Competitive exclusion: phylogeography’s ‘elephant in the room’?

Phylogeographic and evolutionary research programmes have successfully elucidated compelling genetic signatures of earth history. Particularly influential achievements include the demonstration of postglacial recolonization patterns for high-latitude taxa and phylogenetic demonstration of the 'progression rule' along oceanic island chains such as Hawaii. While both of these major biogeographic patterns clearly rely on rapid dispersal over long distances, their phylogeographic detection also apparently relies on the competitive exclusion of secondary dispersers. Such exclusion could occur either between or within species and might reflect fitness differences between lineages or, alternatively, neutral demographic processes (e.g. 'high-density blocking'). Regardless, such spatial genetic patterns would be rapidly eroded were it not for the failure of subsequent dispersers to contribute genetically to newly colonized populations. In addition to its role in revealing colonization patterns, competitive exclusion may also explain the maintenance of historic phylogeographic disjunctions long after the original physical barriers to dispersal have ceased to exist. Additionally, some of the most persuasive evidence of competitive exclusion comes from studies of anthropogenic extinction, where surviving lineages have subsequently expanded their ranges, apparently benefitting from the demise of their prehistoric sisters. Broadly, these biogeographic paradigms are united by the 'disconnect' between dispersal and colonization success, the latter being heavily influenced by inter- and intraspecific competition. Despite its apparent importance, such exclusion (especially within species) has received virtually no attention in the phylogeographic literature. Future studies should aim to test directly for the role of competitive exclusion in constraining the biogeography of highly dispersive taxa.     

Safeguarding China′s Botanical HeritageFoundation item: BGCI′S Program in China——BGCI′s integrated conservation programme in China

China′s rich floral diversity includes more than 33000 vascular plant species, representing approximately 10 percent of all known plant species. Over half of these species are endemic to China. However, China′s rapid economic development in the last 30 years and continuous population growth have seriously damaged plant resources in the wild and the ecological environment, resulting in a dramatic increase in the number of endangered species. There are nearly 4000 to 5000 higher plants that are now threatened or on the verge of extinction. To help halt the loss of Chinese plant diversity, Botanic Gardens Conservation International (BGCI) has developed a China programme and opened its first office based in Guangzhou in 2008. This office works along with Chinese partners aiming to secure Chinese plant diversity through integrated conservation approaches with reintroduction/population reinforcement, engagement of local communities in conservation activities, capacity building in horticulture and environmental education and public outreach.     

‘Lymphocyte-like’cells in ascidians: Precursors for vertebrate lymphocytes?

There has been much speculation that the evolutionary precursors of vertebrate lymphocytes may exist in the ascidians (proto chordates), but conclusive evidence has remained elusive especially as membrane bound immunoglobulin has not been detected in any invertebrate. This paper reviews new evidence which indicates that the ‘lymphocyte-like’ cells in ascidians have functional, as well as morphological, similarities with vertebrate lymphocytes. Firstly, these cells have been linked with in vivo non-self recognition events such as allograft rejection in solitary ascidians and non-fusion reactions between colonial ascidians. Secondly, they have been shown to be cytotoxic towards xenogenic targets in vitro and to use cytolytic mechanisms similar to those of cytotoxic T-cells. Thirdly, they are able to proliferate in vitro in response to mitogens or allogeneic cells. It is therefore suggested that, apart from immunoglobulin production and clonal selection, there is persuasive evidence that the ‘lymphocyte-like’ cells of ascidians constitute a primordial form of vertebrate lymphocyte.     

