bluuebunny/crossref_metadata_2025_split huggingface dataset:
Size‐dependent mortality in a Neotropical savanna tree: the role of height‐related adjustments in hydraulic architecture and carbon allocation
Authors: ZHANG YONG‐JIANG , MEINZER FREDERICK C. , HAO GUANG‐YOU , SCHOLZ FABIAN G. , BUCCI SANDRA J. , TAKAHASHI FREDERICO S. C. , VILLALOBOS‐VEGA RANDOL , GIRALDO JUAN P. , CAO KUN‐FANG , HOFFMANN WILLIAM A. , GOLDSTEIN GUILLERMO 
Published: June 2009

ABSTRACTSize‐related changes in hydraulic architecture, carbon allocation and gas exchange of Sclerolobium paniculatum (Leguminosae), a dominant tree species in Neotropical savannas of central Brazil (Cerrado), were investigated to assess their potential role in the dieback of tall individuals. Trees greater than ∼6‐m‐tall exhibited more branch damage, larger numbers of dead individuals, higher wood density, greater leaf mass per area, lower leaf area to sapwood area ratio (LA/SA), lower stomatal conductance and lower net CO2 assimilation than small trees. Stem‐specific hydraulic conductivity decreased, while leaf‐specific hydraulic conductivity remained nearly constant, with increasing tree size because of lower LA/SA in larger trees. Leaves were substantially more vulnerable to embolism than stems. Large trees had lower maximum leaf hydraulic conductance (Kleaf) than small trees and all tree sizes exhibited lower Kleaf at midday than at dawn. These size‐related adjustments in hydraulic architecture and carbon allocation apparently incurred a large physiological cost: large trees received a lower return in carbon gain from their investment in stem and leaf biomass compared with small trees. Additionally, large trees may experience more severe water deficits in dry years due to lower capacity for buffering the effects of hydraulic path‐length and soil water deficits.
Oxygen isotope enrichment (Δ18O) reflects yield potential and drought resistance in maize
Authors: CABRERA‐BOSQUET LLORENÇ , SÁNCHEZ CIRO , ARAUS JOSÉ LUIS 
Published: June 2009

ABSTRACTMeasurement of stable isotopes in plant dry matter is a useful phenotypic tool for speeding up breeding advance in C3 crops exposed to different water regimes. However, the situation in C4 crops is far from resolved, since their photosynthetic metabolism precludes (at least in maize) the use of carbon isotope discrimination. This paper investigates the use of oxygen isotope enrichment (Δ18O) as a new secondary trait for yield potential and drought resistance in maize (Zea mays L). A set of tropical maize hybrids developed by the International Maize and Wheat Improvement Center was grown under three contrasting water regimes in field conditions. Water regimes clearly affected plant growth and yield. In accordance with the current theory, a decrease in water input was translated into large decreases in stomatal conductance and increases in leaf temperature together with concomitant 18O enrichment of plant matter (leaves and kernels). In addition, kernel Δ18O correlated negatively with grain yield under well‐watered and intermediate water stress conditions, while it correlated positively under severe water stress conditions. Therefore, genotypes showing lower kernel Δ18O under well‐watered and intermediate water stress had higher yields in these environments, while the opposite trend was found under severe water stress conditions. This illustrates the usefulness of Δ18O for selecting the genotypes best suited to differing water conditions.
Origin of Lower Cretaceous (‘Nubian’) sandstones of North‐east Africa and Arabia from detrital zircon U‐Pb SHRIMP dating
Authors: KOLODNER KEREN , AVIGAD DOV , IRELAND TREVOR RUSSELL , GARFUNKEL ZVI 
Published: June 2009

