Ecophysiological Characteristics Research Articles

Increased precipitation attenuates shrub encroachment by facilitating herbaceous growth in a Mongolian grassland

Abstract Widespread shrub encroachment is profoundly impacting the structures and functions of global drylands, and precipitation change is assumed to be one of the most critical factors affecting this phenomenon. However, there is little evidence to show how precipitation changes will affect the process. In this study, we conducted a 6‐year precipitation manipulation experiment (−30%, ambient, +30% and +50%) to investigate the effects of precipitation changes on the growth of shrubs and herbaceous plants in a shrub‐encroached grassland in Inner Mongolia. We found that the increasing precipitation significantly increased the mean height, coverage and above‐ground biomass of herbaceous species, while the growth of shrub species did not exhibit a significant response to precipitation changes. With increasing precipitation, the relative coverage of shrubs decreased, while that of herbs increased. The native dominant herbaceous plant (Leymus chinensis), with more sensitive maximum photosynthetic rate to the precipitation change, showed higher photosynthetic nitrogen use efficiency and water use efficiency than those of the encroached shrub species (Caragana microphylla) at high soil moisture contents, reflecting that the ecophysiological characteristics of L. chinensis might provide it a competitive advantage under increased precipitation. Our findings suggest that increasing precipitation may slow down shrub encroachment by facilitating herbaceous growth in Mongolian grasslands, and consequently affect the forage value and carbon budget in these ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Ecophysiological characteristics of wintering mute swan population in anthropogenically modified environments

Environmental responsibility is becoming part of the social profile of modern society on an international scale. The analysis of ecosystems in the Baltic Sea presents an example of the use and functioning of ecological systems under increased anthropogenic pressure globally. Wintering and feeding swans, i.e. birds wintering in large urban agglomerations, are particularly useful bioindicators of the degrees of environmental pollution. The aim of the study was to assess the element concentrations in the soil of the birds’ habitat and compare these results with metal contents in birds’ feathers and oxidative stress data [diene conjugates (DC) and middle-mass molecules (MM), the activity of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx), and the total antioxidant status (TAS)] in a wintering population of the mute swan (Cygnus olor) living in northern Poland (southern Baltic Sea). Soil samples collected from bird habitats in Słupsk, Gdynia, and Sopot. These areas differ in the levels of anthropogenic pressure (urban agglomerations, recreational activity, and tourism). The analysis showed significant differences in the Al, Si, Ti, Mn, Fe, Cu, Zn, Zr, Rh, and Ru levels between the soil from Słupsk and both Gdynia and Sopot areas and in the Rh and Ru content between all studied areas. Our results indicated high dependence on the localization, age, and sex of the birds, which were assessed by the level of DC in the blood. The study showed a connection between the lipid peroxidation and antioxidant system functioning, high MM values, and a decreased level of the TAS in adult males from Słupsk, compared to juvenile males from the same area. The functioning of the antioxidant system reflected in the activity of antioxidative enzymes and TAS values was as follows: GR > SOD > CAT > GPx and TAS.

Effects of Groundwater Mineralization and Groundwater Depth on Eco-Physiological Characteristics of Robinia pseudoacacia L. in the Yellow River Delta, China