The role of CS<Subscript>2</Subscript> in CS<Subscript>2</Subscript>/NMP mixed solvent in weakening the hydrogen bond of OH–N in coal: a DFT investigation

The interaction processes of trace amounts of N-methyl-2-pyrrolidinone (NMP), CS₂/NMP (1:1 by volume) and pure NMP solvent with the hydrogen bond of OH?N in coal were constructed and simulated by density functional theory methods. The distances and bond orders between the main related atoms, and the hydrogen bond energy of OH?N were calculated. The calculated results show that pure NMP solvent does not weaken the hydrogen bond of OH?N in coal. However, trace amounts of NMP and CS₂/NMP (1:1 by volume) have a strong capacity to weaken the hydrogen bond of OH?N in coal. The H2–N3 distances are elongated from 1.87 Å to 3.80 Å and 3.44 Å, the bond orders of H2–N3 all disappear, and the corresponding hydrogen bond energies of OH?N in coal decrease from 45.72 kJ mol^?1 to 7.06 and 11.24 kJ mol^?1, respectively. These results show that CS₂ added to pure NMP solvent plays an important role in releasing the original capacity of NMP to weaken the hydrogen bond of OH?N in coal, in agreement with experimental observations.     

β-N-Acetylhexosaminidase: What's in a name…?

β-N-Acetylhexosaminidases (EC 3.2.1.52, belonging to CAZy GH families 3, 20 and 84) have recently gained a lot of attention, not only due to their implication in human physiology and disease, but also due to their great potential in the enzymatic synthesis of carbohydrates and glycomimetics. GH family 20 β-N-acetylhexosaminidases, and GH family 3 and 84 β-N-acetylglucosaminidases from all kinds of organisms have been intensively studied from the point of view of their physiological roles, reaction mechanisms, structure and inhibition. Thanks to their outstanding substrate promiscuity, extracellular β-N-acetylhexosaminidases from filamentous fungi are able to cleave and transfer substrates bearing various functionalities, ranging from carboxylates, sulfates, acylations to azides, and even 4-deoxy glycosides. Thus, they have proved to be versatile biosynthetic tools for the preparation of both natural and modified hexosaminides under mild conditions with good yields.     

Stress‐triggered redox signalling: what's in pROSpect?

Reactive oxygen species (ROS) have a profound influence on almost every aspect of plant biology. Here, we emphasize the fundamental, intimate relationships between light‐driven reductant formation, ROS, and oxidative stress, together with compartment‐specific differences in redox buffering and the perspectives for their analysis. Calculations of approximate H₂O₂ concentrations in the peroxisomes are provided, and based on the likely values in other locations such as chloroplasts, we conclude that much of the H₂O₂ detected in conventional in vitro assays is likely to be extracellular. Within the context of scant information on ROS perception mechanisms, we consider current knowledge, including possible parallels with emerging information on oxygen sensing. Although ROS can sometimes be signals for cell death, we consider that an equally important role is to transmit information from metabolism to allow appropriate cellular responses to developmental and environmental changes. Our discussion speculates on novel sensing mechanisms by which this could happen and how ROS could be counted by the cell, possibly as a means of monitoring metabolic flux. Throughout, we place emphasis on the positive effects of ROS, predicting that in the coming decades they will increasingly be defined as hallmarks of viability within a changing and challenging environment.     

Pocket calculator: a humdrum ‘obviator’ in Papua New Guinea?

This article examines the significance of pockets for controlling money in Highland Papua New Guinea. Contextualizing elaborate ‘systems’ for compartmentalizing monies in separate pockets, I draw upon the connection Highlanders make between transaction and skin. Pockets, I argue, offer opportunities to hide one's wealth reserves while gifting, keeping intentions opaque and leaving interlocutors guessing at the meaning of donors' speech, and forcing recipients to perceive their gift as ample. The article suggests that expectations are deliberately conventionalized in order to be exceeded, drawing parallels with Roy Wagner's notion of obviation. After characterizing Gorokan pockets and their gifting ‘logic’, I analyse how pocket‐users are themselves conventionalized as forthright or selfish in local discourse, based upon the pockets they display and where their clothes come from. Giving people clothing that includes pockets is therefore a way to regain control over their capacity to reveal wealth from their pockets.     

