bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sediment type rules the response of aquatic plant communities to dewatering in wetlands
Authors: De Wilde Mélissa , Puijalon Sara , Bornette Gudrun 
Published: November 2016

AbstractQuestionsThe effect of dewatering on aquatic plant communities may vary with sediment properties, such as particle size and organic matter content, as both control water retention in the sediment during dewatering. No study has tested how sediment type affects the short‐term response of plant communities to dewatering. We hypothesized that for the same dewatering event: (1) organic, silt and coarse sediments rank along a gradient of water deficit, with which community resistance and resilience decrease; (2) species survival during the event depend on their known ecological affinity for water; and (3) a peak in species richness associated with an intermediate water deficit occurs in silty habitats.LocationRiverine wetlands in the floodplain of the Ain River, France.MethodsEighteen sampling units were defined, set over three sediment types: gravel‐dominated coarse sediment, silt and organic matter‐dominated sediment. For each sediment type, three sampling units were permanently aquatic, and three sampling units underwent summer dewatering. A survey of species cover was conducted in each sampling unit at four times: before summer dewatering, at the beginning of the event, at the end of the event and 2 months after rewetting. Community resistance and resilience were assessed, as were changes over time in the proportions of species according their water affinity (hydrophytes, amphiphytes and helophytes, documented from the floras), and the effect of dewatering on species renewal and richness.ResultsThe sediment type affected aquatic plant community resistance and resilience, with increasing disturbance intensity for silty, followed by coarse compared with organic sediment. Organic sediment retained water efficiently during dewatering, supporting high community resistance, with the maintenance of amphiphytes and more tolerant hydrophytes. On silty sediment, disturbance was sufficiently high to cause the disappearance of hydrophyte vegetative parts, but propagules rapidly sprouted after rewetting, suggesting their preservation in the sediment and enabling good community resilience. On coarse sediment, a decrease in resident amphiphyte abundance, together with helophyte colonization and maintenance after rewetting were observed. Coarse sediment is not favourable to propagule survival, explaining the low community resilience. Contrary to our hypothesis, a linear positive relationship between disturbance intensity and species richness was observed after dewatering.ConclusionThe present study demonstrates that a simple description of sediment type allows prediction of dewatering impact on aquatic plant communities: organic, silt and coarse sediments were ranked along a gradient of water deficit, along which resistance and resilience decreased.
Effects of sampling effort on estimates of the structure of replacement networks
Authors: Pulgar Manuel , Alcántara Julio M. , Rey Pedro J. 
Published: November 2016

AbstractAimsImportant aspects of plant community dynamics depend on interactions between plant species that affect the processes of recruitment and the replacement of dead individuals by new ones. These interactions blend in the replacement network of the community. The qualitative and functional structure of replacement networks can provide insights on community stability properties. The goal of this study was to analyse how sampling effort affects estimates of different descriptors of replacement networks.LocationMixed pine‐oak forests in southern Spain.MethodsWe sampled the replacement networks of nine forest patches. In each forest we surveyed 16 plots of 25 m × 25 m, locating all the saplings of woody species and noting whether they were recruiting under the canopy of some plant species or in open interspaces. Using the replacement networks from the plots of each forest we constructed curves relating network descriptor estimates to sampling effort. Additionally we calculated the completeness of basic network elements (number of species and interactions) using rarefaction and extrapolation techniques.ResultsNumber of species (S) and connectance (C) stabilized within our range of sampling effort. The estimates of S reached completeness values above 97%. However, the number of interactions in the network (L) and the mean number or interactions per species (k) did not stabilize, although the estimates of L reached completeness values above 86%. With few exceptions, the parameters describing the functional structure of the network and those related to community stability stabilized within our range of sampling effort.ConclusionsOur results suggest that most replacement networks descriptors in the studied forests can be reliably estimated from samples of around 1 ha. Since plots used in forest ecology are commonly around that size, replacement network monitoring can be easily incorporated in forest ecology studies as a highly cost‐effective tool to explore community dynamics. The reliability of replacement network estimates will provide both a solid foundation for further developments and also a straightforward comparison of results obtained from multiple communities.
Economics of Intensively Aerated Catfish Ponds
Authors: Kumar Ganesh , Engle Carole 
Published: November 2016

