Global patterns of diversity among the specialist birds of riverine landscapes

1. Despite the growing view that biodiversity provides a unifying theme in river ecology, global perspectives on richness in riverine landscapes are limited. As a result, there is little theory or quantitative data on features that might have influenced global patterns in riverine richness, nor are there clear indications of which riverine landscapes are important to conservation at the global scale. As conspicuous elements of the vertebrate fauna of riverine landscapes, we mapped the global distributions of all of the world's specialist riverine birds and assessed their richness in relation to latitude, altitude, primary productivity and geomorphological complexity (surface configuration). 2. Specialist riverine birds, typical of high‐energy riverine landscapes and dependent wholly or partly on production from river ecosystems, occur in 16 families. They are represented by an estimated 60 species divided equally between the passerines and non‐passerines. Major radiation has occurred among different families on different continents, indicating that birds have evolved several times into the niches provided by riverine landscapes. 3. Continental richness varies from four species in Europe to 28 in Asia, with richness on the latter continent disproportionately larger than would be expected from a random distribution with respect to land area. Richness is greatest in mountainous regions at latitudes of 20–40°N in the riverine landscapes of the Himalayan mountains, where 13 species overlap in range. 4. Family, genus and species richness in specialist riverine birds all increase significantly with productivity and surface configuration (i.e. relief). However, family richness was the best single predictor of the numbers of species or genera. In keeping with the effect of surface configuration, river‐bird richness peaks globally at 1300–1400 m altitude, and most species occur typically on small, fast rivers where they feed predominantly on invertebrates. Increased lengths of such streams in areas of high relief and rainfall might have been responsible for species–area effects. 5. We propose the hypothesis that the diversity in channel forms and habitats in riverine landscapes, in addition to high temperature and primary productivity, have been prerequisites to the development of global patterns in the richness of specialist riverine organisms. We advocate tests of this hypothesis in other taxonomic groups. We draw attention, however, to the challenges of categorically defining riverine organisms in such tests because (i) rivers grade into many other habitat types across several different ecotones and (ii) `terrestrialisation' processes in riverine landscapes means that they offer habitat for organisms whose evolutionary origins are not exclusively riverine.     

Ants resort to majority concession to reach democratic consensus in the presence of a persistent minority

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Cartography and Clandestinité in Leïla Sebbar’s Shérazade: 17 ans, brune, frisée, les yeux verts

In this paper, I read Leïla Sebbar’s staging in her novel Shérazade: 17 ans, brune, frisée, les yeux verts of the resistance by children of North African and other immigrants in the early 1980s to the French state’s cartographic modes and documents of control. The paper will consider the many uses to which the map was put by the French state in its colonization of North Africa and particularly Algeria, and later in its attempts to control the banlieues its policies of citizenship and cartographic control yielded on the margins of Paris. In this context, I will explore the ways in which the novel’s characters, living clandestinely in a squatt, simultaneously resist, put to use, and even supercede state documents of control as they disrupt everyday life and conduct heists across the city of Paris. The paper will explore unofficial cartographies of Paris, from those afforded by the radios libres and alternative publications such as Libération and Sans Frontièrez, to oral and almost proverbial networks of knowledge criss-crossing the city of Paris, while also tracing the uses to which supplemental cartographic sketches and counterfeit identity cards are put in the pages of the novel. The paper will be in dialogue with theoretical and critical formulations of space, cartography, and state control put forward by Michel de Certeau, Henri Lefebvre, Michel Foucault, and Tom Conley. The paper will conclude with a consideration of the means and limits of resistance by the novel’s characters in the context of this body of theory and criticism.     

Computational Investigations of the Chalcogen-Substituted Carboxylic Acids RC(=O)XH and RC(=X)OH and their Dimers [RC(=O)XH]2 and [RC(=X)OH]2 (X=S, Se, Te)

