Potential Niche Research Articles

Genome-resolved metagenomics and metatranscriptomics reveal niche differentiation in functionally redundant microbial communities at deep-sea hydrothermal vents.

SummaryThe structure and function of microbial communities inhabiting the subseafloor near hydrothermal systems are influenced by fluid geochemistry, geologic setting and fluid flux between vent sites, as well as biological interactions. Here, we used genome‐resolved metagenomics and metatranscriptomics to examine patterns of gene abundance and expression and assess potential niche differentiation in microbial communities in venting fluids from hydrothermal vent sites at the Mid‐Cayman Rise. We observed similar patterns in gene and transcript abundance between two geochemically distinct vent fields at the community level but found that each vent site harbours a distinct microbial community with differing transcript abundances for individual microbial populations. Through an analysis of metabolic pathways in 64 metagenome‐assembled genomes (MAGs), we show that MAG transcript abundance can be tied to differences in metabolic pathways and to potential metabolic interactions between microbial populations, allowing for niche‐partitioning and divergence in both population distribution and activity. Our results illustrate that most microbial populations have a restricted distribution within the seafloor, and that the activity of those microbial populations is tied to both genome content and abiotic factors.

Ectomycorrhizal fungal communities in ice-age relict forests of Pinus pumila on nine mountains correspond to summer temperature.

Ectomycorrhizal (ECM) fungi are critical symbionts of major forest trees, and their communities are affected by various environmental factors including temperature. However, previous knowledge concerning temperature effects does not exclude the effects of host species and coexisting plants, which usually change with temperature, and should be rigorously tested under the same vegetation type. Herein we examined ECM fungal communities in ice-age relict forests dominated by a single host species (Pinus pumila) distributed on nine mountains across >1000 km in Japan. Direct sequencing of rDNA ITS regions identified 154 ECM fungal species from 4134 ECM root-tip samples. Gradient analyses revealed a large contribution of temperature, especially summer temperature, to ECM fungal communities. Additionally, we explored global sequence records of each fungal species to infer its potential temperature niche, and used it to estimate the temperature of the observed communities. The estimated temperature was significantly correlated with the actual temperature of the research sites, especially in summer seasons, indicating inherent temperature niches of the fungal components could determine their distribution among the sites. These results indicate that temperature is still a significant determinant in structuring ECM fungal communities after excluding the effects of host species and coexisting plants. The results also imply that the rising temperature under global warming may have been affecting soil microbes unnoticeably, while such microbial community change may have been contributing to the resilience of the same vegetation.

Ecological niche modelling of cold-water corals in the Southern Ocean (N Antarctic), present distribution and future projections due to temperature changes

Urgent necessity to understand the effect of climatic change on scleractinian cold-water coral (CWC) ecosystems arises from increasing ocean warming and acidification over the last decades. Here, presence-absence records of 12 scleractinian CWC species from research expeditions and literature were compiled and merged with model-generated pseudo-absence data and 14 environmental variables. The best results of nine species distribution models (SDM) were combined to an ensemble habitat suitability model for CWCs in the northern Southern Ocean (Weddell Sea and Antarctic Peninsula) by means of the open source R package ‘biomod2’. Furthermore, two future scenarios of increasing bottom sea temperature were used to investigate the spatial response of scleractinians to temperature change. The resulting (current scenario) potential ecological niches were evaluated with good to excellent statistical measures. The results predict that present areas of highest probability of CWC occurrence are around the Antarctic Peninsula, South Orkney Islands and Queen Maud Land with preference to geomorphic features such as seamounts. The distribution of CWC habitats is mainly driven by distance to coast and ice shelves, bathymetry, benthic calcium carbonate, as well as temperature. Under warming conditions, CWCs are predicted to expand their distribution range by 6 and 10% in 2037 and 2150, respectively, compared to present distribution. The future models using increased bottom temperature revealed a stable CWC distribution for most parts of the study area. However, habitat shifts are expected to the Filchner Trough region, the adjacent continental shelves, as well as to the eastern side of the Antarctic Peninsula.

