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Biological invasions undermine the functional diversity of fish community in a large subtropical river
No full textBiological invasions are considered to be one of the main threats to biodiversity. Invasions lead to a loss of native species, changes to species composition, and a shift in the functioning and stability of ecosystems. In this study, derived from nine consecutive years of monitoring data and based on morphological functional trait values measured at the individual-level, we quantified the functional differences between native and non-native fish species and further assessed how biological invasions impact on species richness and functional diversity in the large subtropical Pearl River in southern China. Specifically, we differentiated intraspecific functional variability by separating individuals of a species according to their different life stages. Our results provided strong evidence that native and non-native fish were significantly different in their functional attributes. Invasion caused no obvious change in species richness; however, the yearly increase in non-native populations was accompanied by a significant decrease in functional niches of native species and change in several aspects of functional diversity in the fish community. Decreasing functional richness, and increasing functional divergence and specialization, indicated that most native species had been replaced by non-native species with different specific functional traits, which may affect ecosystem stability. Notably, this study provided empirical evidence that functional diversity was more sensitive to biological invasions than species richness. Our results show that control of non-native aquatic species is both necessary and urgent in the Pearl River. An understanding of the processes described in this study can form the basis of conservation in fish community, which is critical to sustainable and successful fisheries
Diet simplification selects for high gut microbial diversity and strong fermenting ability in high-altitude pikas
No full textThe gut microbiota in mammals plays a key role in host metabolism and adaptation. However, relatively little is known regarding to how the animals adapts to extreme environments through regulating gut microbial diversity and function. Here, we investigated the diet, gut microbiota, short-chain fatty acid (SCFA) profiles, and cellulolytic activity from two common pika (Ochotona spp.) species in China, including Plateau pika (Ochotona curzoniae) from the Qinghai-Tibet Plateau and Daurian pika (Ochotona daurica) from the Inner Mongolia Grassland. Despite a partial diet overlap, Plateau pikas harbored lower diet diversity than Daurian pikas. Some bacteria (e.g., Prevotella and Ruminococcus) associated with fiber degradation were enriched in Plateau pikas. They harbored higher gut microbial diversity, total SCFA concentration, and cellulolytic activity than Daurian pikas. Interestingly, cellulolytic activity was positively correlated with the gut microbial diversity and SCFAs. Gut microbial communities and SCFA profiles were segregated structurally between host species. PICRUSt metagenome predictions demonstrated that microbial genes involved in carbohydrate metabolism and energy metabolism were overrepresented in the gut microbiota of Plateau pikas. Our results demonstrate that Plateau pikas harbor a stronger fermenting ability for the plant-based diet than Daurian pikas via gut microbial fermentation. The enhanced ability for utilization of plant-based diets in Plateau pikas may be partly a kind of microbiota adaptation for more energy requirements in cold and hypoxic high-altitude environments
LEAF PHYSIOLOGICAL AND ANATOMICAL CHARACTERISTICS OF TWO INDICATOR SPECIES IN THE LIMESTONE REGION OF SOUTHERN CHINA UNDER DROUGHT STRESS
No full textDrought is a critical limiting factor of plant growth, and plants living in arid areas must develop adaptation mechanisms to resist drought stress. In this study, we studied the drought resistance mechanisms of two tree species, Triadica rotundifolia and Cinnamomum burmannii, based on their foliar physiological and anatomical characteristics. These trees are indicator plants in the limestone region of southern China. We evaluated and compared the changes in the contents of chlorophyll, soluble protein, soluble sugars, proline, malondialdehyde (MDA), proline, activity of superoxide dismutase (SOD) and peroxidase (POD), chlorophyll fluorescence parameters, and leaf anatomical structure between these two species. The results showed the following. (1) The content of Chl(a+b), soluble protein, soluble sugar and SOD activity of the two