AbstractTheUScatfish industry is evolving by adopting production‐intensifying practices that enhance productivity. Catfish producers have increased aeration rates over time, and some now use intensive rates of aeration (>9.33kW/ha). Costs and production performance were monitored at commercial catfish farms using high levels of aeration (11.2–18.7 kW/ha) in Alabama, Arkansas, and Mississippi. A multivariate‐cluster analysis was used to identify four different management clusters of intensively aerated commercial catfish farms based on stocking density, size of fingerlings at stocking, and feed conversion ratios (FCR). Breakeven prices of hybrid catfish raised in intensively aerated pond systems were estimated to range from $1.86/kg to $2.17/kg, with the lowest costs associated with the second greatest level of production intensity. The two medium‐intensity clusters generated sufficiently high revenues for long‐term profitability. However, the least‐intensive and the most‐intensive clusters were economically feasible only when catfish and feed prices were closer to less probable market prices. Feed price,FCR, and yield contributed the most to downside risk. Intensive aeration in catfish ponds, up to the levels analyzed in this study, appears to be economically feasible under the medium‐intensity management strategies identified in this analysis.
Penny and penny laid up will be many: large Yellow anacondas do not disregard small prey
Authors: Miranda E. B. P. , Ribeiro‐Jr R. P. , Camera B. F. , Barros M. , Draque J. , Micucci P. , Waller T. , Strüssmann C. 
Published: November 2016

AbstractThe study of diet may help to predict the consequences of ontogeny and sexual size dimorphism in resource use. Although diet changes are expected in dimorphic species, ontogeny can be a factor in determining the degree of diet variation within a species. We studied large sexually dimorphic predator, the Yellow anaconda Eunectes notaeus, to learn how influences of sex and size on diet might lead to intersexual niche divergence, therefore avoiding intraspecific competition. We tested the consequences of sexual size dimorphism via two foraging metrics: prey size and feeding frequency. To test the consequences of ontogeny on trophic niche metrics, we related changes in feeding frequency and maximum prey size to increase in anaconda body size. Finally, we tested whether diet composition changed between sexes to the point where it could lead to reduced competition. While females (the larger sex) did eat larger prey compared to males, this effect disappeared when we removed the effect of body size. Females ate more frequently than males, even with body size effect was removed. Predator‐prey size ratios were positively affected by maximum prey size, and as expected from foraging theory, did not increase minimum prey size. Feeding frequency did not display any ontogenetic effects. While diet composition varied between sexes, overlap is high. This indicates that variations in resource use as a product of sex‐based differences in size are negligible in Yellow anacondas. Although females feed more frequently, this may be an effect of the greater energetic costs of reproduction. Ontogeny has a positive effect on maximum prey size, though this is a general trend, and has already been demonstrated for several other species. Finally, understanding of sex‐based changes in resource use will be improved if it can be determined whether such phenomena are consequences rather than causes for sexual size dimorphism.
Northwest Africa 5790: A previously unsampled portion of the upper part of the nakhlite pile
Authors: Brian Balta J. , Sanborn Matthew E. , Mayne Rhiannon G. , Wadhwa Meenakshi , McSween Harry Y. , Crossley Samuel D. 
Published: November 2016