Lovebirds in the air: trade patterns, establishment success and niche shifts of Agapornis parrots within their non-native range

Understanding the factors influencing the establishment of non-native species is pivotal with regards to the development of effective biosecurity policies. In this paper, we aim to assess the role of climate matching, trade patterns and breeding origin as drivers of establishment success of introduced lovebirds (Agapornis species). A comprehensive database on the worldwide distribution of eight species of non-native lovebirds (including establishment success and population size from 21 countries spanning 27 years) was compiled. We combined climate-based species distribution models with environmental niche analyses to evaluate environmental suitability and potential niche shifts in the introduced range of lovebirds. Then, we tested whether combining habitat suitability with information on trade, introduction effort and breeding origin (captive-bred or wild-caught) of imported birds can improve model predictions at the country level. Although climate-based models fit well with the current distribution of non-native lovebirds at 5-arcminute resolution and significant niche similarity was found for 3 species, we also observed successful establishments in areas climatically distinct from those occupied in native ranges. At the country level, only a significant relationship between the number of established populations and both the number of introduction sites and the year of first importation was observed. A significant effect of breeding origin was not found, but most traded birds had a captive-bred origin. Our work contributes to the growing evidence of the complexity of the invasion process and the difficulty of pre-introduction invasion assessments based solely on the characteristics of the recipient environments for the Agapornis species. Surveillance protocols should be applied to both wild-caught and captive-bred lovebirds, as additional data becomes available to better tease apart the role of origin in those species.

Stem Cells and the Differentiation Hierarchy in Mammary Gland Development.

The mammary gland is a highly dynamic organ that undergoes profound changes within its epithelium during puberty and the reproductive cycle. These changes are fueled by dedicated stem and progenitor cells. Both short- and long-lived lineage-restricted progenitors have been identified in adult tissue as well as a small pool of multipotent mammary stem cells (MaSCs), reflecting intrinsic complexity within the epithelial hierarchy. While unipotent progenitor cells predominantly execute day-to-day homeostasis and postnatal morphogenesis during puberty and pregnancy, multipotent MaSCs have been implicated in coordinating alveologenesis and long-term ductal maintenance. Nonetheless, the multipotency of stem cells in the adult remains controversial. The advent of large-scale single-cell molecular profiling has revealed striking changes in the gene expression landscape through ontogeny and the presence of transient intermediate populations. An increasing number of lineage cell-fate determination factors and potential niche regulators have now been mapped along the hierarchy, with many implicated in breast carcinogenesis. The emerging diversity among stem and progenitor populations of the mammary epithelium is likely to underpin the heterogeneity that characterizes breast cancer.

A positioning strategy for a tourist destination, based on analysis of customers’ perceptions and satisfactions

Purpose The purpose of this paper is to measure the perception and satisfactions of consumers of the tourism product of Kashmir region and identify potential niche markets that could be used in the development of the destination’s positioning strategy. Design/methodology/approach The author used a case study methodology. Self-completion questionnaires were distributed to tourists visiting Kashmir region at the peak of the 2018 tourism season. The scales used were adapted from two authoritative sources. Data from 479 completed questionnaires were analysed quantitatively by a variety of statistical techniques, including factor analysis. Findings Four possible niche markets are identified that can inform the development of the destination’s positioning strategy: nature based, adventure, cultural and culinary. The overall conclusions and discussion of the findings should provide a case-based framework for the practical planning and implementation of positioning strategies in the tourism context. Research limitations/implications The time frame of the study was five summer months in one year, and only actual visitors completed the questionnaire. The study did not assess their evaluation of the quality of the services provided and consumed. Originality/value The overall conclusions and discussion of the findings should provide a case-based framework for the practical planning and implementation of positioning strategies in the tourism context.

Unique secondary metabolites of a Streptomyces strain isolated from extreme salty wetland show antioxidant and antibacterial activities.