AbstractLower Cretaceous sandstones of the type exposed in Israel, deposited over much of North Africa and Arabia as widespread sandstone sheets, typically are mineralogically and texturally mature. Previous petrographic examinations suggested that the Lower Cretaceous sandstones are at least partly a product of recycling and the present study supports this notion. The results of U‐Pb Sensitive High Resolution Ion Micro‐Probe (SHRIMP) dating of detrital zircons from the Lower Cretaceous section exposed in Israel indicate that they are dominated by detrital zircons of Neoproterozoic age, mainly concentrated in the 0·55 to 0·65 Ga interval, with various amounts of older (pre‐Neoproterozoic) zircons (of 0·95 to 1·10, 1·7 to 2·0 and 2·6 to 2·65 Ga age groups). The overall age signal is similar to detrital zircon age spectra previously obtained from the Cambrian–Ordovician sections of Israel and Jordan. Remarkably, the detrital zircon spectra remained almost unchanged for nearly 400 Myr. Thus, the most probable provenance of the Lower Cretaceous sandstone is the recycling of relatively proximal Palaeozoic sandstone. Since first unroofed from above pan‐African terranes closer to the secession of orogeny, the ensuing siliciclastics were recycled repeatedly throughout the Phanerozoic with little additional basement denudation. The Lower Cretaceous sandstone comprises quartz sand that was first eroded from above pan‐African orogens ca 400 Myr prior to deposition.
Architecture of a coarse‐grained channel–levée system: the Rosario Formation, Baja California, Mexico
Authors: KANE IAN A. , DYKSTRA MASON L. , KNELLER BENJAMIN C. , TREMBLAY SACHA , McCAFFREY WILLIAM D. 
Published: June 2009

AbstractSeafloor images of coarse‐grained submarine channel–levée systems commonly reveal complex braid‐plain patterns of low‐amplitude bedforms and zones of apparent bypass; however, mechanisms of channel evolution and the resultant channel‐fill architecture are poorly understood. At Playa Esqueleto the lateral relationships between various elements of a deep‐marine slope channel system are well‐exposed. Specifically, the transition from gravel‐dominated axial thalwegs to laterally persistent marginal sandstones and isolated gravel‐filled scours is revealed. Marginal sandstones pass into a monotonous thin‐bedded succession which built to form relatively low‐relief levées bounding the channel belt; in turn, the levées onlap the canyon walls. Three orders of confinement were important during the evolution of the channel system: (i) first‐order confinement was provided by the erosional canyon which confined the entire system; (ii) confined levées built of turbidite sandstones and mudstones formed the second‐order confinement, and it is demonstrated that these built from overspill at thalweg margins; and (iii) third‐order confinement describes the erosional confinement of coarse‐grained thalwegs and scours. Finer‐grained sediment was transported in suspension and largely was unaffected by topography at the scale of individual thalwegs. Facies and clast analyses of conglomerate overlying channel‐marginal scours reveal that they were deposited by composite gravity flows, which were non‐cohesive, grain‐dominant debris flows with more fluidal cores. These flows were capable of basal erosion but were strongly depositional; frictional freezing at flow margins built gravel levées, while the core maintained a more fluidal transport regime. The resultant architecture consists of matrix‐rich, poorly sorted levées bounding better‐sorted, traction‐dominated cores. The planform geometry is interpreted to have consisted of a low‐sinuosity gravel braid‐plain built by accretion around mid‐channel and bank‐attached bars. This part of the system may be analogous to fluvial systems; however, the finer‐grained sediment load formed thick suspension clouds, probably several orders of magnitude thicker than the relief of braid‐plain topography and therefore controlled by the levées and canyon wall confinement.
Delineation of the geometry of nodes in the Alps–Dinarides hinge zone and recognition of seismogenic nodes (M ≥ 6)
Authors: Gorshkov Alexander I. , Panza Giuliano F. , Soloviev Alexander A. , Aoudia Abdelkrim , Peresan Antonella 
Published: June 2009

AbstractWe introduce a new method based on the analysis of the topographical alignments and used to delineate the structural boundaries of the nodes, which permits the definition of relatively narrow earthquake‐prone areas by the pattern recognition approach. The structurally bounded nodes capable of earthquakes with M ≥ 6.0, identified with pattern recognition, in fact, cover a significantly smaller area of the study region as compared with that defined by Gorshkov et al. (2004) who used conventional circles. The proposed method thus improves the precision in the location of potential large earthquakes.
Slope‐control on the aspect ratio of river basins
Authors: Castelltort Sébastien , Simpson Guy , Darrioulat Alexandre 
Published: June 2009

