bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant species richness and environmental heterogeneity in a mountain landscape: effects of variability and spatial configuration
Authors: Dufour Alexia , Gadallah Fawziah , Wagner Helene H. , Guisan Antoine , Buttler Alexandre
Published: December 2008

The loss of biodiversity has become a matter of urgent concern and a better understanding of local drivers is crucial for conservation. Although environmental heterogeneity is recognized as an important determinant of biodiversity, this has rarely been tested using field data at management scale. We propose and provide evidence for the simple hypothesis that local species diversity is related to spatial environmental heterogeneity. Species partition the environment into habitats. Biodiversity is therefore expected to be influenced by two aspects of spatial heterogeneity: 1) the variability of environmental conditions, which will affect the number of types of habitat, and 2) the spatial configuration of habitats, which will affect the rates of ecological processes, such as dispersal or competition. Earlier, simulation experiments predicted that both aspects of heterogeneity will influence plant species richness at a particular site. For the first time, these predictions were tested for plant communities using field data, which we collected in a wooded pasture in the Swiss Jura mountains using a four‐level hierarchical sampling design. Richness generally increased with increasing environmental variability and “roughness” (i.e. decreasing spatial aggregation). Effects occurred at all scales, but the nature of the effect changed with scale, suggesting a change in the underlying mechanisms, which will need to be taken into account if scaling up to larger landscapes. Although we found significant effects of environmental heterogeneity, other factors such as history could also be important determinants. If a relationship between environmental heterogeneity and species richness can be shown to be general, recently available high‐resolution environmental data can be used to complement the assessment of patterns of local richness and improve the prediction of the effects of land use change based on mean site conditions or land use history.
Scale‐dependent effects of land use on plant species richness of mountain grassland in the European Alps
Authors: Spiegelberger Thomas , Matthies Diethart , Müller‐Schärer Heinz , Schaffner Urs
Published: December 2008

Traditionally managed mountain grasslands in the Alps are species‐rich ecosystems that developed during centuries of livestock grazing. However, changes in land use including fertilisation of well accessible pastures and gradual abandonment of remote sites are increasingly threatening this diversity. In five regions of the Swiss and French Alps we assessed the relationship between land use, soil resource availability, cover of the unpalatable speciesVeratrum album,species richness and vegetation composition of mountain grasslands across four spatial scales ranging from 1 to 1000 m2.

Mean species richness and the increase in the number of species with increasing area were lower in intensively grazed, fertilised pastures than in traditional pastures or in abandoned pastures. Species composition of abandoned pastures differed from that of the other management types. Plant species richness was influenced by different factors at different spatial scales. At the 1 m2scale, plant species richness was negatively related to soil nitrate and influenced by the cover ofV. album,depending on land use: species richness and cover ofV. albumwere negatively correlated in abandoned pastures, but positively correlated in fertilised grasslands. At the 1000 m2scale, a negative effect of fertilization on richness was evident. These results indicate that at small scales species richness in mountain grasslands is determined by competition for light, which should be more important if nutrient availability is high, and by positive and negative interactions with unpalatable plants. In contrast, species richness at the large scale appears to be mainly influenced by land use. This result emphasizes the importance of studying such inter‐relationships at multiple scales. Our study further suggests that the maintenance of the traditional land use scheme is crucial for the conservation of plant species richness of mountain pastures as both intensification and abandonment changed species composition and reduced plant species diversity.
Variability in plant fitness influences range expansion of Leptospermum scoparium
Authors: Price Jodi N. , Morgan John W.
Published: December 2008

A reciprocal transplant experiment was conducted to uncouple genetic and environmental effects on plant fitness of a range‐expanding indigenous shrub, Leptospermum scoparium. Patterns of encroachment differed significantly between three regions of Eucalyptuscamaldulensis woodland in the Grampians National Park, south‐eastern Australia, with greater shrub densities found in the Victoria Valley region. Higher shrub densities in this region are likely due to greater fruit production/shrub, increased field germination and increased early seedling survival. The results of the reciprocal transplant experiment showed increased fitness appears to be due to phenotypic plasticity in response to favourable environmental conditions rather than genotypic variation. Field germination and seedling survival were influenced by region of planting and not seed origin. However, differences in shoot length and biomass of seedlings between the regions were detected after five months of growth in uniform conditions which may indicate genetic differentiation. The results, however, suggest range expansion is partly due to increased plant fitness which is likely a plastic response to favourable environmental conditions, especially soil moisture.
Biogeographic, environmental, and phylogenetic influences on reproductive traits in subtropical forest trees, South Africa
Authors: E. Griffiths Megan , J. Lawes Michael
Published: December 2008

