School of Biological Sciences Publications - UQ eSpace

Agamas exhibit behavioral syndromes: Bolder males bask and feed more but may suffer higher predation

2010-05-23T00:00:00Z

Age and growth in olive ridley seaturtles (Lepidochelys olivacea) from the north-central Pacific: a skeletochronological analysis

2007-08-15T00:00:00Z

The olive ridley is the most abundant seaturtle species in the world but little is known of the demography of this species. We used skeletochronological data on humerus diameter growth changes to estimate the age of North Pacific olive ridley seaturtles caught incidentally by pelagic longline fisheries operating near Hawaii and from dead turtles washed ashore on the main Hawaiian Islands. Two age estimation methods [ranking, correction factor (CF)] were used and yielded age estimates ranging from 5 to 38 and 7 to 24 years, respectively. Rank age-estimates are highly correlated (r = 0.93) with straight carapace length (SCL), CF age estimates are not (r = 0.62). We consider the CF age-estimates as biologically more plausible because of the disassociation of age and size. Using the CF age-estimates, we then estimate the median age at sexual maturity to be around 13 years old (mean carapace size c. 60 cm SCL) and found that somatic growth was negligible by 15 years of age. The expected age-specific growth rate function derived using numerical differentiation suggests at least one juvenile growth spurt at about 10–12 years of age when maximum age-specific growth rates, c. 5 cm SCL year−1, are apparent.

Age determination in individual wild-caught Drosophila serrata using pteridine concentration

2007-08-15T00:00:00Z

Fluorescence spectrophotometry can reliably detect levels of the pteridine 6-biopterin in the heads of individual Drosophila serrata Malloch 1927. Pteridine content in both laboratory and field captured flies is typically a level of magnitude higher than the minimally detectable level (mean(lab)=0.54 units, mean(field)=0.44 units, minimum detectable level=0.01 units) and can be used to predict individual age in laboratory populations with high certainty (r(2)=57%). Laboratory studies of individuals of known age ( from 1 to 48 days old) indicate that while pteridine level increases linearly with age, they also increase in a linear manner with rearing temperature and ambient light levels, but are independent of sex. As expected, the longevity of laboratory-reared males ( at least 48 days) is higher than the range of predicted ages of wild-caught males based on individual pteridine levels (40 days). However, the predictive equation based on pteridine level alone suggested that a number of wild-caught males were less than 0 days old, and the 95% confidence for these predictions based on the inverse regression broad. The age of the oldest wild-caught male is to fall within the range of 2 to 50 days. The effects of temperature and light intensity determined in laboratory study (effect sizes omega(2)=14.3 and respectively) suggests that the calibration of the prediction equation for field populations would significantly improved when combined with fine scaled studies of habitat temperature and light conditions. ability to determine relative age in individual wild-caught D. serrata presents great opportunities for a variety evolutionary studies on the dynamics of populations.

Age estimation of Eretmochelys imbricata by sclerochronology of carapacial scutes

2007-08-14T00:00:00Z

Ageing delays the cellular stages of adventitious root formation in pine

Rasmussen, Amanda og Hunt, Mark A. — 2010-07-11T00:00:00Z

Vegetative propagation programs internationally are affected by the significant decline of rooting success as trees mature. This study compared the cellular stages of root formation in stem cuttings from 15-week-old (juvenile) and 9-y-old (mature) stock plants of the slash Caribbean pine hybrid (Pinus elliottii var. elliottii P. caribaea var. hondurensis). The cellular stages of root formation were the same in both juvenile and mature cuttings, beginning with cell divisions of the vascular cambium forming callus tissue. Within the callus, tracheids differentiated and elongated to form root primordia. Roots in juvenile cuttings developed faster than those in mature cuttings and the juvenile cuttings had a much higher rooting percent at the end of the study (92% and 26% respectively). Cuttings of the two juvenile genotypes had more primary roots (5.5 and 3.3) than the three mature genotypes (0.96, 0.18 and 0.07). The roots of juvenile cuttings were more evenly distributed around the basal circumference when compared with those on cuttings from the mature genotypes. Further work is needed to improve understanding of physiological changes with maturation so that the rooting success and the speed of development in cuttings from mature stock plants can be optimised, hence improving genetic gain.

