Showing papers by "James Cook University published in 2001"

Historical overfishing and the recent collapse of coastal ecosystems.

Abstract: Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.

Regional-scale assembly rules and biodiversity of coral reefs.

Abstract: Tropical reef fishes and corals exhibit highly predictable patterns of taxonomic composition across the Indian and Pacific Oceans. Despite steep longitudinal and latitudinal gradients in total species richness, the composition of these key taxa is constrained within a remarkably narrow range of values. Regional-scale variation in reef biodiversity is best explained by large-scale patterns in the availability of shallow-water habitat. Once habitat area is accounted for, there is surprisingly little residual effect of latitude or longitude. Low-diversity regions are most vulnerable to human impacts such as global warming, underscoring the urgent need for integrated management at multinational scales.

Patterns of coral–dinoflagellate associations in Acropora: significance of local availability and physiology of Symbiodinium strains and host–symbiont selectivity

Abstract: Like other reef-building corals, members of the genus Acropora form obligate endosymbioses with dinoflagellates (zooxanthellae) belonging to the genus Symbiodinium. Both Symbiodinium and its hosts are diverse assemblages, and the relationships between host and algal genotypes are unclear. In this study, we determined phylogenetic relationships between Symbiodinium isolates from a wide range of Acropora species and plotted the algal genotypes onto a molecular phylogeny of 28 Acropora species, using the same samples for the host and symbiont genotyping. In addition, we performed a preliminary survey of zooxanthella distribution in Acropora species from the central Great Barrier Reef. Three of the four known major zooxanthellae clades were represented in the 168 samples examined, and within the major clade C, three distinct subclades were identified. No evidence was found for coevolution, but several clear patterns of specificity were identified. Moreover, composition of the zooxanthella pool varied among locales and in one host species we found light-related patterns of zooxanthella distribution.

Can older males deliver the good genes

Abstract: Females of many species choose to mate with old rather than young males, possibly because older males pass superior genes on to their offspring. Recent theoretical and empirical investigations have rejuvenated interest in the evolution of mating preferences based on age, and in the relationship between longevity and fitness. If the cost of signalling is a reduction in future survival and reproduction, mate choice based on age is one possible outcome when males signal their genetic quality. These recent investigations highlight the importance of understanding sexual selection from a life-history perspective.

The Evolutionary History of the Coral Genus Acropora (Scleractinia, Cnidaria) Based on a Mitochondrial and a Nuclear Marker: Reticulation, Incomplete Lineage Sorting, or Morphological Convergence?

Abstract: This study examines molecular relationships across a wide range of species in the mass spawning scleractinian coral genus Acropora. Molecular phylogenies were obtained for 28 species using DNA sequence analyses of two independent markers, a nuclear intron and the mtDNA putative control region. Although the compositions of the major clades in the phylogenies based on these two markers were similar, there were several important differences. This, in combination with the fact that many species were not monophyletic, suggests either that introgressive hybridization is occurring or that lineage sorting is incomplete. The molecular tree topologies bear little similarity to the results of a recent cladistic analysis based on skeletal morphology and are at odds with the fossil record. We hypothesize that these conflicting results may be due to the same morphology having evolved independently more than once in Acropora and/or the occurrence of extensive interspecific hybridization and introgression in combination with morphology being determined by a small number of genes. Our results indicate that many Acropora species belong to a species complex or syngameon and that morphology has little predictive value with regard to syngameon composition. Morphological species in the genus often do not correspond to genetically distinct evolutionary units. Instead, species that differ in timing of gamete release tend to constitute genetically distinct clades.