The distribution of subtropical forests in South Africa is largely a consequence of climatic change during the Quaternary period. We gathered data for 195 canopy tree species from Afrotemperate, scarp, and coastal forests in KwaZulu‐Natal, South Africa and assessed patterns in reproductive traits using a comparative phylogenetic approach. The overlap in species composition among the forest types reflected the geographic position and colonisation history of the forests. Despite a high degree of phylogenetic conservatism in reproductive traits, there were differences in their expression among forest types. Afrotemperate forests had a higher incidence of wind pollination, consistent with the steep topography, seasonally dry environment, and limited resource availability in the habitat. Scarp forests had more dry brown fruits with abiotic (explosive and wind) dispersal. Coastal forests had the most species with fleshy fruits, zoochory, and large seeds, all traits that may have facilitated the colonisation or persistence of species in this more recent and dynamic community. Since many suites of traits occur together in diverse phylogenetic lines, they represent adaptive complexes that are influenced by biogeography and environmental conditions. Overall, this study demonstrates that biogeography, environmental factors, and phylogenetic history all influence the distribution of reproductive traits in these forest communities.
Emus as non‐standard seed dispersers and their potential for long‐distance dispersal
Authors: Calviño‐Cancela María , R. Dunn Robert , Van Etten Eddie J. B. , B. Lamont Byron
Published: December 2008

Long‐distance seed dispersal may have important consequences for species range, migration rates, metapopulation dynamics, and gene flow. Plants have evolved various adaptations for seed dispersal by standard agents, with typical dispersal distances associated with them. Seeds may also be dispersed by non‐standard agents for which they do not show any apparent adaptation and may reach long distances. By sampling the droppings of emus Dromaius novaehollandiae at three localities in Western Australia, we investigated their potential to act as long‐distance dispersers of seeds with adaptations for dispersal modes other than endozoochory, such as unassisted, ant, wind and exozoochory, for which they act as non‐standard agents. Seventy‐seven plant species with five types of dispersal syndromes were found in the 112 droppings analysed, with at least 68 having viable seeds. Although endozoochory was the most frequent syndrome, the presence of other syndromes was important in terms of number of species (61%) and seeds (50%). Estimates of species richness indicated that an increase in sampling effort would increase the number of species observed, especially among non‐endozoochores. As a consequence of their long gut retention times and high mobility, emus can provide long‐distance dispersal opportunities that may be especially relevant for species with dispersal modes of typically short distances (unassisted, ant).

Our results suggest that the role of emus as non‐standard agents for long‐distance dispersal should be taken into account for understanding current geographic ranges, gene flow and metapopulation dynamics of some plant species, as well as for predicting their future responses to climate change and fragmentation.
Opposite shell‐coiling morphs of the tropical land snailAmphidromus martensishow no spatial‐scale effects
Authors: Craze Paul G. , Bin Elahan Berjaya , Schilthuizen Menno
Published: December 2008

Much can be learned about evolution from the identification of those factors maintaining polymorphisms in natural populations. One polymorphism that is only partially understood occurs in land snail species where individuals may coil clockwise or anti‐clockwise. Theory shows that polymorphism in coiling direction should not persist yet species in several unrelated groups of land snails occur in stably polymorphic populations. A solution to this paradox may advance our understanding of evolution in general. Here, we examine two possible explanations: firstly, negative frequency‐dependent selection due to predation; secondly, random fixation of alternative coiling morphs in tree‐sized demes, giving the impression of wider polymorphism. We test these hypotheses by investigating morph‐clustering of empty shells at two spatial scales inAmphidromus martensipopulations in northern Borneo: the spatial structure of snail populations is relatively easy to estimate and this information may support one or other of the hypotheses under test. For the smaller scale we make novel use of a statistic previously used in botanical studies (the K‐function statistic), which allows clustering of more than one morph to be simultaneously investigated at a range of scales and which we have corrected for anisotropy. We believe this method could be of more general use to ecologists. The results show that consistent clustering or separation of morphs cannot be clearly detected at any spatial scale and that predation is not frequency‐dependent. Alternative explanations that do not require strong spatial structuring of the population may be needed, for instance ones involving a mechanism of selection actively maintaining the polymorphism.
The effects of dispersal and recruitment limitation on community structure of odonates in artificial ponds
Authors: McCauley Shannon J.
Published: December 2008

I examined the effects of isolation on the structure of both adult and larval dragonfly (Odonata: Anisoptera) communities forming at physically identical artificial ponds over two years. Isolation, whether measured by distance to the nearest source habitat or by connectivity to multiple sources, was significantly negatively related to the species richness of dragonflies observed at and collected in these ponds. These results indicate that dispersal and recruitment limitation acted as filters on the richness of communities at these artificial ponds. The richness of larval recruits in artificial ponds was lower than the richness of adult dispersers observed at ponds, and distance from a source habitat explained a greater fraction of the variation in larval than adult richness (83 and 50%, respectively). These results and a male biased sex‐ratio in adults observed at artificial ponds suggest that isolated habitats may be more recruitment limited than observations of dispersers would suggest. A Mantel test indicated there was a spatial component to the composition of communities forming in tanks, and that distance between tanks and community dissimilarity (1‐Jaccard's) were significantly positively related (r=0.52). This pattern suggests that their position with respect to alternative source environments influenced the composition of the communities that recruited into these ponds. These results provide further evidence of recruitment limitation in this system. Results from this study highlight the importance behaviorally limited dispersal may have in taxa morphologically capable of broad dispersal and suggest that the role of dispersal and recruitment limitation may be critical in shaping community structure across habitat gradients that include variation in habitat duration.
Patient acceptance and clinical impact of Bravo monitoring in patients with previous failed catheter‐based studies
Authors: SWEIS R. , FOX M. , ANGGIANSAH R. , ANGGIANSAH A. , BASAVARAJU K. , CANAVAN R. , WONG T.
Published: December 2008

Background  Standard pH monitoring is performed over 24 h with a naso‐oesophageal catheter (C‐pH). Limitations include naso‐pharyngeal discomfort, nausea and social embarrassment resulting in reduced reflux‐provoking activities. Recently a catheter‐free pH‐monitoring technique has become available. The tolerability and diagnostic yield of this system in patients who failed standard monitoring remain unknown.

