Temporal and Spatial Variation of the Skin-Associated Bacteria from Healthy Participants and Atopic Dermatitis Patients

Several factors have been shown to influence the composition of the bacterial communities inhabiting healthy skin, with variation between different individuals, differing skin depths, and body locations (spatial-temporal variation). Atopic dermatitis (AD) is a chronic skin disease also affecting the skin-associated bacterial communities. While the effects of AD have been studied on these processes individually, few have considered how AD disrupts the spatial-temporal variation of the skin bacteria as a whole (i.e., considered these processes simultaneously). Here, we characterized the skin-associated bacterial communities of healthy volunteers and lesional and nonlesional skin of AD patients by metabarcoding the universal V3-V4 16S rRNA region from tape strip skin samples. We quantified the spatial-temporal variation (interindividual variation, differing skin depths, multiple time points) of the skin-associated bacteria within healthy controls and AD patients, including the relative change induced by AD in each. Interindividual variation correlated with the bacterial community far more strongly than any other factors followed by skin depth and then AD status. There was no significant temporal variation found within either AD patients or healthy controls. The bacterial community was found to vary markedly according to AD severity, and between patients without and with filaggrin mutations. Therefore, future studies may benefit from sampling subsurface epidermal communities and considering AD severity and the host genome in understanding the role of the skin bacterial community within AD pathogenesis rather than considering AD as a presence-absence disorder. IMPORTANCE The bacteria associated with human skin may influence skin barrier function and the immune response. Previous studies have attempted to understand the factors that regulate the skin bacteria, characterizing the spatial-temporal variation of the skin bacteria within unaffected skin. Here, we quantified the effect of AD on the skin bacteria on multiple spatial-temporal factors simultaneously. Although significant community variation between healthy controls and AD patients was observed, the effects of AD on the overall bacterial community were relatively low compared to other measured factors. Results here suggest that changes in specific taxa rather than wholesale changes in the skin bacteria are associated with mild to moderate AD. Further studies would benefit from incorporating the complexity of AD into models to better understand the condition, including AD severity and the host genome, alongside microbial composition.

The slowing rate of CpG depletion in SARS-CoV-2 genomes is consistent with adaptations to the human host

Depletion of CpG dinucleotides in SARS-CoV-2 genomes has been linked to virus evolution, host-switching, virus replication, and innate immune responses. Temporal variations, if any, in the rate of CpG depletion during virus evolution in the host remain poorly understood. Here, we analysed the CpG content of over 1.4 million full-length SARS-CoV-2 genomes representing over 170 million documented infections during the first 17 months of the pandemic. Our findings suggest that the extent of CpG depletion in SARS-CoV-2 genomes is modest. Interestingly, the rate of CpG depletion is highest during early evolution in humans and it gradually tapers off almost reaching an equilibrium; this is consistent with adaptations to the human host. Furthermore, within the coding regions, CpG depletion occurs predominantly at codon positions 2-3 and 3-1. Loss of ZAP-binding motifs in SARS-CoV-2 genomes is primarily driven by the loss of the terminal CpG in the motifs. Nonetheless, majority of the CpG depletion in SARS-CoV-2 genomes occurs outside ZAP-binding motifs. SARS-CoV-2 genomes selectively lose CpGs-motifs from a U-rich context; this may help avoid immune recognition by TLR7. SARS-CoV-2 alpha-, beta- and delta-variants of concern have reduced CpG content compared to sequences from the beginning of the pandemic. In sum, we provide evidence that the rate of CpG depletion in virus genomes is not uniform and it greatly varies over time and during adaptations to the host. This work highlights how temporal variations in selection pressures during virus adaption may impact the rate and the extent of CpG depletion in virus genomes.

The influence of seasonality, anthropogenic disturbances, and cyclonic activity on the behavior of northern sportive lemurs (Lepilemur septentrionalis) at Montagne des Français, Madagascar

Anthropogenic tropical deforestation and degradation imminently threaten primates today. Primates living in these disturbed habitats may also be subjected to increasingly severe tropical storms such as cyclones or hurricanes. These disturbances pose an immediate risk to their livelihood and can dramatically alter their habitats, in turn potentially shifting behavioral patterns. We had the unique opportunity to study the effects of seasonality, anthropogenic disturbances, and the immediate effects of a cyclone on the behavior of the critically endangered northern sportive lemur (NSL) in an anthropogenically disturbed forest in Madagascar. Cyclone Enawo made landfall on March 7, 2017 in northeast Madagascar with sustained wind speeds of 230 km/h. We collected behavioral data on nine individual NSLs during both wet and dry seasons, before and after Cyclone Enawo, and in areas of differing human activity, using scan sampling at 5-min intervals. We ran generalized linear mixed models to test the effects of seasonality and disturbances on behavior. We found that NSLs spent more time feeding in dry months compared with wet (Z = -4.21, p < 0.001). More specifically, they spent more time-consuming leaves and vine species in the dry season (Z = -2.26, p = 0.02; Z = -2.3; p = 0.02). We also found that NSLs were observed at lower heights in trees after the cyclone (Z = -2.45; p = 0.016) and spent more time in the interior portions of trees (Z = 3.44; p < 0.001), perhaps due to extensive limb damage of emergent trees documented after the cyclone. Our analyses show that seasonality affected most aspects of NSL behavior, followed by the effects of Cyclone Enawo, with anthropogenic disturbances having little effect. Our data suggest that the behavioral flexibility of NSLs in response to predictable seasonality may enable them to respond similarly to stochastic climatic disturbances. However, their generalist diet may allow them to persist in anthropogenically disturbed landscapes without the need to greatly alter their behavior.