species' seedlings had an increasing trend at first and then a decrease over the entire drought experiment. The change in MDA content was more sensitive in T. rotundifolia, and the peak (33.05 mmol.ml(-1)) appeared on the 28th day of the drought experiment. Comparatively, the proline content and POD activity were more sensitive in C. burmannii, and the proline peak (217.11 mu g.g(-1)) appeared on the 24th day. (2) Under the continuous drought stress, the electron transport rate of the seedlings decreased, whereas the non-photochemical quenching showed different trends for the different species. Severe drought stress in T. rotundifolia caused an increasing trend in the light energy capture efficiency (F-v/F-m), while it declined continuously in C. burmannii. (3) Under the drought stress, the leaves of T. rotundifolia became thicker. The arrangement of spongy tissues became loose, and the ratio of palisade to spongy tissue decreased. However, the leaves of C. burmannii showed a few different features, such as inconspicuous differentiation between palisade and spongy tissues, a high loose degree of leaves, and low packing. (4) The leaf physiological indices had a strong relationship with the anatomy characteristics, as revealed by principal component analysis (PCA); the adaptability to drought tolerance of T rotundifolia was stronger than C. burmannii. In conclusion, T rotundifolia is better able to adapt to drought conditions due to its physiological and anatomical characteristics, which allow the species to better buffer drought-induced physiological responses and variability in leaf structure
The study of simultaneous desulfurization and denitrification process based on the key parameters
No full textThe impacts of different S/N molar ratios and fillers (polyurethane foam, multi-surface hollow spheres, and pall rings) on the process of simultaneous desulfurization and denitrification (SDD) were studied by using anaerobic biotrickling filer (BTF). Furthermore, the SDD mechanism was described by dividing the SDD process into three stages based on pH changes: (I) increase (II) decrease and (III) stable state. The maximum desulfurization and denitrification efficiency (13.5 g-S m(-3) h(-1) and 3.7 g-N m(-3) h(-1), respectively) was achieved by applying polyurethane foam as filler. When S2- and S-0 coexist as electron donors in the SDD system, the functional microbes degrade S2- preferentially. The S/N molar ratios of the influent were higher, and the relative content of sulfate in the products was less. Considering the efficiency and economic benefits, polyurethane foam is suggested as fillers for practical implementations of SDD systems. The S/N molar ratios should be controlled in a 5/3 to 5/2 range and HS-/S2- concentration should be < 16.8 mM. The Thiobacillus genus with more than 40% of relative abundance is absolutely dominant in all reactors, followed by the Rhodanobacter, Arenimonas, and Truepera genera. The microbial community with the function of desulfurization-denitrification in the system had a certain degree of redundancy
Traditional medicines and their in-vitro proof against Staphylococcus aureus in Pakistan`
No full textObjective: To gather the fragmented literature on ethnobotany, phytochemistry and in-vitro activities of medicinal plants of Pakistan being used against common infections caused by Staphylococcus aureus (S. aureus). Methods: A large number of published and unpublished research studies related to the ethnomedicinal, phytochemical and anti-S. aureus activity of medicinal flora of Pakistan published from 1990-2018 were reviewed using online bibliographic databases such as PubMed, Web of Science, Science Direct, ResearchGate and libraries. Results: S. aureus can cause many human ailments including endocarditis, staphylococcal scalded skin syndrome, septic arthritis, respiratory problems with an estimated infection rate of 25%-35% across the globe. This review comprised of 86 medicinal plants. Data showed that people mostly used leaves (50%) for the preparation of traditional medicines. Correlation analysis on the reviewed data revealed that methanolic extract concentrations of medicinal plants was highly significantly positive correlated (r=0.8; P<0.01) with the S. aureus zone of inhibitions. S. aureus reportedly showed complete resistant to the commonly used antibiotic erythromycin. Isolated compounds like altheahexacosanyl lactone, cinnamaldehyde, niloticane, gobicusin A, asparacosin A, muzanzagenin, isoagatharesinol, friedelin, inophynone and eugenol were active against S. aureus. This study provided in-vitro proof for the flora of Pakistan used against different infections caused by S. aureus. Conclusions: Antibacterial agents from natural sources could be more effective against bacterial pathogens and will be helpful in minimizing the adverse effects of synthetic drugs, and hence provides a base for the pharmaceutical industries