Female guppies agree to differ: phenotypic and genetic variation in mate-choice behavior and the consequences for sexual selection

Abstract: Variation among females in mate choice may influence evolution by sexual selection. The genetic basis of this variation is of interest because the elaboration of mating preferences requires additive genetic variation in these traits. Here we measure the repeatability and heritability of two components of female choosiness (responsiveness and discrimination) and of female preference functions for the multiple ornaments borne by male guppies (Poecilia reticulata). We show that there is significant repeatable variation in both components of choosiness and in some preference functions but not in others. There appear to be several male ornaments that females find uniformly attractive and others for which females differ in preference. One consequence is that there is no universally attractive male phenotype. Only responsiveness shows significant additive genetic variation. Variation in responsiveness appears to mask variation in discrimination and some preference functions and may be the most biologically relevant source of phenotypic and genetic variation in mate-choice behavior. To test the potential evolutionary importance of the phenotypic variation in mate choice that we report, we estimated the opportunity for and the intensity of sexual selection under models of mate choice that excluded and that incorporated individual female variation. We then compared these estimates with estimates based on measured mating success. Incorporating individual variation in mate choice generally did not predict the outcome of sexual selection any better than models that ignored such variation.

Direct and indirect sexual selection and quantitative genetics of male traits in guppies (Poecilia reticulata).

Abstract: The ornamentation and displays on which sexual attractiveness and thus mating success are based may be complex and comprise several traits. Predicting the outcome of sexual selection on such complex phenotypes requires an understanding of both the direct operation of selection on each trait and the indirect consequences of selection operating directly on genetically correlated traits. Here we report the results of a quantitative genetic analysis of the ornamentation, sexual attractiveness, and mating success of male guppies (Poecilia reticulata). We analyze male ornamentation both from the point of view of single ornamental traits (e.g., the area of each color) and of composite measures of the way the entire pattern is likely to be perceived by females (e.g., the mean and contrast in chroma). We demonstrate that there is substantial additive genetic variation in almost all measures of male ornamentation and that much of this variation may be Y linked. Attractiveness and mating success are positively correlated at the phenotypic and genetic level. Orange area and chroma, the area of a male's tail, and the color contrast of his pattern overall are positively correlated with attractiveness and/or mating success at the phenotypic and genetic levels. Using attractiveness and mating success as measures of fitness, we estimate gradients of linear directional sexual selection operating on each male trait and use equations of multivariate evolutionary change to predict the response of male ornamentation to this sexual selection. From these analyses, we predict that indirect selection may have important effects on the evolution of male guppy color patterns.

Orbitally induced oscillations in the East Antarctic ice sheet at the Oligocene/Miocene boundary

Abstract: Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3–4 °C warmer than at present and atmospheric CO2 concentrations were twice as high as today1, the Antarctic ice sheets may have been unstable2, 3, 4, 5, 6, 7. Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles8, 9, 10. But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets11. Here we present sediment data from shallow marine cores in the western Ross Sea that exhibit well dated cyclic variations, and which link the extent of the East Antarctic ice sheet directly to orbital cycles during the Oligocene/Miocene transition (24.1–23.7 Myr ago). Three rapidly deposited glacimarine sequences are constrained to a period of less than 450 kyr by our age model, suggesting that orbital influences at the frequencies of obliquity (40 kyr) and eccentricity (125 kyr) controlled the oscillations of the ice margin at that time. An erosional hiatus covering 250 kyr provides direct evidence for a major episode of global cooling and ice-sheet expansion about 23.7 Myr ago, which had previously been inferred from oxygen isotope data (Mi1 event5).

The effect of exogenous abscisic acid on stomatal development, stomatal mechanics, and leaf gas exchange in Tradescantia virginiana.

Abstract: Gas exchange parameters and stomatal physical properties were measured in Tradescantia virginiana plants grown under well-watered conditions and treated daily with either distilled water (control) or 3.0 mM abscisic acid (ABA). Photosynthetic capacity (CO(2) assimilation rate for any given leaf intercellular CO(2) concentration [c(i)]) and relative stomatal sensitivity to leaf-to-air vapor-pressure difference were unaffected by the ABA treatment. However, at an ambient CO(2) concentration (c(a)) of 350 micromol mol(-1), ABA-treated plants operated with significantly lower c(i). ABA-treated plants had significantly smaller stomata and higher stomatal density in their lower epidermis. Stomatal aperture versus guard cell pressure (P(g)) characteristics measured with a cell pressure probe showed that although the form of the relationship was similar in control and ABA-treated plants, stomata of ABA-treated plants exhibited more complete closure at P(g) = 0 MPa and less than half the aperture of stomata in control plants at any given P(g). Scaling from stomatal aperture versus P(g) to stomatal conductance versus P(g) showed that plants grown under ABA treatment would have had significantly lower maximum stomatal conductance and would have operated with lower stomatal conductance for any given guard cell turgor. This is consistent with the observation of lower c(i)/c(a) in ABA-treated plants with a c(a) of 350 micromol mol(-1). It is proposed that the ABA-induced changes in stomatal mechanics and stomatal conductance versus P(g) characteristics constitute an improvement in water-use efficiency that may be invoked under prolonged drought conditions.