[Pollution Characteristics and Source Analysis of Atmospheric VOCs in the Coastal Background of the Pearl River Delta]

As an important precursor of ozone, volatile organic compounds (VOCs) have attracted much attention. This study analyzed the temporal variation and composition of atmospheric VOCs in the coastal background of the Pearl River Delta, using real-time online monitoring data of VOCs obtained at the Yangmeikeng Ecological Environment Monitoring Station from August 2019 to July 2020. The major sources of VOCs were identified using a receptor model based on the PMF (positive matrix factorization) and HYSPLIT (hybrid single particle Lagrangian integrated trajectory) models. The results showed that the annual mean concentration of anthropogenic VOCs in the coastal background area of the Pearl River Delta was 9.30×10^-9(volume fraction). There was obvious seasonal variation of VOCs in this area, with higher values in autumn and winter and lower values in summer. The coastal background area of the Pearl River Delta exhibited a different diurnal variation pattern to that of cities and other backgrounds. While the peak of VOCs concentration mainly occurred in the morning, from 10:00 to 11:00, concentration remained at a low level during the early morning and after 15:00. Ethylene, propylene, toluene, isopentane, isoprene, m/p-xylene, n-butane, and acetylene were the key species that affected the chemical composition of VOCs. The air masses affecting the coastal background area of the Pearl River Delta were mainly short-distance air masses from elsewhere in the province (25%), ocean air masses (27%), coastal air masses (31%), and inland air masses outside the province (17%). Among them, the average concentration of VOCs was lowest under the influence of ocean air masses, which is mainly affected by the mixed source of ship emissions and aging VOCs, gasoline volatilization, and vehicle emissions. In comparison, the concentration level of VOCs increased by 70.1% to 148.8% under the influence of other air masses. The transmission effects of industrial sources, LNG and LPG volatiles, and petrochemical sources were more prominent. Generally, the atmosphere of coastal background areas was severely affected by anthropogenic pollution, especially by air pollution masses transported from the land, while the impact of pollution by ships near shore and tourist traffic cannot be ignored.

The Impacts of Temporal Variation and Individual Differences in Driver Cognitive Workload on ECG-Based Detection

OBJECTIVE

This paper aimed to investigate the robustness of driver cognitive workload detection based on electrocardiogram (ECG) when considering temporal variation and individual differences in cognitive workload.

BACKGROUND

Cognitive workload is a critical component to be monitored for error prevention in human-machine systems. It may fluctuate instantaneously over time even in the same tasks and differ across individuals.

METHOD

A driving simulation study was conducted to classify driver cognitive workload underlying four experimental conditions (baseline, N-back, texting, and N-back + texting distraction) in two repeated 1-hr blocks. Heart rate (HR) and heart rate variability (HRV) were compared among the experimental conditions and between the blocks. Random forests were built on HR and HRV to classify cognitive workload in different blocks and for different individuals.

RESULTS

HR and HRV were significantly different between repeated blocks in the study, demonstrating the time-induced variation in cognitive workload. The performance of cognitive workload classification across blocks and across individuals was significantly improved after normalizing HR and HRV in each block by the corresponding baseline.

CONCLUSION

The temporal variation and individual differences in cognitive workload affects ECG-based cognitive workload detection. But normalization approaches relying on the choice of appropriate baselines help compensate for the effects of temporal variation and individual differences.

APPLICATION

The findings provide insight into the value and limitations of ECG-based driver cognitive workload monitoring during prolonged driving for individual drivers.

Temporal variations in air pollution at two roundabouts in the city of Cotonou (Benin)

BACKGROUND

Air pollution has caused health and environmental problems around the world. In this study we analysed the temporal evolution of air pollution in Cotonou regarding the standards of Benin and of World Health Organization (WHO).

DESIGN AND METHODS

Solar-powered electrochemical sensors (CO: carbon monoxide, SO2: sulphur dioxide, and O3/NO2: ozone/nitrogen dioxide) and photoionization detectors (for NMVOC: nonmethane volatile organic compounds) were permanently installed and monitored from June 2019 to March 2020 at Akpakpa PK3 (A) and Vèdokô Cica-Toyota (B) roundabouts.

