bluuebunny/crossref_metadata_2025 huggingface dataset:
Presidential Address 1988 After the first 200 years: The future of ecology and ecologists in Australia
Authors: McCOMB ARTHUR J.
Published: August 2010

This Address examines the current concerns of ecologists. There is instability in the organization of science at a political level, in funding bodies, and in organizations such as CSIRO and tertiary education institutions. There is less funding for research and development in Australia than in other developed countries, mainly because of poor funding from the private sector, and funds available to the new Australian Research Council are small in relation to applications for support. These factors affect career opportunities for ecologists, although students continue to be attracted to the area.

The state of the Australian environment leaves much to be desired, with widespread land degradation (including erosion and salination), deterioration in water quality, and disease in natural ecosystems; many species are endangered, and there is concern about forest management.

Widespread environmental problems occur despite the fact that, for more than a century, those concerned with land management have been educated in tertiary institutions. More might be done to equip graduates better for solving Australian problems, for informing the public about methods which can be used to correct environmental degradation, and for disseminating research results more directly to managers. While all scientists should emphasize the importance of basic research, it is argued that more recognition should be given to the application of science to management.

Among positive aspect of the present climate are a government commitment to increase numbers in senior school years and in tertiary institutions; entry of graduates into consulting work; use of conservation strategies to enhance interaction between ecology and industry as illustrated by mining, agriculture and forestry; increased activity by organizations which raise funds from the private sector; definition of research priorities; and the identification which Australians have with an image of the countryside.

With this framework of closer links between ecology, practical problem‐solving, and support from industry and the private sector, it is argued that significant progress will be made in the years ahead.
Phytophagous insect‐woody sprout interactions in tropical eucalypt forest. I. Insect herbivory
Authors: FENSHAM R. J.
Published: August 2010

Abstract
Foliar insect damage levels on woody sprouts in the ground layer of two tropical eucalypt forest communities on Melville Island were between 7.8 and 43.2%. Of eight common tree species, Eucalyptus confertiflora was damaged most by insects and Buchanania obovata and Terminalia ferdinandiana the least. Seasonal trends in insect damage were not consistent between plant species and were not always consistent between vegetation types for a particular plant species. The results of this study are not consistent with hypotheses suggesting that insect grazing is a critical determinant of tree species dominance or woody sprout dormancy.
Flora and fauna assemblages vary with local topography in a subtropical eucalypt forest
Authors: Catterall Carla P. , Piper Scott D. , Bunn Stuart E. , Arthur J. Michael
Published: August 2010

Local‐scale spatial patterning (over hundreds of metres) in terrestrial assemblages was investigated by sampling a variety of organisms within a 400 ha eucalypt forest area in the lowlands of south‐east Queensland. Organisms were trees, shrubs, birds, insects extracted from the litter layer, and insects caught in pitfall traps. Each group was sampled using a standardized methodology, and the component taxa were counted and identified to a level commonly used in ecological studies of that organism – varying from species to order levels. Sites adjacent to drainage lines or ephemeral streams were biotically more similar to one another than they were to paired upslope sites 100–200 m distant and 15–35 m higher in altitude. This phenomenon occurred irrespective of the level of taxonomic resolution or type of organism. Within each taxonomic group, some components were mainly riparian, while others were more characteristic of upslope sites. Characteristically riparian taxa included trees in the genus Glochidion, the shrub genus Leptospermum, birds in the Pachycephalidae and Meliphagidae families, and litter invertebrates in the order Acarina. Upslope taxa included shrubs in the Rutaceae, birds in the Artamidae, and ants. Within the groups of trees, birds and litter invertebrates, more taxa were characteristic of riparian than upslope sites. Local scale biotic patterns were more strongly correlated with altitude than with measured soil characteristics; however, microtopographical differences would also be highly correlated with a large suite of covarying environmental features. The patterns of diversity and the implications for survey design and conservation are discussed.
Disturbance mediates the effects of nutrients on developing assemblages of epibiota
Authors: VALDIVIA NELSON , STEHBENS JARROD D. , HERMELINK BJÖRN , CONNELL SEAN D. , MOLIS MARKUS , WAHL MARTIN
Published: August 2010

Local dynamics such as resource enhancement (e.g. nutrient supply) and stochastic events of destruction (disturbances that provide new space) are hypothesized to counteractively affect species diversity and composition. We tested the independent and interactive effects of nutrients and disturbance on the development of assemblages of epibiota attached to vertical surfaces in an oligotrophic system. Nutrient concentrations were manipulated at three levels (ambient, medium and high) while disturbance was manipulated by removing biomass at seven frequencies (0×, 2×, 3×, 4×, 5×, 7×, 12×). Nutrient and disturbance regimes had opposing effects on diversity such that species richness increased with resource enhancement (nutrients) and declined with disturbance. These results support the model that increased heterogeneity of distribution of limiting resources allows the coexistence of species with low and high resource requirements.
Cytokine response of electrolytic ablation in an ex vivo perfused liver model
Authors: Gravante Gianpiero , Ong Seok Ling , Metcalfe Matthew S. , Sorge Roberto , Overton John , Lloyd David M. , Maddern Guy J. , Dennison Ashley R.
Published: August 2010