Groundwater plays a significant role in influencing the growth and distribution of Robinia pseudoacacia L. plantations, with the largest planting area in the Yellow River Delta, by affecting the soil water–salt environment. This study aimed to clarify the mechanism of groundwater’s influence on the growth of R. pseudoacacia under different levels of groundwater mineralization (GWM) and groundwater depth (GWD). We simulated GWM of 0, 2 and 4 g L−1, and GWD of 0.8, 1.3 and 1.8 m. As GWM increased, soil relative water content (SRWC) and soil salt (dissolved salt) content (SSC) increased; sapling biomass (SB), stem mass (SM), leaf mass (LM), photosynthesis characteristics (maximum net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (E) and water use efficiency (WUE)) decreased; root mass (RM), root mass ratio (RMR) and root–shoot ratio (RSR) first increased then decreased; stem mass ratio (SMR) first decreased then increased; and leaf mass ratio (LMR) increased. As GWD increased, SRWC decreased, but SSC first increased then decreased; SB, RM, RMR, RSR, and photosynthesis characteristics increased; SM and LM first increased then decreased; and SMR and LMR decreased. SRWC and SSC were negatively correlated with SB and photosynthesis characteristics. SRWC was negatively correlated with RMR and RSR, whereas it was positively correlated with LMR. SSC was negatively correlated with SMR, whereas it was positively correlated with LMR. The first principal component, including SB, RM, and photosynthesis characteristics, was related to sapling growth. The second principal component, including RMR, SMR, and RSR, was mainly related to biomass allocation. In conclusion, GWM and GWD affected the soil water and salt content, which were key factors influencing the photosynthesis and growth of R. pseudoacacia. Adjustments in biomass allocation and photosynthesis were the main adaptive strategies of R. pseudoacacia to salt, drought, and flooding stress.

Ecophysiology and metabolites of biofilm-forming strains of the microalgal genus Jenufa (Chlorophyceae)

ABSTRACT Microbial biofilms colonizing cultural heritage sites are detrimental due to the production of exudates which deteriorate archaeological surfaces. In this study, a number of microalgal strains isolated from biofilms in hypogea and catacombs were investigated using a multiphasic approach to describe their diversity. Microscopic observations and genetic analyses revealed that the minute coccoid cells belonged to the genus Jenufa. For the first time, ecophysiological characteristics of Jenufa spp strains have been studied and their intracellular, capsular and secreted metabolites quantified. Optimal growth was achieved in nutrient-rich conditions, in which the cells produced substantial amounts of cellular, capsular, colloidal and secreted metabolites. The capsule was composed of high amounts of protein. Under nutrient limitation, Jenufa spp cells produced high quantities of carbohydrates. Both Jenufa cells growing in situ on archaeological surfaces and those cultured in vitro were capable of sustained growth and active secretion of exopolymers for extended periods of time with minimal input of nutrients from outside sources.

Insights into the Evolution of Non‐shivering Thermogenesis from UCP1 of the Naked Mole Rat (Heterocephalus glaber)

Recognized as the primary location of non‐shivering thermogenesis (NST) in eutherian mammals, brown adipose tissue (BAT) functions to accelerate rewarming in hibernators and defend body temperature among newborns and small‐bodied species enduring cold stress. Uncoupling protein 1 (UCP1) is highly expressed in BAT and underlies the molecular mechanism of NST. UCP1 resides in the inner mitochondrial membrane where, upon functional induction by free fatty acids, it catalyzes mitochondrial proton leak, collapsing the proton gradient that stores oxidation energy. The ensuing futile cycling of protons increases substrate oxidation and thus heat production. Central questions remain regarding the exact mechanism by which UCP1 facilitates proton leak, stemming from the lack of a crystal structure of the protein. It is also unknown whether UCP1 function has been shaped by evolution to meet differing thermoregulatory demands of various lineages. We adopt a comparative approach, targeting species with extreme ecophysiological characteristics expected to culminate in drastic differences in thermoregulatory demands and thus UCP1 function, to provide insights into protein structure‐function relationships. For instance, the naked mole rat (NMR; Heterocephalus glaber) is well‐suited to survive in hypoxic burrows that exhibit high year‐round temperatures (30‐34°C). Hinting at a reduced NST capacity, NMRs also display poikilothermy, failing to maintain constant body temperatures when artificially cold challenged. Moreover, NMR UCP1 displays several unique amino acid substitutions, one of which, H145Q (histidine to glutamine), occurs at the well‐known “histidine pair motif”. This motif, typically comprised of histidines at positions 145 and 147, has been hypothesized to be a critical final proton acceptor/donor site shuttling protons into the mitochondrial matrix. The exact mutation that occurs in the NMR, H145Q, was previously shown to diminish hamster UCP1‐mediated proton conductance in proteoliposomes by 90%, calling the functional performance of NMR UCP1 into question. We functionally tested wildtype NMR UCP1 as well as histidine pair mutant combinations at positions 145 and 147, not in the highly artificial system of proteoliposomes, which may promote artefactual protein behaviour, but instead in the more native mammalian environment of HEK293 cells. Using plate‐based respirometry techniques, we demonstrate that wildtype NMR UCP1 uncouples, thus NMRs retain this mechanism of NST. While we hypothesized that reversion of the H145Q mutation would increase UCP1‐mediated proton leak, surprisingly both variants function similarly when activated with free fatty acids and inhibited with guanosine diphosphate (GDP). Likewise, mutation of the histidine at position 147, the other half of the “histidine pair motif”, does not drastically alter UCP1 function. Overall, these data suggest that the “histidine pair motif” may not be crucial for protein function, contrary to previous claims. Comparative functional assessments of UCP1 variants provide a deeper understanding of structure‐function relationships of this enigmatic protein and the evolution of mammalian NST in response to ecophysiological constraints.