Mechanisms of fluid flow and fluid–rock interaction in fossil metamorphic hydrothermal systems inferred from vein–wallrock patterns, geometry and microstructure

Abstract: Comparison of mass transfer patterns, geometry and microstructures developed within and around veins allows the interpretation of processes of fluid flow during deformation, metamorphism and mineralization. A classification of vein types based on the degree of interaction with wallrock (using petrological, geochemical or isotopic indicators) can be used to identify a range of processes, from closed system behaviour in which the vein mass is derived from local wallrock, through to open system behaviour in which the vein mass is derived externally. Microstructural characteristics, such as wallrock selvages, multiple growth events recorded by vein seams and vein crystal morphology, also help to constrain mass transfer patterns during vein formation. We present a range of processes for vein formation, including: (i) the formation of closed system fibrous veins by dissolution–precipitation creep, including varieties in which tensile failure is not required; (ii) pressure- or kinetically dependent closed system segregation veins in which transfer of soluble components from wallrock to vein leaves behind a residual selvage; (iii) similar vein–selvage patterning, but with mass imbalances between vein and wallrock requiring fluid advection through both interconnected fracture networks and in the surrounding permeable rock; and (iv) the proposed formation of veins by fluid ascent in mobile hydrofractures, in which isotopic or chemical disequilibrium within and around the vein suggests that the crack and fluid within it moved essentially as one. The postulate of rapid fluid and mass transfer via such mobile hydrofractures has implications for the release of volatiles from metamorphic terrains. Also, consideration of a broad range of possible vein-forming mechanisms is highly desirable when dealing with mineral deposits found in deformed, metamorphosed rocks, because closed system veining may produce patterns that, if erroneously recognized as being open systems, could lead to false interpretations of the role of tectonic fracturing in ore genesis.

Myrtaceae revisited: a reassessment of infrafamilial groups

Abstract: Cladistic analyses are presented of matK sequence data as well as a nonmolecular database for an identical set of exemplar species chosen to represent the core genera or groups of genera in Myrtaceae. Eleven robust clades are recognized on the molecular data. Polyphyly of the previously recognized Metrosideros and Leptospermum alliances is confirmed, and several smaller informal taxonomic groupings are recognized from among the members of the former alliance, i.e., the Tristania, Tristaniopsis, Metrosideros, and Lophostemon groups. The nonmolecular analysis provides only limited resolution of relationships. A degree of congruence exists between the two analyses in that two separate fleshy-fruited clades, the Acmena and Myrtoid groups, are identified, as are the Eucalypt and Tristania groups, and Psiloxylon and Heteropyxis are the first lineages to diverge in both analyses. A combined analysis recognized all 11 clades that received strong support from the molecular data. A high level of homoplasy is revealed in many of the nonmolecular characters when they are examined against the combined estimate of phylogeny.

Environmental factors associated with the spatial distribution of crustose coralline algae on the Great Barrier Reef

