The association of hospital competition with inpatient costs of stroke: Evidence from China

The main purpose of this article is to analyze the association between hospital competition and stroke inpatient costs. Stroke is selected as the representative of a class of diseases characterized by asymmetric information and lack of autonomy of service choice. A total of 98,061 observations are selected from a medical record dataset in the Sichuan Province. The fixed radius approach of 15 miles and Herfindahl-Hirschman Index (HHI) are employed to define the hospital market and measure the competition intensity, respectively. The log-linear multivariate regression model is used to analyze the association between competition and stroke inpatient costs. The results show that every 10% increase in competition (0.1 unit decrease of HHI value) associated with an average 2.38% decrease in stroke inpatient total costs. We also explore the relationship between competition and sub-group costs of stroke inpatient, finding that hospitals facing more competition incur lower treatment, drug, and consumable costs. Further analysis shows that for-profit, private, and low-level hospitals are more sensitive when facing changes in market competition degree. Our study offers empirical evidence to support the introduction of pro-competition in China's new round of national health reform and provide implications for other countries facing similar health care challenges.

Value based competition in health care's ethical drawbacks and the need for a values-driven approach

Value Based competition in Health Care (VBHC) has become a guiding principle in the quest for high quality health care for acceptable costs. Current literature lacks substantial ethical evaluation of VBHC.In this paper we describe how a single-minded focus on VBHC may cause serious infringements upon at least four medical ethical principles: 1) it tends to neglect patients' personal values; 2) it ignores the intrinsic value of the caring act; 3) it disproportionately replaces trust in professionals with accountability, and 4) it undermines solidarity.Health care needs a next step in VBHC. We suggest a 'Values-Driven Health Care' (VDHC) approach that a) takes patients' personal values as prescriptive and guiding; b) holds a value account that encompasses health care's intrinsic (gift) values; c) is based upon intelligent accountability that supports trust in trustworthy professionals, and d) encourages patients to raise their voices for the shared good of health care.

Medical students preferring a surgical or non-surgical elective differ in their emotional and hormonal responses to a psychological stressor

This study examined a possible link between the elective preferences of medical students (surgical vs. non-surgical) and their emotional and hormonal responses to a psychological stressor. Forty medical students completed a laboratory stressor comprising of 10 puzzles in a time-limited format. Emotional state was assessed before (competitiveness, anxiety) and after (stress, enjoyment) testing, along with changes in salivary testosterone (ΔT) and cortisol (ΔC). Comparisons were made according to individual preferences for a surgical (n = 16) or non-surgical (n = 24) elective. Those seeking surgery had a lower 2D:4D (d = -2.0) with higher competitiveness scores (d = 2.7), but less anxiety (d = -0.9) and stress (d = -0.8). They also had a larger ΔT (17% vs. 6%) and smaller ΔC (7% vs. 12%) from the non-surgical cohort. Significant interrelationships were observed between 2D:4D, competitiveness, anxiety, stress and hormones. In summary, in students at a career stage of considering options in medicine, differences in stress responsivity were seen in those considering surgery, as compared to those considering other specialities.

Research on the synergy of urban system operation-Based on the perspective of urban metabolism

Cities have been posing threats to local environment due to intensive human activities. Disordered urban metabolism can lead to unhealthy urban system operation. Studying urban metabolism can identify the characteristics and structure of urban system operations, thereby promoting sustainable development. We construct an ecological network to model the energy/material flows among the sectors of urban system in Beijing, Shanghai, Tianjin, and Chongqing, which are the most representative cities of China. Ecological network analysis was introduced to survey the system's characteristic of structure and function. Results show that Shanghai's urban metabolic system has the highest synergism with a value of 5.04, followed by Beijing, Chongqing, and Tianjin. Different cities vary considerably in terms of the relationships among the sectors. In Beijing and Chongqing, there is mutualistic relationship between environment and primary industry. Transportation forms a mutualistic relationship with tertiary industry and other sectors Only in Chongqing. The good relationships between primary industry and construction are merely seen in Beijing and Shanghai. However, some relationships are similar in the four cities, for instance, all the relationships between primary industry and advanced industry, and between construction and advanced industry are competition; All the relationships between environment and transportation are mutualism. We further explored the network stability and found that the studied urban systems are all located in a stable status relatively. Our research could reveal the synergy of urban operation, and provide a theoretical basis for optimizing urban metabolic processes by regulating the flows and guidance for sustainable urban development.