Background:  The inflammatory response following hepatic ablation depends on different factors including the method used, the duration and intensity of the treatment and the presence or absence of ischemia. Debate continues about the use of different modalities and whether some aspects of the response may be advantageous by releasing immunological active substances. Little data have been published concerning the cytokine response elicited by hepatic electrolytic ablation (EA). Study of an ex vivo liver model could allow for the evaluation of this response without the influence of confounding systemic factors.

Methods:  Livers explanted from 11 pigs were perfused extracorporeally with normothermic autologous blood. Four of them underwent EA after 1 h of reperfusion. Serum samples were obtained up to 6 h after the reperfusion and assayed for IL‐1β, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, IL‐12, IFN‐γ, TNF‐α.

Results:  Significant changes in the control group were observed for IL‐6 after the second hour and IL‐8 after the first hour compared with baseline levels (P < 0.001). In the EA group, IL‐6 and IL‐12 were raised after the second hour and IL‐8 and IL‐10 after the first hour (P < 0.001). The comparison between groups showed significant differences for IL‐2, IL‐4 (decreased in the EA group compared with controls), IL‐10 and TNF‐α (EA group increased compared with controls; P < 0.001).

Conclusions:  The ex vivo perfused liver model demonstrated changes in levels of IL‐2, IL‐4, IL‐10 and TNF‐α following hepatic EA.
Leader Empowering Behaviour: The Leader's Perspective
Authors: Hakimi Natalia , Van Knippenberg Daan , Giessner Steffen
Published: August 2010

Leader empowering behaviour is an important criterion for leadership effectiveness. However, virtually no research has studied the antecedents of leader empowering behaviour. Therefore, to further our understanding of leadership effectiveness, we need to understand what motivates leaders to behave in certain ways. In two studies, we show how leaders' trust in follower performance and integrity influences leader empowering behaviour, and how this effect is moderated by leader conscientiousness. Study 1 showed that leader empowering behaviour depends not only on the trust leaders have in follower performance and integrity but also on the conscientiousness level of the leader. Study 2 replicated and extended these findings within a different experimental paradigm. We discuss how these findings set the stage for the development of a more comprehensive understanding of the drivers of this important aspect of leadership.
Dynamic Multi‐View Exploration of Shape Spaces
Authors: Busking Stef , Botha Charl P. , Post Frits H.
Published: August 2010

Statistical shape modeling is a widely used technique for the representation and analysis of the shapes and shape variations present in a population. A statistical shape model models the distribution in a high dimensional shape space, where each shape is represented by a single point.

We present a design study on the intuitive exploration and visualization of shape spaces and shape models. Our approach focuses on the dual‐space nature of these spaces. The high‐dimensional shape space represents the population, whereas object space represents the shape of the 3D object associated with a point in shape space.

A 3D object view provides local details for a single shape. The high dimensional points in shape space are visualized using a 2D scatter plot projection, the axes of which can be manipulated interactively. This results in a dynamic scatter plot, with the further extension that each point is visualized as a small version of the object shape that it represents. We further enhance the population‐object duality with a new type of view aimed at shape comparison. This new “shape evolution view” visualizes shape variability along a single trajectory in shape space, and serves as a link between the two spaces described above.

Our three‐view exploration concept strongly emphasizes linked interaction between all spaces. Moving the cursor over the scatter plot or evolution views, shapes are dynamically interpolated and shown in the object view. Conversely, camera manipulation in the object view affects the object visualizations in the other views. We present a GPU‐accelerated implementation, and show the effectiveness of the three‐view approach using a number of real‐world cases. In these, we demonstrate how this multi‐view approach can be used to visually explore important aspects of a statistical shape model, including specificity, compactness and reconstruction error.
Visualization and Analysis‐Oriented Reconstruction of Material Interfaces
Authors: Meredith Jeremy S. , Childs Hank
Published: August 2010

Reconstructing boundaries along material interfaces from volume fractions is a difficult problem, especially because the under‐resolved nature of the input data allows for many correct interpretations. Worse, algorithms widely accepted as appropriate for simulation are inappropriate for visualization. In this paper, we describe a new algorithm that is specifically intended for reconstructing material interfaces for visualization and analysis requirements. The algorithm performs well with respect to memory footprint and execution time, has desirable properties in various accuracy metrics, and also produces smooth surfaces with few artifacts, even when faced with more than two materials per cell.
Visualizing Summary Statistics and Uncertainty
Authors: Potter K. , Kniss J. , Riesenfeld R. , Johnson C.R.
Published: August 2010