Temporal variation in δ<Superscript>13</Superscript>C of ecosystem respiration in the Pacific Northwest: links to moisture stress

We measured seasonal and interannual variations in delta(13)C values within the carbon reservoirs (leaves and soil) and CO(2) fluxes (soil and ecosystem respired CO(2)) of an old growth coniferous forest in the Pacific Northwest USA with relation to local meteorological conditions. There were significant intra-annual and interannual differences in the carbon isotope ratios of CO(2) respired at both the ecosystem (delta(13)C(R)) and the soil levels (delta(13)C(R-soil)), but only limited variations in the carbon isotope ratios of carbon stocks. The delta(13)C(R) values varied by as much as 4.4 per thousand over a growing season, while delta(13)C(R-soil )values changed as much as 6.2 per thousand. The delta(13)C of soil organic carbon (delta(13)C(SOC)) and needle organic carbon (delta(13)C(P)) exhibited little or no significant changes over the course of this study. Carbon isotope discrimination within leaves (Delta(p)) showed systematic decreases with increased canopy height, but remained fairly constant throughout the year (Delta(p)=17.9 per thousand -19.2 per thousand at the top of the canopy, Delta(p)=19.6 per thousand -20.9 per thousand at mid-canopy, Delta(p)=23.3 per thousand -25.1 per thousand at the canopy base). The temporal variation in the delta(13)C of soil and ecosystem respired CO(2) was correlated ( r=0.93, P<0.001) with soil moisture levels, with dry summer months having the most (13)C-enriched values. The dynamic seasonal changes in delta(13)C of respired CO(2) are hypothesized to be the result of fast cycling of recently fixed carbon back to the atmosphere. One scaling consequence of the seasonal and interannual variations in delta(13)C(R) is that inversion-based carbon-cycle models dependent on observed atmospheric CO(2) concentration and isotope values may be improved by incorporating dynamic delta(13)C(R) values to interpret regional carbon sink strength.     

TRH synthesis in “mute” thyrotropinomas: cause‐effect or coincidence?

In the pathogenesis of thyrotropin (TSH) immunopositive pituitary adenomas, trigger mutagenetic events are well recognized. However, the way towards a clinical significant tumor is followed under the pressure of growth factors, among which the intrapituitary synthesis of releasing factors could bring a significant contribution. In this study, the production of thyrotropin releasing hormone (TRH) and beta TSH chain was evaluated at the mRNA level by in situ hybridization and end product level by immunohistochemistry, in 18 patients submitted to neurosurgery for pituitary macroadenomas. The hormonal sampling showed abnormal secretion for FSH in 5 and TSH in 4 patients. Seven cases were immunopositive for TSH, and expressed TSH β mRNA. All but one out of these expressed also TRH mRNA. FSH immunoreactivity was documented in 12/ 18, only one of these being negative for TRH mRNA. Paracrine TRH could contribute to the patogenesis of these "mute" adenomas.     

Sources of variation in consumer-diet δ<Superscript>15</Superscript>N enrichment: a meta-analysis

Measurements of ¹⁵N of consumers are usually higher than those of their diet. This general pattern is widely used to make inferences about trophic relationships in ecological studies, although the underlying mechanisms causing the pattern are poorly understood. However, there can be substantial variation in consumer-diet ¹⁵N enrichment within this general pattern. We conducted an extensive literature review, which yielded 134 estimates from controlled studies of consumer-diet ¹⁵N enrichment, to test the significance of several potential sources of variation by means of meta-analyses. We found patterns related to processes of nitrogen assimilation and excretion. There was a significant effect of the main biochemical form of nitrogenous waste: ammonotelic organisms show lower ¹⁵N enrichment than ureotelic or uricotelic organisms. There were no significant differences between animals feeding on plant food, animal food, or manufactured mixtures, but detritivores yielded significantly lower estimates of enrichment. ¹⁵N enrichment was found to increase significantly with the C:N ratio of the diet, suggesting that a nitrogen-poor diet can have an effect similar to that already documented for fasting organisms. There were also differences among taxonomic classes: molluscs and crustaceans generally yielded lower ¹⁵N enrichment. The lower ¹⁵N enrichment might be related to the fact that molluscs and crustaceans excrete mainly ammonia, or to the fact that many were detritivores. Organisms inhabiting marine environments yielded significantly lower estimates of ¹⁵N enrichment than organisms inhabiting terrestrial or freshwater environments, a pattern that was influenced by the number of marine, ammonotelic, crustaceans and molluscs. Overall, our analyses point to several important sources of variation in ¹⁵N enrichment and suggest that the most important of them are the main biochemical form of nitrogen excretion and nutritional status. The variance of estimates of ¹⁵N enrichment, as well as the fact that enrichment may be different in certain groups of organisms should be taken into account in statistical approaches for studying diet and trophic relationships.     