On the interplay of harvesting and various diffusion strategies for spatially heterogeneous populations

The paper explores the influence of harvesting (or culling) on the outcome of the competition of two species in a spatially heterogeneous environment. The harvesting effort is assumed to be proportional to the space-dependent intrinsic growth rate. The differences between the two populations are the diffusion strategy and the harvesting intensity. In the absence of harvesting, competing populations may either coexist, or one of them may bring the other to extinction. If the latter is the case, introduction of any level of harvesting to the successful species guarantees survival to its non-harvested competitor. In the former case, there is a strip of "close enough" to each other harvesting rates leading to preservation of the original coexistence. Some estimates are obtained for the relation of the harvesting levels providing either coexistence or competitive exclusion.

The digit ratio (2D:4D) relationship with testosterone is moderated by physical training: Evidence of prenatal organizational influences on activational patterns of adult testosterone in physically-active women

BACKGROUND

The 2nd to 4th digit ratio (2D:4D) is regarded as a sexually dimorphic trait governed by prenatal testosterone (T) and estradiol exposure. However, relationships between the 2D:4D and adult sex hormone concentrations are inconsistent in females. Environmental contingencies (e.g., physical training) may provide a stronger basis for establishing these linkages, particularly if the relationships are plastic and not fixed.

AIMS

To investigate associations between 2D:4D, training hours and salivary T (sal-T) measures in physically-active women.

STUDY DESIGN

Descriptive and quasi-experimental monitoring across the follicular (day 7), ovulatory (day 14) and luteal (day 21) phases of three menstrual cycles.

SUBJECTS

35 naturally-cycling women training regularly for sport (range 3-12 h a week).

OUTCOME MEASURES

Morning sal-T concentrations and changes in sal-T to a physical and psychological stimulus (~10 min) were measured.

RESULTS

Both 2D:4D and training hours were related to morning sal-T concentrations in all three menstrual phases (p < 0.01) and their interaction was significant during ovulation. Follow-up testing revealed a negative 2D:4D and sal-T association in women reporting high, but not low, training hours each week. Participant 2D:4D was also related to sal-T changes under physical and/or psychological challenge across each menstrual phase (p < 0.01), whereas training hours and its interaction with 2D:4D were not significant predictors of these outcomes.

CONCLUSIONS

2D:4D linkages with basal and challenge-induced sal-T changes were identified in women undertaking regular physical training. Training hours also moderated the 2D:4D link to morning sal-T, but with some menstrual-phase dependency. These complexities and environmental relationships may help reconcile conflicting results.

Searching with and against each other: Spatiotemporal coordination of visual search behavior in collaborative and competitive settings

Although in real life people frequently perform visual search together, in lab experiments this social dimension is typically left out. Here, we investigate individual, collaborative and competitive visual search with visualization of search partners' gaze. Participants were instructed to search a grid of Gabor patches while being eye tracked. For collaboration and competition, searchers were shown in real time at which element the paired searcher was looking. To promote collaboration or competition, points were rewarded or deducted for correct or incorrect answers. Early in collaboration trials, searchers rarely fixated the same elements. Reaction times of couples were roughly halved compared with individual search, although error rates did not increase. This indicates searchers formed an efficient collaboration strategy. Overlap, the proportion of dwells that landed on hexagons that the other searcher had already looked at, was lower than expected from simulated overlap of two searchers who are blind to the behavior of their partner. The proportion of overlapping dwells correlated positively with ratings of the quality of collaboration. During competition, overlap increased earlier in time, indicating that competitors divided space less efficiently. Analysis of the entropy of the dwell locations and scan paths revealed that in the competition condition, a less fixed looking pattern was exhibited than in the collaborate and individual search conditions. We conclude that participants can efficiently search together when provided only with information about their partner's gaze position by dividing up the search space. Competing search exhibited more random gaze patterns, potentially reflecting increased interaction between searchers in this condition.