Abstract: Crustose coralline algae (CCA) fulfill two key functional roles in coral reef ecosystems: they contribute significantly to reef calcification, and they induce larval settlement of many benthic organisms. Percentage cover of CCA, and environmental conditions, were visually estimated on 144 reefs of the Great Barrier Reef between 10 and 24° latitude S. Reefs were located across the shelf and ranged from turbid near-shore reefs close to rivers to clean-water reefs hundreds of kilometers from coastal influences. On each reef, two sites were surveyed between 0.5 and 18 m depth. Strong cross-shelf trends occurred in cover of CCA, amount of sediment deposited, water clarity, and slope angle. Relative distance across the shelf and sedimentation jointly explained 84% of variation in CCA cover. Three regions running parallel to the shore were identified, with a mean CCA cover of 20% cover on the outer half of the shelf, with a narrow transition region between the two. Within each region, the cover of CCA was unrelated to distance across the shelf, but was related to the sedimentary environment, being relatively higher on reefs with low sediment deposits. On the inner third of the shelf, the most sediment-exposed reefs were unsuitable habitats for CCA. The inverse relationship between CCA and sediment has implications for the recruitment of CCA-specialised organisms, and for rates of reef calcification.

High frequency of ‘super-cyclones’ along the Great Barrier Reef over the past 5,000 years

Abstract: Understanding long-term variability in the occurrence of tropical cyclones that are of extreme intensity is important for determining their role in ecological disturbances1,2,3,4,5, for predicting present and future community vulnerability and economic loss6 and for assessing whether changes in the variability of such cyclones are induced by climate change7. Our ability to accurately make these assessments has been limited by the short (less than 100 years) instrumented record of cyclone intensity. Here we determine the intensity of prehistoric tropical cyclones over the past 5,000 years from ridges of detrital coral and shell deposited above highest tide and terraces that have been eroded into coarse-grained alluvial fan deposits. These features occur along 1,500 km of the Great Barrier Reef and also the Gulf of Carpentaria, Australia. We infer that the deposits were formed by storms with recurrence intervals of two to three centuries8,9,10,11, and we show that the cyclones responsible must have been of extreme intensity (central pressures less than 920 hPa). Our estimate of the frequency of such ‘super-cyclones’ is an order of magnitude higher than that previously estimated (which was once every several millennia12,13,14), and is sufficiently high to suggest that the character of rainforests and coral reef communities were probably shaped by these events.

Market competition, computer-aided manufacturing and use of multiple performance measures: an empirical study

Abstract: This paper reports the results of an empirical investigation into use of multiple measures of performance in manufacturing organisations. More specifically, it examines how a multiple performance measurement system is associated with the intensity of market competition and the application of computer-aided manufacturing processes. To test this association, data were collected from 71 New Zealand-based manufacturing units. The results suggest that greater emphasis on multiple measures for performance evaluation is associated with businesses facing high competition and making greater use of computer-aided manufacturing processes.

Biogeographical concordance and efficiency of taxon indicators for establishing conservation priority in a tropical rainforest biota.

Abstract: Prioritizing areas for conservation requires the use of surrogates for assessing overall patterns of biodiversity. Effective surrogates will reflect general biogeographical patterns and the evolutionary processes that have given rise to these and their efficiency is likely to be influenced by several factors, including the spatial scale of species turnover and the overall congruence of the biogeographical history. We examine patterns of surrogacy for insects, snails, one family of plants and vertebrates from rainforests of northeast Queensland, an area characterized by high endemicity and an underlying history of climate-induced vicariance. Nearly all taxa provided some level of prediction of the conservation values for others. However, despite an overall correlation of the patterns of species richness and complementarity, the efficiency of surrogacy was highly asymmetric; snails and insects were strong predictors of conservation priorities for vertebrates, but not vice versa. These results confirm predictions that taxon surrogates can be effective in highly diverse tropical systems where there is a strong history of vicariant biogeography, but also indicate that correlated patterns for species richness and/or complementarity do not guarantee that one taxon will be efficient as a surrogate for another. In our case, the highly diverse and narrowly distributed invertebrates were more efficient as predictors than the less diverse and more broadly distributed vertebrates.

Conflict, Politics and Crime: Aboriginal Communities and the Police

Abstract: Acknowledgments..List of acronyms..List of tables..1. Introduction..2. The criminalisation of indigenous people..3. The nature of colonial policing..4. From over-policing to zero tolerance..5. Terror, violence and the abuse of human rights..6. Police culture and the use of discretion..7. Policing indigenous women..8. Governance and the policing of contested space..9. The reform of policing policies..10. Policing and postcolonial self-determination..Conclusion..Endnotes..Bibliography..Index

Ecology. Global amphibian population declines.