A gene expression signature of confinement in peripheral blood of red wolves (Canis rufus)

2009-02-17T00:00:00Z

The stresses that animals experience as a result of modification of their ecological circumstances induce physiological changes that leave a signature in profiles of gene expression. We illustrate this concept in a comparison of free range and confined North American red wolves (Canis rufus). Transcription profiling of peripheral blood samples from 13 red wolf individuals in the Alligator River region of North Carolina revealed a strong signal of differentiation. Four hundred eighty-two out of 2980 transcripts detected on Illumina HumanRef8 oligonucleotide bead arrays were found to differentiate free range and confined wolves at a false discovery rate of 12.8% and P < 0.05. Over-representation of genes in focal adhesion, insulin signalling, proteasomal, and tryptophan metabolism pathways suggests the activation of pro-inflammatory and stress responses in confined animals. Consequently, characterization of differential transcript abundance in an accessible tissue such as peripheral blood identifies biomarkers that could be useful in animal management practices and for evaluating the impact of habitat changes on population health, particularly as attention turns to the impact of climate change on physiology and in turn species distributions.

A general model for host plant selection in phytophagous insects

West, S. A. og Cunningham, J. P. — 2007-08-14T00:00:00Z

We develop a general theoretical framework for exploring the host plant selection behaviour of herbivorous insects. This model can be used to address a number of questions, including the evolution of specialists, generalists, preference hierarchies, and learning. We use our model to: (i) demonstrate the consequences of the extent to which the reproductive success of a foraging female is limited by the rate at which they find host plants (host limitation) or the number of eggs they carry (egg limitation); (ii) emphasize the different consequences of variation in behaviour before and after landing on (locating) a host (termed pre- and post-alighting, respectively); (iii) show that, in contrast to previous predictions, learning can be favoured in post-alighting behaviour-in particular, individuals can be selected to concentrate oviposition on an abundant low-quality host, whilst ignoring a rare higher-quality host; (iv) emphasize the importance of interactions between mechanisms in favouring specialization or learning. (C) 2002 Elsevier Science Ltd.

A genetic attack on the defense complex

Gibson, Greg — 2009-03-05T00:00:00Z

An increasing number of non-model organisms are becoming accessible to genetic analysis in the field, as evolutionary biologists develop dense molecular genetic maps. Peichel et al.'s recent study[1] provides a microsatellite-based map for threespine stickleback fish (Gasterosteus aculeatus), and the first evidence for QTL affecting feeding morphology and defensive armor. This species has undergone rapid and parallel morphological and behavioral evolution, and there is now hope that some of the genes responsible for the divergence may soon be identified. BioEssays 24:487-489, 2002. © 2002 Wiley Periodicals, Inc.

A Genetic Defect Caused by a Triplet Repeat Expansion in Arabidopsis thaliana

2009-09-03T00:00:00Z

A genetic linkage map in autotetraploid lucerne adapted to northern Australia, and use of the map to identify DNA markers linked to resistance to Phytophthora medicaginis

2007-08-15T00:00:00Z

Phytophthora root rot, caused by Phytophthora medicaginis, is a major limitation to lucerne ( Medicago sativa L.) production in Australia and North America. Quantitative trait loci (QTLs) involved in resistance to P. medicaginis were identified in a lucerne backcross population of 120 individuals. A genetic linkage map was constructed for tetraploid lucerne using 50 RAPD ( randomly amplified polymorphic DNA), 104 AFLP (amplified fragment length polymorphism) markers, and one SSR ( simple sequence repeat or microsatellite) marker, which originated from the resistant parent (W116); 13 markers remain unlinked. The linkage map contains 18 linkage groups covering 2136.5 cM, with an average distance of 15.0 cM between markers. Four of the linkage groups contained only either 2 or 3 markers. Using duplex markers and repulsion phase linkages the map condensed to 7 homology groups and 2 unassigned linkage groups. Three regions located on linkage groups 2, 14, and 18, were identified as associated with root reaction and the QTLs explained 6 - 15% of the phenotypic variation. The research also indicates that different resistance QTLs are involved in conferring resistance in different organs. Two QTLs were identified as associated with disease resistance expressed after inoculation of detached leaves. The marker, W11-2 on group 18, identified as associated with root reaction, contributed 7% of the phenotypic variation in leaf response in our population. This marker appears to be linked to a QTL encoding a resistance factor contributing to both root and leaf reaction. One other QTL, not identified as associated with root reaction, was positioned on group 1 and contributed to 6% of the variation. This genetic linkage map provides an entry point for future molecular-based improvement of lucerne in Australia, and markers linked to the QTLs we have reported should be useful for marker-assisted selection for partial resistance to P. medicaginis in lucerne.

