Yeast and yeast-like fungi associated with dry indehiscent fruits of Nothofagus nervosa in Patagonia, Argentina

Nothofagus nervosa (Raulí) is a native tree species that yields valuable timber. It was overexploited in the past and is currently included in domestication and conservation programs. Several research programs have focused on the characterization of epiphytic microorganisms because it has been demonstrated that they can affect plant-pathogen interactions and/or promote plant growth. Although the microbial ecology of leaves has been well studied, less is known about microorganisms occurring on seeds and noncommercial fruits. In this work, we analyzed the yeast and yeast-like fungi present on N.?nervosa fruits destined for the propagation of this species, as well as the effects of fruit preservation and seed dormancy-breaking processes on fungal diversity. Morphological and molecular methods were used, and differences between fungal communities were analyzed using a similarity index. A total of 171 isolates corresponding to 17 species were recovered, most of which belong to the phylum Ascomycota. The majority of the species develop mycelia, produce pigments and mycosporines, and these adaptation strategies are discussed. It was observed that the preservation process considerably reduced yeast and yeast-like fungal diversity. This is the first study concerning microbial communities associated with this ecologically and economically important species, and the information presented is relevant to domestication programs.     

Diversity and cell type specificity of local excitatory connections to neurons in layer 3B of monkey primary visual cortex

In the primary visual cortex of macaque monkeys, laminar and columnar axonal specificity are correlated with functional differences between locations. We describe evidence that embedded within this anatomical framework is finer specificity of functional connections. Photostimulation-based mapping of functional input to 31 layer 3B neurons revealed that input sources to individual cells were highly diverse. Although some input differences were correlated with neuronal anatomy, no 2 neurons received excitatory input from the same cortical layers. Thus, input diversity reveals far more cell types than does anatomical diversity. This implies relatively little functional redundancy; despite trends related to laminar or columnar position, pools of neurons contributing uniquely to visual processing are likely relatively small. These results also imply that similarities in the anatomy of circuits in different cortical areas or species may not indicate similar functional connectivity.     

Ontogeny of corticocortical projections of the rat somatosensory cortex.

Rhodamine-coated microspheres (RCMs) were injected into the primary somatosensory cortex (SI) of rats ranging in age from postnatal (PN) day 1 to adulthood. Ipsilateral corticocortical and callosal projections within the SI were identified as early as PN day 1. At the end of the first PN week, ipsilaterally projecting neurons located in sublayer VIb were the first to assume an adult-like pattern of connectivity. Injections at subsequent postnatal ages revealed that an adult pattern of lamination of ipsilateral corticocortical projections within the SI is established between PN weeks 2 and 3, comprising projection neurons from layers II/III, layer V, and sublayer VIb. Therefore, local interactions in the rat SI are mediated not only by pyramidal neurons of layers III and V, derived from the cortical plate, but also by a subpopulation of ontogenetically older neurons located in the sublayer VIb, which may correspond to the subplate neurons of other species. Overall, these results suggest the existence of three independent short-range corticocortical systems of projections within the rat SI, which differ in terms of the laminar distribution and ontogenetic origin of their cells.     

A genetic assessment of seed production areas (SPAs) for restoration

The conservation and restoration of degraded landscapes continues to be a major activity with the demand for seed increasing to meet growing global targets. Seed collected from natural plant populations is often irregular and unpredictable, limiting the diversity of species that can be conserved through restoration programs and the area that can be restored. Seed production areas (SPAs; seed orchards, seed increase) are one option for improving seed supply and quality to meet the demand from conservation and restoration programs. We evaluated genetic diversity, inbreeding and mating system parameters in adults and seed from remnants and SPAs of Acacia montana and Dodonaea viscosa subsp. cuneata, two key restoration species in south-eastern Australia. Overall, we found no significant differences in genetic diversity between remnants and SPAs of both species or between adult and seed cohorts. In contrast, we found significant inbreeding in many remnants and their seed crops suggesting that some inbred seed were used to establish these SPAs. We also found significant inbreeding in some SPAs and their seed crops and that SPAs were often biased towards one to two source remnants. Additional germplasm is now required to broaden the representativeness of remnants in the SPAs and the genetic base of seed being produced for restoration programs.     