Aim  To examine the tolerability and diagnostic outcome of catheter‐free pH‐monitoring technique in patients who failed standard monitoring.

Methods  Patients referred for C‐pH and catheter‐free pH monitoring completed a tolerability questionnaire. Acid exposure in the distal oesophagus and symptom index (SI) were reviewed.

Results  Over 4 years, 883/1751 (50%) of patients with typical reflux symptoms referred for C‐pH were diagnosed with gastro‐oesophageal reflux disease (GERD) based on a pathological percentage time acid exposure (%time pH <4);134 (8%) patients failed C‐pH and, of these, 129 successfully completed 2‐day catheter‐free pH monitoring. Ninety‐eight (76%) of these patients had a pathological percentage pH <4 on either day compared with 49/102 (49%) of contemporaneous C‐pH patients (P < 0.01). There was no difference in SI for heartburn (35% vs. 42%; P = 0.49). The questionnaire demonstrated a preference for catheter‐free pH monitoring (96%) with less restriction in activities of daily living, naso‐pharyngeal discomfort, dysphagia and chest pain.

Conclusions Tolerance and satisfaction with catheter‐free pH monitoring are high in patients who had previously failed C‐pH; catheter‐free pH monitoring assists the definitive diagnosis of GERD in this group.
Proton pump inhibitors increase significantly the risk ofClostridium difficileinfection in a low‐endemicity, non‐outbreak hospital setting
Authors: DALTON B. R. , LYE‐MACCANNELL T. , HENDERSON E. A. , MACCANNELL D. R. , LOUIE T. J.
Published: December 2008

Background Proton pump inhibitors (PPI) have been linked to higher risk ofClostridium difficileinfection (CDI). The relevance of this association in hospitals with low disease activity, where an outbreak strain is nondominant, has been assessed in relatively few studies.

Aim To assess the association of PPI and CDI in a setting of low disease activity.

Methods A retrospective cohort study was conducted at two hospitals. Patients admitted for ≥7 days receiving antibiotics were included. Demographics, exposure to PPI, antibiotics and other drugs in relation to diagnosis of CDI were assessed by univariate and multivariate analyses.

Results Of 14 719 patients, 149 (1%) first episode CDI were documented; PPI co‐exposure increased CDI [1.44 cases/100 patients vs. 0.74 cases/100 non‐exposed (OR: 1.96, 95% CI: 1.42–2.72)]. By logistic regression, PPI days (adjusted OR: 1.01 per day, 95% CI: 1.00–1.02), histamine‐2 blockers, antidepressants, antibiotic days, exposure to medications, age, admission service and length of admission were significant predictors.

Conclusions A statistically significant increase in CDI was observed in antibiotic recipients who received PPI, but the absolute risk increase is modest. In settings of with low rates of CDI, the benefit of PPI therapy outweighs the risk of developing CDI. These data support programmes to decrease inappropriate use of PPI in hospitalized patients.
Primary particle size distribution of eroded material affected by degree of aggregate slaking and seal development
Authors: Warrington D. N. , Mamedov A. I. , Bhardwaj A. K. , Levy G. J.
Published: December 2008

Primary particle size distribution (PSD) of eroded sediment can be used to estimate potential nutrient losses from soil and pollution hazards to the environment. We studied eroded sediment PSDs from three saturated soils, packed in trays (20 × 40 × 4 cm), that had undergone either minimal aggregate slaking (MAS) or severe aggregate slaking (SAS) prior to a 60 mm simulated rainstorm (kinetic energy, 15.9 kJ m−3; droplet diameter, 2.97 mm) and collected runoff at regular intervals. The degree of aggregate slaking was controlled by the rate at which soils were wetted to saturation. The PSDs of eroded materials and of parent soils were determined using a laser particle size analyser. For each soil, PSD frequency curves of eroded sediments and parent soils were generally of a similar shape but most eroded sediments had larger clay contents than their parent soils. In the SAS treatment, cumulative clay enrichment in the eroded materials was inversely related to the parent soil clay content, these being 28.5, 26.6 and 22.8% richer in clay than their parent soils for the loam, sandy clay and clay, respectively. Generally, total clay loss was greater from soils with SAS than from those with MAS because of erosion rates; however, clay enrichment of sediments, compared with parent soil clay contents, was mostly greater in samples with MAS. Greater clay enrichment took place during the early seal development stage in the loam, but could not readily be associated with specific stages of seal development for the clay. In the sandy clay, the relation between seal development and clay enrichment in the eroded material depended on the initial degree of aggregate slaking. The observed large preferential loss of clay by erosion in cultivated soils re‐emphasizes the need to employ erosion control measures.
SWORM: an agent‐based model to simulate the effect of earthworms on soil structure
Authors: Blanchart E. , Marilleau N. , Chotte J.‐L. , Drogoul A. , Perrier E. , Cambier Ch.
Published: December 2008

