Patterns of elevational beta diversity in micro‐ and macroorganisms

Aim While ecologists have long been interested in diversity in mountain regions, elevational patterns in beta diversity are still rarely studied across different life forms ranging from micro‐ to macroorganisms. Also, it is not known whether the patterns in turnover among organism groups are affected by the degree to which the environment is modified by human activities. Location Laojun Mountain, Yunnan Province, China. Methods The beta diversity patterns of benthic microorganisms (i.e. diatoms and bacteria) and macroorganisms (i.e. macroinvertebrates) in a stony stream were simultaneously investigated between elevations of 1820 and 4050 m. Data were analysed by using a distance‐based approach and variation partitioning based on canonical redundancy analysis. Results Analyses of community dissimilarities between adjacent sampling sites showed comparable small‐scale beta diversity along the elevational gradient for the organism groups. However, bacteria clearly showed the lowest elevational turnover when analyses were conducted simultaneously for all pairwise sites. Variation partitioning indicated that species turnover was mostly related to environmental heterogeneity and spatial gradients including horizontal distance and elevation, while purely human impacts were shown to be less important. Main conclusions The elevational beta diversity at large scales was lower for bacteria than for eukaryotic microorganisms or macroorganisms, perhaps indicative of high dispersal ability and good adaptability of bacteria to harsh environmental conditions. However, the small‐scale beta diversity did not differ among the groups. Elevation was the major driver for the turnover of eukaryotic organisms, while the turnover of bacteria was correlated more with environmental variation.     

Measurement of the nucleation of atmospheric aerosol particles

The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year.     

Assessing the current related heterogeneity and diversity patterns of benthic diatom communities in a turbid and a clear water river

Benthic diatoms were sampled in two rapids, in a turbid South-Finnish river (R. Keravanjoki, 22 FTU) and a clear water river in eastern Finland (R. Vaikkojoki, 4 FTU), to evaluate the diversity and spatial distribution patterns of diatom communities and especially their relationships to current velocity. In both rapids, epilithic diatoms were sampled in 15 sampling squares within three current velocity classes (10 cm s^–1, 40 cm s^–1 and 100 cm s^–1). The sampling squares had significantly different diatom communities in the three current velocity classes at both sampling sites, however, separation of the communities was much more pronounced in the clear water river (p < 0.001) than in the turbid river (p < 0.05). In the clear water river, communities at the highest velocity were highly different from those at the lower velocities. On the other hand, in the turbid river, communities were more similar at all velocities. Significant (p < 0.05) indicators for highest current velocity in the clear water R. Vaikkojoki were Fragilaria capucina var. gracilis Hustedt, F. capucina var. rumpens Lange-Bertalot and Meridion circulare Agardh. There were no significant indicators for high current velocity in the turbid R. Keravanjoki. Cocconeis placentula Ehr., Cymbella sinuata Gregory and Navicula lanceolata (Agardh) Ehr. were the three most abundant species in the highest velocity. This study showed that diatom community was highly specialized but low in diversity at the highest velocity in the clear water river. This pattern was not seen in the turbid R. Keravanjoki, indicating that the diatom community could withstand at the higher current velocities. In addition, the results show the importance of sampling in a variety of current regimes, particularly in clear water rivers, in order to properly assess the diatom diversity and community of a river section.     

Surveying biodiversity in protected and managed areas: Algae, macrophytes and macroinvertebrates in boreal forest streams

Extensive surveys of biodiversity in protected and managed areas have not been conducted for a majority of taxonomic groups and ecosystem types, which makes it difficult to assess how large a portion of biodiversity is at least potentially under protection. The situation is the same in boreal regions, and only preliminary analyses of the biodiversity patterns of less well-known organism groups, including many freshwater taxa, within the protected area network have been conducted. We studied patterns of species richness and community composition of algae, macrophytes (bryophytes and vascular plants), and macroinvertebrates of headwater streams draining protected areas and managed forests in a boreal drainage basin in Finland. We found no significant differences in the species richness and community composition of these organism groups between the protected and managed streams. Gamma- and beta-diversity varied strongly among the protected and managed stream groups, yet this variation was contingent on the organism group and the beta-diversity measure used. In general, there was much species turnover within both protected and managed stream groups, masking any between-group differences. However, we found a number of redlisted and rare species in our surveys. Of these species, several macrophyte species occurred more frequently in the protected streams. By contrast, rare species of algae and macrophytes did not generally show such inclinations to the protected streams. We found no strong congruence in species richness or community dissimilarity between algae, macrophytes, and macroinvertebrates, suggesting that the main anthropogenic gradient in terms of forestry is not strong enough to modify stream environmental conditions and thereby shape biodiversity in the focal drainage basin. This finding also suggests that surveys of aquatic biodiversity across protected and managed landscapes should not rely too heavily on the surrogate taxon approach, but instead should consider patterns shown by multiple taxonomic groups that represent biologically and ecologically disparate organisms. Our results indeed suggest that the levels of alpha-, beta-, and gamma-diversity show differing among-taxon responses to forest management and naturalness of headwater streams.     