Abstract: The decline and disappearance of relatively undisturbed populations of amphibians in several high-altitude regions since the 1970s suggests that they may have suffered a global decline, perhaps with a common cause or causes¹⁻³. Houlahan et al.⁴ examined means of trends for 936 amphibian populations and concluded that global declines began in the late 1950s, peaked in the 1960s, and have continued at a reduced rate since. Here we re-analyse their data using a method that accounts for the sampling of different populations over different time periods, and find evidence of a mean global decline in monitored populations only in the 1990s. However it is calculated, the global mean not only masks substantial spatial and temporal variation in population trends and sampling effort, but also fails to distinguish between a global decline with global causes and the cumulative effects of local declines with local causes.

The relationship between swimming ability and habitat use in wrasses (Labridae)

Abstract: Habitat use is described for a local assemblage of wrasses (family Labridae) at the among-habitat and microhabitat scales of two fringing reef sites at Lizard Island, northern Great Barrier Reef. Visual censuses were used to determine the distribution and abundance of species in five reef habitat zones, and their relative positions within the water column over the reef flat. Based on previous theoretical and empirical analysis of labrid locomotion, mean pectoral fin aspect-ratio residuals were used as an estimate of swimming performance to examine the relationship between swimming ability and habitat use. Among-habitat distributions of inferred swimming ability displayed a distinct dichotomy between shallow and deep reef habitat zones, suggesting a relationship with wave energy. High wave energy (shallow) habitats were characterised by labrids with high (above 0.2) pectoral fin aspect-ratio residuals (fish that use lift-based swimming and achieve high sustained swimming speeds). Although low (below –0.2) aspect-ratio residual species were only in abundance in low wave energy (deeper) habitats, they were also present in low numbers (<7 individuals/100 m2) on the high wave energy reef flat. Water-column use within the reef flat indicated that these low aspect-ratio residual species display a restricted use of the water column and may use substratum complexity and boundary layer effects as a refuge from high levels of water movement. Overall, locomotor morphology was a good predictor of among-habitat and microhabitat use for wrasses at this location. We propose that locomotor performance may be a general force in shaping habitat use by wrasses over these two spatial scales. Some deviations from these general patterns are discussed with regard to the role of behaviour as a mediating factor between morphology and ecology.

Trawling and bottlenose dolphins' social structure.

Abstract: Human activities can affect the behaviour of mammals through the modification of habitats, changes in predation pressure or alterations in food distribution and availability. We analysed the association and ranging patterns of 242 individually identified bottlenose dolphins (Tursiops aduncus) in eastern Moreton Bay, Queensland, Australia, and distinguished two separate communities of dolphins. Unlike bottlenose dolphins elsewhere, the communities' core areas overlapped substantially. There was a correlation between the dolphins' responses to fishing activities and community membership-members of one community feed in association with trawlers and members of the other do not. Apart from feeding mode, the communities differed in habitat preference and group sizes. Inadvertent anthropogenic impacts on animals' societies are likely to be far more widespread than just this study and can increase conservation challenges. In this instance, managers need to consider the two communities' differing habitat requirements and their behavioural traditions in conservation planning.

Locomotion in labrid fishes: implications for habitat use and cross-shelf biogeography on the Great Barrier Reef

Abstract: Coral reefs exhibit marked zonation patterns within single reefs and across continental shelves. For sessile organisms these zones are often related to wave exposure. We examined the extent to which wave exposure may shape the distribution patterns of fishes. We documented the distribution of 98 species of wrasses and parrotfishes at 33 sites across the Great Barrier Reef. The greatest difference between labrid assemblages was at the habitat level, with exposed reef flats and crests on mid- and outer reefs possessing a distinct faunal assemblage. These exposed sites were dominated by individuals with high pectoral fin aspect ratios, i.e. fishes believed to be capable of lift-based swimming which often achieve high speeds. Overall, there was a strong correlation between estimated swimming performance, as indicated by fin aspect ratio, and degree of water movement. We propose that swimming performance in fishes limits access to high-energy locations and may be a significant factor influencing habitat use and regional biogeography of reef fishes.