Differential elemental stoichiometry of two Mediterranean evergreen woody plants over a geochemically heterogeneous area

Leaf nutrient composition and stoichiometry reflect complex interactions of the plant with its environment and are useful traits to explore ecological processes and relationships. In the present study, the foliar elemental compositions of two common Mediterranean woody species, the evergreen broad-leaved Quercus ilex and the coniferous Pinus pinaster growing in an area of Central Italy known for geochemical and geothermal anomalies, were investigated. To assess the site-specific and age-dependent pattern of foliar composition and stoichiometry, macronutrients (C, N, P, K, Mg, S) and trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Sb, V, Zn) were determined in leaves and needles of three different ages (6-, 12- and 24-month-old) collected from metalliferous (geothermal, mining) and rural areas. Leaves of Q. ilex showed comparatively high concentrations of micronutrients (i.e., Cu, Fe and Zn), while needles of P. pinaster accumulated significantly high concentrations of potentially toxic elements (i.e., As, Pb and S). No significant trend was found in elemental concentrations in relation to the age of leaves and needles. Multi-element stoichiometry of P. pinaster was driven by the geochemical heterogeneity of the sites, suggesting plastic adaptation at the sites with the most selective edaphoclimatic conditions (i.e., patches with nutrient poor and metalliferous soils). On the other hand, the content of both nutrients and potentially toxic elements in Q. ilex leaves varied little across the study area, reflecting stoichiometric stability; this is consistent with the ecophysiological features of Q. ilex as a late-successional species with a dominant role in the ecosystems of the Mediterranean area. Our findings demonstrate the value of foliar stoichiometric traits for understanding plant adaptation in a heterogeneous environment and also the consequences of biotic interactions during succession.

Study of water deficiency levels on ecophysiological characteristics of sunflower cultivars in Isfahan, Iran

This study was aimed to investigate the effect of drought stress on some ecophysiological characteristics of sunflower cultivars. This study was conducted in the form of split plots in a randomized complete block design with three replications in the Braun area of Isfahan province for the year 2020. Drought stress at three irrigation levels after evaporation of 90, 120, and 150 mm from Class A evaporation pan as non-stress, mild, and severe stress, respectively, in the main plots and five cultivars of sunflower Chiara, Oscar, Fantasia, Hisun 33, and Shams was placed in the subplots. Drought stress affected achene yield, harvest index, and drought tolerance of sunflower cultivars. The highest biophysical water productivity (WPb) was obtained from 90 and then 120-mm irrigation and among sunflower cultivars from Fantasia and Hisun 33 cultivars. The highest economic water productivity (WPe) was obtained with 90-mm irrigation and Fantasia and Hisun 33 cultivars. The highest HI belonged to 90 and then 120-mm irrigation. The highest HI was related to Fantasia, Oscar, and Hisun 33 cultivars, and the lowest HI was related to Shams and Chiara cultivars. The highest and the lowest grain yield were obtained in 90 (control) and 150 mm of evaporation, respectively. The highest grain yield was obtained in Fantasia, Shams, and Oscar cultivars, and the lowest yield was observed in Hisun 33 and Chiara cultivars. In general, drought stress affected yield, HI, crop water productivity (WPc), and drought tolerance of sunflower cultivars.