AbstractWe present a geochemical study of recently discovered Martian meteorite Northwest Africa (NWA) 5790 and use our results to constrain its origin and relationship with the other nakhlites. This nakhlite is a clinopyroxene cumulate composed of phenocrysts of augite, olivine, and rare oxides surrounded by a mesostasis composed of vitrophyric glass, feldspars, oxides, phosphates, and fine‐grained olivines and augite. Petrography, and major and trace element compositions of the phases present are consistent with derivation of NWA 5790 from a parental magma common to all the nakhlites. Olivine cores grew from a distinct, incompatible‐element enriched magma and are surrounded by rims containing augite inclusions that grew from the nakhlite parental liquid, supporting previous arguments for xenocrystic olivine cores in nakhlites. Rare earth element microdistributions suggest derivation of NWA 5790 augites from an evolved, relatively oxidized magma, produced by augite fractionation from the common nakhlite parental liquid. Augite grain shapes and CSD patterns are consistent with rapid cooling and derivation near the top of the nakhlite cumulate pile, but patterns are distinct from other nakhlites thought to have formed near the stratigraphic top. The high mesostasis abundance (~44 vol%) indicates solidification near the top of the nakhlite pile close to locations suggested for nakhlites NWA 817 and Miller Range (MIL) 03346. However, the geochemical and petrographic characteristics of these three samples do not permit their placement in a simple stratigraphic order as would occur in a single lava flow. This lack of simple ordering suggests that the nakhlite lava flow split into multiple sections as would occur during breakouts from a single lava flow. Finally we note that NWA 5790 is unique among currently available nakhlites in having phenocryst abundances low enough to allow it to flow.
Olivine dissolution in molten silicates: An experimental study with application to chondrule formation
Authors: Soulié Camille , Libourel Guy , Tissandier Laurent 
Published: November 2016

AbstractMg‐rich olivine is a ubiquitous phase in type I porphyritic chondrules in various classes of chondritic meteorites. The anhedral shape of olivine grains, their size distribution, as well as their poikilitic textures within low‐Ca pyroxene suggest that olivines suffer dissolution during chondrule formation. Owing to a set of high‐temperature experiments (1450–1540 °C) we determined the kinetics of resorption of forsterite in molten silicates, using for the first time X‐ray microtomography. Results indicate that forsterite dissolution in chondrule‐like melts is a very fast process with rates that range from ~5 μm min−1 to ~22 μm min−1. Forsterite dissolution strongly depends on the melt composition, with rates decreasing with increasing the magnesium and/or the silica content of the melt. An empirical model based on forsterite saturation and viscosity of the starting melt composition successfully reproduces the forsteritic olivine dissolution rates as a function of temperature and composition for both our experiments and those of the literature. Application of our results to chondrules could explain the textures of zoned type I chondrules during their formation by gas‐melt interaction. We show that the olivine/liquid ratio on one hand and the silica entrance from the gas phase (SiOg) into the chondrule melt on the other hand, have counteracting effects on the Mg‐rich olivine dissolution behavior. Silica entrance would favor dissolution by maintaining disequilibrium between olivine and melt. Hence, this would explain the preferential dissolution of olivine as well as the preferential abundances of pyroxene at the margins of chondrules. Incipient dissolution would also occur in the silica‐poorer melt of chondrule core but should be followed by crystallization of new olivine (overgrowth and/or newly grown crystals). While explaining textures and grain size distributions of olivines, as well as the centripetal distribution of low‐Ca pyroxene in porphyritic chondrules, this scenario could also be consistent with the diverse chemical, isotopic, and thermal conditions recorded by olivines in a given chondrule.
A hot topic: the genetics of adaptation to geothermal vents in Mimulus guttatus
Authors: Ferris Kathleen G. 
Published: November 2016