To identify and assess the biological activities of the crude extract of a Streptomyces isolate from a salty wetland, an extreme environment likely to induce secondary metabolism of micro-organisms. The crude extract from the isolate Streptomyces lanatus strain AR2 displayed antibacterial activity against Gram-positive bacteria (MICs ranging from 5 to 50μgml-1 ) and antioxidant activity as revealed in DPPH (2,2-diphenyl-1-picrylhydrazyl) assay (IC50 of 0·74mgml-1 ), ferric reducing antioxidant power (IC50 of 1·12mgml-1 ) and metal-chelating power (IC50 of 1·84mgml-1 ) assays. Accordingly, the extract attenuated the H2 O2 -induced oxidative stress in the eukaryotic cell model Saccharomyces cerevisiae, assessed by flow cytometry. The profiling of secondary metabolites by HPLC-PDA-ESI-MS/MS revealed the presence of 17 compounds, some of which reported in Streptomyces for the first time to the best of our knowledge: genistein-7-O-glucuronide, naringenin-7-O-rutinoside and resveratrol. Streptomyces lanatus AR2 produced unique polyketides and phenolic compounds with noticeable bioactivities, allowing adaptation to the extreme environment. Sabkhat Seijoumi salty wetland represents a potential niche for Streptomyces yielding useful natural products for biotechnological, pharmaceutical and medical applications.

Molecular detection of Treponema species organisms in foremilk and udder cleft skin of dairy cows with digital dermatitis.

Identification of reservoirs and transmission routes of digital dermatitis (DD)-associated Treponema spp. is considered an effective means for controlling DD infection in dairy cows. The objective of this study is to identify and characterize the potential reservoir niches for DD-associated Treponema spp. from healthy udder cleft skin and foremilk in lactating dairy cows. A large dairy farm was visited weekly from March to July 2015. Clinical investigation revealed that a total of 25 lame cows had DD lesions located at the plantar aspect of the interdigital cleft. A total of 75 samples, three per cow, were collected including deep swabs from DD lesions (n = 25), non-aseptically collected foremilk samples (n = 25) and skin swabs from udder cleft (n = 25). Treponema spp. were identified using nested PCR assays and confirmed by DNA sequencing. Results revealed that Treponema phagedenis (T. phagedenis)-like was the most identified species in the foremilk 40% (10/25), in comparison with DD lesions and udder cleft skin samples with 32% (8/25) and 20% (5/25), respectively. On the other hand, Treponema pedis (T. pedis) was the most identified species in the udder cleft skin 80% (20/25), in comparison with DD lesions and foremilk samples with 68% (17/25) and 60% (15/25), respectively. None of the examined samples were identified by PCR as containing DNA from Treponema medium (T. medium) or Treponema vincentii (T. vincentii)-like. To the best of our knowledge, this is the first report for detection of T. phagedenis-like and T. pedis from healthy skin of udder cleft and foremilk samples. Detection of DD Treponema spp. from udder cleft skin and foremilk samples indicates that these sites could be potential reservoirs for spirochetes involved in DD. Udder cleft skin and foremilk may have a role in transmission routes of DD Treponema in dairy farms.

On-Line Analysis of Exhaled Breath Focus Review.

On-line analysis of exhaled breath offers insight into a person's metabolism without the need for sample preparation or sample collection. Due to its noninvasive nature and the possibility to sample continuously, the analysis of breath has great clinical potential. The unique features of this technology make it an attractive candidate for applications in medicine, beyond the task of diagnosis. We review the current methodologies for on-line breath analysis, discuss current and future applications, and critically evaluate challenges and pitfalls such as the need for standardization. Special emphasis is given to the use of the technology in diagnosing respiratory diseases, potential niche applications, and the promise of breath analysis for personalized medicine. The analytical methodologies used range from very small and low-cost chemical sensors, which are ideal for continuous monitoring of disease status, to optical spectroscopy and state-of-the-art, high-resolution mass spectrometry. The latter can be utilized for untargeted analysis of exhaled breath, with the capability to identify hitherto unknown molecules. The interpretation of the resulting big data sets is complex and often constrained due to a limited number of participants. Even larger data sets will be needed for assessing reproducibility and for validation of biomarker candidates. In addition, molecular structures and quantification of compounds are generally not easily available from on-line measurements and require complementary measurements, for example, a separation method coupled to mass spectrometry. Furthermore, a lack of standardization still hampers the application of the technique to screen larger cohorts of patients. This review summarizes the present status and continuous improvements of the principal on-line breath analysis methods and evaluates obstacles for their wider application.