A genome-wide gene expression signature of environmental geography in leukocytes of Moroccan amazighs

2008-11-21T00:00:00Z

A genomewide survey of developmental genes in Ciona intestinalis: III. Genes for Fox, ETS, nuclear receptors and NF- kB

2007-12-04T14:24:17Z

A survey against the draft genome sequence and the cDNA/EST database of Ciona intestinalis identified a number of genes encoding transcription factors regulating a variety of processes including development. In the present study, we describe almost complete sets of genes for Fox, ETS-domain transcription factors, nuclear receptors, and NFkappaB as well as other factors regulating NFkappaB activity, with their phylogenetic nature. Vertebrate Fox transcription factors are currently delineated into 17 subfamilies: FoxA to FoxQ. The present survey yielded 29 genes of this family in the Ciona genome, 24 of which were Ciona orthologues of known Fox genes. In addition, we found 15 ETS genes, 17 nuclear receptor genes, and several NFkappaB signaling pathway genes in the Ciona genome. The number of Ciona genes in each family is much smaller than that of vertebrates, which represents a simplified feature of the ascidian genome. For example, humans have two NFkappaB genes, three Rel genes, and five NFAT genes, while Ciona has one gene for each family. The Ciona genome also contains smaller numbers of genes for the NFkappaB regulatory system, i.e. after the split of ascidians/vertebrates, vertebrates evolved a more complex NFkappaB system. The present results therefore provide molecular information for the investigation of complex developmental processes, and an insight into chordate evolution.

A genomewide survey of developmentally relevant genes in Ciona intestinalis - IV. Genes for HMG transcriptional regulators, bZip and GATA/Gli/Zic/Snail

2007-08-14T00:00:00Z

Many kinds of transcription factors and regulators play key roles in a variety of developmental processes. In the present survey, genes encoding proteins with conserved HMG-box, bZip domains, and some types of zinc finger motifs were surveyed in the completely sequenced genome of Ciona intestinalis. In the present analysis, 21 HMG-box-containing genes and 26 bZip genes were identified as well as four small groups of zinc finger genes in the Ciona genome. The results also showed that a less redundant set of genes is present in the Ciona genome compared with vertebrate genomes. In addition, cDNA clones for almost all genes identified have been cloned and distributed as a Ciona intestinalis Gene Collection Release I. The present comprehensive analysis therefore provides a means to study the role of these transcription factors in developmental processes of basal chordates.

A genomewide survey of developmentally relevant genes in Ciona intestinalis - V. Genes for receptor tyrosine kinase pathway and Notch signaling pathway

2007-08-14T00:00:00Z

In the present survey, we identified most of the genes involved in the receptor tyrosine kinase (RTK), mitogen activated protein kinase (MAPK) and Notch signaling pathways in the draft genome sequence of Ciona intestinalis, a basal chordate. Compared to vertebrates, most of the genes found in the Ciona genome had fewer paralogues, although several genes including ephrin, Eph and fringe appeared to have multiplied or duplicated independently in the ascidian genome. In contrast, some genes including kit/flt, PDGF and Trk receptor tyrosine kinases were not found in the present survey, suggesting that these genes are innovations in the vertebrate lineage or lost in the ascidian lineage. The gene set identified in the present analysis provides an insight into genes for the RTK, MAPK and Notch signaling pathways in the ancient chordate genome and thereby how chordates evolved these signaling pathway.

Aggressive mimics profit from a model-signal receiver mutualism

Cheney, K. L. og Cote, I. M. — 2008-02-18T00:00:00Z

Mimetic species have evolved to resemble other species to avoid predation (protective mimicry) or gain access to food (aggressive mimicry). Mimicry systems are frequently tripartite interactions involving a mimic, model and 'signal receiver'. Changes in the strength of the relationship between model and signal receiver, owing to shifting environmental conditions, for example, can affect the success of mimics in protective mimicry systems. Here, we show that an experimentally induced shift in the strength of the relationship between a model (bluestreak cleaner fish, Labroides dimidiatus) and a signal receiver (staghorn damselfish, Amblyglyphidodon curacao) resulted in increased foraging success for an aggressive mimic (bluestriped fangblenny, Plagiotremus rhinorhynchos). When the parasite loads of staghorn damselfish clients were experimentally increased, the attack success of bluestriped fangblenny on damselfish also increased. Enhanced mimic success appeared to be due to relaxation of vigilance by parasitized clients, which sought cleaners more eagerly and had lower overall aggression levels. Signal receivers may therefore be more tolerant of and/or more vulnerable to attacks from aggressive mimics when the net benefit of interacting with their models is high. Changes in environmental conditions that cause shifts in the net benefits accrued by models and signal receivers may have important implications for the persistence of aggressive mimicry systems.