Interspecific competition and coexistence in a guild of coral-dwelling fishes

Abstract: We investigated the effects of interspecific competition on abundance, habitat partitioning, and coexistence of six closely related species of gobies (genus Gobiodon) that inhabit a range of acroporid coral species at Lizard Island, Great Barrier Reef. After documenting the extent of overlap in habitat use among pairs of species in the field, we used a combination of field and laboratory experiments to investigate the relationship between these patterns and the occurrence of interspecific competition. Experiments in aquaria tested the ability of five of the species to compete against G. histrio, the apparent competitive dominant, including the effects of body size and prior residency. A manipulative field experiment, in which abundance of G. histrio was reduced, tested whether competition with this species limits the abundance of the other five species. Two species competed for space with G. histrio in the field, yet overlap in habitat use with G. histrio was high for one of these species (G. axillaris) and low for the other (G. brochus). In aquaria, G. axillaris and G. histrio preferred the same species of coral and had equivalent, size-based, competitive abilities. The coexistence of G. axillaris and G. histrio at the scale of 10’s metres on the reef can thus be explained by a competitive lottery model. However, differential distributions of these two species across the reef flat and reef crest suggests that resource partitioning or habitat selection at larger spatial scales are also important to their coexistence. In aquaria, G. brochus was an inferior competitor to G. histrio and could only gain access to the preferred species of coral through an advantage in body size or prior residency. Low overlap in habitat use between G. brochus and G. histrio in the field appears to result from niche shifts by the subordinate competitor only, indicating coexistence via an included niche model. The field experiment indicated that the other three other species did not compete for space with G. histrio, and these species exhibited either low (G. rivulatus) or high (G. quinquestrigatus and G. unicolor) overlap in habitat use with G. histrio. Experiments in aquaria demonstrated that G. rivulatus and G. histrio did not compete because they preferred different species of coral. In contrast, G. unicolor and G. histrio exhibited high overlap in habitat use but did not compete because they were able to co-habit the same coral colonies without affecting each other. In aquaria, G. quinquestrigatus and G. histrio preferred the same coral species and G. quinquestrigatus was an inferior competitor, so these species were expected to compete for space in the field. In a field recolonization experiment, coral colonies previously occupied by G. quinquestrigatus were rarely recolonized by G. histrio, indicating that these species coexist because they use different types of coral colonies in the field. The study demonstrates that there is no single relationship between overlap in resource use and the occurrence of interspecific competition, even among closely related species, and that species within a guild can coexist by a diversity of mechanisms.

Polyandry in social Hymenoptera — disunity in diversity?

Abstract: Multiple mating by queens occurs in many species of social Hymenoptera despite its likely costs. Hypotheses to explain multiple mating include a need for more sperm than provided by a single male, the convergence of queen and worker sex-allocation optima and various genetic diversity hypotheses. For some species the sperm need hypothesis fails since queens retain only a single male’s worth of sperm. In other cases, sperm store does increase with the number of matings. Similarly for the sex-allocation and genetic diversity hypotheses, data from some species are in support, those from others are not. Comparative analysis reveals a negative correlation between level of genetic diversity (of which queen mate number is an important determinant) and parasite load; findings in the best-studied case are complex: monandry and higher levels of polyandry are each selectively favored over moderate polyandry. Out of 14 identifiable hypotheses five are judged most useful for future work. Unfortunately, the search for a simple unitary model to explain all cases seems futile. A model encompassing all of these factors is desirable for studies on single species, but would be complex. Comparative analyses remain desirable, but should encompass the likelihood that different factors predominate in different groups.

Expression and evolution of functionally distinct haemoglobin genes in plants.