Patterns of plant carbon,nitrogen,and phosphorus concentration in relation to productivity in China's terrestrial ecosystems
No full textPlant nitrogen (N) and phosphorus (P) content regulate productivity and carbon (C) sequestration in terrestrial ecosystems. Estimates of the allocation of N and P content in plant tissues and the relationship between nutrient content and photosynthetic capacity are critical to predicting future ecosystem C sequestration under global change. In this study, by investigating the nutrient concentrations of plant leaves, stems, and roots across China's terrestrial biomes, we document large-scale patterns of community-level concentrations of C, N, and P. We also examine the possible correlation between nutrient content and plant production as indicated by vegetation gross primary productivity (GPP). The nationally averaged community concentrations of C, N, and P were 436.8, 14.14, and 1.11 mg.g(-1) for leaves; 448.3, 3.04 and 0.31 mg.g(-1) for stems; and 418.2, 4.85, and 0.47 mg.g(-1) for roots, respectively. The nationally averaged leaf N and P productivity was 249.5 g C GPP.g(-1) N.y(-1) and 3, 157.9 g C GPP.g (-1) P.y(-1), respectively. The N and P concentrations in stems and roots were generally more sensitive to the abiotic environment than those in leaves. There were strong power-law relationships between N (or P) content in different tissues for all biomes, which were closely coupled with vegetation GPP. These findings not only provide key parameters to develop empirical models to scale the responses of plants to global change from a single tissue to the whole community but also offer large-scale evidence of biome-dependent regulation of C sequestration by nutrients
Auditory neural networks involved in attention modulation prefer biologically significant sounds and exhibit sexual dimorphism in anurans
No full textAllocating attention to biologically relevant stimuli in a complex environment is critically important for survival and reproductive success. In humans, attention modulation is regulated by the frontal cortex, and is often reflected by changes in specific components of the event-related potential (ERP). Although brain networks for attention modulation have been widely studied in primates and avian species, little is known about attention modulation in amphibians. The present study aimed to investigate the attention modulation networks in an anuran species, the Emei music frog (Babina daunchina). Male music frogs produce advertisement calls from within underground nest burrows that modify the acoustic features of the calls, and both males and females prefer calls produced from inside burrows. We broadcast call stimuli to male and female music frogs while simultaneously recording electroencephalographic (EEG) signals from the telencephalon and mesencephalon. Granger causal connectivity analysis was used to elucidate functional brain networks within the time window of ERP components. The results show that calls produced from inside nests which are highly sexually attractive result in the strongest brain connections; both ascending and descending connections involving the left telencephalon were stronger in males while those in females were stronger with the right telencephalon. Our findings indicate that the frog brain allocates neural attention resources to highly attractive sounds within the window of early components of ERP, and that such processing is sexually dimorphic, presumably reflecting the different reproductive strategies of males and females
Simultaneous quantitative assessment of nine glycosides in tobacco by liquid chromatography-tandem mass spectrometry
No full textA simple and efficient method combining ultrasound-assisted extraction, the conditions of which were optimized by response surface methodology, with liquid chromatography and tandem mass spectrometry was established and validated for the absolute quantification of nine non-volatile neutral glycosides originating from tobacco (Nicotiana tobaccum L.) leaves, comprising three phenolic glycosides, one benzanoid glycoside, and five sesquiterpene glycosides within three isomers, originating from tobacco leaves. Factors of extraction time, sample quantity, extraction solvent, liquid chromatographic conditions, and electrospray ionization parameters were carefully investigated to ensure the selectivity and sensitivity of the method. All calibration curves showed excellent coefficients of determination ranging from 0.9940 to 0.9996, within the range of tested concentrations. The limits of detection and quantification were 2.33-25.9 and 7.06-78.5 ng/mL, respectively. Satisfactory values of accuracy were between 80.1 to 107.9% among different sample matrixes. The relative standard deviations of intra-and inter-day analysis were less than 13.7 and 13.0% respectively. The developed method was successfully applied in a pilot study to determine the amounts of the nine endogenous glycosides in real flue-cured tobacco samples obtained from different habitats in China