Aggressiveness among isolates of Sclerotinia sclerotiorum from sunflower

2008-02-18T00:00:00Z

Isolates of Sclerotinia sclerotiorum differ significantly in aggressiveness on sunflower. In total, 120 isolates were collected from head and basal stem rots of sunflower in two locations in south-east Queensland, Australia. The inoculation of sunflower stems with mycelial plugs and the measurement of lesion development were used to compare aggressiveness between isolates. Rank ordering of isolates indicated differences, with a few isolates displaying high and low aggressive abilities. Differences in aggressiveness were more indicative of a continuous variation rather than discrete groups. Isolate aggressiveness did not correspond to the location of collection nor to the mode of pathogen reproduction or infection from which they were derived. Statistically significant differences between the isolates differed according to the statistical test employed, as different multiple comparison procedures had a greater influence in interpretation of aggressiveness than the isolates themselves. Results indicate individual isolates do not maintain discrete aggressive abilities across the multiple comparison procedures, with the exception of weakly aggressive isolates.

A global marker database for Phytophthora infestans

2007-08-13T00:00:00Z

A marker database was compiled for isolates of the potato and tomato late blight pathogen, Phytophthora infestans, originating from 41 locations which include 31 countries plus 10 regions within Mexico. Presently, the database contains information on 1,776 isolates for one or more of the following markers: restriction fragment length polymorphism (RFLP) fingerprint consisting of 23 bands; mating type; dilocus allozyme genotype; mitochondrial DNA haplotype; sensitivity to the fungicide metalaxyl; and virulence. In the database, 305 entries have unique RFLP fingerprints and 258 entries have unique multilocus genotypes based on RFLP fingerprint, dilocus allozyme genotype, and mating type. A nomenclature is described for naming multilocus genotypes based on the International Organization for Standardization (ISO) two-letter country code and a unique number, Forty-two previously published multilocus genotypes are represented in the database with references to publications. As a result of compilation of the database, seven new genotypes were identified and named. Cluster analysis of genotypes from clonally propagated populations worldwide generally confirmed a previously published classification of old and new genotypes. Genotypes from geographically distant countries were frequently clustered, and several old and new genotypes were found in two or more distant countries. The cluster analysis also demonstrated that A2 genotypes from Argentina differed from all others. The database is available via the Internet, and thus can serve as a resource for Phytophthora workers worldwide.

A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests

2010-07-15T00:00:00Z

1807-2007: A great anniversary celebration

Jamieson, B. G. M. — 2008-02-18T00:00:00Z

Agricultural legacy, climate, and soil influence the restoration and carbon potential of woody regrowth in Australia

2010-10-17T00:00:00Z

Opportunities for dual restoration and carbon benefits from naturally regenerating woody ecosystems in agricultural landscapes have been highlighted recently. The restoration capacity of woody ecosystems depends on the magnitude and duration of ecosystem modification, i.e., the ''agricultural legacy.'' However, this legacy may not influence carbon sequestration in the same way as restoration because carbon potential depends primarily on biomass accumulation, with little consideration of other attributes and functions of the ecosystem. Our present study simultaneously assesses the restoration and carbon potential of Acacia harpophylla regrowth, an extensive regrowth ecosystem in northeastern Australia. We used a landscape-scale survey of A. harpophylla regrowth to test the following hypotheses: (1) management history, in combination with climatic and edaphic factors, has long-term effects on stem densities, and (2) higher-density stands have lower restoration and carbon potential, which is also influenced by climatic and edaphic factors. We focused on the restoration of forest structure, which was characterized using stem density, aboveground biomass, stem heights, and stem diameters. Data were analyzed using multilevel models within the hierarchical Bayesian model (HBM) framework. We found strong support for both hypotheses. Repeated attempts at clearing Brigalow (A. harpophylla ecosystem) regrowth increases stem densities, and these densities remain high over the long term, particularly in high-rainfall areas and on gilgaied, high-clay soils (hypothesis 1). In models testing hypothesis 2, interactions between stem density and stand age indicate that higher-density stands have slower biomass accumulation and structural development in the long term. After accounting for stem density and stand age, annual rainfall had a positive effect on biomass accumulation and structural development. Other climate and soil variables were retained in the various models but had weaker effects. Spatial extrapolations of the HBMs indicated that the central and eastern parts of the study region are most suitable for biomass accumulation; however, these may not correspond to the areas that historically supported the highest biomass Brigalow forests. We conclude that carbon and restoration goals are largely congruent within areas of similar climate. At the regional scale, however, spatial prioritization of restoration and carbon projects may only be aligned where carbon benefits will be high. © 2010 by the Ecological Society of America.

