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Ecology and Evolution Jun 2024Within carnivore guilds, dominant competitors (e.g., lions, ) are limited primarily by the density of prey, while subordinate competitors (e.g., African wild dogs, )...
Within carnivore guilds, dominant competitors (e.g., lions, ) are limited primarily by the density of prey, while subordinate competitors (e.g., African wild dogs, ) have been limited by the density of dominant competitors. Historically, the fitness and population density of subordinate competitors have not been tightly linked to prey density. However, populations of large herbivores have declined substantially across sub-Saharan Africa due to human impacts, and where prey depletion is severe, fitness costs for competitive subordinates may begin to outweigh the benefits of competitive release. Using long-term intensive monitoring of African wild dogs in Zambia's Luangwa Valley Ecosystem (LVE), we tested the effects of prey depletion on survival and reproduction. We hypothesized that African wild dog fitness would be lower in prey-depleted areas, despite lower lion densities. Our study area included four contiguous regions that varied in protection level, prey density, and lion density. We fit Bayesian Cormack-Jolly-Seber and closed-capture models to estimate effects on survival and population density, and generalized linear models to estimate effects on reproductive success. We found that the LVE is a stronghold for African wild dogs, with an estimated median density of 4.0 individuals/100 km. Despite this high density, survival and reproduction differed among regions, and both components of fitness were substantially reduced in the region with the lowest prey density. Anthropogenic prey depletion is becoming an important limiting factor for African wild dogs. If prey depletion (or any other form of habitat degradation) becomes severe enough that its fitness costs outweigh the benefits of competitive release, such changes can fundamentally alter the balance between limiting factors for competitively subordinate species.
PubMed: 38932965
DOI: 10.1002/ece3.11402 -
Ecology and Evolution Jun 2024is one of the most notorious invasive aquatic snail, capable of influencing various aquatic organisms through their secretions. and are the most prevalent and...
is one of the most notorious invasive aquatic snail, capable of influencing various aquatic organisms through their secretions. and are the most prevalent and powerful bioturbators in aquatic ecosystems. However, the mechanism of 's secretions affecting bioturbators remains unknown. This study aimed to investigate the effects of 's secretion on and . and were treated for 24 h with and the native species secretions at different densities (1 or 20). The migration numbers and aggregation rate of indicated that secretion caused to become alert and migrate away from the nucleus community, resulting in poor population identification, especially at high concentrations. Moreover, the antioxidant enzymatic activity, lipid peroxidation, intestinal microbial diversity, and composition of the two bioturbators were analyzed. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration were elevated following secretion treatment, indicating oxidative damage. Furthermore, the composition and diversity of intestinal microbiota of and were changed. The abundance of functional microbiota decreased, and pathogenic bacteria such as became dominant in the intestines of both bioturbators. The current research evaluates the effects of secretion on the behavior, oxidative stress, and intestinal microbial composition and diversity of two bioturbators, providing new insights into the assessment of post-invaded ecosystems.
PubMed: 38932957
DOI: 10.1002/ece3.11591 -
Ecology and Evolution Jun 2024Maintenance metabolism as the minimum energy expenditure needed to maintain homeothermy (a high and stable body temperature, ), reflects the magnitude of metabolic...