Effects of moso bamboo (Phyllostachys edulis) expansion on soil microbial community in evergreen broad-leaved forest

The special eco-physiological characteristics of moso bamboo (Phyllostachys edulis) facilitate their fast invasion in nature ecosystems. The widespread expansion of moso bamboo causes degradation of adjacent forest ecosystem and change of landscape, as well as soil properties and microbial community composition. However, how moso bamboo expansion affects soil microbial composition is far from fully understood. Herein, we selected four moso bamboo expansion transects with three forest types at the Anji Lingfeng temple forest farm, Zhejiang Province, including evergreen broadleaved forest (BLF), mixed P. edulis and broadleaved forest (MEF) and P. edulis forest (PEF). We examined the effects of moso bamboo expansion on soil properties and soil microbial phospholipid fatty acids (PLFAs). Our results showed that soil pH was higher in moso bamboo forest than in MEF and BLF by 0.37 and 0.32 unit. In contrast, soil organic carbon, ammonium, and nitrate contents significantly decreased. Biomass of soil microbial groups displayed a decreasing trend except arbuscular mycorrhizal fungi, and the microbial richness index (SR) and diversity index (H) decreased significantly. In summary, moso bamboo expansion affected soil nutrient and carbon inputs, which was an important factor affecting soil microbial community structure. Results of redundancy analysis showed that changes of soil organic carbon and ammonium content were the main factors driving soil microbial community.

A methodological framework integrating habitat suitability and landscape connectivity to identify optimal regions for insecticide application: A case study in Tongzhou, China

Insecticide application is still a standard method in pest management. However, the current regions for insecticide application usually focus on the host of the pest but ignore the migration pathways, continually resulting in pests’ periodic outbreaks. This research provides a valuable modeling framework to identify optimal regions for insecticide application to solve this problem. This modeling framework optimizes insecticide areas based on habitat suitability and landscape connectivity, combining the MaxEnt and circuit theory. We conducted a case study in Beijing, China, to elucidate the application of this modeling framework. The input data included 517 occurrence points of Semiothisa cinerearia collected in the fieldwork and the environmental variables related to the eco-physiological characteristics of this species. The results indicated that the Chinese scholar tree (Styphnolobium japonicum) was the most vulnerable species. Increasing the pesticide region by 11.9% at some crucial corridors of the target species, the pest management effectiveness increased by 27.7%, compared with the pesticide applied only to the Chinese scholar trees. In summary, this study proposed a convenient and efficient modeling methodology for planning optimal regions for insecticide application.

Ecophysiological features of Larix sibirica in urban ecosystems of the Kola north in the railway influence zone

For the first time, a study of the ecophysiological features of the introduced Larix sibirica (middle-aged plantations old 40-50 years) was carried out at a tree nursery and railway stations in four cities in the Kola Subarctic. Content of photosynthetic pigments (per fresh weight) ranged 1185 – 1894 μg·g-1 (chlorophyll a), 377 – 666 μg·g-1 (chlorophyll b), and 256 – 387 μg·g-1 (carotenoids). Exception was found for the specimens from Murmansk (significantly higher) and Olenegorsk (significantly lower values). High content of Fe was found in needles (1865 – 4278 mg·kg-1), however, it did not lead to any damage or abnormalities in the development of Larix sibirica. A close positive correlation was shown between the Fe and Mn contents (r = 0.91). Ni and Cu content in needles increased in all cities from 3 to 8 times in comparison with the background, Pb content increased only in the cities of Apatity and Olenegorsk (2–4 times). The amount of Cd and Zn was found within the optimal range. This study revealed the negative effects of the main pollutants (Ni, Cu, and Pb from the mining industry) on chlorophyll a (r = -0.81) and carotenoids (r = -0.70).