Soil structure can be defined as the spatial organization of solid mineral and organic particles, and pore space. It is of great importance for soil functioning as it drives ecosystem functions (carbon sequestration, emission of greenhouse gases, nutrient cycling, primary productivity, etc.). Soil structure results from biotic and abiotic factors. Among biotic factors, numerous studies have shown the importance of organic matter, microorganisms, roots and invertebrates. Earthworms are known to play a key role in soil structure formation and maintenance through a continuous production of biogenic structures (casts and burrows). As far as we know, no models describe or quantify the effect of soil invertebrates on soil aggregation and porosity. It is a challenge to describe the physical soil environment for purposes of modelling because a soil is a multi‐scale heterogeneous, three‐dimensional and dynamic environment. An approach based on fractal theory (often used in soil sciences) was chosen to model such a real complex environment; it was integrated into a multi‐agent system (MAS), which allows us to simulate agents (e.g. earthworms) situated in a virtual world (e.g. soil). It is a bottom‐up approach that allows us to describe a system at a micro level (e.g. earthworms and their local soil environment) in order to observe, during simulations, macroscopic changes (e.g. soil structure evolution, organic matter dynamics, and microbial functions). In this paper we describe the SWORM (for ‘Simulated Worms’) model and the simulator, and present the results of the simulation applied to a case study. The effect of compacting and decompacting earthworm species on the structure of humid savanna soil at Lamto in Côte d’Ivoire has been widely studied. Quantitative and graphical outputs (e.g. thin sections of the virtual soil) indicate that the simulator was able to reproduce the effects of both compacting and decompacting species. Different ways to improve the model are discussed.
Airborne radiometric survey data and a DTM as covariates for regional scale mapping of soil organic carbon across Northern Ireland
Authors: Rawlins B. G. , Marchant B. P. , Smyth D. , Scheib C. , Lark R. M. , Jordan C.
Published: December 2008

Soil scientists require cost‐effective methods to make accurate regional predictions of soil organic carbon (SOC) content. We assess the suitability of airborne radiometric data and digital elevation data as covariates to improve the precision of predictions of SOC from an intensive survey in Northern Ireland. Radiometric data (K band) and, to a lesser extent, altitude are shown to increase the precision of SOC predictions when they are included in linear mixed models of SOC variation. However the statistical distribution of SOC in Northern Ireland is bimodal and therefore unsuitable for geostatistical analysis unless the two peaks can be accounted for by the fixed effects in the linear mixed models. The upper peak in the distribution is due to areas of peat soils. This problem may be partly countered if soil maps are used to classify areas of Northern Ireland according to their expected SOC content and then different models are fitted to each of these classes. Here we divide the soil in Northern Ireland into three classes, namely mineral, organo‐mineral and peat. This leads to a further increase in the precision of SOC predictions and the median square error is 2.2 %2. However a substantial number of our observations appear to be mis‐classified and therefore the mean squared error in the predictions is larger (30.6 %2) since it is dominated by large errors due to mis‐classification. Further improvement in SOC prediction may therefore be possible if better delineation between areas of large SOC (peat) and small SOC (non‐peat) could be achieved.
Co‐operative action of interleukin‐10 and interferon‐γ to regulate dendritic cell functions
Authors: Yanagawa Yoshiki , Iwabuchi Kazuya , Onoé Kazunori
Published: December 2008

Interleukin‐10 (IL‐10) and interferon‐γ (IFN‐γ) double producer is found in a subpopulation of T regulatory type 1 (Tr1) and T helper type 1 (Th1) cells. Consequently, it is of interest how IL‐10 and IFN‐γ influence the immune system. However, few studies have addressed the co‐operative action of these ‘immunosuppressive’ and ‘immunostimulatory’ cytokines. Here, we examine the effect of IL‐10 combined with IFN‐γ on dendritic cell (DC) functions. Murine bone marrow‐derived conventional DCs were stimulated with IL‐10 and/or IFN‐γ for 24 hr. Tumour necrosis factor‐α and IL‐12 p40 production by DCs treated with both IL‐10 and IFN‐γ was significantly lower than that by DCs treated with IL‐10 or IFN‐γ alone. Major histocompatibility complex class II expression on DCs treated with both cytokines was attenuated compared with that on DCs treated with either cytokine alone. In contrast, levels of inducible nitric oxide synthase and indoleamine 2,3‐dioxygenase, which appear to suppress T‐cell responses and promote tolerance, in DCs treated with both cytokines were higher than those in DCs treated with IL‐10 or IFN‐γ alone. Simultaneous treatment with IL‐10 and IFN‐γ significantly suppressed the ability of DCs to activate CD4+ T cells compared with treatment with either cytokine. Therefore, IL‐10 and IFN‐γ co‐operatively suppress the immunostimulatory functions of DCs.
Yersinia pestis and host macrophages: immunodeficiency of mouse macrophages induced by YscW
Authors: Bi Yujing , Du Zongmin , Han Yanping , Guo Zhaobiao , Tan Yafang , Zhu Ziwen , Yang Ruifu
Published: December 2008