The graphical depiction of uncertainty information is emerging as a problem of great importance. Scientific data sets are not considered complete without indications of error, accuracy, or levels of confidence. The visual portrayal of this information is a challenging task. This work takes inspiration from graphical data analysis to create visual representations that show not only the data value, but also important characteristics of the data including uncertainty. The canonical box plot is reexamined and a new hybrid summary plot is presented that incorporates a collection of descriptive statistics to highlight salient features of the data. Additionally, we present an extension of the summary plot to two dimensional distributions. Finally, a use‐case of these new plots is presented, demonstrating their ability to present high‐level overviews as well as detailed insight into the salient features of the underlying data distribution.
The Readability of Path‐Preserving Clusterings of Graphs
Authors: Archambault Daniel , Purchase Helen C. , Pinaud Bruno
Published: August 2010

Graph visualization systems often exploit opaque metanodes to reduce visual clutter and improve the readability of large graphs. This filtering can be done in a path‐preserving way based on attribute values associated with the nodes of the graph. Despite extensive use of these representations, as far as we know, no formal experimentation exists to evaluate if they improve the readability of graphs.

In this paper, we present the results of a user study that formally evaluates how such representations affect the readability of graphs. We also explore the effect of graph size and connectivity in terms of this primary research question. Overall, for our tasks, we did not find a significant difference when this clustering is used. However, if the graph is highly connected, these clusterings can improve performance. Also, if the graph is large enough and can be simplified into a few metanodes, benefits in performance on global tasks are realized. Under these same conditions, however, performance of local attribute tasks may be reduced.
Toward a Lagrangian Vector Field Topology
Authors: Fuchs Raphael , Kemmler Jan , Schindler Benjamin , Waser Jürgen , Sadlo Filip , Hauser Helwig , Peikert Ronald
Published: August 2010

In this paper we present an extended critical point concept which allows us to apply vector field topology in the case of unsteady flow. We propose a measure forunsteadinesswhich describes the rate of change of the velocities in a fluid element over time. This measure allows us to select particles for which topological properties remain intact inside a finite spatio‐temporal neighborhood. One benefit of this approach is that the classification of critical points based on the eigenvalues of the Jacobian remains meaningful. In the steady case the proposed criterion reduces to the classical definition of critical points. As a first step we show that finding an optimal Galilean frame of reference can be obtained implicitly by analyzing the acceleration field. In a second step we show that this can be extended by switching to the Lagrangian frame of reference. This way the criterion can detect critical points moving along intricate trajectories. We analyze the behavior of the proposed criterion based on two analytical vector fields for which a correct solution is defined by their inherent symmetries and present results for numerical vector fields.
An Exploratory Technique for Coherent Visualization of Time‐varying Volume Data
Authors: Tikhonova A. , Correa C. D. , Ma K.‐L.
Published: August 2010

The selection of an appropriate global transfer function is essential for visualizing time‐varying simulation data. This is especially challenging when the global data range is not known in advance, as is often the case in remote and in‐situ visualization settings. Since the data range may vary dramatically as the simulation progresses, volume rendering using local transfer functions may not be coherent for all time steps. We present an exploratory technique that enables coherent classification of time‐varying volume data. Unlike previous approaches, which require pre‐processing of all time steps, our approach lets the user explore the transfer function space without accessing the original 3D data. This is useful for interactive visualization, and absolutely essential for in‐situ visualization, where the entire simulation data range is not known in advance. Our approach generates a compact representation of each time step at rendering time in the form of ray attenuation functions, which are used for subsequent operations on the opacity and color mappings. The presented approach offers interactive exploration of time‐varying simulation data that alleviates the cost associated with reloading and caching large data sets.
Matrix Trees
Authors: Andrysco Nathan , Tricoche Xavier
Published: August 2010

We propose a new data representation for octrees and kd‐trees that improves upon memory size and algorithm speed of existing techniques. While pointerless approaches exploit the regular structure of the tree to facilitate efficient data access, their memory footprint becomes prohibitively large as the height of the tree increases. Pointerbased trees require memory consumption proportional to the number of tree nodes, thus exploiting the typical sparsity of large trees. Yet, their traversal is slowed by the need to follow explicit pointers across the different levels. Our solution is a pointerless approach that represents each tree level with its own matrix, as opposed to traditional pointerless trees that use only a single vector. This novel data organization allows us to fully exploit the tree's regular structure and improve the performance of tree operations. By using a sparse matrix data structure we obtain a representation that is suited for sparse and dense trees alike. In particular, it uses less total memory than pointer‐based trees even when the data set is extremely sparse. We show how our approach is easily implemented on the GPU and illustrate its performance in typical visualization scenarios.
Infliximab efficacy in nail psoriasis. A retrospective study in 48 patients
Authors: Fabroni C , Gori A , Troiano M , Prignano F , Lotti T
Published: August 2010

Background  Nail psoriasis occurs in up to half of psoriatic patients and can lead to significant physical impairment and pain. To date, patients and clinicians are actually dissatisfied by current therapeutic approaches.