Semiempirical and ab initio theoretical methods have been used to investigate molecular structures of the chalcogen-substituted carboxylic acid isomers RC(=O)XH (chalcogenol acid) and RC(=X)OH (chalcogenon acid). A recent experimental report suggests that the chalcogenon isomers, although less stable at room temperature, predominate at low temperature in polar solvents and that there is only a small barrier to isomerization between the isomers. Theoretical calculations have been used to locate minimum energy structures of chalcogen-substituted carboxylic acid isomers and to calculate energy differences between pairs of isomers. Carboxylic acids are well known to dimerize, especially in the gas phase and in non-polar solvents. We have, therefore, also calculated energies of dimerization of the chalcogen-substituted acids by optimizing the geometries of the symmetric dimers. We note that the PM3 level of theory is only qualitatively correct for sulfur- and selenium-containing species but fails even qualitatively for the tellurium-containing compounds. Ab initio results confirm the experimental observations and provide good estimates of both isomerization and dimerization energies. We conclude that for many functional groups with tautomers RC(=X)YH and RC(=Y)XH, the more acidic tautomer is the one with the acid proton on the smaller, more electronegative atom, although in many cases this may not be the more stable tautomer.Electronic Supplementary Material available.     

Preparation of chloroplast DNA from pea plastids isolated in a medium of high ionic strength

A simple, rapid, and inexpensive method for the preparation and purification of chloroplast DNA (cpDNA) from pea has been developed. The crucial step is the isolation of chloroplasts in a medium of high ionic strength (I congruent equal to 1.40 M). CpDNA from pea prepared according to this method has successfully been used for restriction enzyme mapping, Southern transfers, and cloning.     

Validation of the first step of the heuristic refinement method for the derivation of solution structures of proteins from NMR data

A new method for the analysis of NMR data in terms of the solution structure of proteins has been developed. The method consists of two steps: first a systematic search of the conformational space to define the region allowed by the initial set of experimental constraints, and second, the narrowing of this region by the introduction of additional constraints and optional refinement procedures. The search of the conformational space is guided by heuristics to make it computationally feasible. The method is therefore called the heuristic refinement method and is coded in an expert system called PROTEAN. The paper describes the validation of the first step of the method using an artificial NMR data set generated from the known crystal structure of sperm whale carbon monoxymyoglobin. It is shown that the initial search procedure yields a low-resolution structure of the myoglobin molecule, accurately reproducing its main topological features, and that the precision of the structure depends on the quality of the initial data set.     

Use of time in a decision‐making process by a parasitoid

1. Time perception is seldom studied in invertebrates, with the limited experimental evidence being insufficient to provide a comprehensive pattern of the capacity of invertebrates to measure time and use it in decision‐making processes. 2. In this study, it was hypothesized that insect parasitoids have evolved the capacity to measure time precisely and to use it to optimize foraging decisions related to host exploitation. To examine time perception in females of the gregarious egg parasitoid Trichogramma euproctidis, the present study used their ability to adjust their investment (number of eggs laid) in a host to the initial transit duration (interval between the first contact with the host and the following contact with the substrate). Females utilize this method to assess host egg size, as a large egg necessarily requires more time to evaluate than a small host. In this study, the initial transit duration for a given sized egg was artificially extended by suspending it. 3. For similar sized hosts, female T. euproctidis significantly increased both oviposition duration and progeny allocation following a longer initial transit duration. 4. These results demonstrate the intrinsic capacity of this parasitoid to measure time and to adjust their progeny investment accordingly. This is believed to be one of the few demonstrations of a retrospective measure of time in an invertebrate.     

Female and male Texas cichlids (Herichthys cyanoguttatum) do not fight by the same rules

Selection usually acts differently on males and females duringintrasexual competition for resources and/or mates. Nevertheless,agonistic behavior has been examined both theoretically andempirically mostly in males. Our research questions whethermales and females follow the same rules of engagement in intrasexualcontests as predicted by the sequential assessment model (SAM).The SAM predicts negative correlations between contest intensityand duration and the magnitude of asymmetry in resource holdingpower (RHP) between the contestants, such that the most escalatedcontests are those between similarly endowed individuals. Westaged male and female intrasexual contests with varying degreesof body size asymmetry under a round robin design using themonogamous Texas cichlid fish (Herichthys cyanoguttatum) asa study case. We used Mantel's matrix analysis to compare howthe behavioral content, duration, structure, and outcome ofmale and female contests were affected by the relative bodysize of the contestants. In the case of males, relative sizein each contest predicted outcome, duration, and frequency ofconventional and escalated behaviors according to prevailingtheory. Female contest structure and outcome, however, werenot predicted by the relative size of contestants. We discussour results in terms of other asymmetries that might be importantin structuring female contests, and we propose potential approachesto study female–female aggression.