Abstract: Haemoglobin genes have been found in a number of plant species, but the number of genes known has been too small to allow effective evolutionary inferences. We present nine new non-symbiotic haemoglobin sequences from a range of plants, including class 1 haemoglobins from cotton, Citrus and tomato, class 2 haemoglobins from cotton, tomato, sugar beet and canola and two haemoglobins from the non-vascular plants, Marchantia polymorpha (a liverwort) and Physcomitrella patens (a moss). Our molecular phylogenetic analysis of all currently known non-symbiotic haemoglobin genes and a selection of symbiotic haemoglobins have confirmed the existence of two distinct classes of haemoglobin genes in the dicots. It is likely that all dicots have both class 1 and class 2 non-symbiotic haemoglobin genes whereas in monocots we have detected only class 1 genes. The symbiotic haemoglobins from legumes and Casuarina are related to the class 2 non-symbiotic haemoglobins, whilst the symbiotic haemoglobin from Parasponia groups with the class 1 non-symbiotic genes. Probably, there have been two independent recruitments of symbiotic haemoglobins. Although the functions of the two non-symbiotic haemoglobins remain unknown, their patterns of expression within plants suggest different functions. We examined the expression in transgenic plants of the two non-symbiotic haemoglobins from Arabidopsis using promoter fusions to a GUS reporter gene. The Arabidopsis GLB1 and GLB2 genes are likely to be functionally distinct. The class 2 haemoglobin gene (GLB2) is expressed in the roots, leaves and inflorescence and can be induced in young plants by cytokinin treatment in contrast to the class 1 gene (GLB1) which is active in germinating seedlings and can be induced by hypoxia and increased sucrose supply, but not by cytokinin treatment.

A small region of the dengue virus-encoded RNA-dependent RNA polymerase, NS5, confers interaction with both the nuclear transport receptor importin-beta and the viral helicase, NS3.

Abstract: The dengue virus RNA-dependent RNA polymerase, NS5, and the protease/helicase, NS3, are multidomain proteins that have been shown to interact both in vivo and in vitro. A hyperphosphorylated form of NS5 that does not interact with NS3 has been detected in the nuclei of virus-infected cells, presumably as the result of the action of a functional nuclear localization sequence within the interdomain region of NS5 (residues 369–405). In this study, it is shown by using the yeast two-hybrid system that the C-terminal region of NS3 (residues 303–618) interacts with the N-terminal region of NS5 (residues 320–368). Further, it is shown that this same region of NS5 is also recognized by the cellular nuclear import receptor importin-β. The interaction between NS5 and importin-β and competition by NS3 with the latter for the same binding site on NS5 were confirmed by pull-down assays. The direct interaction of importin-β with NS5 has implications for the mechanism by which this normally cytoplasmic protein may be targetted to the nucleus.

Fighting without weaponry: a review of male-male contest competition in butterflies

Abstract: The males of many butterfly species compete via pair-wise intrasexual contests, yet lack any obvious morphological traits conventionally associated with animal aggression. The evolution of contest behavior in this group is therefore interesting because the means by which individuals are able to inflict costs upon each other during combat are unclear. Here we review the relevant empirical information within a game-theoretical context in order to analyze contest-related costs and mechanisms of dispute settlement. Territorial butterfly contests carry obvious role asymmetries, and individuals in the 'resident' role are more likely to win across all studied species. We use this phenomenon as a framework for gaining further insight into the evolution of contest settlement in this group. Four principal hypotheses are evaluated: (1) that residency is used as an arbitrary convention, (2) that residents stand to gain a greater payoff if successful, (3) that residency bestows higher resource-holding potential (RHP) on males in that role, and (4) that residents are males of intrinsically higher RHP. We found most support for the latter explanation (the 'superior-competitor' hypothesis), partly because the alternatives require a restrictive set of ecological conditions, but also due to positive support for the idea of intrinsic RHP. The strongest evidence is provided by species in which repeated interactions (between the same individuals) always have the same outcome, regardless of changes in residency status. However, we also found a consistent effect on contest duration due to apparent 'confusion over residency,' which suggests a conventional element to contest behavior. Although butterfly contests must be costly in some way, the literature provides limited insight into how costs accrue, and hence the determinants of contest RHP remain obscure. We suggest that careful experimentation, using 'natural' manipulations where possible, should prove most beneficial in identifying costs and exploring schedules of contest settlement in this group. Moreover, future investigations should be sensitive to the fact that butterfly territoriality and associated male-male interactions are seated within a broader ecological and life-historical context.