Objective  Our main aim is to evaluate Infliximab efficacy in nail psoriasis.

Methods  We performed an open‐label and uncontrolled retrospective study considering all psoriatic patients presenting recalcitrant nail involvement and receiving Infliximab in our Department during the period between January 2008 and March 2009. We calculated nail psoriasis severity index (NAPSI) score at 0, 14, 22 and 38 weeks and percentage of patients achieving NAPSI‐50,‐75,‐90 at 14, 22 and 38 weeks.

Results  We observed a rapid nail improvement in most cases after 22 weeks of Infliximab therapy, but a complete nail clearing was reached in only five (10.4%) patients. We don’t have a follow‐up longer than 38 weeks to assess long‐term efficacy of this treatment in nail psoriasis.

Conclusions  Infliximab, in our experience, has proved to be effective in reducing nail lesions and, in some cases, even clearing them. Our data demonstrate long‐term efficacy of this biological agent in nail psoriasis.
Agreeing in Principle: Utilitarianism and Economic Values as Support for the European Union in Central and Eastern Europe
Authors: LOVELESS MATTHEW
Published: August 2010

Using new mass surveys in central and eastern Europe, this article tests utilitarianism and economic values as the bases of support for the European Union. Advancing our understanding, the empirical findings point to increasingly nuanced economic criteria as the perception of social inequality strongly and independently influences EU support.
An intertidal Rhabdopleura (Hemichordata, Pterobranchia) from Fiji
Authors: Dilly P. N. , Ryland J. S.
Published: August 2010

Rhabdopleura has been discovered living in coral rubble on reefs in Fiji. The habitat is unusual, being the underside of coral boulders in the intertidal zone. Some features of the environment and the fauna associated with the Rhabdopleura are briefly described. The Rhabdopleura zooids exhibit other modes of tube building besides the regular cylindrical horizontal and erect tubes. The colony ramifies through interstices in the dead coral and the zooids can line larger cavities within the coral with coenecial tissue. It is probably these cavities, together with the overall porosity of coral, that retain enough water to keep the zooids alive while the intertidal reef flat is exposed to the air. Within the depths of the coral the black stolons are frequently naked. The species is probably R. normani Allman.
The photophore morphology of Selenoteuthis scintillans Voss and other lycoteuthids (Cephalopoda: Lycoteuthidae)
Authors: Herring P. J. , Dilly P. N. , Cope Celia
Published: August 2010

Females and juveniles of Selenoteuthis scintillans have photophores of several structural types, distributed on the tentacles and eyeballs, and within the mantle cavity and tail. Three distinct photophore types can be recognized on the basis of their accessory structures, though their photocytes are identical. The tail and some tentacular photophores (Type 1) lack any accessory optical structures; other tentacular and abdominal photophores (Type 2) have collagenous diffusing fibres; the anal and ocular photophores (Type 3) have a variety of iridosomes but no collagen. The distal tentacular organ is a double structure composed of a unit each of Type 1 and Type 2. Ocular photophores 1 and 5 are also double structures, composed of two Type 3 units. The photophores closely resemble in structure those of Lycoteuthis diadema. The photocytes have a marked fluorescence and luminesce on treatment with dilute hydrogen peroxide. The bio‐luminescence intensity of the tail organ may be modified by chromatophore movements and has a blue‐green spectral emission.

The photophores of juvenile Lampadioteuthis megaleia are similar in structure to those of Selenoteuthis but somewhat less complex. A comparison between the morphology of the photophores of lycoteuthid and enoploteuthid squids emphasizes the close similarity between the two families. At the ultrastructural level, certain photophores of both families have very characteristic microvillous blood vessels associated with the photocytes.
The significance of sesamoids and retro‐articular processes for the mechanics of joints
Authors: Alexander R. McN. , Dimery Nicola J.
Published: August 2010

Extensor muscles may insert by means of flexible tendons that wrap round the joint, through rigid sesamoids, or on to retro‐articular processes. The three types of joint are examined, and equations are derived relating the force required in the muscle to the force exerted on the environment. A selection of mammalian joints are analysed to illustrate the theoretical conclusions.
Surface‐mound formation by the Tuco‐tuco, Ctenomys fulvus (Rodentia: Ctenomyidae), with comments on earth‐pushing in other fossorial mammals
Authors: Hickman Graham C.
Published: August 2010

Surface‐mound formation by Ctenomys fulvus (and evidently most Ctenomyidae, an autochthonous South American family) differs from most other fossorial mammals in that soil is transported to the surface by kicking with the hind feet (a habit shared with most Bathyergidae. the African mole‐rats). The greatly enlarged hind feet of Ctenomys are the largest for any terrestrial fossorial group. The eyes of Ctenomys, also different from many mole types, are large and appear better protected by hind foot soil‐pushing. The manner in which the stocky tail of Ctenomys supports the body above the substratum while kicking synchronously with the hind feet is unusual for any mammal.