Agrobacterium rhizogenes-mediated transformation of soybean to study root biology

2008-04-14T00:00:00Z

A growth model of the cockle (Cerastoderma edule L.) tested in the Oosterschelde estuary (The Netherlands)

2009-03-11T00:00:00Z

We present an ecophysiological model of the bivalve Cerastoderma edule that simulates individual growth and reproduction under ambient conditions in temperature and food availability in the Oosterschelde estuary, SW Netherlands. The model contains feedback loops in the uptake and metabolism of food and in the partitioning of carbon to the internal state variables: somatic tissue, storage, organic shell matrix and gametes. The model was calibrated for 24 parameters, based on random distributions of parameter values. This procedure includes an estimate of confidence intervals of the output variables. The simulated growth of shell length and animal wet and dry weight reflected the observed values of growth in the field for the period 1993 – 1997. The model is a tool for the integration of ecophysiological knowledge of this species and also for carrying-capacity studies of shellfish culture and for environmental management of populations in estuarine and coastal areas. D 2005 Elsevier B.V. All rights reserved.

A harness for attachment of satellite transmitters on flatback turtles

Sperling, J. B. og Guinea, M. L. — 2007-08-15T00:00:00Z

A histological study of emu (Dromaius novaehollandiae) skin

Weir, K. A. og Lunam, C. A. — 2008-01-25T00:00:00Z

The skin of the emu Dromaius novaehollandiae is described in its entirety by light microscopy for the first time, therefore providing a basis for comparison with the integument of volant birds. The epidermal and dermal layers have a similar arrangement to other avian species. The concentration of lipid spheres in the basal layer of the epidermis is unique to emus. Although no differences in collagen density with depth of the dermis were observed, collagen bundle diameter is significantly smaller in the stratum superficiale compared to the stratum compactum (P = 0.001). The extensive stratum laxum, comprised predominantly of adipose tissue, may be an evolutionary adaptation to support the large feathers and also enhance insulation against ambient subzero temperatures. Males have a significantly thicker cellular epidermis (P = 0.024) and stratum compactum (P = 0.04) than females. In contrast, females have denser collagen (P = 0.04) within the stratum superficiale and stratum compactum.

A Hox/HOM homeobox gene in sponges.

2007-12-05T00:00:00Z

The hox/hom previous termhomeobox genesnext term code for DNA-binding proteins that confer positional information during animal development; these previous termgenesnext term have been found in a wide range of triploblasts and in cnidarians. We report here the identification of a hox/hom previous termgenenext term and two other previous termhomeobox genesnext term in the genomes of previous termsponges.next term This finding extends the detection of hox/hom previous termgenesnext term to the lowest metazoan phylum and suggests a monophyletic origin of the kingdom Animalia. Because, in culture, previous termspongenext term cells quickly reaggregate, differentiate and construct tissue after disaggregation, they can provide a useful model system for characterization of the basic roles of previous termhomeobox genesnext term in the control of cellular differentiation

Aipysurus mosaicus, a new species of egg-eating sea snake (Elapidae: Hydrophiinae), with a redescription of Aipysurus eydouxii (Gray, 1849)

2012-10-31T00:00:00Z

Airborne Pinus pollen in the atmosphere of Brisbane, Australia and relationships with meteorological parameters

2007-08-14T00:00:00Z

Relationships between weather parameters andairborne pollen loads of Pinus inBrisbane, Australia have been investigated overthe five-year period, June 1994–May 1999.Pinus pollen accounts for 4.5% of the annualairborne pollen load in Brisbane where thePinus season is confined to the winter months,July–early September. During the samplingperiod loads of 11–>100 grains m3 wererecorded on 24 days and 1–10 grains m3 on204 days. The onset and peak dates wereconsistent across each season, whereas the enddates varied. The onset of the Pinuspollen season coincided with the coolestaverage monthly temperatures (< 22°C),lowest rainfall (< 7mm), and four weeks afterdaily minimum temperatures fell to 5–9°Cin late autumn. Correlations obtained betweendaily airborne Pinus pollen counts andtemperature/rainfall parameters show thatdensities of airborne Pinus pollen arenegatively correlated with maximum temperature(p < 0.0001), minimum temperature (p < 0.0001)and rainfall (p < 0.05) during the mainpollination period. The mean duration of eachpollen season was 52 days; longer seasons wereshown to be directly related to lower averageseasonal maximum temperatures (r2 = 0.85,p = 0.025). These results signify that maximumand minimum temperatures are the majorparameters that influence the onset andduration of the Pinus pollen season inthe environs of Brisbane. Respiratory allergyis an important health issue in Brisbane,Australia, but it remains unknown whether ornot airborne Pinus pollen is acontributing factor.