Corticomuscular Transmission of Tremor Signals by Propriospinal Neurons in Parkinson's Disease

Cortical oscillatory signals of single and double tremor frequencies act together to cause tremor in the peripheral limbs of patients with Parkinson''s disease (PD). But the corticospinal pathway that transmits the tremor signals has not been clarified, and how alternating bursts of antagonistic muscle activations are generated from the cortical oscillatory signals is not well understood. This paper investigates the plausible role of propriospinal neurons (PN) in C3–C4 in transmitting the cortical oscillatory signals to peripheral muscles. Kinematics data and surface electromyogram (EMG) of tremor in forearm were collected from PD patients. A PN network model was constructed based on known neurophysiological connections of PN. The cortical efferent signal of double tremor frequencies were integrated at the PN network, whose outputs drove the muscles of a virtual arm (VA) model to simulate tremor behaviors. The cortical efferent signal of single tremor frequency actuated muscle spindles. By comparing tremor data of PD patients and the results of model simulation, we examined two hypotheses regarding the corticospinal transmission of oscillatory signals in Parkinsonian tremor. Hypothesis I stated that the oscillatory cortical signals were transmitted via the mono-synaptic corticospinal pathways bypassing the PN network. The alternative hypothesis II stated that they were transmitted by way of PN multi-synaptic corticospinal pathway. Simulations indicated that without the PN network, the alternating burst patterns of antagonistic muscle EMGs could not be reliably generated, rejecting the first hypothesis. However, with the PN network, the alternating burst patterns of antagonist EMGs were naturally reproduced under all conditions of cortical oscillations. The results suggest that cortical commands of single and double tremor frequencies are further processed at PN to compute the alternating burst patterns in flexor and extensor muscles, and the neuromuscular dynamics demonstrated a frequency dependent damping on tremor, which may prevent tremor above 8 Hz to occur.     

Indices for monitoring biodiversity change: Are some more effective than others?

Statistically rigorous methods for summarizing and reporting trends in the intactness of biodiversity are a key element of effective biodiversity monitoring programs. There are four major approaches for translating complex monitoring data into easily communicated summary statistics: (1) traditional diversity indices such as species richness and Simpson's diversity, (2) species intactness indices based on occurrence, (3) species intactness indices based on abundance, and (4) multivariate community indices. We use simulated data to evaluate the effectiveness of 13 indices from these four categories based on statistical robustness, sensitivity to errors and noise in the data, ecological relevance, and ease of communication. We show that indices that calculate species intactness using equations like Buckland's arithmetic mean index are the most effective for use in large-scale biodiversity intactness monitoring programs. Traditional diversity indices are unsuitable for monitoring of biodiversity intactness, and multivariate indices can be highly sensitive to errors and noise in the data. Finally, we provide guidelines for the application of these indices in biodiversity intactness monitoring.     

自然林下与田间根腐三七根际微生物群落特征及比较分析

【背景】三七根际微生物群落特征与其土传根腐病害密切相关,而针对自然林下根腐三七的相关研究鲜见报道。【目的】比较分析自然林下与田间根腐三七根际土壤微生物群落的组成特征,结合土壤理化性质与酶活性分析,为三七根腐病害防治与仿野生栽培提供科学依据。【方法】采集自然林下与田间根腐三七根际土壤,利用高通量测序技术,分析土壤细菌与真菌群落的物种组成与多样性,并测定土壤理化性质和酶活性。【结果】自然林下与田间根腐三七根际土壤中细菌和真菌群落组成具有明显差异,自然林下根腐三七根际土壤中担子菌门(Basidiomycota)、酸杆菌门(Acidobacteria)和疣微菌门(Verrucomicrobia)的相对丰度较高,而田间根腐三七根际土壤中子囊菌门(Ascomycota)、变形菌门(Proteobacteria)和绿弯菌门(Chloroflexi)的相对丰度较高。在属分类水平,镰刀菌属(Fusarium)是自然林下根腐三七根际土壤中的优势菌群,相对丰度为17.30%,而癣囊腔菌属(Plectosphaerella)是田间根腐三七根际土壤中的优势菌群,相对丰度为22.55%;Candidatus Ba...     

