A morphometric and molecular study in Tortula subulata complex (Pottiaceae, Bryophyta)

Specimens belonging to Tortula subulata complex ( T. inermis , T. mucronifolia and T. subulata ) were analysed using a combination of morphometric methods based on quantitative characters [principal component analysis (PCA), discriminant analysis (DA); 76 samples)] and molecular methods (ITS1 – 5.8S rRNA gene and ITS2; 47 samples) to assess patterns of morphological and molecular differentiation within this complex of taxa. The study shows that four species can be recognized: T. mucronifolia , T. subulata , T. inermis and T. subulata var. angustata with bistratose border, which is elevated to the species rank as T. schimperi nom. nov. The most valuable quantitative characters for identification of these species are the strata number of the marginal laminal cells, the ratio of middle marginal laminal cell width/middle marginal laminal cell length, basal membrane of peristome length, middle laminal cell width and papillae number on the middle laminal cells. The internal transcribed spacer (ITS) data suggest that this group of taxa is not monophyletic, T. mucronifolia being close to Protobryum bryoides (= Tortula protobryoides ). The remaining species seem to be a monophyletic group, T. schimperi being the sister group of the clade composed by T. inermis and T. subulata . T. subulata is considered to be of high morphological variability, for which ITS sequences did not resolve the internal relationships.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 333–350.     

Two aberrant serpent-eagles may be visual mimics of bird-eating raptors

Two independent cases of visual mimicry involving snake-eating eagles as mimics and more powerful bird-eating hawks as models are proposed. One pair of species is formed by the sympatric West African Serpent-eagle Dryotriorchis spectabilis and Cassin's Hawk Eagle Spizaetus africanus (= Aquila africana ), inhabiting the tropical forests of the African Gulf of Guinea. The second case involves the Madagascar Serpent-eagle Eutriorchis astur and the Madagascar Goshawk Accipiter henstii , both sympatric and endemics of forests in Madagascar. Similarity in plumage colour and pattern as well as in body size and proportions are remarkable in both cases. The species mimicry pairs are in both cases not closely related phylogenetically and greatly differ in diet, making it unlikely that common ancestry or shared foraging strategies explain the resemblance in plumage coloration and pattern. Mimicry may have evolved because the mimic serpent-eagles obtain (the following hypotheses are not mutually exclusive): (1) a foraging advantage by deceiving their snake prey as they may not flee from bird-eating raptors such as the models, (2) a lowered predation or harassment by the models or other predators, and/or (3) reduced mobbing by small birds, which tend to avoid bird-eating raptors. Alternatively, the similarities in plumage described here may be the result of random convergence due to constraints in the evolution of plumage colours and patterns in diurnal raptors.     

Sex differences in circulating antibodies in nestling Pied Flycatchers Ficedula hypoleuca

Sex differences in immune function are relatively well studied in vertebrate animals, although the patterns are not always clear in birds. The study of immune responses in nestlings of wild bird populations may constitute an appropriate way to investigate inherent intersexual differences while controlling for environmental conditions such as parasitism that affect male and female individuals growing in the same nest. We studied whether the cell‐mediated immune response, as measured by phytohaemagglutinin (PHA) injection, and the levels of circulating antibodies differ between sexes of Pied Flycatcher nestlings Ficedula hypoleuca. No sex differences in nestling cell‐mediated immune response were found, but females showed significantly higher levels of plasma immunoglobulins than males did. Although nestling birds may not have a fully functional humoral immune defence, our study indicates that sex differences in the humoral component exist at this early stage of life. Given the importance of antibodies in the fight against parasite, bacterial and viral infections, the intrinsic sex disparity in circulating antibodies may have important implications for the life history of each sex.     

Land‐use changes may explain the recent range expansion of the Black‐shouldered Kite Elanus caeruleus in southern Europe

Occasional observations of Black‐shouldered Kites Elanus caeruleus in Europe date back to the mid‐19th century, but it was only recorded as a breeding species in the early 1960s in Portugal and a few years later in neighbouring Spain. This recent colonization, possibly from Africa where the species is abundant, may be due to climate change, land‐use changes in southern Europe, or both. As a first step to understanding this range expansion process we have developed a habitat selection model using data from the current strongholds of its European distribution. Comparing the proportion of different habitat types around 46 breeding sites and 45 randomly chosen plots, we have found that the area of cultivated parklands known as dehesas in Spain is a strong predictor of the current distribution range of breeding pairs of Black‐shouldered Kites. Specifically, the percentage of dehesas with planted cereal and a low density of trees (i.e. < 7 trees/ha and thus a savannah‐like habitat) within the study plots explained 44.6% of the residual deviance in our model. The minimal adequate model classified 81.3% of breeding sites and random plots correctly. Our results suggest that Black‐shouldered Kites may have taken advantage of the gradual increase of cultivated dehesas in the second half of the 20th century to expand its range in Europe. This particular type of dehesa is structurally similar to the African savannahs where the species thrives and may offer a higher density of rodents than traditional dehesas, which primarily contain pastureland for livestock ranching.     

Effect of water availability on leaf water isotopic enrichment in beech seedlings shows limitations of current fractionation models

Current models of leaf water enrichment predict that the differences between isotopic enrichment of water at the site of evaporation (Δ_e) and mean lamina leaf water enrichment (Δ_L) depend on transpiration rates ( E ), modulated by the scaled effective length ( L ) of water isotope movement in the leaf. However, variations in leaf parameters in response to changing environmental conditions might cause changes in the water path and thus L . We measured the diel course of Δ_L for ¹⁸O and ²H in beech seedlings under well-watered and water-limited conditions. We applied evaporative enrichment models of increasing complexity to predict Δ_e and Δ_L, and estimated L from model fits. Water-limited plants showed moderate drought stress, with lower stomatal conductance, E and stem water potential than the control. Despite having double E , the divergence between Δ_e and Δ_L was lower in well-watered than in water-limited plants, and thus, L should have changed to counteract differences in E . Indeed, L was about threefold higher in water-limited plants, regardless of the models used. We conclude that L changes with plant water status far beyond the variations explained by water content and other measured variables, thus limiting the use of current evaporative models under changing environmental conditions.     