Airway smooth muscle proliferation in asthma: The potential of vascular leakage to contribute to pathogenesis

2009-11-12T00:00:00Z

Proliferation of the non-vascular smooth muscle in the walls of the bronchi and bronchioles is a prominent histopathological feature of asthma and is thought to contribute to airway hyperreactivity and narrowing. Increased vascular permeability with plasma leakage is also a feature of asthma pathology and causes submucosal oedema. We hypothesize that, in asthmatics, the accumulation of enriched plasma in the environment surrounding airway smooth muscle promotes respiratory smooth muscle mitogenesis and hyperplasia. This situation represents the in vivo correlate of the increase in airway smooth muscle cell growth seen in vitro with increasing concentrations of serum in the culture medium. Thus, we hypothesize that vascular leakage in the airways in asthma is a primary pathogenic event leading to airway smooth muscle hyperplasia and hypertrophy, and consequently airway narrowing, promoting the characteristic bronchial hyperreactivity associated with narrowing of the airway lumen.

A jumping mesostigmatan: Saltiseius hunteri, n.g., n. sp. (Acari: Mesostigmata: Trigynaspida: Saltiseiidae, n. fam.).

Walter, D. E. — 2008-06-10T00:00:00Z

A key to the microhylid frogs of Australia, and new distributional data.

Hoskin, C.J. — 2009-04-18T00:00:00Z

The frog family Microhylidae is represented in Australia by Cophixalus (14 species) and Austrochaperina (5 species). The majority of these species have small rainforest distributions in north-east Queensland, primarily at higher altitude. Research on Australian microhylid frogs is increasing due to recognition of their importance in assessments of biodiversity and evolutionary history of rainforest areas, and due to their predicted susceptibility to global climate change. Accurate species identification is therefore imperative. Most of the Australian species are morphologically very similar, making identification (even between the two genera) difficult. A key to identify all 19 Australian microhylid species is provided, based on a combination of morphology, colour and pattern, calls, and distributions. The key is suitable for use in the field as well as for preserved specimens. Distributional data incorporating new records from recent fieldwork is also presented.  Microhylidae, distribution, key, Cophixalus, Austrochaperina, Australia, Wet Tropics.

A landscape genetics approach for quantifying the relative influence of historic and contemporary habitat heterogeneity on the genetic connectivity of a rainforest bird

2009-12-08T00:00:00Z

A landscape-scale test of the predictive ability of a spatially explicit model for population viability analysis

2007-08-13T00:00:00Z

1. Although population viability analysis (PVA) is widely employed, forecasts from PVA models are rarely tested. This study in a fragmented forest in southern Australia contrasted field data on patch occupancy and abundance for the arboreal marsupial greater glider Petauroides volans with predictions from a generic spatially explicit PVA model. This work represents one of the first landscape-scale tests of its type. 2. Initially we contrasted field data from a set of eucalypt forest patches totalling 437 ha with a naive null model in which forecasts of patch occupancy were made, assuming no fragmentation effects and based simply on remnant area and measured densities derived from nearby unfragmented forest. The naive null model predicted an average total of approximately 170 greater gliders, considerably greater than the true count (n = 81). 3. Congruence was examined between field data and predictions from PVA under several metapopulation modelling scenarios. The metapopulation models performed better than the naive null model. Logistic regression showed highly significant positive relationships between predicted and actual patch occupancy for the four scenarios (P = 0.001-0.006). When the model-derived probability of patch occupancy was high (0.50-0.75, 0.75-1.00), there was greater congruence between actual patch occupancy and the predicted probability of occupancy. 4. For many patches, probability distribution functions indicated that model predictions for animal abundance in a given patch were not outside those expected by chance. However, for some patches the model either substantially over-predicted or under-predicted actual abundance. Some important processes, such as inter-patch dispersal, that influence the distribution and abundance of the greater glider may not have been adequately modelled. 5. Additional landscape-scale tests of PVA models, on a wider range of species, are required to assess further predictions made using these tools. This will help determine those taxa for which predictions are and are not accurate and give insights for improving models for applied conservation management.