Environmental niche modeling for some species of the genus Anthrax Scopoli (Diptera: Bombyliidae) in Egypt, with special notes on St. Catherine protected area as a suitable habitat

The genus Anthrax Scopoli is a well-known genus of bee flies, with 16 species recorded from Egypt, out of about 250 species known worldwide. Six of these species seem to be endangered or threatened (at least in a part of their distribution range) as they disappeared from most of their Egyptian localities which faced severe changes in the floral and faunal composition during the last 50 years. These changes may be attributed to urbanization or modern agricultural activities that caused severe degradation of natural habitats of these species. Maximum entropy (Maxent) modeling was used to predict the potential climatic niches of these six Anthrax species, namely: Anthrax aethiops, Anthrax chionanthrax, Anthrax dentate, Anthrax melanista, Anthrax lucidus, and Anthrax trifasciatus. The Maxent model performed better than random for the six species, with an average test AUC value of 0.95 for A. aethiops bezzii, 0.83 for A. chionanthrax, and 0.98 for A. dentate, 0.86 for A. melanista, 0.96 for A. lucidus and 0.99 for A. trifasciatus. A set of four variables were selected for each species from 19 bioclimatic and 3 topographic variables, based on correlation analyses. The study showed that the current distributions of A. dentata, A. lucidus and A. trifasciatus were largely explained by the altitude, but A. chionanthrax and A. melanista were so far dominated by temperature, whereas on A. aethiops bezzii was strongly related to precipitation variables. St. Catherine protected area showed high habitat suitability for all species except A. lucidus. The suitable habitat for A. trifasciatus was restricted to this protected area, however, future scenarios of climatic changes through the area predict a great degradation in habitat suitability for this species. These results can be used for making powerful conservation management decisions in St. Catherine Protectorate to incorporate these Anthrax spp. in any present or future conservation programs.

The Atrioventricular Junction: A Potential Niche Region for Progenitor Cells in the Adult Human Heart.

A stem cell niche is a microenvironment where stem cells reside in a quiescent state, until activated. In a previous rat model, we combined 5-bromo-2-deoxy-uridine labeling with activation of endogenous stem cells by physical exercise and revealed a distinct region, in the atrioventricular junction (AVj), with features of a stem cell niche. In this study, we aim to investigate whether a similar niche exists in the human heart. Paired biopsies from AVj and left ventricle (LV) were collected both from explanted hearts of organ donors, not used for transplantation (N = 7) and from severely failing hearts from patients undergoing heart transplantation (N = 7). Using antibodies, we investigated the expression of stem cell, hypoxia, proliferation and migration biomarkers. In the collagen-dense region of the AVj in donor hearts, progenitor markers, MDR1, SSEA4, ISL1, WT1, and hypoxia marker, HIF1-α, were clearly detected. The expression gradually decreased with distance from the valve. At the myocardium border in the AVj costaining of the proliferation marker Ki67 with cardiomyocyte nuclei marker PCM1 and cardiac Troponin-T (cTnT) indicated proliferation of small cardiomyocytes. In the same site we also detected ISL1+/WT1+/cTnT cells. In addition, heterogeneity in cardiomyocyte sizes was noted. Altogether, these findings indicate different developmental stages of cardiomyocytes below the region dense in stem cell marker expression. In patients suffering from heart failure the AVj region showed signs of impairment generally displaying much weaker or no expression of progenitor markers. We describe an anatomic structure in the human hearts, with features of a progenitor niche that coincided with the same region previously identified in rats with densely packed cells expressing progenitor and hypoxia markers. The data provided in this study indicate that the adult heart contains progenitor cells and that AVj might be a specific niche region from which the progenitors migrate at the time of regeneration.

Comparative Genomics of Marine Sponge-Derived Streptomyces spp. Isolates SM17 and SM18 With Their Closest Terrestrial Relatives Provides Novel Insights Into Environmental Niche Adaptations and Secondary Metabolite Biosynthesis Potential.