ITC Studies of Ribosome/Antibiotics Interactions

The fight against multiresistant bacteria responsible for nosocomial diseases has recently been classified as an absolute priority by the World Health Organization. For some organisms, priority status has even been assessed as critical, as almost all currently available antibiotics are now inefficient against these "super-bacteria." Ribosome is a major target of several antibiotics, and extensive biochemical and structural studies led to a better understanding of the mechanism of action of drugs targeting translation (Blair et al., Nat Rev Microbiol 13:42-51, 2015; Lin et al., Annu Rev Biochem 87:451-478, 2018; Wilson, Nat Rev Microbiol 12:35-48, 2014; Yonath, Annu Rev Biochem 74:649-79, 2005). However, our knowledge regarding thermodynamic data of compounds targeting the ribosome, which are yet essential for a complete understanding of translation inhibition mechanisms by drugs, is still very poor.In this chapter we describe the use of ITC microcalorimetry to investigate the binding of bacterial ribosome to two antibiotics targeting the peptide tunnel: macrolides and proline-rich antimicrobial peptides (PrAMPs). This strategy yields reliable and artifact-free binding parameters for antibiotics and provides an original view on ribosome/antibiotics interactions.

Competition, seed dispersal and hunting: what drives germination and seedling survival in an Afrotropical forest?

Disentangling the contributions of different processes that influence plant recruitment, such as competition and seed dispersal, is important given the increased human-mediated changes in tropical forest ecosystems. Previous studies have shown that seedling communities in an Afrotropical rainforest in southeastern Nigeria are strongly affected by the loss of important seed-dispersing primates, including Cross River gorillas (Gorilla gorilla diehli), chimpanzee (Pan troglodytes elioti) and drill (Mandrillus leucophaeus). Here we study how germination and survival of tree seedlings are affected by competition and reduced seed dispersal in three contiguous forest reserves, in southeastern Nigeria, with similar mature tree species composition and structure. We use an experimental design aimed at manipulating the effect of competition among seedlings in three protected and three hunted sites within the reserves. We use a total of sixty 5 × 5 m plots of three types: plots cleared of all seedlings, plots selectively cleared of all primate-dispersed seedlings and control plots. All seedlings were identified, measured, assigned to dispersal mode and tagged, and after 1 year we evaluated survival, mortality and new recruits. We found that in hunted sites germination of abiotically dispersed species was over four times higher in cleared plots compared to control plots, whereas germination of primate-dispersed species was the same, which indicated that dispersal limitation was the dominant force in seedling recruitment in hunted sites. This was supported by the fact that the germination of all dispersal modes in the selectively cleared plots in protected sites was similar to the control plots in the same sites, but germination of abiotically dispersed species was significantly lower than in cleared plots in hunted sites. Competition among seedlings was mostly evident from the fact that 75 % more seedlings of primate-dispersed species germinated in cleared compared to control plots in protected sites. We conclude that inter-seedling competition may be irrelevant to seedling recruitment in hunted sites, where dispersal limitation appears to be a much stronger force shaping the seedling plant community, and thus hunting indirectly reverses the importance of competition and dispersal limitation in structuring seedling communities.