RESULTS

CO and SO2 concentrations at both roundabouts were significantly higher on weekends than on weekdays. The concentrations of NMVOC and O3 / NO2 on Sunday differed considerably from the other days of the week at A and B, respectively. There was a positive linear correlation between the concentrations of CO and SO2, O3 / NO2 and SO2, and CO O3 / NO2 to B, and only between CO and O3 / NO2, in A. At the two sites, the average of SO2 concentrations (in μg/m3) were higher than the WHO standard (500) for an exposure of 10 minutes (2258 A and 2143 B) and the Benin standard (1300) for 1 hour exposure (2181 in A and 2092 in B).

CONCLUSION

Air pollution varies in hours and days in Cotonou. Standards are respected, except for SO2. Particular attention should be paid to the concentrations and the possible sources of gas. More sophisticated monitoring system should be put in place.

The Bacterial Community Diversity of Bathroom Hot Tap Water Was Significantly Lower Than That of Cold Tap and Shower Water

Microbial drinking water quality in premise plumbing systems (PPSs) strongly affects public health. Bacterial community structure is the essential aspect of microbial water quality. Studies have elucidated the microbial community structure in cold tap water, while the microbial community structures in hot tap and shower water are poorly understood. We sampled cold tap, hot tap, and shower water from a simulated PPS monthly for 16 consecutive months and assessed the bacterial community structures in those samples via high-throughput sequencing of bacterial 16S rRNA genes. The total relative abundance of the top five most abundant phyla (Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Firmicutes) was greater than 90% among the 24 identified phyla. The most abundant families were Burkholderiaceae, Sphingomonadaceae, unclassified Alphaproteobacteria, unclassified Corynebacteriales, and Mycobacteriaceae. A multiple linear regression suggests that the bacterial community diversity increased with water temperature and the age of the simulated PPS, decreased with total chlorine residual concentration, and had a limited seasonal variation. The bacterial community in hot tap water had significantly lower Shannon and Inverse Simpson diversity indices (p < 0.05) and thus a much lower diversity than those in cold tap and shower water. The paradoxical results (i.e., diversity increased with water temperature, but hot tap water bacterial community was less diverse) were presumably because (1) other environmental factors made hot tap water bacterial community less diverse, (2) the diversity of bacterial communities in all types of water samples increased with water temperature, and (3) the first draw samples of hot tap water could have a comparable or even lower temperature than shower water samples and the second draw samples of cold tap water. In both a three-dimensional Non-metric multidimensional scaling ordination plot and a phylogenetic dendrogram, the samples of cold tap and shower water cluster and are separate from hot tap water samples (p < 0.05). In summary, the bacterial community in hot tap water in the simulated PPS had a distinct structure from and a much lower diversity than those in cold tap and shower water.

Respiratory viral infections in hospitalised paediatric patients in the tropics

AIM

Respiratory viruses are a huge disease burden globally. An understanding of the seasonal trends and the ability to predict peak periods of respiratory virus disease incidence is useful for clinical care.

METHODS

This is a retrospective analysis of paediatric hospitalizations of laboratory-confirmed viral respiratory tract infections in KK Women's and Children's Hospital, Singapore, from 1 January 2011 to 31 December 2016. Standard direct immunofluorescence was used to detect respiratory syncytial virus (RSV), influenza A and B viruses, parainfluenza 1, 2 and 3 viruses, metapneumovirus and adenovirus.

RESULTS

A total of 97 840 specimens were analysed with a positive detection rate of 23.8%. RSV made up the largest proportion (42% of the total positive results), predominating between May to September. Influenza A had two peaks, June to July and December to January. Type 3 was the most common parainfluenza virus and showed annually recurring peaks. In contrast, parainfluenza 1 and 2, metapneumovirus and adenovirus had a biennial pattern. The test of seasonality detected identifiable seasonality for RSV and parainfluenza 3 virus.

CONCLUSIONS

In conclusion, respiratory viruses have different and overlapping seasonality in tropical Singapore. Respiratory virus testing for patients admitted for acute respiratory infection is useful to target antiviral therapies and appropriate infection control practices.

[Light-absorbing Properties and Sources of PM2.5 Organic Components at a Suburban Site in Northern Nanjing]

The light absorption of organic components in PM_2.5 was investigated at a suburban site in northern Nanjing from September 2018 to September 2019, and PM_2.5 compositional data and principal component analysis (PCA) were used to identify the sources of light-absorbing organic carbon (brown carbon, BrC). The results showed that the average light absorption coefficients of water-soluble organic carbon (WSOC) and methanol extractable organic carbon (MEOC) were (3.22±2.18) Mm^-1 (Abs_365,w) and (7.69±4.93) Mm^-1(Abs_365,m), respectively. Significant correlations were observed between Abs_365,w and mass concentrations of WSOC (r=0.72, P<0.01) and between Abs_365,m and mass concentrations of MEOC (r=0.62, P=0.04). Both Abs_365,w and Abs_365,m exhibited seasonal variations, with higher values during winter than during summer,and higher diel variations at night than during the day. This can be attributed to meteorological characteristics during the winter and nighttime, i.e., decreased boundary layer height and increased atmospheric stability, enhanced primary emissions in winter,and stronger photobleaching effects during the summer and during the day. The annual average Abs_365,m/Abs_365,w ratio (2.60±0.92) was much larger than the average mass ratio of MEOC/WSOC (1.37±0.30), indicating that the water-insoluble fraction of MEOC had a stronger light absorption effect and dominated BrC absorption. No strong correlation (r<0.60) was observed between WSOC, MEOC, Abs_365,m, and mass concentrations of K⁺, indication that biomass burning was not the main source of BrC in the study location. The mass absorption efficiency of WSOC (MAE_365,w) and MEOC (MAE_365,m) and their ratios (MAE_365,m/MAE_365,w) showed similar seasonal variations to Abs₃₆₅. The average MAE₃₆₅ value of the water-insoluble fraction of MEOC (4.10±5.15) m²·g^-1 was 6.0 and 2.9 times higher than that of MAE_365,w and MAE_365,m, respectively, suggested that BrC absorption was primarily attributable to water-insoluble components. In comparison to the absorption Ångström exponent of WSOC (Å_WSOC), Å_MEOC displayed marked temporal variability, which might be related to the seasonal variation in the emission of water-insoluble chromophores. According to the PCA results, the light absorption of PM_2.5 organic was mainly attributed to secondary formation and anthropogenic primary emissions rather than biomass burning.