The virulence of the pathogenic Yersinia species depends on a plasmid‐encoded type III secretion system (T3SS) that transfers six Yersinia outer protein (Yop) effector proteins into the cytoplasm of eukaryotic cells, leading to disruption of host defence mechanisms. It is shown in this study that Yersinia pestis YscW, a protein of the T3SS injectisome, contributes to the induction of a deficiency in phagocytosis in host macrophages and a reduction in their antigen‐presenting capacity. A Y. pestis strain lacking yscW had no effect on uptake by host macrophages. In mice infected with wild‐type Y. pestis, the yscW mutant or a complement strain, immunodeficiency was observed in host macrophages compared with those from uninfected mice. However, the phagocytosis and antigen presenting capacities of macrophages infected by yscW mutant strain both in vivo and in vitro were significantly higher than those by wild type strain. Consistent with this finding, when YscW was expressed in the RAW264·7 macrophage cell line, phagocytosis and antigen‐presenting capacities were significantly lower than those of the control groups. These results indicate that Y. pestis YscW may directly induce immunodeficiency in murine macrophages by crippling their phagocytosis and antigen‐presenting capacities. These data provide evidences to Y. pestis pathogenesis that some proteins in T3SS injectisome, such as YscW protein, might play independent roles in disrupting host defense apart from their known functions.
Autoantibodies to myelin basic protein (MBP) in healthy individuals and in patients with multiple sclerosis: a role in regulating cytokine responses to MBP
Authors: Hedegaard Chris J. , Chen Ning , Sellebjerg Finn , Sørensen Per Soelberg , Leslie R. Graham Q. , Bendtzen Klaus , Nielsen Claus H.
Published: December 2008

Anti‐myelin basic protein (‐MBP) autoantibodies have generally been considered to be absent from sera from healthy individuals, but to be detectable in sera from some patients with multiple sclerosis (MS). However, their pathogenic role is uncertain. We demonstrate the presence of MBP‐reactive autoantibodies in sera from 17 healthy individuals and 17 MS patients. The addition of MBP to the sera caused a dose‐dependent deposition of MBP and co‐deposition of immunoglobulin M (IgM) and fragments of complement component 3 (C3) on allogeneic monocytes. Calcium chelation abrogated the immunoglobulin deposition, indicating that formation of complement‐activating immune complexes played a role in the binding process. Furthermore, MBP elicited tumour necrosis factor (TNF)‐α and interleukin (IL)‐10 production by normal mononuclear cells in the presence of serum from both patients and controls. Mononuclear cells from MS patients responded to MBP with the production of interferon (IFN)‐γ, IL‐4 and IL‐5, in addition to TNF‐α and IL‐10. The production of IFN‐γ and IL‐5 was increased when MS serum was added rather than normal serum. Denaturation of MBP strongly inhibited MBP deposition and the MBP‐induced IgM deposition and cytokine production, indicating that these events were facilitated by autoantibodies recognizing conformational epitopes on MBP. We infer that MBP‐elicited TNF‐α and IL‐10 responses are promoted to equal extents by naturally occurring MBP autoantibodies and autoantibodies contained in MS sera. However, the latter seem to be more efficient in facilitating the production of IFN‐γ and IL‐5.
The collision of the Indian plate with Asia: molecular evidence for its impact on the phylogeny of freshwater crabs (Brachyura: Potamidae)
Authors: Shih Hsi‐Te , Yeo Darren C. J. , Ng Peter K. L.
Published: December 2008

Aim  We used molecular data to answer the following questions: (1) Is morphology‐based (and to some extent, geography‐based) classification of the freshwater crab family Potamidae congruent with a molecular phylogeny? (2) What historical biogeographical event could have shaped this phylogeny?

Location  Material from the entire geographical range of the family Potamidae was analysed, including specimens from East Asia (China, Taiwan, the Ryukyus), Southeast Asia, South Asia (northern India, the Middle East and Near East), North Africa, and southern Europe.

Methods  Mitochondrial DNA sequences encoding 503 base pairs (excluding the variable regions) of the large subunit rRNA (16S rRNA) gene were obtained from 72 species belonging to 49 potamid genera, representing 51% of all known genera in this species‐rich family. Sequences were compared by means of phylogenetic analyses (minimum evolution, Bayesian inference, maximum likelihood and maximum parsimony) and Bayesian relaxed molecular clock estimates.