Combined effect of environmental temperature and density-dependent processes on the evolution of seasonal metabolic rate patterns

Species exhibit large diversity in their seasonal metabolic patterns which are traditionally explained by habitat specific seasonal temperature changes and various thermoregulatory adaptations. However, due to seasonal changes in resource abundances, density-dependent, ecological processes can also be important selective forces shaping the evolution of metabolic patterns. In the present theoretical study, the combined effect of environmental temperature and resource availability on the evolutionarily stable metabolic strategies is investigated in a consumer-resource model. Our results suggest that, under a broad range of circumstances, density-dependent mechanisms favor the selection of active metabolic regulation, where the metabolic rate differs from the thermally optimal value. This effect may be temporary, limited only to a brief period at seasonal changes, or permanent depending on the implied energetic cost and the relative timescale of environmental changes as compared to the generation time.

Evidence of temporal niche separation via low flowering time overlap in an old-field plant community

Flowering time is a trait that reflects the timing of specific resource requirements by plants. Consequently, several predictions have been made related to how species are assembled within communities according to flowering time. Strong overlap in flowering time among coexisting species may result from clustered abiotic resources, or contribute to improved pollination success. Conversely, low flowering time overlap (asynchrony) among coexisting species may reduce competition for soil, light, or pollinator resources and alleviate interspecific pollen transfer. Here, we present evidence that coexisting species in an old-field community generally overlap less in flowering time than expected under a commonly used and statistically validated null model. Flowering time asynchrony was more pronounced when abundance data were used (compared to presence-absence data), and when analyses focused on species that share bees as pollinators. Control and herbivore-exclusion plots did not differ in flowering time overlap, providing no evidence of the reduction in overlap expected to result from increased competition. Our results varied with the randomization algorithm used, emphasizing that the choice of algorithm can influence the outcome of null models. Our results varied between 2 years, with patterns being less clear in the second year, when both growing season and flowering times were contracted. Finally, we found evidence that further supports a previous finding that higher plot-level flowering time overlap was associated with higher proportions of introduced species. Reduced flowering time overlap among species in our focal community may promote coexistence via temporal niche differentiation and reduced competition for pollinators and other abiotic resources.

Where to look for the morals in markets?

There is a heated debate on whether markets erode social responsibility and moral behavior. However, it is a challenging task to identify and measure moral behavior in markets. Based on a theoretical model, we examine in an experiment the relation between trading volume, prices and moral behavior by setting up markets that either impose a negative externality on third parties or not. We find that moral behavior reveals itself in lower trading volume in markets with a negative externality, while prices mostly depend on the market structure. We further investigate individual characteristics that explain trading behavior in markets with negative externalities.

Differentiation in prefrontal cortex recruitment during childhood: Evidence from cognitive control demands and social contexts

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Using fNIRS, we examined how children recruit PFC while engaging cognitive control.

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Activation increased with cognitive control demands more in left than right PFC.

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It was higher in left PFC in competitive than cooperative contexts, and in right PFC in cooperative and neutral compared to competitive contexts.

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Older children showed greater variations in PFC activation than younger children.

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Cognitive control is supported by more differentiated PFC recruitment with age.

Emerging cognitive control during childhood is largely supported by the development of distributed neural networks in which the prefrontal cortex (PFC) is central. The present study used fNIRS to examine how PFC is recruited to support cognitive control in 5–6 and 8-9-year-old children, by (a) progressively increasing cognitive control demands within the same task, and (b) manipulating the social context in which the task was performed (neutral, cooperative, or competitive), a factor that has been shown to influence cognitive control. Activation increased more in left than right PFC with cognitive control demands, a pattern which was more pronounced in older than younger children. In addition, activation was higher in left PFC in competitive than cooperative contexts, and higher in right PFC in cooperative and neutral than competitive contexts. These findings suggest that increasingly efficient cognitive control during childhood is supported by more differentiated recruitment of PFC as a function of cognitive control demands with age.

Parasitic plasmid-host dynamics and host competition in flowing habitats

Competition and coexistence were examined for two bacterial species, each potentially carrying a fitness-reducing, parasitic plasmid that was vertically transmitted with possible loss through segregation. Here, the fitness reduction of hosts was due to a toxin produced by plasmid-bearing cells and inhibiting plasmid-free cells. These populations were placed in a flow reactor habitat representing an idealized mammal gut. It was numerically shown that parasitic plasmids can mediate coexistence of competing host species, in conditions where plasmid-free hosts could not coexist. Numerical construction of a coexistence example suggests that it arises only for a narrow parameter range. In particular, both rates of segregation and the growth costs of plasmid carriage must be relatively low.

