h period. We used a dry sclerophyll landscape managed for commercial timber production to investigate the effects of sex and diel period on habitat selection by the swamp wallaby (Wallabia bicolor). We predicted that selection would be (i) affected by both sex and diel period; and (ii) positively related to lateral cover during the day, but to food resources at night. Non‐metric multidimentional scaling indicated that some of the available habitats differed markedly with respect to visibility (an indicator of lateral cover), fern cover, forb cover, wallaby density and a forage quality index, providing the basis for non‐random habitat selection. At the landscape scale, wallabies showed strong selection for 5‐year‐old regenerating sites, selected against 10‐year‐old regenerating sites and unharvested forest, and avoided recently harvested (3–10 months post‐harvest) sites completely. At the scale of individual home ranges, a pooled male and female sample demonstrated selection for unharvested forest over recently harvested sites during both diurnal and nocturnal periods. A separate analysis showed that both sex and diel period influenced the selection of 5‐ and 10‐year‐old sites and the surrounding unharvested forest. Using a novel approach, we demonstrated that diurnal habitat selection by both sexes was negatively correlated with visibility, representing stronger selection for areas with more lateral cover. Nocturnal selection by females was positively correlated with values of a forage quality index, but this was not the case for males. We hypothesise that the observed patterns of selection were driven by the need to find food and avoid predators, but were also affected by the different reproductive strategies of males and females. Our results demonstrate the importance of incorporating factors such as sex and diel period into analyses of habitat selection.     

Preference induction and the benefits of floral resources for a facultative florivore

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Projecting climate change impacts on species distributions in megadiverse South African Cape and Southwest Australian Floristic Regions: Opportunities and challenges

Increasing evidence shows that anthropogenic climate change is affecting biodiversity. Reducing or stabilizing greenhouse gas emissions may slow global warming, but past emissions will continue to contribute to further unavoidable warming for more than a century. With obvious signs of difficulties in achieving effective mitigation worldwide in the short term at least, sound scientific predictions of future impacts on biodiversity will be required to guide conservation planning and adaptation. This is especially true in Mediterranean type ecosystems that are projected to be among the most significantly affected by anthropogenic climate change, and show the highest levels of confidence in rainfall projections. Multiple methods are available for projecting the consequences of climate change on the main unit of interest – the species – with each method having strengths and weaknesses. Species distribution models (SDMs) are increasingly applied for forecasting climate change impacts on species geographic ranges. Aggregation of models for different species allows inferences of impacts on biodiversity, though excluding the effects of species interactions. The modelling approach is based on several further assumptions and projections and should be treated cautiously. In the absence of comparable approaches that address large numbers of species, SDMs remain valuable in estimating the vulnerability of species. In this review we discuss the application of SDMs in predicting the impacts of climate change on biodiversity with special reference to the species‐rich South West Australian Floristic Region and South African Cape Floristic Region. We discuss the advantages and challenges in applying SDMs in biodiverse regions with high levels of endemicity, and how a similar biogeographical history in both regions may assist us in understanding their vulnerability to climate change. We suggest how the process of predicting the impacts of climate change on biodiversity with SDMs can be improved and emphasize the role of field monitoring and experiments in validating the predictions of SDMs.     

A latitudinal gradient in tree growth response to climate warming in the Siberian taiga

We investigated the climate response of three Siberian taiga species, Larix cajanderi, Picea obovata, and Pinus sylvestris, across a latitudinal gradient in central Siberia. We hypothesized that warming is more frequently associated with increased growth for evergreen conifers (P. obovata and P. sylvestris) than for L. cajanderi, and for northern than for southern sites; we also hypothesized that increased growth is associated with a positive trend in normalized difference vegetation index (NDVI). In mixed stands, growth of L. cajanderi and P. obovata increased over time, but the larger growth increases in P. obovata may presage a shift in competitive balance between these species. Climate response varied among and within populations of all species, and positive responses to temperature prevailed at northern sites, where trees grew faster in years with warm early summers. Negative responses to warming declined along the south to north latitudinal gradient. We observed considerable variability in climate response within populations which even exceeded that among species or sites. Tree response to climate was correlated with NDVI trends, indicating that patterns of tree‐growth response to climate were indicative of a coherent landscape‐scale response to warming. Our findings suggest that increased productivity with warming is likely only in the northern reaches of the Siberian taiga. An increased prevalence of evergreen conifers in areas currently dominated by deciduous Larix species also seems likely.