秦岭及陕北黄土区辽东栎林群落物种多样性特征

应用５种物种多样性测度指标及４种物种—多度分布模型对秦岭和黄土区辽东栎林种子植物物种多样性及木本植物种—多度分布进行了对比研究,结果表明：秦岭辽东栎林无论是群落物种多样性还是各层次的物种多样性均高于黄土区辽东栎林。秦岭辽东栎林木本植物种—多度分布符合对数正态分布而黄土区辽东栎林则符合对数级数分布,分布区气候差异是造成两类辽东栎林物种多样性差异的主要原因。物种—多度分布分析与物种多样性分析结果是一致的。     

Does adaptive radiation of a host lineage promote ecological diversity of its bacterial communities? A test using gut microbiota of Anolis lizards

Adaptive radiations provide unique opportunities to test whether and how recent ecological and evolutionary diversification of host species structures the composition of entire bacterial communities. We used 16S rRNA gene sequencing of faecal samples to test for differences in the gut microbiota of six species of Puerto Rican Anolis lizards characterized by the evolution of distinct ‘ecomorphs’ related to differences in habitat use. We found substantial variation in the composition of the microbiota within each species and ecomorph (trunk‐crown, trunk‐ground, grass‐bush), but no differences in bacterial alpha diversity among species or ecomorphs. Beta diversity analyses revealed subtle but significant differences in bacterial composition related to host phylogeny and species, but these differences were not consistently associated with Anolis ecomorph. Comparison of a trunk‐ground species from this clade (A. cristatellus) with a distantly related member of the same ecomorph class (A. sagrei) where the two species have been introduced and are now sympatric in Florida revealed pronounced differences in the alpha diversity and beta diversity of their microbiota despite their ecological similarity. Comparisons of these populations with allopatric conspecifics also revealed geographic differences in bacterial alpha diversity and beta diversity within each species. Finally, we observed high intraindividual variation over time and strong effects of a simplified laboratory diet on the microbiota of A. sagrei. Collectively, our results indicate that bacterial communities are only weakly shaped by the diversification of their lizard hosts due to the strikingly high levels of bacterial diversity and variation observed within Anolis species.     

A Test of the Utility of Exotic Tree Plantations for Understory Birds and Food Resources in the Colombian Andes1

The spatial distribution and abundance of animals are in part determined by the distribution and abundance of their resource base. In the Central Andes of Colombia, monospecific tree plantations have been used to recover vegetative cover in watershed protection programs, but these plantations differ from natural forests in structure, composition, and resources available to wildlife. To evaluate these plantations as habitat for wildlife, we compared the diversity and abundance of understory birds, flowers, and fruits between juxtaposed 40‐yr‐old patches of exotic Chinese ash (Fraxinus chinensis) plantations and naturally regenerated forest of the same age. We observed more fruiting species in the regenerated forest, but there were no differences in total flower and fruit availability between habitat types. We also observed differences between habitats in the size of some understory shrubs, but these differences did not lead to differences between habitats in the diversity and abundance of birds. Capture rates of nectarivores correlated with resource abundance at sampling plot scale, but no such correlation was found for frugivores. Understory frugivorous birds are apparently functioning at a larger spatial scale than the patchiness created by the two habitats. Nectarivorous birds are responding to small‐scale patchiness in resource availability, but not to the different habitats. These results indicate that at small scales, the ash plantation understory provides adequate habitat for birds.     

Impact of habitat diversity on the sampling effort required for the assessment of river fish communities and IBI

The spatial variation in the fish communities of four small Belgian rivers with variable habitat diversity was investigated by electric fishing to define the minimum sampling distance required for optimal fish stock assessment and determination of the Index of Biotic Integrity. This study shows that the standardised sampling distance of 100 m was not always sufficient to collect most species present. The required minimum sampling distance seems to be correlated with habitat diversity. In homogeneous streams, a mean sample distance of 282, 452 and 572 m is necessary to capture 80, 90 and 95% of all species present, respectively. In heterogeneous streams, these sample distances decrease to 217, 380 and 503 m. Hence, at least 300 m should be sampled to catch most species present with a single-pass sampling method. However, our results show that a 100 m sampling distance as presently used in the Flemish monitoring programs is sufficient to accurately describe the ecological quality since differences in IBI evaluation between adjacent stretches could at least for some rivers be explained by differences in habitat heterogeneity.     