Results  The family Potamidae was found to be monophyletic with two major lineages, and there was support for the recognition of two mostly allopatric subfamilies, Potaminae and Potamiscinae. This is largely consistent with the current classification proposed. The ‘Potamiscinae’ clade comprised three subclades: (1) a well‐supported ‘eastern Asia’ subclade that included species from the eastern part of the range (China, Taiwan, the Ryukyus, the Philippines, Indochina, Malay Peninsula, northern India and Myanmar/Burma); (2) a weakly supported ‘Sunda Shelf islands’ subclade that included species from the larger Southeast Asian islands on the Sunda Shelf (Borneo, Sumatra and Java); and (3) a ‘Socotra’ subclade that comprised only Socotrapotamon from Socotra Island, off the north‐east coast of Africa.

Main conclusions  The discrete distribution of the two subfamilies in Europe/Asia is hypothesized to be the result of vicariance due to the collision of the Indian tectonic plate with the Asian continent, and the orogeny that caused the separation of the two freshwater crab lineages around 22.8 Ma. Within the Potamiscinae, the ‘Sunda Shelf islands’ subclade separated from other potamiscines around 21.1 Ma; and the endemic fauna of the East Asian islands (Taiwan, the Ryukyus and mainland Japan) was isolated from the Asian continent c. 8.4 Ma, following the opening of the Okinawa Trough. The ‘Socotra’ subclade diverged from the ‘eastern Asia’ subclade at 19.1 Ma during the Miocene. Its taxonomic position, however, remains unclear as the members of this clade possess the key potamine character of a transverse ridge on thoracic sternite 8, suggesting that this may in fact be a relict potamid group.
Phylogeny and biogeography of the dung beetle genus Phanaeus (Coleoptera: Scarabaeidae)
Authors: PRICE DANA L.
Published: December 2008

Abstract The dung beetle genus Phanaeus as currently recognized by Edmonds (1994) consists of 51 species placed in 13 species groups and two subgenera. Here, I examine the phylogeny and biogeography of this genus by analysing the mitochondrial cytochrome oxidase subunit I (530 bp), nuclear large subunit ribosomal RNA (28S, D2 region), and 67 morphological characters for 28 species of Phanaeus. Both maximum parsimony and Bayesian analyses from the combined data yielded well‐resolved trees, although low bootstrap and posterior probability support were found for basal nodes. The phylogenetic hypotheses presented here suggest that the subgenera Phanaeus s.str. and Notiophanaeus should each be elevated to the status of full genus. With the exception of the eucraniine outgroups, the paleano species group of the genus Phanaeus is recovered as sister to all other taxa, including the outgroups Oxysternon, Sulcophanaeus and Coprophanaeus. High bootstrap values and posterior probabilities supported the species groups endymion, tridens and vindex. Biogeographical analyses suggest an ancestral distribution for Phanaeus in the Andes in South America, although numerous dispersal events evidently have produced a complicated biogeographical history.
The effect of acute high light and low temperature stresses on the ascorbate–glutathione cycle and superoxide dismutase activity in two Dunaliella salina strains
Authors: Haghjou Maryam M , Shariati Mansour , Smirnoff Nicholas
Published: December 2008

Dunaliella species accumulate carotenoids and their role in protection against photooxidative stress has been investigated extensively. By contrast, the role of other antioxidants in this alga, has received less attention. Therefore, the components of the ascorbate–glutathione cycle, along with superoxide dismutase (E.C. 1.15.1.1) and peroxidase (E.C. 1.11.1.11) activity were compared in two strains of Dunaliella salina. Strain IR‐1 had two‐fold higher chlorophyll and β‐carotene concentration than Gh‐U. IR‐1 had around four‐fold higher superoxide dismutase, ascorbate peroxidase and pyrogallol peroxidase activities than Gh‐U on a protein basis. Ascorbate and glutathione concentrations and redox state did not differ between strains and there was little difference in the activity of ascorbate–glutathione cycle enzymes (monodehydroascorbate reductase [E.C. 1.6.5.4], dehydroascorbate reductase [E.C. 1.8.5.1] and glutathione reductase [E.C. 1.8.1.7]). The response of these antioxidants to high light and low temperature was assessed by transferring cells from normal growth conditions (28°C, photon flux density of 100 μmol m−2 s−1)to 28°C/1200 μmol m−2 s−1; 13°C/100 μmol m−2 s−1; 13°C/1200 μmol m−2 s−1 and 28°C/100 μmol m−2 s−1 for 24 h. Low temperature and combined high light‐low temperature decreased chlorophyll and β‐carotene in both strains indicating that these treatments cause photooxidative stress. High light, low temperature and combined high light‐low temperature treatments increased the total ascorbate pool by 10–50% and the total glutathione pool by 20–100% with no consistent effect on their redox state. Activities of ascorbate–glutathione cycle enzymes were not greatly affected but all the treatments increased superoxide dismutase activity. It is concluded that D. salina can partially adjust to photooxidative conditions by increasing superoxide dismutase activity, ascorbate and glutathione.
The transgene pyramiding tobacco with betaine synthesis and heterologous expression of AtNHX1 is more tolerant to salt stress than either of the tobacco lines with betaine synthesis or AtNHX1
Authors: Duan XiaoGuang , Song YingJie , Yang AiFang , Zhang JuRen
Published: December 2008