Neonicotinoid Seed Treatments Have Significant Non-target Effects on Phyllosphere and Soil Bacterial Communities

The phyllosphere and soil are dynamic habitats for microbial communities. Non-pathogenic microbiota, including leaf and soil beneficial bacteria, plays a crucial role in plant growth and health, as well as in soil fertility and organic matter production. In sustainable agriculture, it is important to understand the composition of these bacterial communities, their changes in response to disturbances, and their resilience to agricultural practices. Widespread pesticide application may have had non-target impacts on these beneficial microorganisms. Neonicotinoids are a family of systemic insecticides being vastly used to control soil and foliar pests in recent decades. A few studies have demonstrated the long-term and non-target effects of neonicotinoids on agroecosystem microbiota, but the generality of these findings remains unclear. In this study, we used 16S rRNA gene amplicon sequencing to characterize the effects of neonicotinoid seed treatment on soil and phyllosphere bacterial community diversity, composition and temporal dynamics in a 3-year soybean/corn rotation in Quebec, Canada. We found that habitat, host species and time are stronger drivers of variation in bacterial composition than neonicotinoid application. They, respectively, explained 37.3, 3.2, and 2.9% of the community variation. However, neonicotinoids did have an impact on bacterial community structure, especially on the taxonomic composition of soil communities (2.6%) and over time (2.4%). They also caused a decrease in soil alpha diversity in the middle of the growing season. While the neonicotinoid treatment favored some bacterial genera known as neonicotinoid biodegraders, there was a decline in the relative abundance of some potentially beneficial soil bacteria in response to the pesticide application. Some of these bacteria, such as the plant growth-promoting rhizobacteria and the bacteria involved in the nitrogen cycle, are vital for plant growth and improve soil fertility. Overall, our results indicate that neonicotinoids have non-target effects on phyllosphere and soil bacterial communities in a soybean-corn agroecosystem. Exploring the interactions among bacteria and other organisms, as well as the bacterial functional responses to the pesticide treatment, may enhance our understanding of these non-target effects and help us adapt agricultural practices to control these impacts.

Impact of land use on shallow groundwater quality characteristics associated with human health risks in a typical agricultural area in Central China

Groundwater pollution seriously threatens water resource safety due to high-intensity land use throughout the world. However, the relationship between groundwater pollution characteristics and land use in alluvial plains is still unclear. In this study, the effects of land use on shallow groundwater quality and human health risk were investigated via two sampling campaigns in a typical alluvial plain, namely, Jianghan Plain, China. Results show that the shallow groundwater in this area was polluted by nitrogen (with average concentrations of 5.12 mg/L in the dry season and 4.46 mg/L in the rainy season) and phosphorus (0.29 and 0.13 mg/L in the two seasons, respectively). The nutrient concentrations during the dry season were significantly higher than those during the rainy season (p < 0.05). Correlation analysis indicated that the concentration of nutrients was significantly positively correlated with cultivated land and negatively correlated with water and residence, suggesting that land use patterns can affect the groundwater quality. The best buffer where land use patterns affect the total N concentration was about 1000 m for cultivated land and water, while the optimal ranges for ammonium N were about 1000 and 2500 m for the areas, respectively. For the total phosphorus, a radius of 2000 m leads to the best fitting effect on both areas. Human health risk assessment showed that the total health risk indexes in about 75% of the samples were higher than 1, indicating the potential risk of the shallow groundwater in this area to human health. The results indicate that land use patterns will greatly affect the shallow groundwater quality. Thus, adjusting the land use pattern can improve the water quality and reduce health risks. Identification and selection of appropriate management solutions for the groundwater protection should be based on not only water quality problems but also surface land use patterns.

Using ecological context to interpret spatiotemporal variation in natural selection

Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator-mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator-mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path-analytical approach, we assessed several functional components of selection, and linked variation in pollinator-mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross-pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross-pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.