When do herbivorous insects compete? A phylogenetic meta-analysis

When herbivorous insects interact, they can increase or decrease each other's fitness. As it stands, we know little of what causes this variation. Classic competition theory predicts that competition will increase with niche overlap and population density. And classic hypotheses of herbivorous insect diversification predict that diet specialists will be superior competitors to generalists. Here, we test these predictions using phylogenetic meta-analysis. We estimate the effects of diet breadth, population density and proxies of niche overlap: phylogenetic relatedness, physical proximity and feeding-guild membership. As predicted, we find that competition between herbivorous insects increases with population density as well as phylogenetic and physical proximity. Contrary to predictions, competition tends to be stronger between than within feeding guilds and affects specialists as much as generalists. This is the first statistical evidence that niche overlap increases competition between herbivorous insects. However, niche overlap is not everything; complex feeding guild effects indicate important indirect interactions.

Competition in the chemostat with an undesirable lethal competitor

In this study, we compare the effects of competitors in a chemostat when one of the competitors is lethal to the other. The first competitor ("the mutant") is the desired organism because it provides a benefit, such as a substance that is harvested. However, when the mutant undergoes cell division the result may return to the original ("wild type") organism that produces a substance ("toxin") that is lethal to the mutant. We introduce an external inhibitor that negatively affects the growth of the wild type organism but that does not affect the mutant. The goal is for the mutant to dominate in the competition while co-existing with its wild type relative that is controlled. In this manner, we hope that understanding the dynamics of the system will help in designing methods to control the purity of the harvesting vessel without having to periodically restart the process more than necessary. We show that it is possible for co-existence in which the undesirable wild-type coexists with the mutant. However, it is also possible to destabilize the system and cause the extinction of the mutant.

Effects of the removal or reduction in density of the malaria mosquito, Anopheles gambiae s.l., on interacting predators and competitors in local ecosystems

New genetic control methods for mosquitoes may reduce vector species without direct effects on other species or the physical environment common with insecticides or drainage. Effects on predators and competitors could, however, be a concern as Anopheles gambiae s.l. is preyed upon in all life stages. We overview the literature and assess the strength of the ecological interactions identified. Most predators identified consume many other insect species and there is no evidence that any species preys exclusively on any anopheline mosquito. There is one predatory species with a specialisation on blood-fed mosquitoes including An. gambiae s.l.. Evarcha culicivora is a jumping spider, known as the vampire spider, found around Lake Victoria. There is no evidence that these salticids require Anopheles mosquitoes and will readily consume blood-fed Culex. Interspecific competition studies focus on other mosquitoes of larval habitats. Many of these take place in artificial cosms and give contrasting results to semi-field studies. This may limit their extrapolation regarding the potential impact of reduced An. gambiae numbers. Previous mosquito control interventions are informative and identify competitive release and niche opportunism; so while the identity and relative abundance of the species present may change, the biomass available to predators may not.

Application of metabolic division of labor in simultaneous removal of nitrogen and thiocyanate from wastewater

Metabolic division of labor is a key ecological strategy in bacteria to allow concurrent execution of multiple tasks through functional differentiation and metabolite exchange. While it is prevalent in nature, a lot of novel interactions remain to be further explored for improved wastewater biological treatment. Here, we present a combined experimental and modeling study on the simultaneous removal of nitrogen and thiocyanate from wastewater by using a syntrophic microbial community. The syntrophic division of labor was achieved by coupling autotrophic denitrification (AD) and anaerobic ammonium oxidation (AN) through both cooperative and competitive interactions. We demonstrated that the syntrophic community can achieve almost complete removal of all pollutants under certain initial conditions. We then perturbed the initial condition by varying the concentration ratio between ammonium to thiocyanate as well as the biomass ratio between AD and AN. Our observations show that adding ammonium negatively impacts the thiocyanate removal efficiency and adding anammox bacteria have opposite effects on the removal efficiency of thiocyanate and ammonium. Using a mathematical model, we simultaneously varied these two initial conditions and identified the parameter regime where our syntrophic ecosystem can be most efficient in removing total nitrogen. By highlighting the utility of syntrophic pair of functional bacteria in removing pollutants, our study will facilitate the rational design of more complex microbial consortia for the removal of toxic and hazardous compounds from industrial wastewater.