The emergence of antibiotic resistant microorganisms has led to an increased need for the discovery and development of novel antimicrobial compounds. Frequent rediscovery of the same natural products (NPs) continues to decrease the likelihood of the discovery of new compounds from soil bacteria. Thus, efforts have shifted toward investigating microorganisms and their secondary metabolite biosynthesis potential, from diverse niche environments, such as those isolated from marine sponges. Here we investigated at the genomic level two Streptomyces spp. strains, namely SM17 and SM18, isolated from the marine sponge Haliclona simulans, with previously reported antimicrobial activity against clinically relevant pathogens; using single molecule real-time (SMRT) sequencing. We performed a series of comparative genomic analyses on SM17 and SM18 with their closest terrestrial relatives, namely S. albus J1074 and S. pratensis ATCC 33331 respectively; in an effort to provide further insights into potential environmental niche adaptations (ENAs) of marine sponge-associated Streptomyces, and on how these adaptations might be linked to their secondary metabolite biosynthesis potential. Prediction of secondary metabolite biosynthetic gene clusters (smBGCs) indicated that, even though the marine isolates are closely related to their terrestrial counterparts at a genomic level; they potentially produce different compounds. SM17 and SM18 displayed a better ability to grow in high salinity medium when compared to their terrestrial counterparts, and further analysis of their genomes indicated that they possess a pool of 29 potential ENA genes that are absent in S. albus J1074 and S. pratensis ATCC 33331. This ENA gene pool included functional categories of genes that are likely to be related to niche adaptations and which could be grouped based on potential biological functions such as osmotic stress, defense; transcriptional regulation; symbiotic interactions; antimicrobial compound production and resistance; ABC transporters; together with horizontal gene transfer and defense-related features.

Enhancement of CO2 Absorption in Water through pH Control and Carbonic Anhydrase–A Technical Assessment

This paper provides an industrial-scale technical assessment of absorption of CO2 in water to react into bicarbonate (HCO3−), with the goal of storing HCO3− in the oceans as a carbon sequestration technology. A potential advantage of the process is that it will not require a CO2 transport and storage infrastructure that will be expensive for small-scale and remote emission sources. Process simulations are utilized to estimate absorber column length and for mass flow estimations of water and base required for a target capture rate of 90%. The results indicate that the process is technically feasible under specific conditions, with pH regulation being highly important, although the demand for base represents a limiting factor. Yet, a potential niche for the process is CO2 capture at smaller plants emitting small amounts of CO2.

The application of high-throughput sequencing technology to analysis of amoA phylogeny and environmental niche specialisation of terrestrial bacterial ammonia-oxidisers

BackgroundCharacterisation of microbial communities increasingly involves use of high throughput sequencing methods (e.g. MiSeq Illumina) that amplify relatively short sequences of 16S rRNA or functional genes, the latter including ammonia monooxygenase subunit A (amoA), a key functional gene for ammonia oxidising bacteria (AOB) and archaea (AOA). The availability of these techniques, in combination with developments in phylogenetic methodology, provides the potential for better analysis of microbial niche specialisation. This study aimed to develop an approach for sequencing of bacterial and archaeal amoA genes amplified from soil using bioinformatics pipelines developed for general analysis of functional genes and employed sequence data to reassess phylogeny and niche specialisation in terrestrial bacterial ammonia oxidisers.ResultsamoA richness and community composition differed with bioinformatics approaches used but analysis of MiSeq sequences was reliable for both archaeal and bacterial amoA genes and was used for subsequent assessment of potential niche specialisation of soil bacteria ammonia oxidisers. Prior to ecological analysis, phylogenetic analysis of Nitrosospira, which dominates soil AOB, was revisited using a phylogenetic analysis of 16S rRNA and amoA genes in available AOB genomes. This analysis supported congruence between phylogenies of the two genes and increased previous phylogenetic resolution, providing support for additional gene clusters of potential ecological significance. Analysis of environmental sequences using these new sequencing, bioinformatics and phylogenetic approaches demonstrated, for the first time, similar niche specialisation in AOB to that in AOA, indicating pH as a key ecological factor controlling the composition of soil ammonia oxidiser communities.ConclusionsThis study presents the first bioinformatics pipeline for optimal analysis of Illumina MiSeq sequencing of a functional gene and is adaptable to any amplicon size (even genes larger than 500 bp). The pipeline was used to provide an up-to-date phylogenetic analysis of terrestrial betaproteobacterial amoA genes and to demonstrate the importance of soil pH for their niche specialisation and is broadly applicable to other ecosystems and diverse microbiomes.