Temporal variation in soil bacterial communities can be confounded with spatial variation

Investigating temporal variation in soil bacterial communities advances our fundamental understanding of the causal processes driving biological variation, and how the composition of these important ecosystem members may change into the future. Despite this, temporal variation in soil bacteria remains understudied, and the effects of spatial heterogeneity in bacterial communities on the detection of temporal changes is largely unknown. Using 16S rRNA gene amplicon sequencing, we evaluated temporal patterns in soil bacterial communities from indigenous forest and human-impacted sites sampled repeatedly over a 5-year period. Temporal variation appeared to be greater when fewer spatial samples per site were analysed, as well as in human-impacted compared to indigenous sites (P < 0.01 for both). The biggest portion of variation in bacterial community richness and composition was explained by soil physicochemical variables (13-24%) rather than spatial distance or sampling time (<1%). These results highlight the importance of adequate spatiotemporal replication when sampling soil communities for environmental monitoring, and the importance of conducting temporal research across a wide variety of land uses. This will ensure we have a true understanding of how bacterial communities change over space and time; the work presented here provides important considerations for how such research should be designed.

Anuran accents: Continental-scale citizen science data reveal spatial and temporal patterns of call variability

Many animals rely on vocal communication for mating advertisement, territorial displays, and warning calls. Advertisement calls are species-specific, serve as a premating isolation mechanism, and reinforce species boundaries. Nevertheless, there is a great deal of interspecific variability of advertisement calls. Quantifying the variability of calls among individuals within a species and across species is critical to understand call evolution and species boundaries, and may build a foundation for further research in animal communication. However, collecting a large volume of advertisement call recordings across a large geographic area has traditionally posed a logistical barrier. We used data from the continental-scale citizen science project FrogID to investigate the spatial and temporal patterns of call characteristics in six Australian frog species. We found intraspecific call variability in both call duration and peak frequency across species. Using resampling methods, we show that variability in call duration and peak frequency was related to the number of individuals recorded, the geographic area encompassed by those individuals, and the intra-annual time difference between those recordings. We conclude that in order to accurately understand frog advertisement call variation, or "anuran accents," the number of individuals in a sample must be numerous (N ≥ 20), encompass a large geographic area relative to a species' range, and be collected throughout a species' calling season.

Spatial and Temporal Variability in Trihalomethane Concentrations in the Bromine-Rich Public Waters of Perth, Australia

High concentrations of trihalomethanes (THMs) in public water supplies potentially pose a health hazard, but exposure assessment remains a complex task. To interpret research findings and monitoring data for THMs, it is important to evaluate spatial and temporal variations in both total THM and the individual constituent compounds (including brominated species). We therefore aimed to determine the concentrations, and spatial and temporal variability of concentrations, of THMs public water supplies in Perth, Western Australia, which is known historically to have high brominated THM concentrations. We analysed water samples from 21 water distribution zones around Perth (including Busselton and Bunbury) across different seasons over a period of two years. A total of 250 samples provided a median total THM of 72 µg/L (range of 0-157 µg/L), which falls well within Australia's National Health and Medical Research Council guidelines. The concentration of all species, including brominated forms, also fell the World Health Organization's guidelines. Total THM concentrations were typically higher in spring and summer. A high degree of spatial variability was detected and appears to relate to the source water. Both the temporal and spatial variability in THM concentrations have implications for epidemiological studies, and monitoring.

Temporal dynamics of sexual dimorphism in a dioecious species

BACKGROUND AND AIMS

Sexual dimorphism for floral traits is common in dioecious plant species. Beyond its significance for understanding how selection acts on plant traits through male vs. female reproductive function, sexual dimorphism has also been proposed as a possible risky characteristic for insect-pollinated plants, as it could drive pollinators to forage mostly on male plants. However, even though most flowering plant species spread their flowering across several weeks or months, the temporal variation of floral phenotypes and sexual dimorphism have rarely been investigated.

METHODS

We performed a survey of male and female plants from the dioecious generalist-pollinated Silene dioica (Caryophyllaceae) in a common garden experiment, over two consecutive flowering seasons. Flower number and floral size were measured each week, as well as pollen quantity and viability in male plants.

KEY RESULTS

Sexual dimorphism was found for all investigated floral traits, with males showing an overall higher investment in flower production and flower size. Males and females showed a similar temporal decline in flower size. The temporal dynamics of daily flower number differed between sexes, with males showing a peak in the middle of their flowering season, whereas flower production by females was quite stable over time. At the scale of the experimental population, both individual and floral sex ratios appeared to vary across the flowering season. Moreover, because the onset of flowering varied among plants, the magnitude of sexual dimorphism in floral size also fluctuated strongly through time.

CONCLUSIONS

Capturing male/female differences with only one temporal measurement per population may not be informative. This opens stimulating questions about how pollinator behaviour and resulting pollination efficiency may vary across the flowering season.