Mating in the pseudogamic apomictic Anemopaegma acutifolium DC: another case of pseudo‐self‐compatibility in Bignoniaceae?

Self‐compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosperm development in ovules of unpollinated pistils, which indicates obligate pseudogamy. Thus, the aim of the present work is to study the breeding system and post‐pollination events to test if there is similar pseudogamous development irrespective of pollination treatment. We analysed fruit and seed set obtained in controlled experimental pollinations, as well as embryo number per seed, and the progress of ovule penetration, fertilisation and early endosperm development between self‐ and cross‐pollinated pistils. We found that the species is self‐fertile and that spontaneous selfing fruit set is also possible, although emasculated flowers never form fruits. Selfed pistils were as efficient as crossed ones for all parameters analysed, except for a delay in endosperm development observed in the former that may be an effect of the late‐acting self‐incompatibility. Therefore, the avoidance of selfed pistil abortion seems to be promoted by the presence of adventitious embryos and a normal endosperm. We conclude that A. acutifolium shows apomixis‐related pseudo‐self‐compatibility, as in other self‐fertile apomictic species of Bignoniaceae, which confer reproductive assurance and increases fruit‐set and persistence ability in fast‐changing tropical habitats.     

Spontaneous succession in Central‐European man‐made habitats: What information can be used in restoration practice?

Abstract. The results of previous studies concerning spontaneous vegetation succession in various man‐made or disturbed habitats in Central Europe are discussed in relation to restoration ecology. An attempt is made to answer the main questions which are important to restoration programs. These concern the rate and direction of succession; participation of target species and communities, woody species, ruderals and aliens; arresting or diverting succession; changes in species diversity; variability of successional pathways and the role of abiotic environmental conditions. The great potential for using successional theory in restoration programs is emphasized.     

Sex differences in scent‐marking in sifaka: Mating conflict or male services?

Male and female interests can either be in conflict or serve as a basis for exchange. Communication is thus an important aspect of intersexual relationships. Verreaux's sifaka (Propithecus verreauxi verreauxi), like many prosimians, uses chemical signals as one form of communication. The goals of this study were to determine 1) if males and females exhibit sex differences in their scent-marking behavior, and 2) if scent-marking is an example of mating conflict or cooperation. All occurrences of scent-marks, scent-mark context, and scent-mark style were collected on 23 sifaka in the Kirindy Forest of western Madagascar for 7 months (September 2001-March 2002). Scent-mark rates were collected using continuous focal animal sampling from November 2000-March 2002. Home-range data were collected using monthly censuses and instantaneous focal sampling throughout those 17 months. The pressures of behavioral ecology seem to have shaped scent-marking in sifaka: the sexes exhibited significantly different scent-marking behavior. Results from this study are consistent with the hypotheses that 1) females scent-mark to advertise their presence and mark their resources, 2) clean-chested males use scent-marks as between-group communication to advertise their presence, and 3) stained-chested males use scent-marks as a form of olfactory mate-guarding. Scent-marking does not appear to be a "service" that males provide to females, because overmarking limits female communication rather than adding to the overall number of scent-marks. Scent-marking behavior is a crucial aspect of the mating conflict and for understanding intersexual relationships in sifaka.     

Stannous fluoride in dentifrice: an effective anti‐plaque agent in the elderly?