Clear Victory for Chlamydia: The Subversion of Host Innate Immunity.

As obligate intracellular bacterial pathogens, members of the Chlamydia genera are the pivotal triggers for a wide range of infections, which can lead to blinding trachoma, pelvic inflammation, and respiratory diseases. Because of their restricted parasitism inside eukaryotic cells, the pathogens have to develop multiple strategies for adaptation with the hostile intracellular environment—intrinsically present in all host cells—to survive. The strategies that are brought into play at different stages of chlamydial development mainly involve interfering with diverse innate immune responses, such as innate immune recognition, inflammation, apoptosis, autophagy, as well as the manipulation of innate immune cells to serve as potential niches for chlamydial replication. This review will focus on the innate immune responses against chlamydial infection, highlighting the underlying molecular mechanisms used by the Chlamydia spp. to counteract host innate immune defenses. Insights into these subtle pathogenic mechanisms not only provide a rationale for the augmentation of immune responses against chlamydial infection but also open avenues for further investigation of the molecular mechanisms driving the survival of these clinically important pathogens in host innate immunity.

Niche overlap and dietary resource partitioning in an African large carnivore guild

AbstractUnderstanding and quantifying a large carnivores’ feeding behaviour is a key component in determining its functional significance in an ecosystem, both in terms of its top‐down influence on prey species, but also its relationships with sympatric carnivores. Dietary overlap is one of the numerous niche dimensions used to characterize resource partitioning and potential competition within a community. We characterize the diet, potential dietary niche overlap and prey preference of a large African carnivore guild on small fenced protected areas. To quantify the potential inter‐ and intraspecific foraging competition, we analysed 5,128 kills, representing 35 prey species made by African wild dogs Lycaon pictus (n = 553), cheetahs Acinonyx jubatus (1,427), lions Panthera leo (2,648) and leopards P. pardus (500). Our results show that large African carnivores in small protected areas are exposed to considerable overlap in dietary resource utilization. At the interspecific level, African wild dogs and cheetahs displayed the greatest vulnerability to potential dietary competition. Lions exhibited marked differences in prey preference, mass and species utilization compared to the other carnivores. African wild dogs and cheetah females with dependent offspring occupied the greatest potential for dietary competition within the large carnivore guild. Using a case study based on the preferred biomass of prey available, we estimate the sustainable density of large carnivores at a small fenced prospective African wild dog reintroduction site. African wild dogs displayed the lowest mean predicted density compared to all sympatric predators with an expected population size of 7 individuals. Our research highlights the need to assess the influence of competitive forces in structuring and restoring large predators to portions of their historical range by identifying species most vulnerable to a potential reintroduction attempt. In the absence of controlled experiments, elucidating the influences of exploitation competition is challenging, and only through manipulating sympatric species presence and densities can these complex interactions be fully understood.

Ecological niche modeling as a cumulative environmental impact assessment tool for biodiversity assessment and conservation planning: A case study of critically endangered plant Lagerstroemia minuticarpa in the Indian Eastern Himalaya

Cumulative environmental impact assessment (CEIA) at river basin level for hydroelectric projects is an evolving concept and has proved to be a useful tool to assess the cumulative impact of developmental projects on the natural ecosystems. However, the generality of CEIA studies is often contested because of methodological limitations, especially in the domain of biodiversity conservation and conservation planning. Ecological niche modeling (ENM) can be a useful tool in CEIA studies for conservation planning of threatened plants in hydroelectric project (HEP) areas. We elucidate this hypothesis taking the example of Lagerstroemia minuticarpa Debberm. ex P.C. Kanjilal, a critically endangered tree species in the Indian Eastern Himalaya. Standard ecological methods were employed to document occurrence records, estimate population size, and characterize habitats. ENM was used to estimate the species potential environmental niche and distribution areas. The possible impacts of HEPs on the potential habitats were predicted by overlaying the HEPs on the potential area map as well as using the conceptual network diagram. The study revealed that the species occupies an environmental niche characterized by humid to per-humid conditions, and is distributed mostly in the Lohit and Teesta basins. Potential areas of the species with high environmental suitability coincide with 19 HEPs, which point to a potential threat to the survival of the species. Network diagram indicated that project activities might deteriorate the habitats thereby affecting the population and regeneration of the species. Our study provides a framework for developing appropriate measures for species conservation and reintroduction at basin level using ENM.