Global trends in the incidence and mortality of esophageal cancer from 1990 to 2017

BACKGROUND

The incidence and mortality of esophageal cancer are high, with 5.90 new cases and 5.48 deaths per 100 000 people worldwide in 2017. The prognosis of esophageal cancer is poor, with an overall 5-year survival rate of less than 20%. Esophageal cancer in different geographical locations has different etiologies, and the incidence and mortality of esophageal cancer continue to rise in some regions.

METHODS

We collected incidence and mortality data by age and gender for 195 countries and territories from 1990 to 2017 in the Global Burden of Disease (GBD) database. And we used these data to calculate the estimated annual percentage change (EAPC) to quantify trends in morbidity and mortality. Then we analyzed the gender- and age-specific incidence and mortality in esophageal cancer to targeted high-risk populations. Finally, we analyzed the correlation between the age-standardized mortality rate (ASMR) and both the EAPC and social-demographic index (SDI), and we calculated the Pearson correlation coefficient.

RESULTS

We found that Malawi, East Asia, and high-middle SDI regions had the highest age-standardized incidence rate (ASIR) and ASMR, and the ASIR and ASMR in western Sub-Saharan Africa showed an upward trend. Our study also showed that the incidence and mortality in esophageal cancer were highest in men and in the 70+ years age group, and they presented a decreasing trend in most regions, but the 15-49 years age groups in Australasia, Caribbean, and Oceania and the 70+ years age group in High-Income North America, Oceania and high-SDI regions presented an increasing trend. There were significant negative associations between ASMR at baseline and EAPC and between ASMR and SDI in 2017.

CONCLUSION

By analyzing the global distribution of incidence and mortality in esophageal cancer, trends over time, and gender and age specificity, we can understand the heterogeneity of its global trends. This heterogeneity can help us to identify high-risk groupsand to provide clues for the exploration of the etiology and early prevention of the disease.

[Characteristics of VOCs and Their Roles in Ozone Formation at a Regional Background Site in Beijing, China]

As important precursors of near-surface ozone, secondary organic aerosols (SOAs), and volatile organic compounds (VOCs) play an important role in photochemical reactions and fine particle formation. In this study, real-time VOCs were measured continuously by Syntech Spectras GC955 analyzers at the regional background site of the North China Plain from September 1 to 27, 2017. The VOC concentration levels, compositions, spatiotemporal variations, and the ozone formation potential during the observation period were investigated. The potential sources of initial VOCs indicated from the diagnostic ratios were further studied. The averaged total mixing ratio of VOCs was 12.53×10^-9. Among all measured VOC species, alkanes were the most abundant species, which accounted for 65.3% of the total concentrations, followed by alkenes (26.7%) and aromatics (6.5%). In addition, the total OH radical loss rate of VOCs (L^·OH) was 5.2 s^-1. In particular, the contribution of C4-C5 alkenes to L^·OH was as high as 61%, followed by C2-C3 alkenes, with a 12.8% contribution of L^·OH. The average ozone formation potential of VOCs was 36.5×10^-9. Among all the measured VOC species, alkenes were the most abundant species, which accounted for 71.2%. Among alkenes, the contribution of C4-C5 alkenes was the most prominent. Although the concentration of alkanes in Shangdianzi was much higher than other VOC species, the ozone formation potential was lower. Diagnostic ratios and source implications suggested that Shangdianzi was affected mainly by biomass/biofuel/coal burning, with substantially elevated benzene levels during the observation period, whereas a slight influence of traffic-related emissions was observed.

Tree diversity effects through a temporal lens: Implications for the abundance, diversity and stability of foraging birds

Tree diversity exerts a strong influence on consumer communities, but most work has involved single time point measurements over short time periods. Describing temporal variation associated with diversity effects over longer time periods is necessary to fully understand the effects of tree diversity on ecological function. We conducted a year-long study in an experimental system in southern Mexico assessing the effects of tree diversity on the abundance and diversity of foraging birds. To this end, we recorded bird visitation patterns in 32 tree plots (21 × 21 m; 12 tree species monocultures, 20 four-species polycultures) every 45 days (n = 8 surveys) and for each plot estimated bird abundance, richness, functional diversity (FD) and phylogenetic diversity (PD). In each case, we reported temporal (intra-annual) variation in the magnitude of tree diversity effects, and calculated the temporal stability of these bird responses. Across surveys, tree diversity noticeably affected bird responses, demonstrated by significantly higher abundance (43%), richness (32%), PD (25%) and FD (25%) of birds visiting polyculture plots compared to monoculture plots, as well as a distinct species composition between plot types. We also found intra-annual variation in tree diversity effects on these response variables, ranging from surveys for which the diversity effect was not significant to surveys where a significant 80% increase (e.g. for bird FD and PD) was observed in polyculture relative to monoculture plots. Notably, tree diversity increased the stability of all bird responses, with polycultures having a greater stability abundance (18%), richness (38%), PD (32%), and FD (35%) of birds visiting tree species polycultures compared to monocultures. These results show that tree diversity not only increases bird visitation to plots, but also stabilizes bird habitat usage over time in ways that could implicate insurance-related mechanisms. Such findings are highly relevant for understanding the long-term effects of plant diversity on vertebrates and the persistence of bird-related ecosystem functions. More work is needed to unveil the ecological mechanisms behind temporal variation in vertebrate responses to tree diversity and their consequences for community structure and function.