Albicidin antibiotic and phytotoxin biosynthesis in Xanthomonas albilineans requires a phosphopantetheinyl transferase gene

Huang, GZ og Zhang, LH og Birch, RG — 2008-06-10T00:00:00Z

Xanthomonas albilineans produces a family of highly potent antibiotics and phytotoxins called albicidins, which are key pathogenesis factors in the systemic development of leaf scald disease of sugarcane. A gene (xabA) required for albicidin biosynthesis encodes a peptide of 278 amino acids, including the signature sequence motifs for phosphopantetheinyl transferases (PPTases) that activate polyketide and non-ribosomal peptide synthetases. The Escherichia coli entD gene, which encodes a PPTase involved in biosynthesis of enterobactin (a siderophore), restored biosynthesis of albicidin (a DNA replication inhibitor) in X. albilineans Tox(-) LS156 (xabA::Tn5). We conclude that XabA is a PPTase required for post-translational activation of synthetases in the albicidin biosynthetic pathway. This is the first antibiotic or toxin biosynthesis gene characterized from the genus Xanthomonas, and the first demonstration that antibiotic synthetases in the Pseudomonadaceae, like those in the Enterobacteriaceae and in Gram-positive bacteria, can require activation by a PPTase. Coupled with the recent demonstration of a separate albicidin biosynthetic gene cluster, the results indicate the possibility for overproduction of albicidins, which allows better understanding and application of these potent inhibitors of prokaryote DNA replication. (C) 2000 Elsevier Science B.V. All rights reserved.

Albicidin detoxification - A case study in plant genetic engineering to destroy toxins from microbial pathogens

Birch, R. G. — 2008-06-06T00:00:00Z

Aldrovandais sister to Dionaea (Droseraceae): molecular evidence for the common origin of snap-traps among carnivorous plants

2007-08-24T00:00:00Z

Algal blooms on coral reefs with low anthropogenic impact in the Great Barrier Reef

Burgess, S. C. — 2011-09-10T00:00:00Z

Alien and native birds in South Africa: patterns, processes and conservation

Hugo, Sanet og Van Rensburg, Berndt J. — 2012-10-05T00:00:00Z

The spatial distribution of alien species richness often correlates positively with native species richness, and reflects the role of human density and activity, and primary productivity and habitat heterogeneity, in facilitating the establishment and spread of alien species. Here, we investigate the relationship between the spatial distribution of alien bird species, human density, and anthropogenic and natural environmental conditions. Next, we examined the relationship between the spatial distribution of alien bird species and native bird species richness. We examined alien species richness as a response variable, using correlative analyses that take spatial autocorrelation into account. Further, each alien bird species was examined as a response variable, using logistic regression procedures based on binary presence–absence data. A combination of human density and natural habitat heterogeneity best explained the spatial distribution of alien species richness. This contrasts with the results for individual alien species and with previous studies on other non-native taxa showing the importance of primary productivity and anthropogenic habitat modification as explanatory variables. In general, native species richness is an important correlate of the spatial distribution of alien species richness and individual alien species, with alien species being more similar to common species than to rare species.

Alien phytogeographic regions of southern Africa: numerical classification, possible drivers, and regional threats

2012-10-05T00:00:00Z

Alien phytogeographic regions of southern Africa: Numerical classification, possible drivers, and regional threats

2012-07-29T00:16:04Z

The distributions of naturalised alien plant species that have invaded natural or semi-natural habitat are often geographically restricted by the environmental conditions in their new range, implying that alien species with similar environmental requirements and tolerances may form assemblages and characterise particular areas. The aim of this study was to use objective numerical techniques to reveal any possible alien phytogeographic regions (i.e. geographic areas with characteristic alien plant assemblages) in southern Africa. Quarter degree resolution presence records of naturalised alien plant species of South Africa, Lesotho, Swaziland, Namibia and Botswana were analysed through a divisive hierarchical classification technique, and the output was plotted on maps for further interpretation. The analyses revealed two main alien phytogeographic regions that could be subdivided into eight lower level phytogeographic regions. Along with knowledge of the environmental requirements of the characteristic species and supported by further statistical analyses, we hypothesised on the main drivers of alien phytogeographic regions, and suggest that environmental features such as climate and associated biomes were most important, followed by human activities that modify climatic and vegetation features, such as irrigation and agriculture. Most of the characteristic species are not currently well-known as invasive plant species, but many may have potential to become troublesome in the future. Considering the possibility of biotic homogenization, these findings have implications for predicting the characteristics of the plant assemblages of the future. However, the relatively low quality of the dataset necessitates further more in-depth studies with improved data before the findings could be directly beneficial for management.