Adsorption behaviour and mechanisms of cadmium and nickel on rice straw biochars in single- and binary-metal systems

Adsorption mechanisms and competition between Cd²⁺ and Ni²⁺ for adsorption by rice straw biochars prepared at 400 °C (RB400) and 700 °C (RB700) were investigated in this study. Based on the Langmuir model, the maximum adsorption capacities (mg g^-1) of Cd²⁺ and Ni²⁺ on RB400 and RB700 were in the order of Cd²⁺ (37.24 and 65.40) > Ni²⁺ (27.31 and 54.60) in the single-metal adsorption isotherms and Ni²⁺ (25.20 and 32.28) > Cd²⁺ (24.22 and 26.78) in the binary-metal adsorption isotherms. Cd²⁺ competed with Ni²⁺ for binding sites at initial metal concentrations >10 mg L^-1 for RB400 and > 20 mg L^-1 for RB700. The adsorption sites for Cd²⁺ and Ni²⁺ on the biochars largely overlapped, and the binding of Cd²⁺ and Ni²⁺ to these sites was affected by the occupation sequence of these metals. For Cd²⁺ and Ni²⁺ adsorption in the binary system, cation exchange and precipitation were the dominant adsorption mechanisms on RB400 and RB700, respectively, accounting for approximately 36% and 60% of the adsorption capacity. Competition decreased the contribution of cation exchange but increased that of precipitation and other potential mechanisms. Results from this study suggest that types and concentrations of metal ions should be taken into account when removing metal contaminants from water or soil using biochars.

Fitness costs associated with multiple resistance to dicamba and atrazine in Chenopodium album

Detrimental pleiotropic effects of resistance mutation(s) were observed for multiple-resistant phenotypes (resistant to both atrazine and dicamba). The multiple-resistant phenotypes had lower growth rates and less capacity for vegetative growth compared to the phenotypes only resistant to atrazine. The fitness costs that are conferred by herbicide resistance alleles can affect the rate of herbicide resistance evolution within populations. We evaluated the direct fitness costs involved with multiple resistance to dicamba and atrazine (R1 and R2) in Chenopodium album by comparing the performance of multiple-resistant phenotypes to those phenotypes that were only resistant to atrazine (S1 and S2). The R1 and R2 phenotypes were consistently shorter and produced less dry matter than the S1 and S2 phenotypes. The R1 and R2 phenotypes were shown to have lower relative growth rates (RGR) and net assimilation rates (NAR) than the S1 and S2 phenotypes at an early stage of growth. However, there was no significant difference in RGR between the R1 and R2 and, S1 and S2 phenotypes at a later stage of growth, though the R1 and R2 phenotypes still had a lower NAR at this later stage. Further investigations using a neighbouring crop competition approach showed that the R1 and R2 phenotypes were weaker competitors, and exhibited significantly less capacity for vegetative growth compared to the S1 and S2 phenotypes during competition. Overall, the results of this study revealed multiple- resistance to atrazine and dicamba endowed a significant fitness penalty to C. album, and it is possible that the frequency of multiple-resistant individuals would gradually decline once selection pressure from herbicides was discontinued.