Long-term trends in fruit production in a tropical forest at Ngogo, Kibale National Park, Uganda

Fruit production in tropical forests varies considerably in space and time, with important implications for frugivorous consumers. Characterizing temporal variation in forest productivity is thus critical for understanding adaptations of tropical forest frugivores, yet long-term phenology data from the tropics, in particular from African forests, are still scarce. Similarly, as the abiotic factors driving phenology in the tropics are predicted to change with a warming climate, studies documenting the relationship between climatic variables and fruit production are increasingly important. Here we present data from 19 years of monitoring the phenology of 20 tree species at Ngogo in Kibale National Park, Uganda. Our aims were to characterize short- and long-term trends in productivity and to understand the abiotic factors driving temporal variability in fruit production. Short-term (month-to-month) variability in fruiting was relatively low at Ngogo, and overall fruit production increased significantly through the first half of the study. Among the abiotic variables we expected to influence phenology patterns (including rainfall, solar irradiance, and average temperature), only average temperature was a significant predictor of monthly fruit production. We discuss these findings as they relate to the resource base of the frugivorous vertebrate community inhabiting Ngogo.

Spatial and temporal variation in prey color patterns for background matching across a continuous heterogeneous environment

In heterogeneous habitats, camouflage via background matching can be challenging because visual characteristics can vary dramatically across small spatial scales. Additionally, temporal variation in signaling functions of coloration can affect crypsis, especially when animals use coloration seasonally for intraspecific signaling (e.g., mate selection). We currently have a poor understanding of how wild prey optimize background matching within continuously heterogeneous habitats, and whether this is affected by requirements of intraspecific signaling across biological seasons. Here, we quantified color patterns of a wild population of shore skink (Oligosoma smithi), a variably colored lizard endemic to New Zealand, to (a) investigate whether background matching varies across a vegetation gradient; (b) assess potential signaling functions of color; and (c) to determine whether there is a trade-off between requirements for crypsis and intraspecific signaling in coloration across seasons. Although all pattern types occurred throughout the vegetation gradient, we found evidence for background matching in skinks across the vegetation gradient, where dorsal brightness and pattern complexity corresponded with the proportion of vegetation cover. There was also a significant disparity between ventral color (saturation) of juveniles and adults, and also between sexes, suggestive of sex recognition. However, there was little indication that color was condition-dependent in adults. Despite some evidence for a potential role in signaling, crypsis did not greatly differ across seasons. Our study suggests that selection favors a mix of generalist and specialist background matching strategies across continuously heterogeneous habitats.

Temporal variation in effect sizes in a long-term, split-plot field experiment

Ecological field experiments initiate successional and evolutionary changes among resident species, yet effect sizes are often reported as if they were constants. Few ecological studies have addressed their questions through long-term, experimental approaches, and many questions remain unanswered regarding temporal patterns in ecological effect sizes. We document temporal variation in effect sizes in response to pulse and press manipulations in a long-term factorial field experiment at Nash's Field, England. The experiment comprises seven treatments applied in a split-plot design to test the single and interactive effects of herbivory by insects, molluscs, and rabbits, liming, nutrient limitation (applied as press experiments), competition (exclusion of grasses or herbs with specific herbicides), and seed limitation (pulse experiments) on plant community dynamics. The response of all vascular plant species was followed for two decades. High species richness was positively related to the minus-grass herbicide in the first decade and negatively related to both nitrogen addition and the abundance of dominant species in both decades. Many significant effects appeared quickly, but some large effects were not detected until year 15. Press experiments produced some long-lasting effects, but effect sizes changed due to both idiosyncratic "year effects" and secular trends. For pulse experiments, most effects, including positive and negative responses to herbicide application and the invasion of most of the sown species, disappeared quickly. However, some endured or grew monotonically, such as the invasion of two sown species that benefited from particular combinations of the press treatments. The fastest effects to appear were the responses from established species. Many of these responses were negative, likely resulting from reduced niche dimensionality and competitive exclusion by new dominant species. Contrarily, one of the largest community-level effects took well over a decade to appear: the natural invasion by one species, which responded to a four-way interaction between experimental treatments. The insights gained from individual effects increased with the duration of the lag before their first appearance, drawing attention to the importance of long-term, manipulative field experiments. This experiment also reinforces the point that factorial experiments are the most insightful way to explore ecological interactions.