The body facing forward while pushing soil, the position favoured by most mole‐types, allows for the scanning of the surface for predators and defence through the use of teeth, claws and direct vocalizing, while hind foot soil‐pushing conserves energy by negating the need to turn around in the tunnel after digging, and again after depositing soil on the surface. Studies are required to determine the efficiency of various predators on the capture of mole‐types as soil is being pushed on to the surface, perhaps the most significant selective pressure on the manner of pushing soil.
The ranging and nesting behaviour of Wood mice,Apodemus sylvaticus(Rodentia: Muridae), as revealed by radio‐tracking
Authors: WOLTON R. J.
Published: August 2010

The social organization, nightly movements and nesting behaviour of Wood mice.Apodemus sylvaticus(L.), were studied by radio‐tracking 35 individuals in a deciduous wood in north‐east Scotland. The radios, which were mounted on collars and weighed 2·4 g, were only attached to mice weighing more than 20 g. During the breeding season (mid‐March to December), when all the mice tracked were reproductively active, male ranges were on average 3·6 times as big (5110 m2) as those of females (1424 m2); male ranges overlapped considerably whilst females probably maintained ranges largely exclusive of one another. The ranges of males overlapped those of females apparently at random, each male's range encompassing parts of about five to ten females' ranges. Individuals' ranges changed position with time, although no total displacements were noted. No long‐term bisexual associations were recorded. Nests appeared to be located at random within ranges, and nest sites were changed frequently. In summer, mice nested solitarily, whilst in winter they nested in groups of up to at least three. Typically, mice moved extensively over their ranges each night, males moving further between successive radio‐fixes than females, and having fewer activity loci. Throughout the year, mice occasionally left their normal home ranges on excursions, sometimes over 100 m in length.
Elastic properties of the feet of deer (Cervidae)
Authors: Dimery Nicola J. , Ker R. F. , Alexander R. McN.
Published: August 2010

Dynamic tests have been performed on the feet of deer, and on tendons removed from the feet, to determine their elastic properties. The results have been used to calculate the strain energy stored in each foot while it is on the ground in a fast galloping stride. This is compared with an estimate of the work done by the leg, and the energy‐saving rǒle of tendon elasticity is assessed.
Growth and morphology of nestling Hooded crows Corvus corone cornix, a sexually dimorphic bird species
Authors: Rofstad Gunnar
Published: August 2010

The growth and morphology of nestling Hooded crows, Corvus corone cornix, were studied at Trondheim, Central Norway, during 1980 and 1981. The sexual size dimorphism of the nestlings developed while they were in the nest, but was less pronounced than that of the juvenile birds. Female young grew relatively faster than the males. The size variation of the morphological characters studied was greater in the males than in the females, during the entire nestling period. The order of development of the different morphological characters seemed to be adapted to the needs of the nestlings during the nestling period. Growth of the bone and bill characters was the highest priority, body weight and feather characters the lowest. In general, the sizes of the different morphological characters were highly intercorrelated, particularly those that developed at the same time during the growth period. In the favourable breeding season of 1981, the nestlings were larger than in the unfavourable season of 1980. The high priority characters of the males increased more in size than did those of the females, and the low priority characters of the females increased more in size than did those of the males. About 75% of the nestlings could be correctly sexed from their external morphological characteristics. The findings support the view that the parental cost of rearing a male offspring is greater than that of a female.
Energetics of age‐specific reproductive effort in female Harp seals, Phoca groenlandica
Authors: Atewart Robert E. A.
Published: August 2010

The theory of reproductive effort is commonly viewed in the perspective of the cost of offspring to the parent. This interpretation predicts that older females make a greater reproductive effort than younger females, for whom the cost of lost future offspring is less. The benefit early‐born offspring represent in future generations is greater than that of late‐born offspring in most natural populations, so, alternatively, young females should make a greater reproductive effort. These hypotheses were investigated in nursing Harp seals by examining age‐specific reproductive effort in terms of energetic maternal investment.

Younger Harp seal females lost weight at the same rate as did older females. Moreover. since younger, growing females tended to start lactation with less blubber than older females. weight loss during 10 days (d) of lactation represented a greater proportion of stored energy for young females. A successfully weaned pup, therefore, constituted a greater reproductive effort for them than for older females, consistent with benefit–oriented predictions from theory.

A model is presented to outline the components of an annual energy budget for female Harp seals in the context of reproductive effort. This model indicates that young females may devote a greater proportion of their annual net energy to reproduction and take a greater risk of lost future reproduction. It also identifies areas of inadequacy of existing data on pinniped energy budgets.
Peripheral innervation pattern in myotomal muscle of two teleosts as revealed by intracellular marking
Authors: Egginton S. , Johnston I. A.
Published: August 2010

Spinal nerves of abdominal and trunk segments from cod (Gadus morhua L.) and freshwater eel (Anguilla anguilla L.) were examined by light and electron microscopy and major differences in peripheral innervation patterns investigated.