Quantification of 1H NMR spectra of human cerebrospinal fluid: a protocol based on constrained total-line-shape analysis

A protocol for quantitative ¹H NMR analysis of human cerebrospinal fluid (hCSF) was built up and assessed as based on Constrained Total-Line-Shape (CTLS) fitting. In this method, linear constraints were applied to spectral structures. The ¹H NMR spectra of 45 human CSF samples were measured and quantified using the CTLS method. The quantification strategies based on total-line-shape fitting are discussed. The metabolic model for CTLS includes 31 metabolites covering 85% of the total spectral intensity, excluding the protein contribution. Prior to data analysis, the data was divided into patients with no Alzheimer’s disease (AD), but with a normal AD marker profile (the peptide β-amyloid₄₂ and tau protein) present in CSF, and into controls that do not have an AD marker profile in CSF. Unexpectedly large variations in metabolite concentrations within the two patient groups were detected, but an analysis of variance revealed a significant (P = 0.027) difference only in the concentration of creatinine which was higher in patients that had a normal AD marker profile. Multivariate classification tools such as self-organizing maps (SOM) failed in separation of the two classes.     

Machine Vision Based Measurement of Dynamic Contact Angles in Microchannel Flows

When characterizing flows in miniaturized channels, the determination of the dynamic contact angle is important. By measuring the dynamic contact angle, the flow properties of the flowing liquid and the effect of material properties on the flow can be characterized. A machine vision based system to measure the contact angle of front or rear menisci of a moving liquid plug is described in this article. In this research, transparent flow channels fabricated on thermoplastic polymer and sealed with an adhesive tape are used. The transparency of the channels enables image based monitoring and measurement of flow variables, including the dynamic contact angle. It is shown that the dynamic angle can be measured from a liquid flow in a channel using the image based measurement system. An image processing algorithm has been developed in a MATLAB environment. Images are taken using a CCD camera and the channels are illuminated using a custom made ring light. Two fitting methods, a circle and two parabolas, are experimented and the results are compared in the measurement of the dynamic contact angles.     

Regional and global elevational patterns of microbial species richness and evenness

Although elevational gradients in microbial biodiversity have attracted increasing attention recently, the generality in the patterns and underlying mechanisms are still poorly resolved. Further, previous studies focused mostly on species richness, while left understudied evenness, another important aspect of biodiversity. Here, we studied the elevational patterns in species richness and evenness of stream biofilm bacteria and diatoms in six mountains in Asia and Europe. We also reviewed published results for elevational richness patterns for soil and stream microbes in a literature analysis. Our results revealed that even within the same ecosystem type (that is, stream) or geographical region, bacteria and diatoms showed contrasting patterns in diversity. Stream microbes, including present stream data, tend to show significantly increasing or decreasing elevational patterns in richness, contrasting the findings for soil microbes that typically showed nonsignificant or significantly decreasing patterns. In all six mountains for bacteria and in four mountains for diatoms, species richness and evenness were positively correlated. The variation in bacteria and diatom richness and evenness were substantially explained by anthropogenic driven factors, such as total phosphorus (TP). However, diatom richness and evenness were also related to different main drivers as richness was mostly related to pH, while evenness was most explained by TP. Our results highlight the lack of consistent elevational biodiversity patterns of microbes and further indicate that the two facets of biodiversity may respond differently to environmental gradients.     