Ecophysiological differences between vesicomyid species and metabolic capabilities of their symbionts influence distribution patterns of the deep‐sea clams

AbstractThis study provides an analysis of vesicomyid bivalve–symbiont community distribution across cold seep and hydrothermal vent areas in the Guaymas Basin (Gulf of California, Mexico). Using a combination of morphological and molecular approaches including fluorescent in situ hybridization (FISH), and electronic microscopy observations, vesicomyid clam species and their associated symbionts were characterized and results were analyzed in light of geochemical conditions and other on‐site observations. A greater diversity of vesicomyids was found at cold seep areas, where three different species were present (Phreagena soyoae [syn. kilmeri], Archivesica gigas, and Calyptogena pacifica). In contrast, A. gigas was the only species sampled across the hydrothermal vent area. The same haplotype of A. gigas was found in both hydrothermal vent and cold seep areas, highlighting possible contemporary exchanges among neighboring vents and seeps. In either ecosystem, molecular characterization of the symbionts confirmed the specificity between symbionts and hosts and supported the hypothesis of a predominantly vertical transmission. In addition, patterns of clams could reflect potential niche preferences for each species. The occurrence of numerous traces of vesicomyid movements on sediments in the sites colonized by A. gigas seemed to indicate that this species might have a better ability to move. Furthermore, variation in gill sulfur content could reveal a higher plasticity and sulfur storage capacity in A. gigas. Thus, the distribution of vesicomyid species across the chemosynthetic areas of the Guaymas Basin could be explained by differences in biological traits of the vesicomyid species that would allow A. gigas to more easily exploit transient and punctual sources of available sulfide than P. soyoae.

Fine-scale diversity patterns in belowground microbial communities are consistent across kingdoms.

The belowground environment is heterogeneous and complex at fine spatial scales. Physical structures, biotic components and abiotic conditions create a patchwork mosaic of potential niches for microbes. Questions remain about mechanisms and patterns of community assembly belowground, including: Do fungal and bacterial communities assemble differently? How do microbes reach the roots of host plants? Within a 4 m2 plot in alpine vegetation, high throughput sequencing of the 16S (bacteria) and ITS1 (fungal) ribosomal RNA genes was used to characterise microbial community composition in roots and adjacent soil of a viviparous host plant (Bistorta vivipara). At fine spatial scales, beta-diversity patterns in belowground bacterial and fungal communities were consistent, although compositional change was greater in bacteria than fungi. Spatial structure and distance-decay relationships were also similar for bacteria and fungi, with significant spatial structure detected at <50 cm among root- but not soil-associated microbes. Recruitment of root microbes from the soil community appeared limited at this sampling and sequencing depth. Possible explanations for this include recruitment from low-abundance populations of soil microbes, active recruitment from neighbouring plants and/or vertical transmission of symbionts to new clones, suggesting varied methods of microbial community assembly for viviparous plants. Our results suggest that even at relatively small spatial scales, deterministic processes play a significant role in belowground microbial community structure and assembly.

Past, present, and future geographic range of an oro-Mediterranean Tertiary relict: The juniperus drupacea case study

Juniperus drupacea is a unique relict species found in the mountains of southern Greece, southern Turkey, and western Syria and Lebanon. The aim of this study was to describe the natural range of this juniper by determining the current locations of its populations and to predict a theoretical range for the species based on current, past, and future climatic conditions. We used data from the literature, herbarium materials, and our unpublished field notes (about 500 georeferenced points in total) to determine the current natural distribution of J. drupacea (realized niche). To predict suitable conditions with the program MaxEnt, we used data from the WordClim database, which allowed estimation of the potential niche. The potential niche of J. drupacea was much wider during the Last Glacial Maximum (LGM) and was severely restricted during the Eemian interglacial period. Depending on the climate scenario, this species could become endangered in the future due to climate changes. Considering the relatively restricted geographic range of J. drupacea and the decreasing numbers of localities where it is found, conservation strategies should be adopted to allow for preservation of its genetic and morphological diversity.