Histochemically stained frozen sections clearly resolve the focal (terminal) innervation of eel fast fibres (one endplate/fibre) and the multiple innervation pattern of cod trunk muscle (around 20 endplates/fibre). Sub junctional folds are absent from eel and poorly developed in cod neuro‐muscular junctions (NMJs). A single population of synaptic vesicles with mean diameter of22–25 nm is found in the NMJs of both species.

Cobalt chloride was used as an intracellular marker to map the branching between spinal roots and fast muscle endplates. Evidence was obtained for substantial inter‐segmental branching of the ventral rami in cod but not in eel. Previous classification schemes, dividing fishes according to the presence of separate or mixed motor and sensory axon populations within the ventral rami, are shown to be dependent upon sample location. In this study, the ventral rami of both species contain mixed populations, having modal diameters around 2 μm and8–12 μm, with the proportion of small diameter (sensory) axons much higher in cod than eel. The results suggest a more coarse control of body curvature in cod but an increased importance of pro‐prioreceptors in generating the locomotory wave.
Temporal and spatial variation of dental pattern in the voles, Microtus arvalis, of the Orkney Islands
Authors: Corbet Gordon B.
Published: August 2010

A sample of first lower molars of Microtus arvalis of Neolithic age from the Orkney island of Westray was compared with respect to size and shape with other Neolithic and Recent samples of the species. The results show (1) a decline in size since the Neolithic on Westray (as on Orkney Mainland) and (2) divergence in shape between populations from Westray and Orkney Mainland since the Neolithic. Comparisons were also made with continental samples, and explanations of the origin and large size of the Orkney voles are reviewed.
Mechanical design of hedgehog spines and porcupine quills
Authors: Vincent J. F. V. , Owers P.
Published: August 2010

The spines or quills of hedgehogs and porcupines are morphologically and mechanically different. In simple terms, it seems that the quills of porcupines are proportioned to be as long as possible without bending too easily when loaded axially. By contrast, the spines of the hedgehog are as short as possible while still able to bend when loaded axially. In addition, the hedgehog spines have an internal morphology which delays the onset of local buckling under these loads, thus enabling the spines to absorb larger amounts of mechanical energy. By contrast, the quills of Hystrix are designed to break at the tip. Thus, whilst the quills of the porcupine seem to be well adapted for keeping an enemy as far away as possible, the spines of the hedgehog probably have this as an incidental function. Their main function is much more likely to be that of a shock absorber or storage of impact energy when the animal falls from a height, a behavioural attribute which is reportedly common.
Bark‐stripping by Grey squirrels (Sciurus carolinensis)
Authors: Kenward R. E. , Parish T.
Published: August 2010

To investigate why Grey squirrels strip bark from young trees, squirrel populations and tree quality were studied at 30 English Midland woods. In young beech and sycamore woodlands, the area of bark which Grey squirrels stripped from each tree was strongly related to the phloem width (volume per unit area) of the tree, and not to the phloem sugar content. Variation in bark‐stripping between woods was strongly related to average phloem widths in each plantation. The extent of bark‐stripping also correlated with juvenile squirrel density, but only in years with relatively little squirrel breeding. There was a tendency for damage to recur in previously damaged areas, in a pattern suggesting that squirrels had learned the habit. The results indicate that bark‐stripping can be initiated by young squirrels, perhaps through agonistic gnawing or exploratory feeding, or by older squirrels which have learned the habit, but that severe damage occurs only where the tree phloem is suitable.
The biology of terns nesting at Aldabra Atoll, Indian Ocean, with particular reference to breeding seasonality
Authors: Diamond A. W. , Prŷs‐Jones R. P.
Published: August 2010

Five species of tern breed on Aldabra Atoll (09° 24′ S; 46° 20′ E). The Caspian tern Sterna caspia and Crested tern S. bergii feed exclusively in very shallow reef/lagoon water, the Fairy tern Gygis alba and Brown noddy Anous stolidus feed out at sea, and the Black‐naped tern Sterna sumatrana is intermediate in its foraging. Both of the shallow‐water species lay during the south‐east monsoon season, the Caspian tern from April to August and the Crested tern from June to August, but the Crested tern also lays in December and January. The remaining three species have extended laying periods largely circumscribed by the north‐west monsoon season from November to March. Breeding population size of the Caspian tern is in the low tens and of the Brown noddy in the low thousands, with the other species each numbering in the hundreds. The distribution and abundance of the nine species of tern breeding within the Seychelles (sensu lato) vary on the different island groups in a manner interpretable in terms of depth of the surrounding waters. Systematic differences between the central Seychelles and Aldabra groups in timing of breeding by terns which feed out at sea may be associated with seasonal latitudinal movement of the divergence zone between the South Equatorial Current and the Equatorial Counter‐current, acting via correlated latitudinal shifts of prey species and game‐fish abundance.
Broadening the Extinction Debate: Population Deletions and Additions in California and Western Australia
Authors: Hobbs Richard J. , Mooney Harold A.
Published: August 2010