Maintenance metabolism as the minimum energy expenditure needed to maintain homeothermy (a high and stable body temperature, ), reflects the magnitude of metabolic machinery and the associated costs of self-maintenance in endotherms (organisms able to produce heat endogenously). Therefore, it can interact with most, if not all, organismal functions, including the behavior-fitness linkage. Many endothermic animals can avoid the costs of maintaining homeothermy and temporally reduce and metabolism by entering heterothermic states like torpor, the most effective energy-saving strategy. Variations in BMR, behavior, and torpor use are considered to be shaped by food resources, but those conclusions are based on research studying these traits in isolation. We tested the effect of ecological contexts (food availability and predation risk) on the interplay between the maintenance costs of homeothermy, heterothermy, and exploration in a wild mammal-the yellow-necked mouse. We measured maintenance metabolism as basal metabolic rate (BMR) using respirometry, distance moved (exploration) in the open-field test, and variation in (heterothermy) during short-term fasting in animals captured at different locations of known natural food availability and predator presence, and with or without supplementary food resources. We found that in winter, heterothermy and exploration (but not BMR) negatively correlated with natural food availability (determined in autumn). Supplementary feeding increased mouse density, predation risk and finally had a positive effect on heterothermy (but not on BMR or exploration). The path analysis testing plausible causal relationships between the studied traits indicated that elevated predation risk increased heterothermy, which in turn negatively affected exploration, which positively correlated with BMR. Our study indicates that adaptive heterothermy is a compensation strategy for balancing the energy budget in endothermic animals experiencing low natural food availability. This study also suggests that under environmental challenges like increased predation risk, the use of an effective energy-saving strategy predicts behavioral expression better than self-maintenance costs under homeothermy.
PubMed: 38932950
DOI: 10.1002/ece3.11579 -
Ecology and Evolution Jun 2024Food availability varies considerably over space and time in wetland systems, and consumers must be able to track those changes during energetically-demanding points in...
Food availability varies considerably over space and time in wetland systems, and consumers must be able to track those changes during energetically-demanding points in the life cycle like breeding. Resource tracking has been studied frequently among herbivores, but receives less attention among consumers of macroinvertebrates. We evaluated the change in resource availability across habitat types and time and the simultaneous density of waterfowl consumers throughout their breeding season in a high-elevation, flood-irrigated system. We also assessed whether the macroinvertebrate resource density better predicted waterfowl density across habitats, compared to consistency (i.e., temporal evenness) of the invertebrate resource or taxonomic richness. Resource density varied marginally across wetland types but was highest in basin wetlands (i.e., ponds) and peaked early in the breeding season, whereas it remained relatively low and stable in other wetland habitats. Breeding duck density was positively related to resource density, more so than temporal resource stability, for all species. Resource density was negatively related to duckling density, however. These results have the potential to not only elucidate mechanisms of habitat selection among breeding ducks in flood-irrigated landscapes but also suggest there is not a consequential trade-off to selecting wetland sites based on energy density versus temporal resource stability and that good-quality wetland sites provide both.
PubMed: 38932948
DOI: 10.1002/ece3.11568 -
Ecology and Evolution Jun 2024Understanding which factors shape and maintain biodiversity is essential to understand how ecosystems respond to crises. Biodiversity observed in ecological communities...
Understanding which factors shape and maintain biodiversity is essential to understand how ecosystems respond to crises. Biodiversity observed in ecological communities is a result of the interaction of various factors which can be classified as either neutral- or niche-based. The importance of these processes has been debated, but many scientists believe that both processes are important. Here, we use unique ecosystems in groundwater-filled lava caves near Lake Mývatn, to examine the importance of neutral- versus niche-based factors for shaping invertebrate communities. We studied diversity in benthic and epibenthic invertebrate communities and related them to ecological variables. We hypothesized that if neutral processes are the main drivers of community structure we would not see any clear relationship between the structure of community within caves and ecological factors. If niche-based processes are important we should see clear relationships between community structure and variation in ecological variables across caves. Both communities were species poor, with low densities of invertebrates, showing the resource limited and oligotrophic nature of these systems. Unusually for Icelandic freshwater ecosystems, the benthic communities were not dominated by Chironomidae (Diptera) larvae, but rather by crustaceans, mainly Cladocera. The epibenthic communities were not shaped by environmental variables, suggesting that they may have been structured primarily by neutral processes. The benthic communities were shaped by the availability of energy, and to some extent pH, suggesting that niche-based processes were important drivers of community structure, although neutral processes may still be relevant. The results suggest that both processes are important for invertebrate communities in freshwater, and research should focus on understanding both of these processes. The ponds we studied are representative of a number of freshwater ecosystems that are extremely vulnerable for human disturbance, making it even more important to understand how their biodiversity is shaped and maintained.