Spatio-temporal Variation of Groundwater Quality and Source Apportionment using Multivariate Statistical Techniques for the Hutuo River Alluvial-Pluvial Fan, China

Groundwater quality deterioration has become an environmental problem of widespread concern. In this study, we used a water quality index (WQI) and multivariate statistical techniques to assess groundwater quality and to trace pollution sources in the Hutuo River alluvial-pluvial fan, China. Measurement data of 17 variables in 27 monitoring sites from three field surveys were obtained and pretreated. Results showed that there were 53.09% of NO₃⁻, 18.52% of SO₄²⁻ and 83.95% of total hardness (TH) in samples that exceeded the Grade III standard for groundwater quality in China (GB/T 14848-2017). Based on WQI results, sampling sites were divided into three types: high-polluted sites, medium-polluted sites and low-polluted sites. The spatial variation in groundwater quality revealed that concentrations of total dissolved solids (TDS), Cl⁻, TH and NO₃⁻ were the highest in high-polluted sites, followed by medium-polluted and low-polluted sites. The temporal variation in groundwater quality was controlled by the dilution of rainwater. A principal component analysis (PCA) revealed that the primary pollution sources of groundwater were domestic sewage, industrial sewage and water–rock interactions in the dry season. However, in the rainy and transition seasons, the main pollution sources shifted to domestic sewage and water–rock interactions, nonpoint pollution and industrial sewage. According to the absolute principal component scores-multivariate linear regression (APCS-MLR), most water quality parameters were primarily influenced by domestic sewage. Therefore, in order to prevent the continuous deterioration of groundwater quality, the discharge of domestic sewage in the Hutuo River alluvial-pluvial fan region should be controlled.

Temporal Variation of the Presence of Rhodnius prolixus (Hemiptera: Reduviidae) Into Rural Dwellings in the Department of Casanare, Eastern Colombia

Rhodnius prolixus (Stål, 1859) is the major vector of Trypanosoma cruzi in Colombia and Venezuela. The species is strongly associated with high-altitude ecotopes, such as sylvatic palms (Attalea butyracea), where spatially and temporally stable infestations are established. We investigated temporal variation in regards to the presence of R. prolixus in rural dwellings in the department of Casanare (eastern Colombia) over a period of 12 mo. Thirty houses were sampled from January to December 2017 by installing Maria sensors, collecting triatomines through community entomological surveillance, and conducting a monthly search in each house. The collection of specimens from the houses varied significantly by month with the higher number of collections occurring in the low-rainfall season and the lower number of collections occurring in the months of increased precipitation. The proportions of males, females, and nymphs also varied significantly throughout the time period: nymphs (fifth instar only) were reported only during May, July, and September and significantly greater numbers of females than males were reported in the inspected dwellings in all months. Density, crowding, and colonization indices varied according to the season. A bloodmeal analysis revealed 17 different hosts. A total of 42 randomly selected R. prolixus specimens were subjected to molecular analyses for detection of T. cruzi DNA with 22 found positive (infection prevalence of 52%). In conclusion, we observed a high presence of R. prolixus (infected with T. cruzi) in dwellings close to native palm plantations. These findings indicate a high risk of vector transmission of T. cruzi for people in the study areas and challenges for the current vector control schemes in the region.

Eleven years' data of grassland management in Germany

Background

The 150 grassland plots were located in three study regions in Germany, 50 in each region. The dataset describes the yearly grassland management for each grassland plot using 116 variables.

General information includes plot identifier, study region and survey year. Additionally, grassland plot characteristics describe the presence and starting year of drainage and whether arable farming had taken place 25 years before our assessment, i.e. between 1981 and 2006. In each year, the size of the management unit is given which, in some cases, changed slightly across years.

Mowing, grazing and fertilisation were systematically surveyed:

Mowing is characterised by mowing frequency (i.e. number of cuts per year), dates of cutting and different technical variables, such as type of machine used or usage of conditioner.

For grazing, the livestock species and age (e.g. cattle, horse, sheep), the number of animals, stocking density per hectare and total duration of grazing were recorded. As a derived variable, the mean grazing intensity was then calculated by multiplying the livestock units with the duration of grazing per hectare [LSU days/ha]. Different grazing periods during a year, partly involving different herds, were summed up to an annual grazing intensity for each grassland.

For fertilisation, information on the type and amount of different types of fertilisers was recorded separately for mineral and organic fertilisers, such as solid farmland manure, slurry and mash from a bioethanol factory. Our fertilisation measures neglect dung dropped by livestock during grazing. For each type of fertiliser, we calculated its total nitrogen content, derived from chemical analyses by the producer or agricultural guidelines (Table 3).

All three management types, mowing, fertilisation and grazing, were used to calculate a combined land use intensity index (LUI) which is frequently used to define a measure for the land use intensity. Here, fertilisation is expressed as total nitrogen per hectare [kg N/ha], but does not consider potassium and phosphorus.

Information on additional management practices in grasslands was also recorded including levelling, to tear-up matted grass covers, rolling, to remove surface irregularities, seed addition, to close gaps in the sward.

New information

Investigating the relationship between human land use and biodiversity is important to understand if and how humans affect it through the way they manage the land and to develop sustainable land use strategies. Quantifying land use (the ‘X’ in such graphs) can be difficult as humans manage land using a multitude of actions, all of which may affect biodiversity, yet most studies use rather simple measures of land use, for example, by creating land use categories such as conventional vs. organic agriculture. Here, we provide detailed data on grassland management to allow for detailed analyses and the development of land use theory. The raw data have already been used for > 100 papers on the effect of management on biodiversity (e.g. Manning et al. 2015).