Effects of light intensity and nitrogen deposition on ecophysiological characteristics of Coreopsis grandiflora1

Light heterogeneity commonly occurs in natural environments, and N deposition has increased sharply in recent decades, affecting both the growth and invasion of exotic plants. We used an exotic species, Coreopsis grandiflora, distributed in natural and urban areas throughout China, to study the combined effects of light exposure and N addition on leaf physiology, height, crown area, total biomass (TB), and phenotypic plasticity. We exposed C. grandiflora seedlings to one of three light (15, 65, and 100% of full irradiation) and one of three nitrogen treatments (0, 8, and 20 g N m–2 yr–1). The shade significantly increased leaf chlorophyll, N, and P concentrations, aboveground biomass allocation, and specific leaf area, allowing plants to capture more light, which did not result in a change in TB, indicating that C. grandiflora seedlings have shade tolerance. Nitrogen addition generally increased the TB, leaf biomass, crown area and leaf N concentration. In addition, N supply did not increase TB of C. grandiflora in the shade. For approximately half of the traits measured, the phenotypic plasticities of C. grandiflora responding to light differ greatly from those responding to N addition. Under light and N deposition treatments, photosynthetic N use efficiency had higher phenotypic plasticity than other leaf physiological traits, whereas the maximum quantum yield of photosystem II, leaf N, and P concentrations had lower phenotypic plasticity, suggesting that hierarchical plasticity occurs among the various leaf physiological traits. Light intensity increased the plasticity of C. grandiflora in response to N deposition. Thus, with high plasticity, invasiveness of C. grandiflora may increase under high N deposition and illumination conditions.

Ecophysiology of the kleptoplastidic dinoflagellate Shimiella gracilenta: I. spatiotemporal distribution in Korean coastal waters and growth and ingestion rates

To explore the ecophysiological characteristics of the kleptoplastidic dinoflagellate Shimiella gracilenta, we determined its spatiotemporal distribution in Korean coastal waters and growth and ingestion rates as a function of prey concentration. The abundance of S. gracilenta at 28 stations from 2015 to 2018 was measured using quantitative realtime polymerase chain reaction. Cells of S. gracilenta were detected at least once at all the stations and in each season, when temperature and salinity were 1.7–26.4°C and 9.9–35.6, respectively. Moreover, among the 28 potential prey species tested, S. gracilenta SGJH1904 fed on diverse prey taxa. However, the highest abundance of S. gracilenta was only 3 cells mL-1 during the study period. The threshold Teleaulax amphioxeia concentration for S. gracilenta growth was 5,618 cells mL-1, which was much higher than the highest abundance of T. amphioxeia (667 cells mL-1). Thus, T. amphioxeia was not likely to support the growth of S. gracilenta in the field during the study period. However, the maximum specific growth and ingestion rates of S. gracilenta on T. amphioxeia, the optimal prey species, were 1.36 d-1 and 0.04 ng C predator- 1 d-1, respectively. Thus, if the abundance of T. amphioxeia was much higher than 5,618 cells mL-1, the abundance of S. gracilenta could be much higher than the highest abundance observed in this study. Eurythermal and euryhaline characteristics of S. gracilenta and its ability to feed on diverse prey species and conduct kleptoplastidy are likely to be responsible for its common spatiotemporal distribution.