Previous studies have shown that the overexpression of betA (encoding choline dehydrogenase from Escherichia coli) or AtNHX1 (a vacuolar Na+/H+ antiport from Arabidopsis thaliana) gene can improve the salt tolerance of transgenic plants. However, little is known about the effects of the transgene pyramiding of betA and AtNHX1. Here, betA + AtNHX1 transgene pyramiding tobacco was produced by sexual crossing, and the salt tolerance was evaluated at the cellular and plant levels. In NaCl stress, the Na+ concentration in vacuoles and vacuolar membrane potential of transgene pyramiding cells were similar to those of AtNHX1‐transgenics, and much higher than those of betA‐transgenics when detected using fluorescent dye staining; transgene pyramiding cells showed a higher protoplast viability and comparable mitochondrial activity as compared with single transgenics; and transgene pyramiding plants showed comparable Na+ content in leaves as compared with AtNHX1‐transgenics and remarkably higher than betA‐transgenics; and transgene pyramiding lines exhibited higher percentage of seed germination, better seedling growth and higher fresh weight than lines that had betA or AtNHX1 alone. Based on the integrative analysis of salt tolerance, the consistency between the cellular level and the whole plant level was confirmed and the transgene pyramiding plants exhibited improved salt tolerance, but compared with the plants with betA or AtNHX1 alone, the differences were relatively small. Other mechanisms involved in salt tolerance should be considered to further enhance transgene pyramiding plants salt tolerance.
Different involvement of the mitochondrial, plastidial and cytosolic ascorbate–glutathione redox enzymes in heat shock responses
Authors: Locato Vittoria , De Pinto Maria Concetta , De Gara Laura
Published: December 2008

Plant survival under heat stress requires the activation of proper defence mechanisms to avoid the impairment of metabolic functions. Heat stress leads to the overproduction of reactive oxygen species (ROS) in the cell. In plants, the ascorbate (ASC)‐GSH cycle plays a pivotal role in controlling ROS levels and cellular redox homeostasis. Ascorbate peroxidase (APX) is the enzyme of this cycle mainly involved in ROS detoxification. In this study, the ASC‐GSH cycle enzymes were analysed in the cytosol, mitochondria and plastids of tobacco Bright Yellow‐2 cultured cells. The cells were also subjected to two different heat shocks (HSs; 35 or 55°C for 10 min) and the cell compartments were isolated in both conditions. The results reported here indicate that moderate HS (35°C) does not affect cell viability, whereas cell exposure to 55°C HS induces programmed cell death (PCD). In relation to ASC‐GSH cycle, the three analysed compartments have specific enzymatic profiles that are diversely altered by the HS treatments. The cytosol contains the highest activity of all ASC‐GSH cycle enzymes and the data reported here suggest that it acts as a redox buffer for the whole cells. In particular, the cytosolic APX seems to be the most versatile enzyme, being its activity enhanced after moderate HS and reduced during PCD induction, whereas the other APX isoenzymes are only affected in the cells undergoing PCD. The relevance of the changes in the different ASC‐GSH cycle isoenzymes in allowing cell survival or promoting PCD is discussed.
Five questions on ecological speciation addressed with individual‐based simulations
Authors: THIBERT‐PLANTE X. , HENDRY A. P.
Published: December 2008

We use an individual‐based simulation model to investigate factors influencing progress toward ecological speciation. We find that environmental differences can quickly lead to the evolution of substantial reproductive barriers between a population colonizing a new environment and the ancestral population in the old environment. Natural selection against immigrants and hybrids was a major contributor to this isolation, but the evolution of sexual preference was also important. Increasing dispersal had both positive and negative effects on population size in the new environment and had positive effects on natural selection against immigrants and hybrids. Genetic divergence at unlinked, neutral genetic markers was low, except when environmental differences were large and sexual preference was present. Our results highlight the importance of divergent selection and adaptive divergence for ecological speciation. At the same time, they reveal several interesting nonlinearities in interactions between environmental differences, sexual preference, dispersal and population size.
Egg jelly influences sperm motility in the externally fertilizing frog,Crinia georgiana
Authors: SIMMONS L. W. , ROBERTS J. D. , DZIMINSKI M. A.
Published: December 2008

Recentin vitrofertilization studies have revealed female and male × female interaction effects on the probability of fertilization. These findings suggest a mechanism of cryptic female choice via sperm–egg interactions. The egg jelly of anuran amphibians contains proteins that facilitate the chemoattraction and binding of sperm for fertilization. Here we show that egg jelly also influences the onset of motility and swimming velocity of motile sperm in the frogCrinia georgiana. Moreover, we found significant among female variation in the effects of egg jelly on sperm motility. We discuss this finding with respect to male and female effects on nonrandom fertilization observed in this species.
Evaluation of offspring size–number invariants in 12 species of lizard
Authors: ULLER T. , WHILE G. M. , WAPSTRA E. , WARNER D. A. , GOODMAN B. A. , SCHWARZKOPF L. , LANGKILDE T. , DOUGHTY P. , RADDER R. S. , ROHR D. H. , BULL C. M. , SHINE R. , OLSSON M.
Published: December 2008