Holocene peatland development and carbon stock of Zoige peatlands, Tibetan Plateau: a modeling approach
No full textDespite the many studies about peatland development and carbon dynamics in China, especially for Zoige peatlands on the eastern edge of the Tibetan Plateau, few apply modeling as an effective approach to study peatland development. In order to fill up the knowledge gaps of China alpine peatland development and to provide a comparison with previous research, we studied the Zoige peatlands in Holocene with a modeling approach. Simulated results were obtained by the Holocene peatland model (HPM). Driving data was reconstructed based on paleoclimate studies. Model calibration and performance index validation were done by comparing the model output with literature data about peat age depth. Based on our results, the peat cohort mass mean accumulation rate was 0.45 mm year(-1) (ranging from 0.38 to 0.50 mm year(-1)). The mean C accumulation rate was about 0.026 kg C m(-2) year(-1) (ranging from 0.023 to 0.029 kg C m(-2) year(-1)), with a peak accumulation rate around 7 ka to 6 ka BP during the Holocene. The peat depth was 5.38 m (ranging from 4.6 to 5.99 m). The total peat storage in Zoige was about 1.76 Pg (ranging from 1.58 to 2.29 pg), and the carbon stock was estimated as 0.432 pg C (ranging from 0.348 to 0.479 pg C) in Zoige peatlands during the Holocene. After model calibration and validation, simulated results indicated that peat development and carbon accumulation were controlled by variation of water table depth (WTD). Simulated results indicated that the Zoige peatlands are the most important component of peatlands in China in terms of carbon stock. Though HPM lacks in driving data of temperature and incomplete climate factors, its limitations in the parameter setting should not offset the added value of the modeling approach in improving our understanding of peatland carbon and their controlling factor dynamics at the long-term scales in the Zoige region where there are very few studies so far
Can abandoned peatland pasture sequestrate more carbon dioxide from the atmosphere than an adjacent pristine bog in Newfoundland, Canada?
No full textNet ecosystem exchange of carbon dioxide (NEE) and its components, gross primary productivity (GPP) and ecosystem respiration (ER), were compared between a bog and an abandoned peatland pasture within the same peatland complex in western Newfoundland, Canada. Measurements based on the eddy covariance technique from April 2014 to April 2016 were used to examine the influence of agricultural management and abandonment on peatland carbon dioxide (CO2) exchange. NEE, GPP and ER at both sites showed pronounced seasonal variation, peaking near the middle growing season. The maximum net CO2 uptake rate of -28.61 mu mol m(-2) s(-1) and emission rate of 14.39 mu mol m(-2) s(-1) at the pasture were significantly higher than those at the bog (-9.67 mu mol m(-2) s(-1) and 5.50 mu mol m(-2) s(-1), respectively). Daytime average GPP was related to photosynthetic photon flux density and air temperature and the nighttime average ER decreased with soil water content, but increased with surface soil temperature for both sites. Annual NEE of the pasture (-128 +/- 60 g C m(-2) yr(-1) in 2014-15 and -124 +/- 56 g C m(-2) yr(-1) in 2015-16) was considerably larger than that of the bog (-46 +/- 36 g C m(-2) yr(-1) in 2014-15). GPP of 1086 +/- 141 g C m(-2) yr(-1) in 2014-15 and 982 +/- 123 g C m(-2) yr(-1) in 2015-16 and ER of 957 129 g C m(-2) yr(-1) in 2014-15 and 858 +/- 112 g C m(-2) yr(-1) in 2015-16 at the pasture were approximately twice the magnitude of the corresponding fluxes at the bog. The difference in GPP between the bog and pasture was mainly related to their different aboveground biomass. Higher ER at the pasture was probably related to its lower water table depth, greater substrate availability and higher autotrophic respiration. Unlike previous findings that managed peat lands are large CO2 emitters, our results suggest that abandoned peatland pastures can function like natural grasslands and sequester considerable amounts of CO2 from the atmosphere