Phytoplankton growth rates in the Amundsen Sea (Antarctica) during summer: The role of light

In the Amundsen Sea, significant global warming accelerates ice melt, and is consequently altering many ocean properties such as sea ice concentration, surface freshening, water column stratification, and underwater light properties. To examine the influence of light, which is one of the fundamental factors for phytoplankton growth, incubation experiments and field surveys were performed during the austral summer of 2016. In the incubation experiments, phytoplankton abundance and carbon biomass significantly increased with increasing light levels, probably indicating light limitation. Growth rates of the small pennates (mean 0.42 d−1) increased most rapidly with an increase in light, followed by those of Phaeocystis antarctica (0.31 d−1), and the large diatoms (0.16 d−1). A short-term study during the field survey showed that phytoplankton distribution in the surface layer was likely controlled by different responses to light and the sinking rate of each species. These results suggest that the approach adopted by previous studies of explaining phytoplankton ecology as a characteristic of two major taxa, namely diatoms and P. antarctica, in the coastal Antarctic waters might cause errors owing to oversimplification and misunderstanding, since diatoms comprise several species that have different ecophysiological characteristics.

Biodiversity and biocatalyst activity of culturable hydrocarbonoclastic fungi isolated from Marac\u2013Moruga mud volcano in South Trinidad

Mud volcanoes (MVs) are visible signs of oil and gas reserves present deep beneath land and sea. The Marac MV in Trinidad is the only MV associated with natural hydrocarbon seeps. Petrogenic polyaromatic hydrocarbons (PAHs) in its sediments must undergo biogeochemical cycles of detoxification as they can enter the water table and aquifers threatening ecosystems and biota. Recurrent hydrocarbon seep activity of MVs consolidates the growth of hydrocarbonoclastic fungal communities. Fungi possess advantageous metabolic and ecophysiological features for remediation but are underexplored compared to bacteria. Additionally, indigenous fungi are more efficient at PAH detoxification than commercial/foreign counterparts and remediation strategies remain site-specific. Few studies have focused on hydrocarbonoclastic fungal incidence and potential in MVs, an aspect that has not been explored in Trinidad. This study determined the unique biodiversity of culturable fungi from the Marac MV capable of metabolizing PAHs in vitro and investigated their extracellular peroxidase activity to utilize different substrates ergo their extracellular oxidoreductase activity (> 50% of the strains decolourized of methylene blue dye). Dothideomycetes and Eurotiomycetes (89% combined incidence) were predominantly isolated. ITS rDNA sequence cluster analysis confirmed strain identities. 18 indigenous hydrocarbonoclastic strains not previously reported in the literature and some of which were biosurfactant-producing, were identified. Intra-strain variability was apparent for PAH utilization, oil-tolerance and hydroxylase substrate specificity. Comparatively high levels of extracellular protein were detected for strains that demonstrated low substrate specificity. Halotolerant strains were also recovered which indicated marine-mixed substrata of the MV as a result of deep sea conduits. This work highlighted novel MV fungal strains as potential bioremediators and biocatalysts with a broad industrial applications.

Funneliformis mosseae Application Improves the Oil Quantity and Quality and Eco-physiological Characteristics of Soybean (Glycine max L.) Under Water Stress Conditions

Funneliformis mosseae Application Improves the Oil Quantity and Quality and Eco-physiological Characteristics of Soybean (Glycine max L.) Under Water Stress Conditions

Fast restore of the structure and composition of hemiepiphytes after a heavy-snowfall event in a subtropical forest