Relative importance of spatial processes and environmental factors in shaping alpine meadow communities

Aims Spatial processes and environmental control are the two distinct, yet not mutually exclusive forces of community structuring, but the relative importance of these factors is controversial due to the species-specific dispersal ability, sensitivity towards environmental variables, organism's abundance and the effect of spatial scale. In the present paper, we explored spatial versus environmental control in shaping community composition (i.e. β-diversity) and species turnover (i.e. change of β-diversity) at an alpine meadow along a slope aspect gradient on the Qinghai–Tibetan Plateau at different spatial scales of sampling (quadrats and plots), by taking account of seed dispersal mode and abundance.Methods We examined the relative importance of spatial processes and environmental factors using all species and four additional subsets of selected species. Moreover, we attempted to explore the effect of scale (quadrat refers to scale of ~0.3 m and plot of ~8 m) on their counter balance. The data were analyzed both by variation partitioning and multiple regressions on distance matrices. The spatial structure was modelled using Moran's eigenvector maps (MEM).Important findings Both spatial processes and environmental factors were important determinants of the community composition and species turnover. The community composition in the alpine meadow was controlled by spatially structured environment (17.6%), space independent of environment (18.0%) and a negligible effect of environment independent of space (4.4%) at the scale of quadrats. These three components contributed 21.8, 9.9 and 13.9%, respectively, at the scale of plots. The balance between the forces at different spatial scales drove community structures along the slope aspect gradient. The importance of environmental factors on β-diversity at alpine meadow increased with scale while that of spatial processes decreased or kept steady, depending on dispersal mode and abundance of species comprising the subset. But the 'pure' effect of spatial processes on species turnover increased with scale while that of environmental factors decreased. This discrepancy highlights that β-diversity and species turnover were determined jointly by spatial processes and environmental factors. We also found that the relative roles of these processes vary with spatial scale. These results underline the importance of considering species-specific dispersal ability and abundance of species comprising the communities and the appropriate spatial scale in understanding the mechanisms of community assembly.     

Disrupted Sperm Function and Fertilin β Processing in Mice Deficient in the Inositol Polyphosphate 5-Phosphatase Inpp5b

Inpp5b is an ubiquitously expressed type II inositol polyphosphate 5-phosphatase. We have disrupted the Inpp5b gene in mice and found that homozygous mutant males are infertile. Here we examine the causes for the infertility in detail. We demonstrate that sperm from Inpp5b^−/− males have reduced motility and reduced ability to fertilize eggs, although capacitation and acrosome exocytosis appear to be normal. In addition, fertilin β, a sperm surface protein involved in sperm-egg membrane interactions that is normally proteolytically processed during sperm transit through the epididymis, showed reduced levels of processing in the Inpp5b^−/− animals. Inpp5b was expressed in the Sertoli cells and epididymis and at low levels in the developing germ cells; however, mice lacking Inpp5b in spermatids and not in other cell types generated by conditional gene targeting, were fully fertile. The abnormalities in mutant sperm function and maturation appear to arise from defects in the functioning of Sertoli and epididymal epithelial cells. Our results directly demonstrate a previously unknown role for phosphoinositides in normal sperm maturation beyond their previously characterized involvement in the acrosome reaction. Inpp5b^−/− mice provide an excellent model to study the role of Sertoli and epididymal epithelial cells in the differentiation and maturation of sperm.     

Forest tree growth is linked to mycorrhizal fungal composition and function across Europe

Most trees form symbioses with ectomycorrhizal fungi (EMF) which influence access to growth-limiting soil resources. Mesocosm experiments repeatedly show that EMF species differentially affect plant development, yet whether these effects ripple up to influence the growth of entire forests remains unknown. Here we tested the effects of EMF composition and functional genes relative to variation in well-known drivers of tree growth by combining paired molecular EMF surveys with high-resolution forest inventory data across 15 European countries. We show that EMF composition was linked to a three-fold difference in tree growth rate even when controlling for the primary abiotic drivers of tree growth. Fast tree growth was associated with EMF communities harboring high inorganic but low organic nitrogen acquisition gene proportions and EMF which form contact versus medium-distance fringe exploration types. These findings suggest that EMF composition is a strong bio-indicator of underlying drivers of tree growth and/or that variation of forest EMF communities causes differences in tree growth. While it may be too early to assign causality or directionality, our study is one of the first to link fine-scale variation within a key component of the forest microbiome to ecosystem functioning at a continental scale.Subject terms: Microbial ecology, Forest ecology, Fungal ecology, Biogeochemistry