PubMed: 38932944
DOI: 10.1002/ece3.11560 -
Ecology and Evolution Jun 2024Aquatic ecosystems globally have been invaded by molluscs. is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded...
Aquatic ecosystems globally have been invaded by molluscs. is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of , particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The present study aimed to assess the current distribution, densities, and population structures of in invaded habitats on the Limpopo and Phongolo River systems in South Africa. This was accomplished by collecting aquatic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples were collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for was found to be the dominant molluscan species in habitats where it was present and all size classes from newborn to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between and the selected water quality parameters. Higher densities and newborn recruitment of were observed in the spring than in autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure, densities, and impacts of in invaded habitats, particularly for relatively newly invaded regions such as southern Africa.
PubMed: 38932941
DOI: 10.1002/ece3.11544 -
Frontiers in Public Health 2024The Chinese government proposes to establish a hierarchical diagnosis and treatment system, and attaches great importance to community health services. Under the...
BACKGROUND
The Chinese government proposes to establish a hierarchical diagnosis and treatment system, and attaches great importance to community health services. Under the background of population aging and the increase of older adults with disability, this study aimed to analyze the effect of spatial accessibility of community health services on the activities of daily living (ADL) among older adults in China.
METHODS
A research sample of 7,922 older adults from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) data in 2018 was adopted. There were 2,806 participants in the treatment group and 5,116 participants in the control group. The propensity score matching method was adopted to match the treatment and control groups to calculate the values of average treatment effects on treated (ATT).
RESULTS
The results of kernel density matching method showed that the factual ADL score of the treatment group was 10.912, the counterfactual ADL score of the control group was 10.694, and the ATT value was 0.218 ( < 0.01). The spatial accessibility of community health services could significantly improve the activities of daily living among older adults in China. Meanwhile, there was urban-rural heterogeneity in the impact of spatial accessibility of community health services on the activities of daily living of older adults in China. The effect value in urban samples (ATT = 0.371, < 0.01) was higher than that in rural samples (ATT = 0.180, < 0.01).
CONCLUSION
Spatial accessibility of community health services could improve the activities of daily living among older adults in China. The Chinese government should take actions to improve the distribution of community health service resources.
Topics: Humans; Activities of Daily Living; China; Aged; Propensity Score; Male; Female; Health Services Accessibility; Community Health Services; Aged, 80 and over; Longitudinal Studies; Rural Population
PubMed: 38932781
DOI: 10.3389/fpubh.2024.1335712 -
Frontiers in Public Health 2024Aging, as a global demographic issue, is characterized by its rapid growth, which drives an increase in people's healthcare awareness. The emergence of wellness bases...
BACKGROUND
Aging, as a global demographic issue, is characterized by its rapid growth, which drives an increase in people's healthcare awareness. The emergence of wellness bases caters to this market demand. Therefore, the identification of potential areas suitable for wellness activities and the construction of wellness bases, referred to as Wellness Target Areas (WTAs), becomes a crucial first step. Currently, commonly used identification methods are mostly based on traditional statistical approaches, which are often complex, cumbersome, and subject to potential risks of subjective assumptions, affecting the reliability of WTAs identification results. Longevity level serves as a comprehensive indicator reflecting the natural and socio-economic environment of a region, making it the most indicative of the regional wellness environment status.
METHODS
This study proposes using longevity level as the benchmark for WTAs identification to simplify the identification process and reduce the impact of subjective bias on the results. The study focuses on 129 county-level units in Yunnan Province. Firstly, the Geodetector (GD) is utilized to explore the complex interaction between the longevity level and the geographical environment to determine regional wellness factors. Secondly, using ArcGIS and geographical weighted regression (GWR), the study investigates the role of different wellness factors, ultimately classifying and grading the WTAs.
RESULTS
The longevity level in Yunnan Province exhibits a pattern of multi-point clustering, forming three major longevity regions. Factors that significantly influence longevity level include annual average precipitation, sunshine duration, PM content, per capita disposable income, density of tourist attractions, and distance from residential areas to hospitals. Based on the degree of longevity and the contribution rate of influencing factors, Yunnan Province's WTAs are classified into three levels and two types (natural and comprehensive).