Since epiphytes mainly obtain water and nutrients from surrounding air, they are extremely sensitive to environmental changes, making them reliable bio-indicators for monitoring climate change. Hemiepiphytes are one common form of epiphytic plants, consisting of primary and secondary hemiepiphytes. It is thus reasonable to suppose that the hemiepiphytes should respond strongly to an extreme change in local climatic conditions. Based on survey data of hemiepiphytes (all the investigated species are primary hemiepiphytes) on trees before (2014) and after (2018) a heavy snowfall event (2015, depth of 50 cm), we examined differences in the distribution and abundance of individuals, population structure, and the general network structure of hemiepiphyte–host associations in a subtropical forest in the Ailao Mountains (Yunnan Province, in southwest China). Contrary to our hypothesis, the results revealed no significant changes for the distribution and abundance of this hemiepiphyte community before and after the heavy-snowfall event. The population structure of all hemiepiphytes (pooled) shifted from a dynamic to a stable state, but did not change on a per species basis. According to the constructed network's parameters, no significant differences were found between years, except for changed web asymmetry, linkage density, and interaction evenness. Our results suggest hemiepiphytes are highly resilient to extreme weather perturbations: within just four years after the snowfall, the community was nearly fully restored to its prior composition and structure. We propose this resilience capability is linked to their ecophysiological characteristics and distributions on host trees.

Use of physiological attributes to select native forest species for forest restoration in the southern Atlantic forest biome, Brazil

In subtropical regions, the selection of species for restoration is conducted as a part of phytosociological studies. This may be complemented by physiological characterization of the species in response to light. The objectives of this study were to identify the physiological attributes performance of native forest species that are conducive to restoration and to identify groups of species for planting in altered areas, under different light intensities south of the Atlantic Forest biome, in Brazil. Seedlings of 12 native species were cultivated in the nursery in full sun and shade, and the net CO2 assimilation rate (A), water use efficiency (WUE), and quantum yield potential of photosystem II (Fv/Fm) were determined for these seedlings. Cluster analysis allowed the differentiation of these species into three groups (Cl-I, Cl-II, and Cl-III) based on the similarity of physiological attributes. In Cl-I, we identified species with an A of 7 μmol CO2 m−2·s−1 and high Fv/Fm values when plants were growing in the shade. The Cl-II group had the highest A (≅12 μmol CO2 m−2·s−1) and WUE. The Cl-III group demonstrated an A of ≅ 5 μmol CO2 m−2·s−1 when the species was growing in full sun or under shade. The results demonstrate that forest species exhibit differences in terms of their A values in response to exposure to varying light intensities (that is, shade or full sun). The analysis of eco-physiological characteristics is fundamental in identifying the most suitable species for planting in forest restoration; this allows for adequate planning of recovery projects. Citharexylum montevidensis, Inga marginata, and Luehea divaricata are the species that were used for initial planting in full sun, which may complement the low density of Ceiba speciosa and Inga vera. For enrichment conditions in the southern Atlantic Forest biome, Cedrela fissilis, Handroanthus heptaphyllus, Vitex megapotamica, Ocotea puberula, Casearia sylvestris, Aspidosperma olivaceum, and Cupania vernalis are considered most appropriate for restoration.

Climate Change Impacts on Tropical Reptiles: Likely Effects and Future Research Needs Based on Sri Lankan Perspectives

The tropical island nation of Sri Lanka has a rich terrestrial and aquatic reptilian fauna. However, like most other tropical countries, the threat of climate change to its reptile diversity has not been adequately addressed, in order to manage and mitigate the extinction threats that climate change poses. To address this shortfall, a review of the international literature regarding climate change impacts on reptiles was undertaken with specific reference to national requirements, focusing on predicted changes in air temperature, rainfall, water temperature, and sea level. This global information base was then used to specify a national program of research and environmental management for tropical countries, which is urgently needed to address the shortcomings in policy-relevant data, its availability and access so that the risks of extinction to reptiles can be clarified and mitigated. Specifically, after highlighting how climate change affects the various eco-physiological features of reptiles, we propose research gaps and various recommendations to address them. It is envisaged that these assessments will also be relevant to the conservation of reptilian biodiversity in other countries with tropical and subtropical climatic regimes

Cultivation of Dominant Freshwater Bacterioplankton Lineages Using a High-Throughput Dilution-to-Extinction Culturing Approach Over a 1-Year Period.