Current discussions of biodiversity frequently center on the question of species extinction, and much of conservation biology focuses on this topic. We argue that species extinction often represents the endpoint of a process of population extinctions, and that the deletion of populations over much of a species’ range is likely to be of as much or more concern than the final extinction of that species. Population extinctions often result from habitat destruction and modification, which can be widespread. The result is that species can be deleted from most of their former range but continue to persist in small refuge areas. Moreover, species additions in the form of invasive species are frequently more numerous than extinctions in any given area. Such invasions often result in dramatic changes in ecosystem structure or function and can be instrumental in hastening the extinction of native populations. We examine these premises using two examples from California and Western Australia. These two contrasting areas show broadly similar trends in species extinctions, range contractions, and invasions, and they illustrate the fact that, by concentrating on species extinctions, many of the important human effects on biodiversity can be overlooked.

Ampliando el Debate sobre Extinción: Eliminación y Adición de Poblaciones en California y Australia del Oeste

Discusiones recientes sobre biodiversidad frecuentemente se centran en la extinción de las especies y una buena parte de la biología de la conservación se enfoca en este tema. Nosotros argumentamos que la extinción de especies representa frecuentemente el punto final de un proceso de extinciones de poblaciones y que la desaparición de poblaciones en la mayoría del rango de una especie es probablemente tanto o mas preocupante como la extinción final de las especies. Extinciones de poblaciones constantemente resultan de la destrucción y modificación del hábitat; lo cual puedo ocurrir con una extensión amplia. El resultado es que las especies pueden ser eliminadas de la mayoría de su rango original, pero continúan persistiendo en pequeñas áreas de refugio. Mas aún, la adición de especies en forma de especies invasivas son con frecuencia mas numerosas que las extinciones en un área determinada. Estas invasiones resultan frecuentemente en cambios dramáticos en la estructura of función del ecosistema y pueden ser el instrumento acelerador de la extinción de especies nativas. Examinamos estas premisas usando los ejemplos de California y Australia del Oeste. Estas dos contrastantes áreas muestran amplias tendencias similares en la extinción de especies, contracciones en rangos de distribución e invasiones. Además ilustran el hecho de que al enfocarnos en la extinción de especies muchos de los impactos humanos importantes en la biodiversiadad pueden ser desestimados.
Present and Future Taxonomic Selectivity in Bird and Mammal Extinctions
Authors: Russell Gareth J. , Brooks Thomas M. , McKinney Michael M. , Anderson C. Gregory
Published: August 2010

We compared the distribution of historical bird and mammal species extinctions across genera and families with the distribution we would expect if these extinctions had occurred at random with respect to taxonomy. We then repeated the comparison for species listed in various categories of threat according to the 1996 Red List of the World Conservation Union. We found the distributions of extinctions and threat classifications to be almost always nonrandom—“selective”—with clustering in certain genera and families. Furthermore, extinctions tended to be clustered in taxa that contain few species; species in smaller genera tended to have higher probabilities of extinction. This tendency was strong for historical extinctions but was reduced or absent for some categories of threat. We attribute this to a change in the causes of extinction whereby predation and introduced species have been joined or superseded by widespread habitat loss. We then assessed the implications of this variable selectivity for the past and likely future losses of genera and families. In most cases, the number of lost taxa rises. Finally, we made predictions about minimum losses of taxa at specific dates in the future and showed that, despite the reduction in some forms of selectivity, we will still lose more taxa than if species extinctions were random.

Selectividad Taxonómica Presente y Futura Extinciones de Aves y Mamíferos

Se comparó la distribución de las extinciones históricas de especies de aves y mamíferos con la distribución que se esperaría si las extinciones hubieran ocurrido al azar con respecto a la taxonomía. La comparación fue repetida para las especies incluidas en distintas categorías de riesgo en la Lista Roja de la UICN. En casi todos los casos se encontró que las distribuciones de las extinciones y de las categorías de riesgo no estaban distribuidas al azar, sin que fueron ‘selectivas,’ con distribución agrupada en ciertos géneros y familias. Se observó, además, que las extinciones tendieron a estar agrupadas en taxones que contienen pocas especies; las especies en géneros más pequeños tienden a tener mayores probabilidades de extinción. Esta tendencia fue fuerte para las extinciones históricas, pero reducida o ausente para algunas categorías de riesgo. Esto se atribuyó a un cambio en las causas de extinción, donde la predación y las especies introducidas se han sumado o han sido reemplazadas por la gran destrucción de hábitat. Se evaluaron luego las consecuencias de esta selectividad variable para las extinciones de géneros y familias en el pasado y en un futuro probable. En la mayoría de los casos el número de taxones extinguidos aumenta. Finalmente, se hicieron predicciones acerca de las extinciones mínimas de taxones en el futuro, demostrándose que, a pesar de la reducción en algunas formas de selectividad, se extinguirán más taxones que si las extinciones fueran al azar.
New Insights on Cheetah Conservation through Demographic Modeling
Authors: Crooks Kevin R. , Sanjayan M. A. , Doak Daniel F.
Published: August 2010