Monitoring large herbivore diversity at different scales: comparing direct and indirect methods

Monitoring of large herbivores is central to research and management activities in many protected areas. Monitoring programs were originally developed to estimate (trends in) population sizes of individual species. However, emphasis is shifting increasingly towards conservation of diversity and communities instead of individual species, as a growing literature shows the importance of herbivore diversity for ecosystem functioning. We argue that the design of monitoring programs has not yet been adapted well to this new conservation paradigm. Using large herbivore census data from Hluhluwe-iMfolozi Park, South Africa, we studied how monitoring methodology (observational counts vs. dung counts) and spatial scale interact in influencing estimates of large herbivore species richness and diversity. Dung counts resulted in higher herbivore species richness and diversity estimates than direct observational counts, especially at finer monitoring resolutions (grid cells smaller than 25 km²). At monitoring resolutions coarser than 25 km² both methods gave comparable diversity estimates. The methods also yielded different spatial diversity estimates, especially at finer resolutions. Grid cells with high diversity according to the dung count data did not necessarily have high diversity according to the observational counts, as shown by low correlation of grid cell values of both methods. We discuss these results in the light of estimates of the sampling effort of each method and, hence, suggest new monitoring designs that are more suitable for tracking temporal and spatial trends in large herbivore diversity and community composition.     

Barrels, stripes, and fingerprints in the brain—Implications for theories of cortical organization

In the last decade improvements in the histological processing of cortical tissue in conjunction with the investigation of additional mammalian species in comparative brain studies has expanded the information available to guide theories of cortical organization. Here I review some of these recent findings in the somatosensory system with an emphasis on modules related to specializations of the peripheral sensory surface. The diversity of modular representations, or cortical “isomorphs” suggest that information from the sensory sheet guides many of the features of cortical maps and suggest that cortex is not constrained to form circular units in the form of a traditional cortical column.     

Potentials for monitoring gene level biodiversity: using Sweden as an example

Programs for monitoring biological diversity over time are needed to detect changes that can constitute threats to biological resources. The convention on biological diversity regards effective monitoring as necessary to halt the ongoing erosion of biological variation, and such programs at the ecosystem and species levels are enforced in several countries. However, at the level of genetic biodiversity, little has been accomplished, and monitoring programs need to be developed. We define “conservation genetic monitoring” to imply the systematic, temporal study of genetic variation within particular species/populations with the aim to detect changes that indicate compromise or loss of such diversity. We also (i) identify basic starting points for conservation genetic monitoring, (ii) review the availability of such information using Sweden as an example, (iii) suggest categories of species for pilot monitoring programs, and (iv) identify some scientific and logistic issues that need to be addressed in the context of conservation genetic monitoring. We suggest that such programs are particularly warranted for species subject to large scale enhancement and harvest—operations that are known to potentially alter the genetic composition and reduce the variability of populations.     

Genetic diversity and structure of urban populations of Pieris butterflies assessed using amplified fragment length polymorphism

Conservation programs in urban ecosystems need to determine the genetic background in populations of urban dwellers. We examined the genetic diversity and structure of Pieris rapae and P. melete using AFLP markers, and compared them between species and between urban and rural environments. As a result: (i). in both species, there was no reduction in genetic diversity within urban populations by direct comparison of diversity measurements, although the analysis of molecular variance suggested significant reductions in the variance within seasonal subpopulations in urban populations; (ii). P. rapae retained greater genetic diversity within species and populations; (iii). populations of both species showed significant genetic differentiation, and P. melete was more strongly subdivided; (iv). in both species, geographically close populations did not cluster with one another in the upgma analysis; (v). there was no genetic isolation due to geographical distance in either species; (vi). the genetic composition of seasonal subpopulations differed in urban populations of both species, and the genetic distances among subpopulations were correlated with seasonal differences in P. rapae and with temporal differences in P. melete. These results indicate that the genetic diversity in urban populations of both species was reduced at times, but was maintained by dispersal from genetically differentiated populations. Differences in the ability and mode of dispersal in the two species may be reflected in the degree of population subdivision and patterns of seasonal change in the genetic composition.     