AbstractAlthough it is traditionally thought that drainage basins are geometrically similar, we present new results which indicate that the aspect ratio of weakly dissected river basins at large scales (10–103 km2) depends on the surface slope: steeper surfaces develop narrower and lengthier basins whereas more gently dipping surfaces develop more equant and wider basins. This relationship is interpreted to be related to the nature of water flow over rough surfaces, with steeper slopes causing less flow convergence and lengthier and narrower basins. We derive an empirical relationship that can be used to infer the slope of a surface on which a river basin acquired its geometry based solely on a measure of its basin form. This relation provides a unique means of inferring the relative chronology of river basin development with respect to surface tilting and therefore provides a direct link between river basin morphology and tectonics.
Long‐term fluctuations in volcanic activity: implications for future environmental impact
Authors: Rymer Hazel , Locke Corinne A. , Borgia Andrea , Martinez Maria , Brenes Jorge , Van der Laat Rodolfo , Williams‐Jones Glyn 
Published: June 2009

AbstractAcidic crater lakes at persistently active volcanoes act as both an index and a moderator of volcanic processes. A catastrophic drop in lake level can therefore lead to serious local environmental damage. In the early 1990s, the crater lake at Poás volcano, Costa Rica diminished, and acid aerosols erupted with devastating consequences for local health, environment and economy. The first indications of this event can be  retrospectively identified to have started from 1985, on the basis of our unique 20‐year data time series, which provides evidence for the shallow intrusion of magma. New data presented in this article show similar trends and we conclude that Poás has now entered another active period with renewed intrusion. Severe environmental damage in this region is expected within the next few years if the current trend continues.
Efficacy of the solar water disinfection method in turbid waters experimentally contaminated with Cryptosporidium parvum oocysts under real field conditions
Authors: Gómez‐Couso H. , Fontán‐Saínz M. , Sichel C. , Fernández‐Ibáñez P. , Ares‐Mazás E. 
Published: June 2009

SummaryObjective  To investigate the efficacy of the solar water disinfection (SODIS) method for inactivating Cryptosporidium parvum oocysts in turbid waters using 1.5 l polyethylene terephthalate (PET) bottles under natural sunlight.Methods  All experiments were performed at the Plataforma Solar de Almería, located in the Tabernas Desert (Southern Spain) in July and October 2007. Turbid water samples [5, 100 and 300 nephelometric turbidity units (NTU)] were prepared by addition of red soil to distilled water, and then spiked with purified C. parvum oocysts. PET bottles containing the contaminated turbid waters were exposed to full sunlight for 4, 8 and 12 h. The samples were then concentrated by filtration and the oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide.Results  After an exposure time of 12 h (cumulative global dose of 28.28 MJ/m2; cumulative UV dose of 1037.06 kJ/m2) the oocyst viabilities were 11.54%, 25.96%, 41.50% and 52.80% for turbidity levels of 0, 5, 100 and 300 NTU, respectively, being significantly lower than the viability of the initial isolate (P < 0.01).Conclusions  SODIS method significantly reduced the potential viability of C. parvum oocysts on increasing the percentage of oocysts that took up the dye PI (indicator of cell wall integrity), although longer exposure periods appear to be required than those established for the bacterial pathogens usually tested in SODIS assays.
Outcome, timing and adverse events in therapeutic hypothermia after out‐of‐hospital cardiac arrest
Authors: NIELSEN N. , HOVDENES J. , NILSSON F. , RUBERTSSON S. , STAMMET P. , SUNDE K. , VALSSON F. , WANSCHER M. , FRIBERG H. ,   for the Hypothermia Network
Published: June 2009