A lipase-like gene from Heliothis virescens ascovirus (HvAV-3e) is essential for virus replication and cell cleavage

Smede, M og Hussain, M og Asgari, S — 2009-11-12T00:00:00Z

A lipidomic approach to understanding free fatty acid lipogenesis derived from dissolved inorganic carbon within cnidarian-dinoflagellate symbiosis

2012-11-13T15:24:13Z

Allocating biosecurity resources between preventing, detecting, and eradicating island invasions

2011-12-27T00:00:00Z

Allocating conservation resources between areas where persistence of a species is uncertain

2011-09-02T00:00:00Z

Allometric Analysis beyond heterogeneous regression slopes: Use of the Johnson‐Neyman technique in comparative biology

White, Craig R. — 2009-02-26T00:00:00Z

Allometric estimation of metabolic rate from heart rate in penguins

2008-03-28T00:00:00Z

Studies of the relationship between heart rate (f(H)) and rate of oxygen consumption ((V) over dot(O2)), which are then used to predict field metabolic rate, frequently fail to incorporate body mass as a predictive variable. This is a potentially important omission in the study of animals whose body mass fluctuates substantially during their annual cycle. In an attempt further to improve estimates of field metabolic rate from f(H), we re-evaluated data on M-b, f(H) and (V) over dot(O2) from previous studies of macaroni penguins (Eudpytes chrysolophus) and king penguins (Aptenodytes patagonicus) and derived a new relationship to integrate these three quantities. This relationship is at least as accurate and precise as previously deter-mined relationships. We applied this same principle to published data on 11 of the 20 recognised penguin taxa to derive a relationship to predict,, from f(H) and M-b in penguins of any species. This result has interesting implications in terms of reducing the logistical burden in studies of field metabolic rate. (C) 2005 Elsevier Inc. All rights reserved.

Allometric estimation of metabolic rates in animals

White, Craig R. — 2011-01-28T00:00:00Z

Allometric scaling of discontinuous gas exchange patterns in the locust Locusta migratoria throughout ontogeny

2012-10-14T00:08:16Z

Allometric scaling of mammalian metabolism

White, Craig R. og Seymour, Roger S. — 2008-03-28T15:29:25Z

Allometric scaling of maximum metabolic rate: the influence of temperature

2008-11-27T00:00:00Z

# Maximum aerobic metabolic rate, measured in terms of rate of oxygen consumption during exercise ( ), is well known to scale to body mass (M) with an exponent greater than the value of 0·75 predicted by models based on the geometry of systems that supply nutrients. # 2. Recently, the observed scaling for (∝M0·872) has been hypothesized to arise because of the temperature dependence of biological processes, and because large species show a greater increase in muscle temperature when exercising than do small species. # 3. Based on this hypothesis, we predicted that will be positively related to ambient temperature, because heat loss is restricted at high temperatures and body temperature is likely to be elevated to a greater extent than during exercise in the cold. # 4. This prediction was tested using a comparative phylogenetic generalized least-squares (PGLS) approach, and 34 measurements of six species of rodent (20·5–939 g) maximally exercising at temperatures from –16 to 30 °C. # 5. is unrelated to testing temperature, but is negatively related to acclimation temperature. We conclude that prolonged cold exposure increases exercise-induced by acting as a form of aerobic training in mammals, and that elevated muscle temperatures of large species do not explain the scaling of across taxa.

Allometric scaling relationships of jumping performance in the striped marsh frog Limnodynastes peronii

Wilson, RS og Franklin, CE og James, RS — 2008-06-10T00:00:00Z

We constructed a force platform to investigate the scaling relationships of the detailed dynamics of jumping performance in striped marsh frogs (Limnodynastes peronii). Data were used to test between two alternative models that describe the scaling of anuran jumping performance; Hill's model, which predicts mass-independence of jump distance, and Marsh's model, which predicts that jump distance increases as M-0.2, where M is body mass. From the force platform, scaling relationships were calculated for maximum jumping force (F-max), acceleration, take-off velocity (U-max), mass- specific jumping power (P-max), total jumping distance (D-J) and total contact time for 75 L. peronii weighing between 2.9 and 38.4 g. F-max was positively correlated with body mass and was described by the equation F-max=0.16M(0.61), while P-max decreased significantly with body mass and was described by the equation P-max=347M(-0.46). Both D-J and U-max were mass- independent over the post-metamorph size range, and thus more closely resembled Hill's model for the scaling of locomotion. We also examined the scaling relationships of jumping performance in metamorph L. peronii by recording the maximum jump distance of 39 animals weighing between 0.19 and 0.58 g. In contrast to the post-metamorphic L. peronii, D-J and U-max were highly dependent on body mass in metamorphs and were described by the equations D-J=38M(0.53) and U-max=1.82M(0.23), respectively. Neither model for the scaling of anuran jumping performance resembled data from metamorph L. peronii. Although the hindlimbs of post-metamorphic L. peronii scaled geometrically (body mass exponent approximately 0.33), the hindlimbs of metamorphs showed greater proportional increases with body mass (mass exponents of 0.41-0.42).