New species and records of tree ferns (Cyatheaceae, Pteridophyta) from the northern Andes

AbstractFour new species of Cyatheaceae from Ecuador are described: Alsophila conantiana Lehnert, Cyathea brucei Lehnert, C. moranii Lehnert, and C. sylvatica Lehnert. Range extensions are documented for Alsophila esmeraldensis R.C. Moran and Cyathea macrocarpa (C. Presl) Domin.For full article, see Electronic Supplement at: http://www.senckenberg.de/odes/06-13.ht

Influence of Increasing Nutrient Availability on Fern and Lycophyte Diversity

Increased nutrient supply can have drastic effects on natural ecosystems, especially in naturally nutrient-poor ones such as most tropical rainforests. Many studies have focused on the reaction of trees to fertilization, but little is known about herbaceous plants. Ferns are a particularly common group in tropical forests, spanning all vegetation types and zones. Here, we assess how seven years of moderate addition of nitrogen (N), phosphorus (P), and N+P along an elevational gradient (1000–3000 m) have impacted richness and composition of fern and lycophyte assemblages in tropical montane rain forests growing on naturally nutrient deficient soils in the Ecuadorian Andes. We found that fertilization does not affect overall species richness, but that there were strong differences in species abundances (∼60% of species), both negative and positive, that were apparently related to the systematic affiliations and ecological properties of the affected species. These diverse responses of ferns to fertilization provide insight into the sensitivity and complexity of the relationships of nutrient availability and community composition in tropical forests

Comparative analysis of mycorrhizal communities associated with Struthiopteris spicant (L.) Weiss across Europe and North America

IntroductionFerns constitute the second largest group of vascular plants. Previous studies have shown that the diversity and composition of fern communities are influenced by resource availability and water stress, among other factors. However, little is known about the influence of these environmental factors on their biotic interactions, especially regarding the relationship between mycorrhizal fungi and ferns. The present study compares the mycorrhizal communities associated with 36 populations of Struthiopteris spicant L. Weiss across Europe and North America. This species exhibits a great tolerance to variations in light, nutrient, and pH conditions, and it can survive with and without mycorrhizae.MethodsWith the aim of determining which environmental factors impact the composition and abundance of the root-associated fungal communities in this species, we used an ITS-focused metabarcoding approach to identify the mycorrhizal fungi present and analyzed the influence of climatic and edaphic variables at global and regional scalesResults and discussionWe encountered striking differences in the relative abundance of arbuscular mycorrhizal fungi (AMF) between S. spicant populations at both spatial levels. We recorded a total of 902 fungal ASVs, but only 2– 4% of the total fungal diversity was observed in each individual, revealing that each fern had a unique fungal community. Light availability and the interactive action of pH and soil nitrogen concentration showed a positive influence on AMF relative abundance, explaining 89% of the variance. However, environmental factors could only explain 4– 8% of the variability in AMF community composition, indicating that it might be determined by stochastic processes. These results support the hypothesis that ferns may be more independent of mycorrhization than other plant groups and interact with fungi in a more opportunistic manner

Adiciones a la pteridoflora de Tabasco, México: la importancia del bosque mesófilo de montaña

Background and Aims: The ejido Villa de Guadalupe of the municipality of Huimanguillo, Tabasco, contains the only fragment of humid montane forest in the state, which has been little explored floristically. This study is an addition to those previously published, where reports of new records increase considerably the richness of fern species known so far for Tabasco state. The main objective is to update the knowledge of the pteridophyte flora of this state, emphasizing the importance of the humid montane forest.Methods: Epiphytic and terrestrial fern collections were made randomly on the north and northeast face of the Las Flores mountain (450-1000 m a.s.l.) in the municipality of Huimanguillo. Specimens were identified mainly by dichotomous keys and distributed to national and foreign herbaria.Key results: A total of 64 species of ferns and lycopods were recorded. The best represented families were Polypodiaceae, Dryopteridaceae and Hymenophyllaceae. We highlight the records of 30 species that had not previously been reported in the state of Tabasco. Even of the genera Cochlidium, Elaphoglossum, Hypolepis, Odontosoria, Parapolystichum, Polytaenium, Saccoloma and Sphaeropteris, this is the first report for the state.Conclusions: The new additions to the pteridophyte flora of Tabasco lead to a count of 169 species for the state, which updates the information known so far (137 species) and shows the need of continued regional floristic inventories. The present study represents one of the few published papers that document the richness of a specific taxonomic group in the humid montane forest of the state.Antecedentes y Objetivos: El ejido Villa de Guadalupe del municipio Huimanguillo, Tabasco, mantiene el único fragmento de bosque mesófilo de montaña en el estado, mismo que ha sido florísticamente poco explorado. Este estudio se suma a otros anteriormente publicados, donde los reportes de nuevos registros aumentan considerablemente la riqueza de especies de helechos y licopodios conocidas hasta ahora para Tabasco. El objetivo principal es actualizar el conocimiento de la pteridoflora de la entidad, enfatizando la importancia del bosque mesófilo de montaña.Métodos: Se realizaron colectas al azar de helechos epífitos y terrestres en la cara norte y noreste del cerro Las Flores (450-1000 m s.n.m.) en el municipio Huimanguillo. Los especímenes fueron identificados principalmente mediante claves taxonómicas y distribuidos en herbarios nacionales y extranjeros.Resultados clave: Se registraron en total 64 especies de helechos y licopodios. Las familias mejor representadas fueron Polypodiaceae, Dryopteridaceae e Hymenophyllaceae. Se destaca el registro de 30 especies que no habían sido reportadas previamente en el estado de Tabasco. Para los géneros Cochlidium, Elaphoglossum, Hypolepis, Odontosoria, Parapolystichum, Polytaenium, Saccoloma y Sphaeropteris, este es el primer reporte para la entidad.Conclusiones: Las nuevas adiciones a la pteridoflora de Tabasco proporcionan un recuento de 169 especies para el estado, lo cual actualiza la información conocida hasta ahora (137 especies) y manifiesta la necesidad de continuar con la realización de inventarios florísticos regionales. El presente estudio representa uno de los pocos trabajos publicados que documentan la riqueza de un grupo taxonómico en específico en el bosque mesófilo de montaña del estado