Background: Therapeutic hypothermia (TH) after cardiac arrest protects from neurological sequels and death and is recommended in guidelines. The Hypothermia Registry was founded to the monitor outcome, performance and complications of TH.Methods: Data on out‐of‐hospital cardiac arrest (OHCA) patients admitted to intensive care for TH were registered. Hospital survival and long‐term outcome (6–12 months) were documented using the Cerebral Performance Category (CPC) scale, CPC 1–2 representing a good outcome and 3–5 a bad outcome.Results: From October 2004 to October 2008, 986 TH‐treated OHCA patients of all causes were included in the registry. Long‐term outcome was reported in 975 patients. The median time from arrest to initiation of TH was 90 min (interquartile range, 60–165 min) and time to achieving the target temperature (≤34 °C) was 260 min (178–400 min). Half of the patients underwent coronary angiography and one‐third underwent percutaneous coronary intervention (PCI). Higher age, longer time to return of spontaneous circulation, lower Glasgow Coma Scale at admission, unwitnessed arrest and initial rhythm asystole were all predictors of bad outcome, whereas time to initiation of TH and time to reach the goal temperature had no significant association. Bleeding requiring transfusion occurred in 4% of patients, with a significantly higher risk if angiography/PCI was performed (2.8% vs. 6.2%P=0.02).Conclusions: Half of the patients survived, with >90% having a good neurological function at long‐term follow‐up. Factors related to the timing of TH had no apparent association to outcome. The incidence of adverse events was acceptable but the risk of bleeding was increased if angiography/PCI was performed.
Testosterone, growth and the evolution of sexual size dimorphism
Authors: COX R. M. , STENQUIST D. S. , CALSBEEK R. 
Published: June 2009

AbstractThe integration of macroevolutionary pattern with developmental mechanism presents an outstanding challenge for studies of phenotypic evolution. Here, we use a combination of experimental and comparative data to test whether evolutionary shifts in the direction of sexual size dimorphism (SSD) correspond to underlying changes in the endocrine regulation of growth. First, we combine captive breeding studies with mark‐recapture data to show that male‐biased SSD develops in the brown anole lizard (Anolis sagrei) because males grow significantly faster than females as juveniles and adults. We then use castration surgeries and testosterone implants to show that castration inhibits, and testosterone stimulates, male growth. We conclude by reviewing published testosterone manipulations in other squamate reptiles in the context of evolutionary patterns in SSD. Collectively, these studies reveal that the evolution of SSD has been accompanied by underlying changes in the effect of testosterone on male growth, potentially facilitating the rapid evolution of SSD.
Phenotypic divergence but not genetic distance predicts assortative mating among species of a cichlid fish radiation
Authors: STELKENS R. B. , SEEHAUSEN O. 
Published: June 2009

AbstractThe hypothesis of ecological divergence giving rise to premating isolation in the face of gene flow is controversial. However, this may be an important mechanism to explain the rapid multiplication of species during adaptive radiation following the colonization of a new environment when geographical barriers to gene flow are largely absent but underutilized niche space is abundant. Using cichlid fish, we tested the prediction of ecological speciation that the strength of premating isolation among species is predicted by phenotypic rather than genetic distance. We conducted mate choice experiments between three closely related, sympatric species of a recent radiation in Lake Mweru (Zambia/DRC) that differ in habitat use and phenotype, and a distantly related population from Lake Bangweulu that resembles one of the species in Lake Mweru. We found significant assortative mating among all closely related, sympatric species that differed phenotypically, but none between the distantly related allopatric populations of more similar phenotype. Phenotypic distance between species was a good predictor of the strength of premating isolation, suggesting that assortative mating can evolve rapidly in association with ecological divergence during adaptive radiation. Our data also reveals that distantly related allopatric populations that have not diverged phenotypically, may hybridize when coming into secondary contact, e.g. upon river capture because of diversion of drainage systems.
Adaptive brain size divergence in nine‐spined sticklebacks (Pungitius pungitius)?
Authors: GONDA A. , HERCZEG G. , MERILÄ J. 
Published: June 2009

AbstractMost studies seeking to provide evolutionary explanations for brain size variability have relied on interspecific comparisons, while intraspecific studies utilizing ecologically divergent populations to this effect are rare. We investigated the brain size and structure of first‐generation laboratory‐bred nine‐spined sticklebacks (Pungitius pungitius) from four geographically and genetically isolated populations originating from markedly different habitats. We found that the relative size of bulbus olfactorius and telencephalon was significantly larger in marine than in pond populations. Significant, but habitat‐independent population differences were also found in relative brain and cerebellum sizes. The consistent, habitat‐specific differences in the relative size of bulbus olfactorius and telencephalon suggest their adaptive reduction in response to reduced (biotic and abiotic) habitat complexity in pond environments. In general, the results suggest that genetically based brain size and structure differences can evolve relatively rapidly and in repeatable fashion with respect to habitat structure.
Major disruption of gene expression in hybrids between young sympatric anadromous and resident populations of brook charr (Salvelinus fontinalis Mitchill)
Authors: MAVAREZ JESUS , AUDET CELINE , BERNATCHEZ LOUIS 
Published: June 2009