The hydrodynamic and sedimentary setting of nearshore coral reefs, central Great Barrier Reef shelf, Australia: Paluma Shoals, a case study

Abstract: The Great Barrier Reef (GBR) shelf contains a range of coral reefs on the highly turbid shallow inner shelf, where interaction occurs with terrigenous sediments. The modern hydrodynamic and sedimentation regimes at Paluma Shoals, a shore-attached ‘turbid-zone’ coral reef, and at Phillips Reef, a fringing reef located 20 km offshore, have been studied to document the mechanisms controlling turbidity. At each reef, waves, currents and near-bed turbidity were measured for a period of ≈1 month. Bed sediments were sampled at 135 sites. On the inner shelf, muddy sands are widespread, with admixed terrigenous and carbonate gravel components close to the reefs and islands, except on their relatively sheltered SW side, where sandy silty clays occur. At Paluma Shoals, the coral assemblage is characteristic of inner-shelf or sheltered habitats on the GBR shelf (dominated by Galaxea fascicularis, up to >50% coral cover) and is broadly similar to that at Phillips Reef, further offshore and in deeper water. The sediments of the Paluma Shoals reef flats consist of mixed terrigenous and calcareous gravels and sands, with intermixed silts and clays, whereas the reef slope is dominated by gravelly quartz sands. The main turbidity-generating process is wave-driven resuspension, and turbidity ranges up to 175 nephelometric turbidity units (NTU). In contrast, at Phillips Reef, turbidity is 40 NTU probably occurs for a total of >40 days each year, and relatively little time is spent at intermediate turbidities (15–50 NTU). The extended time spent at either low or high turbidities is consistent with the biological response of some species of corals to adopt two alternative mechanisms of functioning (autotrophy and heterotrophy) in response to different levels of turbidity. Sedimentation rates over periods of hours may reach the equivalent of 10 000 times the mean global background terrigenous flux (BTF) of sediment to the sea floor, i.e. 10 000 BTF, over three orders of magnitude greater than the Holocene average for Halifax Bay of <3 BTF. As elsewhere along the nearshore zone of the central GBR, dry-season hydrodynamic conditions form a primary control upon turbidity and the distribution of bed sediments. The location of modern nearshore coral reefs is controlled by the presence of suitable substrates, which in Halifax Bay are Pleistocene and early Holocene coarse-grained (and relatively stable) alluvial deposits.

Cytometric and functional analyses of NK and NKT cell deficiencies in NOD mice.

Abstract: Defects in NK and NKT cell activities have been implicated in the etiology of type 1 (autoimmune) diabetes in NOD mice on the basis of experiments performed using surrogate phenotypes for the identification of these lymphocyte subsets. Here, we have generated a congenic line of NOD mice (NOD.b-Nkrp1(b)) which express the allelic NK1.1 marker, enabling the direct study of NK and NKT cells in NOD mice. Major deficiencies in both populations were identified when NOD.b-Nkrp1(b) mice were compared with C57BL/6 and BALB.B6-Cmv1(r) mice by flow cytometry. The decrease in numbers of peripheral NK cells was associated with an increase in their numbers in the bone marrow, suggesting that a defect in NK cell export may be involved. In contrast, the most severe deficiency of NKT cells found was in the thymus, indicating that defects in thymic production were probably responsible. The deficiencies in NK cell activity in NOD mice could only partly be accounted for by the reduced numbers of NK cells, and fewer NKT cells from NOD mice produced IL-4 following stimulation, suggesting that NK and NKT cells from NOD mice shared functional deficiencies in addition to their numerical deficiencies. Despite the relative lack of IL-4 production by NOD NKT cells, adoptive transfer of alpha beta TCR(+)NK1.1(+) syngeneic NKT cells into 3-week-old NOD recipients successfully prevented the onset of spontaneous diabetes. As both NK and NKT cells play roles in regulating immune responses, we postulate that the synergistic defects reported here contribute to the susceptibility of NOD mice to autoimmune disease.