The optimal division of resources into offspring size vs. number is one of the classic problems in life‐history evolution. Importantly, models that take into account the discrete nature of resource division at low clutch sizes suggest that the variance in offspring size should decline with increasing clutch size according to an invariant relationship. We tested this prediction in 12 species of lizard with small clutch sizes. Contrary to expectations, not all species showed a negative relationship between variance in offspring size and clutch size, and the pattern significantly deviated from quantitative predictions in five of the 12 species. We suggest that the main limitation of current size–number models for small clutch sizes is that they rely on assumptions of hierarchical allocation strategies with independence between allocation decisions. Indeed, selection may favour alternative mechanisms of reproductive allocation that avoid suboptimal allocation imposed by the indivisible fraction at low clutch sizes.
Demographic factors and genetic variation influence population persistence under environmental change
Authors: WILLI YVONNE , HOFFMANN ARY A.
Published: December 2008

Population persistence has been studied in a conservation context to predict the fate of small or declining populations. Persistence models have explored effects on extinction of random demographic and environmental fluctuations, but in the face of directional environmental change they should also integrate factors affecting whether a population can adapt. Here, we examine the population‐size dependence of demographic and genetic factors and their likely contributions to extinction time under scenarios of environmental change. Parameter estimates were derived from experimental populations of the rainforest species, Drosophila birchii, held in the lab for 10 generations at census sizes of 20, 100 and 1000, and later exposed to five generations of heat‐knockdown selection. Under a model of directional change in the thermal environment, rapid extinction of populations of size 20 was caused by a combination of low growth rate (r) and high stochasticity in r. Populations of 100 had significantly higher reproductive output, lower stochasticity in r and more additive genetic variance (VA) than populations of 20, but they were predicted to persist less well than the largest size class. Even populations of 1000 persisted only a few hundred generations under realistic estimates of environmental change because of low VA for heat‐knockdown resistance. The experimental results document population‐size dependence of demographic and adaptability factors. The simulations illustrate a threshold influence of demographic factors on population persistence, while genetic variance has a more elastic impact on persistence under environmental change.
Male–male competition, female mate choice and their interaction: determining total sexual selection
Authors: HUNT JOHN , BREUKER CASPER J. , SADOWSKI JENNIFER A. , MOORE ALLEN J.
Published: December 2008

Empirical studies of sexual selection typically focus on one of the two mechanisms of sexual selection without integrating these into a description of total sexual selection, or study total sexual selection without quantifying the contributions of all of the mechanisms of sexual selection. However, this can provide an incomplete or misleading view of how sexually selected traits evolve if the mechanisms of sexual selection are opposing or differ in form. Here, we take a two‐fold approach to advocate a direction for future studies of sexual selection. We first show how a quantitative partitioning and examination of sexual selection mechanisms can inform by identifying illustrative studies that describe both male–male competition and female mate choice acting on the same trait. In our sample, the most common trait where this occurred was body size, and selection was typically linear. We found that male–male competition and female mate choice can be reinforcing or opposing, although the former is most common in the literature. The mechanisms of sexual selection can occur simultaneously or sequentially, and we found they were more likely to be opposing when the mechanisms operated sequentially. The degree and timing that these mechanisms interact have important implications for the operation of sexual selection and needs to be considered in designing studies. Our examples highlight where empirical data are needed. We especially lack standardized measures of the form and strength of selection imposed by each mechanism of sexual selection and how they combine to determine total sexual selection. Secondly, using quantitative genetic principles, we outline how the selection imposed by individual mechanisms can be measured and combined to estimate the total strength and form of sexual selection. We discuss the evolutionary consequences of combining the mechanisms of sexual selection and interpreting total sexual selection. We suggest how this approach may result in empirical progress in the field of sexual selection.
Metapopulation persistence in fragmented landscapes: significant interactions between genetic and demographic processes
Authors: THEODOROU K. , SOUAN H. , COUVET D.
Published: December 2008

We formulated a mathematical model in order to study the joint influence of demographic and genetic processes on metapopulation viability. Moreover, we explored the influence of habitat structure, matrix quality and disturbance on the interplay of these processes. We showed that the conditions that allow metapopulation persistence under the synergistic action of genetic and demographic processes depart significantly from predictions based on a mere superposition of the effects of each process separately. Moreover, an optimal dispersal rate exists that maximizes the range of survival rates of dispersers under which metapopulation persists and at the same time allows the largest sustainable patch removal and patch‐size reduction. The relative impact of patch removal and patch‐size reduction depends both on matrix quality and the dispersal strategy of the species: metapopulation persistence is more affected by patch‐size reduction (patch removal) for low (high)‐dispersing species, in presence of a low (high) quality matrix. Avoidance of inbreeding, through increased dispersal when the rate of inbreeding in a population is large, has positive effects on low‐dispersing species, but impairs the persistence of high‐dispersing species. Finally, size heterogeneity between patches largely influences metapopulation dynamics; the presence of large patches, even at the expense of other patches being smaller, can have positive effects on persistence in particular for species of low dispersing ability.