High European sauropod dinosaur diversity during Jurassic–Cretaceous transition in Riodeva (Teruel, Spain)

Abstract:  Up to now, more than 40 dinosaur sites have been found in the latest Jurassic – earliest Cretaceous sedimentary outcrops (Villar del Arzobispo Formation) of Riodeva (Iberian Range, Spain). Those already excavated, as well as other findings, provide a large and diverse number of sauropod remains, suggesting a great diversity for this group in the Iberian Peninsula during this time. Vertebrae and ischial remains from Riodevan site RD-13 are assigned to Turiasaurus riodevensis (a species described in RD-10, Barrihonda site), which is part of the Turiasauria clade. This is the first time that a taxon is attributed to Turiasaurus genus out of its type site. A Neosauropod caudal vertebra from the RD-11 site has been classified as Diplodocinae indet., supporting the previous attribution on an ilion also found in Riodeva (CPT-1074) referring to the Diplodocidae clade. New remains from the RD-28, RD-41 and RD-43 sites, of the same age, among which there are caudal vertebrae, are assigned to Macronaria. New sauropod footprints from the Villar del Arzobispo Formation complete the extraordinary sauropod record coming to light in the area. The inclusion of other sauropods from different contemporaneous exposures in Teruel within the Turiasauria clade adds new evidence of a great diversity of sauropods in Iberia during the Jurassic–Cretaceous transition. Turiasauria distribution contributes to the understanding of European and global palaeobiogeography.     

The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ13C chemostratigraphy

The extensive work carried out during more than a decade by the International Subcommission on Ordovician Stratigraphy has resulted in a new global classification of the Ordovician System into three series and seven stages. Formal Global Boundary Stratotype Section and Points (GSSPs) for all stages have been selected and these and the new stage names have been ratified by the International Commission on Stratigraphy. Based on a variety of biostratigraphic data, these new units are correlated with chronostratigraphic series and stages in the standard regional classifications used in the UK, North America, Baltoscandia, Australia, China, Siberia and the Mediterranean‐North Gondwana region. Furthermore, based mainly on graptolite and conodont zones, the Ordovician is subdivided into 20 stage slices (SS) that have potential for precise correlations in both carbonate and shale facies. The new chronostratigraphic scheme is also tied to a new composite δ¹³C curve through the entire Ordovician.     

FLUORESCENT MEASUREMENTS OF DNA, RNA AND PROTEINS TO PERFORM COMPARATIVE ANALYSES OF MICROBIAL COMMUNITIES FROM THE ENVIRONMENTS

Simple and rapid methods for the quantification of DNA, RNA and proteins using specific fluorescent dyes are proposed for the comparison and monitoring of microbial communities from the environment. The purpose of this study was the use of straightforward in situ methods which voided the need for preservation of samples and the risk of potential degradation and quantitative changes during transportation. Aside from this, methods used to obtain information on environmental microbial communities are generally time-consuming and present certain difficulty above all when working on solid substrates such as soils and rocks. New generation fluorescent dyes that bind specifically to DNA, RNA and proteins allow simple and rapid estimates of these biomolecules in crude environmental samples.

PRACTICAL APPLICATIONS

Monitoring the metabolic state of microbial communities on different substrates and environments is a requirement for comparing samples and assessing the participation of microorganisms in a variety of processes. Solid substrates are not easily analyzed by microscopic techniques and they require long processing times and tedious work. Aside from this, only a minor fraction (<1%) of microorganisms in most natural environments can be cultured in standard microbiological media ( Ward et al. 1990 ). Other studies using incorporation of labeled substrates to approach activity rates or biomolecule extractions represent complex and long procedures during environmental studies.In order to evaluate microbial communities in a variety of substrates and environments, rapid and simple methods are proposed by measuring DNA, RNA and/or proteins using specific fluorescent dyes, without a need for prior purification, from crude solid samples.     

The value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean members of the genus Pinus

This study reports the value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean species of the genus Pinus (P. nigra subsp. salzmannii, P. pinaster, P. pinea and P. halepensis), with the aim of using these characters to identify isolated cuticles and stomata in palynology slides. Preparations were made of the cuticles of pine needles belonging to one natural Iberian population of each of the above species. A number of epidermal morphological characteristics were then recorded with the aim of distinguishing these species from one another. The structure of the stomatal complex (the shape and arrangement of the subsidiary cells) was different in each species. The aperture of the epistomatal chamber was significantly smaller in P. pinea than in the other species examined, and the variables recorded for the thickening of the guard cells provided relationships that clearly distinguished all four taxa. The width and length of the stomata and the upper woody lamellae, the central distance between the external limits of the medial lamellae borders and the length of the stem were the most useful variables in this respect. The present results contribute to the ongoing discussion regarding the taxonomic classification of the members of Pinus, and provide valuable clues for the identification of Iberian Mediterranean pine species from small pine needle fragments or isolated stomata. After validation of the present results for multiple populations, these results could also be used to help identify fossil leaf macroremains and the scattered/isolated stomata commonly observed in palaeopalynological samples. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 436–448.