Although many culture-independent molecular analyses have elucidated a great diversity of freshwater bacterioplankton, the ecophysiological characteristics of several abundant freshwater bacterial groups are largely unknown due to the scarcity of cultured representatives. Therefore, a high-throughput dilution-to-extinction culturing (HTC) approach was implemented herein to enable the culture of these bacterioplankton lineages using water samples collected at various seasons and depths from Lake Soyang, an oligotrophic reservoir located in South Korea. Some predominant freshwater bacteria have been isolated from Lake Soyang via HTC (e.g., the acI lineage); however, large-scale HTC studies encompassing different seasons and water depths have not been documented yet. In this HTC approach, bacterial growth was detected in 14% of 5,376 inoculated wells. Further, phylogenetic analyses of 16S rRNA genes from a total of 605 putatively axenic bacterial cultures indicated that the HTC isolates were largely composed of Actinobacteria, Bacteroidetes, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Verrucomicrobia. Importantly, the isolates were distributed across diverse taxa including phylogenetic lineages that are widely known cosmopolitan and representative freshwater bacterial groups such as the acI, acIV, LD28, FukuN57, MNG9, and TRA3–20 lineages. However, some abundant bacterial groups including the LD12 lineage, Chloroflexi, and Acidobacteria could not be domesticated. Among the 71 taxonomic groups in the HTC isolates, representative strains of 47 groups could either form colonies on agar plates or be revived from frozen glycerol stocks. Additionally, season and water depth significantly affected bacterial community structure, as demonstrated by 16S rRNA gene amplicon sequencing analyses. Therefore, our study successfully implemented a dilution-to-extinction cultivation strategy to cultivate previously uncultured or underrepresented freshwater bacterial groups, thus expanding the basis for future multi-omic studies.

Ecophysiological Features Shape the Distribution of Prophages and CRISPR in Sulfate Reducing Prokaryotes.

Sulfate reducing prokaryotes (SRP) are a phylogenetically and physiologically diverse group of microorganisms that use sulfate as an electron acceptor. SRP have long been recognized as key players of the carbon and sulfur cycles, and more recently, they have been identified to play a relevant role as part of syntrophic and symbiotic relations and the human microbiome. Despite their environmental relevance, there is a poor understanding about the prevalence of prophages and CRISPR arrays and how their distribution and dynamic affect the ecological role of SRP. We addressed this question by analyzing the results of a comprehensive survey of prophages and CRISPR in a total of 91 genomes of SRP with several genotypic, phenotypic, and physiological traits, including genome size, cell volume, minimum doubling time, cell wall, and habitat, among others. Our analysis discovered 81 prophages in 51 strains, representing the 56% of the total evaluated strains. Prophages are non-uniformly distributed across the SRP phylogeny, where prophage-rich lineages belonged to Desulfovibrionaceae and Peptococcaceae. Furthermore, our study found 160 CRISPR arrays in 71 SRP, which is more abundant and widely spread than previously expected. Although there is no correlation between presence and abundance of prophages and CRISPR arrays at the strain level, our analysis showed that there is a directly proportional relation between cellular volumes and number of prophages per cell. This result suggests that there is an additional selective pressure for strains with smaller cells to get rid of foreign DNA, such as prophages, but not CRISPR, due to less availability of cellular resources. Analysis of the prophage genes encoding viral structural proteins reported that 44% of SRP prophages are classified as Myoviridae, and comparative analysis showed high level of homology, but not synteny, among prophages belonging to the Family Desulfovibrionaceae. We further recovered viral-like particles and structures that resemble outer membrane vesicles from D. vulgaris str. Hildenborough. The results of this study improved the current understanding of dynamic interactions between prophages and CRISPR with their hosts in both cultured and hitherto-uncultured SRP strains, and how their distribution affects the microbial community dynamics in several sulfidogenic natural and engineered environments.