Slowly but surely: gradual diversification and phenotypic evolution in the hyper-diverse tree fern family Cyatheaceae

Background and Aims The tremendously unbalanced distribution of species richness across clades in the tree of life is often interpreted as the result of variation in the rates of diversification, which may themselves respond to trait evolution. Even though this is likely a widespread pattern, not all diverse groups of organisms exhibit heterogeneity in their dynamics of diversification. Testing and characterizing the processes driving the evolution of clades with steady rates of diversification over long periods of time are of importance in order to have a full understanding of the build-up of biodiversity through time. Methods We studied the macroevolutionary history of the species-rich tree fern family Cyatheaceae and inferred a time-calibrated phylogeny of the family including extinct and extant species using the recently developed fossilized birth–death method. We tested whether the high diversity of Cyatheaceae is the result of episodes of rapid diversification associated with phenotypic and ecological differentiation or driven by stable but low rates of diversification. We compared the rates of diversification across clades, modelled the evolution of body size and climatic preferences and tested for trait-dependent diversification. Key Results This ancient group diversified at a low and constant rate during its long evolutionary history. Morphological and climatic niche evolution were found to be overall highly conserved, although we detected several shifts in the rates of evolution of climatic preferences, linked to changes in elevation. The diversification of the family occurred gradually, within limited phenotypic and ecological boundaries, and yet resulted in a remarkable species richness. Conclusions Our study indicates that Cyatheaceae is a diverse clade which slowly accumulated morphological, ecological and taxonomic diversity over a long evolutionary period and provides a compelling example of the tropics as a museum of biodiversity

Self-Assembled Nanometer-Scale Magnetic Networks on Surfaces: Fundamental Interactions and Functional Properties

Nanomagnets of controlled size, organized into regular patterns open new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Self-assembling processes on various types of substrates allow designing fine-structured architectures and tuning of their magnetic properties. Here, starting from a description of fundamental magnetic interactions at the nanoscale, we review recent experimental approaches to fabricate zero-, one-, and two-dimensional magnetic particle arrays with dimensions reduced to the atomic limit and unprecedented areal density. We describe systems composed of individual magnetic atoms, metal-organic networks, metal wires, and bimetallic particles, as well as strategies to control their magnetic moment, anisotropy, and temperature-dependent magnetic behavior. The investigation of self-assembled subnanometer magnetic particles leads to significant progress in the design of fundamental and functional aspects, mutual interactions among the magnetic units, and their coupling with the environment

Simulating Supersonic Turbulence in Galaxy Outflows

We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throughout the simulation. Pockets of hot, diffuse gas around individual OB associations sweep up thick shells of material that persist for long times due to the cooling instability. The overlapping of high-pressure, rarefied regions leads to a collective central outflow that escapes the galaxy by eating away at the exterior gas through turbulent mixing, rather than gathering it into a thin, unstable shell. Supersonic, turbulent gas naturally avoids dense regions where turbulence decays quickly and cooling times are short, and this further enhances density contrasts throughout the galaxy- leading to a complex, chaotic distribution of bubbles, loops and filaments as observed in NGC 1569 and other outflowing starbursts.Comment: 22 pages, 13 figures, MNRAS, in pres

All-cause mortality and serum insulin-like growth factor I in primary care patients

Objective: Previous population-based studies provided conflicting results regarding the association of total serum insulin-like growth factor I (IGF-I) and mortality. The aim of the present study was to assess the relation of IGF-I levels with all-cause mortality in a prospective study. Design: DETECT (Diabetes Cardiovascular Risk-Evaluation: Targets and Essential Data for Commitment of Treatment) is a large, multistage, and nationally representative study of primary care patients in Germany. The study population included 2463 men and 3603 women. Death rates were recorded by the respective primary care physician. Serum total IGF-I levels were determined by chemiluminescence immunoassays and categorized into three groups (low, moderate, and high) according to the sex- and age-specific 10th and 90th percentiles. Results: Adjusted analyses revealed that men with low [hazard ratio (HR) 1.70 (95% confidence interval [CI] 1.05–2.73), p=0.03] and high [HR 1.76 (95% CI 1.09–2.85), p=0.02] IGF-I levels had higher risk of all-cause mortality compared to men with moderate IGF-I levels. The specificity of low IGF-I and high IGF-I levels increased with lower and higher cut-offs, respectively. No such association became apparent in women. Conclusions: The present study revealed a U-shaped relation between IGF-I and all-cause mortality in male primary care patients