Researchers have recently argued that ecological factors, especially high levels of cub predation, are more important than genetic impoverishment in limiting wild populations of the endangered cheetah (Acinonyx jubatus). Despite considerable controversy, however, the forces actually driving cheetah population dynamics remain unclear. We used a combination of demographic techniques to investigate how variation in survival and reproduction might influence the population persistence of wild cheetahs. We parameterized our models using detailed demographic data from recently published, long‐term ecological projects on cheetahs of the Serengeti. Results suggest that the influence of juvenile survivorship on population growth rate is relatively small compared to the large effects of adult survivorship. This result is consistent across a range of vital rates and is robust to deviations due to sampling error and environmental variability. These conclusions cast a new light on the current cheetah controversy and, more generally, counsel caution in the interpretation of ecological data for conservation and management.

 Nuevas Ideas para la Conservación del Leopardo Mediante Modelado Demográfico 

Recientemente los investigadores han argumentado que los factores ecológicos, especialmente altos niveles de depredación de cachorros, son mas importantes que el empobrecimiento genético en poblaciones silvestres limitadas del leopardo (Acinonyx jubatus), amenazado de extinción. Sin embargo, a pesar de considerables controversias, las fuerzas que actualmente conducen a las poblaciones del leopardo no son claras. Utilizamos una combinación de técnicas demográficas para investigar como la variación en la sobrevivencia y reproducción puede influir en la persistencia de poblaciones de leopardos. Nuestros modelos fueron parametrizados usando datos demográficos detallados de proyectos de largo plazo recientemente publicados de leopardos del Serengeti. Los resultados sugieren que la influencia de la supervivencia de juveniles en el crecimiento poblacional es relativamente pequeña en comparación con los grandes efectos de la sobrevivencia de los adultos. Estos resultados son consistentes a lo largo de un rango de tasas vitales y es robusto a desviaciones debidas a errores de muestreo y variabilidad ambiental. Estas conclusiones proyectan una nueva luz en la actual controversia sobre leopardos y en lo general aconsejan precaución en la interpretación de datos ecológicos para conservación y manejo.
A Reevaluation of the Role of Prairie Dogs in Great Plains Grasslands
Authors: Stapp Paul
Published: August 2010

Recent articles in the scientific literature and popular press have argued for federal protection for prairie dogs (Cynomys ludovicianus) based on their role as a keystone species in North American grasslands. A critical evaluation of published studies, however, reveals that our knowledge of the effects of prairie dogs on other animals may be more limited and equivocal than these articles suggest. Moreover, differences in responses to grazing and disturbance of the types of grasslands inhabited by prairie dogs suggest that prairie dogs may affect the vegetation and fauna of these systems differently, yet we know little about their ecological role in many grasslands. Future research may provide convincing evidence that prairie dogs have disproportionately large, unique effects on prairie ecosystems, but it may be premature to characterize prairie dogs as keystone species in grasslands throughout the Great Plains. Despite decades of interest in and study of the effects of this conspicuous and influential species, large gaps in our knowledge of the ecology of prairie dogs persist and warrant additional research.

Reevalución del Papel de Perros de Pradera en los Pastizales de la Gran Planicie

Artículos recientes en la literatura científica y la prensa han argumentado la protección federal de los perros de pradera (Cynomys ludovicianus) en base a su papel como especie clave en los pastizales de Norteamérica. Sin embargo, una evaluación crítica de los estudios publicados revela que nuestro conocimiento de los efectos de los perros de pradera en otros animales puede ser más limitado y equívoco de lo que estos artículos sugieren. Mas aún, diferencias en respuestas a pastoreo y otras perturbaciones etre los tipos de pastizales habitados por los perros de pradera sugieren que los perros pueden afectar la vegetación y la fauna de estos sistemas de forma diferente, sin embargo, conocemos muy poco sobre su papel ecológico en muchos pastizales. Información futura podría proveer evidencias convincentes de que los perros de pradera tienen efectos desproporcionadamente grandes y únicos en los ecosistemas de pradera, pero sería prematuro caracterizar a los perros como una especie clave en pastizales a lo largo de la Gran Planicie. A pesar de décadas de interés y estudio de los efectos de estas especies conspicuas e influyentes, aún permanecen grandes espacios vacíos en el conocimiento de la ecología de los perros de pradera, mismos que merecen investigación adicional.