Identifying the individual loci and mutations that underlie adaptation to extreme environments has long been a goal of evolutionary biology. However, finding the genes that underlie adaptive traits is difficult for several reasons. First, because many traits and genes evolve simultaneously as populations diverge, it is difficult to disentangle adaptation from neutral demographic processes. Second, finding the individual loci involved in any trait is challenging given the respective limitations of quantitative and population genetic methods. In this issue of Molecular Ecology, Hendrick et al. (2016) overcome these difficulties and determine the genetic basis of microgeographic adaptation between geothermal vent and nonthermal populations of Mimulus guttatus in Yellowstone National Park. The authors accomplish this by combining population and quantitative genetic techniques, a powerful, but labour‐intensive, strategy for identifying individual causative adaptive loci that few studies have used (Stinchcombe & Hoekstra ). In a previous common garden experiment (Lekberg et al. 2012), thermal M. guttatus populations were found to differ from their closely related nonthermal neighbours in various adaptive phenotypes including trichome density. Hendrick et al. (2016) combine quantitative trait loci (QTL) mapping, population genomic scans for selection and admixture mapping to identify a single genetic locus underlying differences in trichome density between thermal and nonthermal M. guttatus. The candidate gene, R2R3 MYB, is homologous to genes involved in trichome development across flowering plants. The major trichome QTL, Tr14, is also involved in trichome density differences in an independent M. guttatus population comparison (Holeski et al. 2010) making this an example of parallel genetic evolution.
Coevolution, local adaptation and ecological speciation
Authors: Thompson John N. 
Published: November 2016

Coevolution is one of the major processes organizing the earth's biodiversity, but it remains unclear when and how it may generate species diversity. The study by Parchman et al. () in this issue of Molecular Ecology provides the clearest evidence to date that divergent local adaptation in a coevolving interaction may lead to speciation on one side of an interaction but not necessarily on the other side. Red crossbills in North America have diversified into ecotypes that specialize on different conifer species, use different calls and vary in the extent to which they are nomadic or sedentary. This new study evaluated genomic divergence among nine crossbill ecotypes. The authors found low overall genomic divergence among many of the ecotypes, but the sedentary South Hills crossbills, which are specialized to eat the seeds of a unique population of lodgepole pines, showed substantial divergence from other crossbills at a small number of genomic regions. These results corroborate past studies showing local coadaptation of the morphological traits of South Hills crossbills and lodgepole pines, and premating isolation of the South Hills crossbills from other populations. Together, the past and new results suggest that local coevolution with lodgepole pines has led to reduced gene flow between South Hills crossbills and other crossbills.
Sperm competition shapes gene expression and sequence evolution in the ocellated wrasse
Authors: Dean Rebecca , Wright Alison E. , Marsh‐Rollo Susan E. , Nugent Bridget M. , Alonzo Suzanne H. , Mank Judith E. 
Published: November 2016

AbstractGene expression differences between males and females often underlie sexually dimorphic phenotypes, and the expression levels of genes that are differentially expressed between the sexes are thought to respond to sexual selection. Most studies on the transcriptomic response to sexual selection treat sexual selection as a single force, but postmating sexual selection in particular is expected to specifically target gonadal tissue. The three male morphs of the ocellated wrasse (Symphodus ocellatus) make it possible to test the role of postmating sexual selection in shaping the gonadal transcriptome. Nesting males hold territories and have the highest reproductive success, yet we detected feminization of their gonadal gene expression compared to satellite males. Satellite males are less brightly coloured and experience more intense sperm competition than nesting males. In line with postmating sexual selection affecting gonadal gene expression, we detected a more masculinized expression profile in satellites. Sneakers are the lowest quality males and showed both de‐masculinization and de‐feminization of gene expression. We also detected higher rates of gene sequence evolution of male‐biased genes compared to unbiased genes, which could at least in part be explained by positive selection. Together, these results reveal the potential for postmating sexual selection to drive higher rates of gene sequence evolution and shape the gonadal transcriptome profile.
Gut microbial ecology of lizards: insights into diversity in the wild, effects of captivity, variation across gut regions and transmission
Authors: Kohl Kevin D. , Brun Antonio , Magallanes Melisa , Brinkerhoff Joshua , Laspiur Alejandro , Acosta Juan Carlos , Caviedes‐Vidal Enrique , Bordenstein Seth R. 
Published: November 2016