AbstractGenome‐wide analyses of the transcriptome have suggested that male‐biased genes are the first targets of genomic incompatibilities (g.i.) in inter‐specific hybrids. However, those studies have almost invariably focused on Drosophila species that diverged at least 0.9 Ma, and with sterile male hybrids. Here, we use microarrays to analyse patterns of gene expression in very closely related (divergence <12 000 years), sympatric, but ecologically divergent anadromous and resident populations of brook charr (Salvelinus fontinalis) and their F1 hybrids. Our results show a dramatic breakdown of gene expression patterns in hybrids compared with their parental relatives. Several disrupted genes are related to energetic metabolism, immune response, osmoregulation and protection against oxidative stress, and none has sex‐biased functions. Besides, pure individuals show no expression differences at most of the genes disrupted in hybrids, which may suggest the operation of some form of stabilizing selection. Taken together, these results both confirm the idea that perturbations of regulatory networks represent a significant source of g.i. and support the suggestion that developmental pathways can diverge through time without any manifest change in the phenotypic outcome. While the role of other evolutionary forces (e.g. genetic drift) cannot be ruled out, this study suggests that ecological selective processes may provide the initial driving force behind disruption of gene expression in inter‐specific hybrids.
Aphid genotypes vary in their response to the presence of fungal endosymbionts in host plants
Authors: BIERI A. P. S. , HÄRRI S. A. , VORBURGER C. , MÜLLER C. B. 
Published: June 2009

AbstractGenetic variation for fitness‐relevant traits may be maintained in natural populations by fitness differences that depend on environmental conditions. For herbivores, plant quality and variation in chemical plant defences can maintain genetic variation in performance. Apart from plant secondary compounds, symbiosis between plants and endosymbiotic fungi (endophytes) can produce herbivore‐toxic compounds. We show that there is significant variation among aphid genotypes in response to endophytes by comparing life‐history traits of 37 clones of the bird cherry‐oat aphid Rhopalosiphum padi feeding on endophyte‐free and endophyte‐infected tall fescue Lolium arundinaceum. Clonal variation for life‐history traits was large, and most clones performed better on endophyte‐free plants. However, the clones differed in the relative performance across the two environments, resulting in significant genotype × environment interactions for all reproductive traits. These findings suggest that natural variation in prevalence of endophyte infection can contribute to the maintenance of genetic diversity in aphid populations.
Duets in Yellow‐Naped Amazons: Variation in Syntax, Note Composition and Phonology at Different Levels of Social Organization
Authors: Dahlin Christine R. , Wright Timothy F. 
Published: June 2009

AbstractComplex vocal signals composed of multiple notes are used by many species. Such signals may vary in a number of features such as the rules that govern note order and timing (syntax), the relative number and types of different notes (note composition), and the acoustic structure of notes (phonology). Previous research examining male song in songbirds typically has shown greater conservation of syntax than phonology. Here we investigated whether these patterns of variation are also found in the duets of parrots. We examined geographic variation in the pair duets of yellow‐naped amazons,Amazona auropalliata, at five sites within one vocal dialect. We also examined variation at several levels of social organization, including within pairs, among pairs and among sites, to assess where variability was greatest. Variation was highest at the within‐pair level, although variation was also present at all other levels and for all of the duet factors. We hypothesize that variation at the among‐site level allows duets to indicate site membership, while variation at the within‐pair level allows pairs to change their duet to match their current social or physical environment. Syntax and phonology are also more conserved than note composition for all levels of social organization. This pattern may result because note composition is less important in duet function than syntax or phonology, or because development of syntax and phonology is more heavily influenced by genetic templates.