Objective: The aim of this study was to examine differences in plaque accumulation in elderly patients using two toothpastes, with either 0.2% sodium fluoride (NaF) or 0.4% stannous fluoride (SnF₂), but otherwise identical. Background data: The prevalence of denate elderly is increasing. Plaque both causes caries and is associated with an increased mortality rate in frail elderly patients with pneumonia. Therefore, the effective removal of plaque is important. Ingredients with an anti‐plaque effect, such as SnF₂, that can be used in toothpaste, are effective in plaque inhibition Materials and methods: Thirty‐two frail elderly women, 82–98 years of age (mean, 88 years) and living in a residential home, participated in a double‐blind crossover study. They brushed their teeth for 4 weeks with each toothpaste. Treatment outcome was a change in the plaque index (PI) on four anterior teeth and four molars. Results: anova showed statistically significant differences between the treatments (F = 4.21, p = 0.02). A post hoc test showed that SnF₂ produced a statistically significantly lower PI than did NaF. Conclusion: SnF₂ in toothpaste may be effective in inhibiting plaque accumulation in the elderly.     

Territoriality in Lake Eyre Dragons Ctenophorus maculosus: are Males ‘Superterritorial’?

The Australian Lake Eyre dragon, Ctenophorus maculosus, lives on dry salt lakes in the Australian interior. An unusual characteristic of this habitat is that windblown insects are the major food resource, which makes it impossible for males to defend site-related resources. Male territory size is not correlated to male size; thus, males do not seem to defend trophic territories in relation to their own energy demands. Instead, males with higher densities of lookout sites have larger territories, and males with larger territories have more mates. In consequence, males primarily seem to guard sexual resources on territories that are not economically defensible from a trophic point of view; males appear to conform to the concept of ‘superterritoriality’ (sensu Stamps 1983).     

Plant-Knowledge Adaptation in an Urban Setting: <Emphasis Type="Italic">Candomblé</Emphasis> Ethnobotany in New York City

Candomblé is an African-Brazilian religion that resulted from the adaptation of West African (especially Yoruba) beliefs in Brazil during and after the slave trade. This study seeks to understand the current evolution of Candomblé ethnobotanical knowledge as it travels from Brazil to New York City (NYC), therefore going through a second adaptation process. We identified which Brazilian plant species are still in use, which are being incorporated and/or replaced, and what factors are contributing to the ethnobotanical adaptation that is taking place in NYC. To accomplish this, we compiled an inventory of liturgical plants used by five highly skilled Candomblé practitioners living in NYC and then compared the vernacular and binomial Latin names of these plants to inventories previously published in Brazil by other authors. By doing this, we were able to distinguish patterns of knowledge continuity, assimilation, or substitution. Nearly two-thirds of the species identified in NYC’s inventory were cases of knowledge continuity, where most plants were used by at least four practitioners. Many of these frequently used species have survived the adaptation process from Africa to Brazil, and now from Brazil to NYC. Practitioners also assimilated (20%) and substituted (16%) some species. The assimilation process was mainly influenced by Santería, another Yoruba-derived religion widely practiced in NYC. Substitutions, however, were driven by two distinct forces. In one cohort (7%), species were morphologically and organoleptically similar to the original material, and replacements were mostly influenced by the easy accessibility of botanical materials. The other cohort (9%) was marked by a logical substitution process based on Yoruba rules of plant classification. Our results show that Candomblé practitioners in NYC are maintaining a notable level of cultural continuity, while cautiously assimilating new species and consciously or subconsciously replacing others. Although both accessibility of plant material and cultural forces play a role in the adaptation mechanism, the latter appears to be the most relevant to these highly skilled practitioners.     

Membrane Protein Chaperones: A New Twist in the Tail?

The integration of tail-anchored membrane proteins at the endoplasmic reticulum occurs via a specialised ATP-dependent pathway, but the cytosolic factors involved have proven elusive. A novel ATPase that mediates this process has now been identified.     

Q&amp;A: what are brassinosteroids and how do they act in plants?

Brassinosteroids (BRs) are a class of polyhydroxylated steroidal phytohormones in plants with similar structures to animals’ steroid hormones. Brassinosteroids regulate a wide range of physiological processes including plant growth, development and immunity. Brassinosteroid signalling and its integration with other signalling pathways have been investigated thoroughly at the molecular level.