CONCLUSION
Our study aims to establish a connection between longevity level and the selection of wellness bases, exploring regional wellness factors through the relationship between longevity phenomena and geographical environment, identifying potential construction areas for wellness bases (i.e., WTAs), providing new insights for the precise selection of wellness bases, effectively enhancing the scientificity of site selection, promoting population health, and contributing to the global aging process with better health.
Topics: Humans; China; Longevity; Health Promotion; Aged
PubMed: 38932766
DOI: 10.3389/fpubh.2024.1387850 -
Vaccines Jun 2024During the coronavirus disease (COVID-19) pandemic healthcare workers (HCWs) acquired immunity by vaccination or exposure to multiple variants of severe acute...
During the coronavirus disease (COVID-19) pandemic healthcare workers (HCWs) acquired immunity by vaccination or exposure to multiple variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our study is a comparative analysis between subgroups of HCWs constructed based on the number of SARS-CoV-2 infections, vaccination, and the dominant variant of SARS-CoV-2 in the population. We collected and analyzed data using the χ test and density incidence of reinfections in Microsoft Excel for Mac, Version 16.84, and MedCalc, 22.026. Of the 829 HCWs, 70.1% (581) had only one SARS-CoV-2 infection and 29.9% (248) had two infections. Of the subjects with two infections, 77.4% (192) worked in high-risk departments and 93.2% (231) of the second infections were registered during Omicron dominance. The density incidence of reinfections was higher in HCWs vaccinated with the primary schedule than those vaccinated with the first booster, and the incidence ratio was 2.8 (95% CI: 1.2; 6.7). The probability of reinfection was five times lower (95% CI: 2.9; 9.2) in HCWs vaccinated with the primary schedule if the first infection was acquired during Omicron dominance. The subjects vaccinated with the first booster had a density incidence of reinfection three times lower (95% CI: 1.9; 5.8) if the first infection was during Omicron. The incidence ratio in subgroups constructed based on characteristics such as gender, age group, job category, and department also registered significant differences in density incidence. The history of SARS-CoV-2 infection by variant is important when interpreting and understanding public health data and the results of studies related to vaccine efficacy for hybrid immunity subgroup populations.
PubMed: 38932411
DOI: 10.3390/vaccines12060682 -
Vaccines May 2024The dengue virus, the primary cause of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is the most widespread mosquito-borne virus worldwide. In...
The dengue virus, the primary cause of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, is the most widespread mosquito-borne virus worldwide. In recent decades, the prevalence of dengue fever has increased markedly, presenting substantial public health challenges. Consequently, the development of an efficacious vaccine against dengue remains a critical goal for mitigating its spread. Our research utilized Celcradle™, an innovative tidal bioreactor optimized for high-density cell cultures, to grow Vero cells for dengue virus production. By maintaining optimal pH levels (7.0 to 7.4) and glucose concentrations (1.5 g/L to 3.5 g/L) during the proliferation of cells and viruses, we achieved a peak Vero cell count of approximately 2.46 × 10, nearly ten times the initial count. The use of Celcradle™ substantially decreased the time required for cell yield and virus production compared to conventional Petri dish methods. Moreover, our evaluation of the immunogenicity of the Celcradle™-produced inactivated DENV4 through immunization of mice revealed that sera from these mice demonstrated cross-reactivity with DENV4 cultured in Petri dishes and showed elevated antibody titers compared to those from mice immunized with virus from Petri dishes. These results indicate that the dengue virus cultivated using the Celcradle™ system exhibited enhanced immunogenicity relative to that produced in traditional methods. In conclusion, our study highlights the potential of the Celcradle™ bioreactor for large-scale production of inactivated dengue virus vaccines, offering significant promise for reducing the global impact of dengue virus infections and accelerating the development of effective vaccination strategies.
PubMed: 38932292
DOI: 10.3390/vaccines12060563