Photosynthetic rates and vegetative production of Sorghastrum nutans in response to competition at two strip mines and a railroad prairie

The effect of differing environmental conditions on competition for resources was investigated by a comparison of net photosynthetic rate (PN) and vegetative production of Indiangrass [Sorghastrum nutans (L.) Nash.] at two strip mine sites with differing reclamation histories, and a railroad prairie site where this species occurs naturally. The treatment for a competition experiment consisted of tying back all species of neighboring plants around a target plant, and measuring its PN and vegetative performance during the growing season. Environmental variables at each site were also measured during the growing season. Soil bulk density and pH were higher at the two mine sites than at the prairie site, and soil texture, nutrients, and water potential were different at each of the three sites. PN of target plants compared closely among the three sites, and were lowest for plants at the railroad prairie. The competition experiment indicated that lower canopy leaves were most affected by competition for photosynthetically active radiation (PAR) at all sites. Significant differences in PN of upper canopy leaves were found between treatment and control plants at one of the mine sites. This site had higher soil water potentials and higher soil levels of P and K than the other mine site or the railroad prairie. Target plants at the other mine site experienced a low competition for PAR, likely due to lower soil moisture availability and therefore lower aboveground productivity. The largest differences in PN and irradiances between upper and lower canopy leaves occurred in target plants with neighbors at the railroad prairie, likely due to inter-specific competition. Vegetative production of the target plants also reflected the environment at each site, but did not reflect PN differences between treatments. S. nutans is well adapted to the varying environment at these three sites, and aboveground competition for radiant energy was probably not as limiting for this C4 grass as belowground competition.     

Are there habitats that contribute best to plant species diversity in coastal dunes?

The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered species, and (b) how each habitat contributes to the total species diversity of the coastal environment. A random stratified sampling approach based on a detailed land cover map was applied to construct rarefaction curves for each habitat type and to estimate total species richness. In addition, the number of exclusive, rare and endangered species was calculated for each habitat type. Results highlight the importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized dune) in species conservation because they harbour progressively higher species richness. However, differences among these habitats were not significant, so no particular species rich “hotspots” could be evidenced. On the contrary, rarefaction curves show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows the highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful biodiversity conservation programs in these coastal environments, it is imperative not only to conserve biologically rich hotspots but also to include species poor habitats containing endangered or unique elements. Thus, the complete coastal vegetation mosaic including all coastal habitats is important to adequately characterize the plant species diversity of coastal dune ecosystems.     

Using rarity to infer how dendritic network structure shapes biodiversity in riverine communities

Dispersal of organisms connects physical localities, but the strength of connection varies widely. Variability in the influence of dispersal can be predictable in sharply defined networks like river systems because some sections of the network are more isolated, leading to different balances of local (i.e. environmental filtering, species interactions) and regional (i.e. dispersal‐driven) processes in structuring communities. We examined the influence of spatial isolation on the relative contributions of α‐ and β‐diversity to regional (γ) diversity, and examined how that influence differed between common and rare species in stream macroinvertebrate communities. One explanation for rarity on a regional scale is that common species are habitat generalists while rare species are specialists. Therefore, common species should be influenced more by dispersal‐driven processes while rare species should be more influenced by local processes. We predicted that for rare taxa, β‐diversity should represent a higher fraction of γ‐diversity in isolated headwaters but that differences between rare and common taxa with regard to the contribution of β‐diversity to γ‐diversity should be less distinct in well‐connected mainstem habitats. To test these predictions, we used macroinvertebrate communities from 634 sites across 22 watersheds. Regardless of rarity, β‐ and γ‐diversity were higher in headwaters compared to mainstems. However, α‐diversity was similar regardless of isolation for rare assemblages. But contrary to our predictions, common assemblages of predators and herbivores did exhibit differences in α‐diversity between locations. Our predictions were strongly supported for two guilds of consumers, the detritivores and collectors, but less so for herbivores and predators. However, these results make sense considering differences in life histories between the groups. For detritivores and collectors, species turnover (β‐diversity) was higher in isolated regions in river networks, and rarity exacerbated this effect, resulting in higher regional diversity of rare species, supporting the general theory that rarity reflects habitat specialization.