AbstractAnimals maintain complex associations with a diverse microbiota living in their guts. Our understanding of the ecology of these associations is extremely limited in reptiles. Here, we report an in‐depth study into the microbial ecology of gut communities in three syntopic and viviparous lizard species (two omnivores: Liolaemus parvus and Liolaemus ruibali and an herbivore: Phymaturus williamsi). Using 16S rRNA gene sequencing to inventory various bacterial communities, we elucidate four major findings: (i) closely related lizard species harbour distinct gut bacterial microbiota that remain distinguishable in captivity; a considerable portion of gut bacterial diversity (39.1%) in nature overlap with that found on plant material, (ii) captivity changes bacterial community composition, although host‐specific communities are retained, (iii) faecal samples are largely representative of the hindgut bacterial community and thus represent acceptable sources for nondestructive sampling, and (iv) lizards born in captivity and separated from their mothers within 24 h shared 34.3% of their gut bacterial diversity with their mothers, suggestive of maternal or environmental transmission. Each of these findings represents the first time such a topic has been investigated in lizard hosts. Taken together, our findings provide a foundation for comparative analyses of the faecal and gastrointestinal microbiota of reptile hosts.
Identification of Wind Loads and Estimation of Structural Responses of Super‐Tall Buildings by an Inverse Method
Authors: Zhi Lunhai , Li Q.S. , Fang Mingxin 
Published: November 2016

AbstractThis article presents a Kalman‐filter‐based estimation algorithm for identification of wind loads on a super‐tall building using limited structural responses. In practice, acceleration responses are most convenient to be measured among wind‐induced dynamic responses of structures. The proposed inverse method allows estimating the unknown wind loads and structural responses of a super‐tall building using limited acceleration measurements. Taipei 101 Tower is a super‐tall building with 101 stories and a height of 508 m. Field measurements and numerical simulations of the wind effects on Taipei 101 Tower are conducted. The wind loads acting on the super‐tall building are estimated based on the wind‐induced responses determined from the numerical simulations and the refined finite‐element model of the structure, which are in good agreement with the exact results. The stability performance of the proposed algorithm is evaluated. The influence of noise levels in the measurements and covariance matrix of noise on the identification accuracy are investigated and discussed based on the L‐curve method. Finally, the wind loads and structural responses are reconstructed based on the field‐measured accelerations during Typhoon Matsa. The accuracy of the identified results is verified by comparing the reconstructed acceleration responses with the field measurements. The results of this study show that the proposed inverse approach can provide accurate predictions of the wind loads and wind‐induced responses of super‐tall buildings based on limited measured responses.
SecA functions in vivo as a discrete anti‐parallel dimer to promote protein transport
Authors: Banerjee Tithi , Lindenthal Christine , Oliver Donald 
Published: November 2016

SummarySecA ATPase motor protein plays a central role in bacterial protein transport by binding substrate proteins and the SecY channel complex and utilizing its ATPase activity to drive protein translocation across the plasma membrane. SecA has been shown to exist in a dynamic monomer–dimer equilibrium modulated by translocation ligands, and multiple structural forms of the dimer have been crystallized. Since the structural form of the dimer remains a controversial and unresolved question, we addressed this matter by engineering ρ‐benzoylphenylalanine along dimer interfaces corresponding to the five different SecA X‐ray structures and assessing their in vivo photo‐crosslinking pattern. A discrete anti‐parallel 1M6N‐like dimer was the dominant if not exclusive dimer found in vivo, whether SecA was cytosolic or in lipid or SecYEG‐bound states. SecA bound to a stable translocation intermediate was crosslinked in vivo to a second SecA protomer at its 1M6N interface, suggesting that this specific dimer likely promotes active protein translocation. Taken together, our studies strengthen models that posit, at least in part, a SecA dimer‐driven translocation mechanism.