Aggregation and negative interactions in low-diversity and unsaturated monogenean (Platyhelminthes) communities in Astyanax aeneus (Teleostei) populations in a neotropical river of Mexico

We studied monogenean communities of 11 populations of Astyanax aeneus (Günther) separated by small geographical distances along 60 km of the Lacantún river in Chiapas, Mexico, in February and August 2012. We found 12 monogenean taxa. Amongst these, five species specialist for Astyanax were widely distributed regionally, constituting 90% of the total collected monogeneans, with one of these species dominating most component communities. The high similarities in terms of composition between the component communities (S_Jaccard > 60%) as well as in terms of the abundance and composition between infracommunities (S_{Bray Curtis} > 40%), provide empirical evidence that transmission, both between hosts at the same location and between component communities, is high and effective. No resemblance pattern was detected between locations in terms of their spatial distribution. The composition of these communities was spatially and temporally consistent over the two very different weather periods sampled. These communities were not saturated. Our analysis suggests that the potential richness of the infracommunities is proportional to the number of monogenean species available in the component community. We found aggregation in the populations and between monogenean species. Intraspecific aggregation is density dependent, suggesting that intraspecific competition for space is not a limiting factor for the development of the population. We evaluated the associations for each species pair and detected 77% negative interactions (134/177 associations), suggesting that interspecific competition plays an important role in shaping these communities. The negative correlations of abundance between pairs of species contributes to confirmation of competition. Intraspecific aggregation increased relative to interspecific aggregation with richness in the component community, facilitating coexistence of the species. Our results suggest that these are interactive communities, where monogeneans disperse efficiently from a common source, colonize patches (hosts) together, and compete with other species even at low population densities. Finally, the coexistence of these species is favored by the unpredictable recruitment and aggregated use of fragmented resources.

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We explore richness and coexistence of monogeneans of a small fish in a large river.

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Empirical evidence that transmission between hosts/locations is efficient is provided.

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We provide empirical evidence of unsaturated/low density but interactive communities.

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Monogeneans show intra and interspecific aggregation both density-dependent.

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They establish regionally consistent negative interactions repeated between locations.

Local adaptation in dispersal in multi-resource landscapes

The distribution of resources in space has important consequences for the evolution of dispersal-related traits. Dispersal moderates patterns of gene flow and, consequently, the potential for local adaptation to spatially differentiated resource types. We lack both models and experiments that evaluate how dispersal evolves in landscapes with multiple resources. Here, we investigate the evolution of dispersal in landscapes that contain two resource types that differ in their spatial autocorrelations. Individuals may possess ecological traits that give them a fitness advantage on one or the other resource. We find that resources differing in their spatial autocorrelation select for different optimal dispersal strategies and, further, that some multi-resource landscapes can support the stable coexistence of distinct dispersal strategies. Whether divergence in dispersal strategies between resource specialists occurs depends on the underlying structure of the resources and the degree of linkage between dispersal strategies and ecological specialization. This work indicates that the spatial autocorrelation of resources is an important factor in determining when evolutionary branching is likely to occur, and sheds light on when secondary isolating mechanisms should arise between locally adapted specialists.

Colonization and Competition Dynamics of Plant Growth-Promoting/Inhibiting Bacteria in the Phytosphere of the Duckweed Lemna minor

Despite the considerable role of aquatic plant-associated bacteria in host plant growth and nutrient cycling in aquatic environments, the mode of their plant colonization has hardly been understood. This study examined the colonization and competition dynamics of a plant growth-promoting bacterium (PGPB) and two plant growth-inhibiting bacteria (PGIB) in the aquatic plant Lemna minor (common duckweed). When inoculated separately to L. minor, each bacterial strain quickly colonized at approximately 10⁶ cells per milligram (plant fresh weight) and kept similar populations throughout the 7-day cultivation time. The results of two-membered co-inoculation assays revealed that the PGPB strain Aquitalea magnusonii H3 consistently competitively excluded the PGIB strain Acinetobacter ursingii M3, and strain H3 co-existed at almost 1:1 proportion with another PGIB strain, Asticcacaulis excentricus M6, regardless of the inoculation ratios (99:1-1:99) and inoculation order. We also found that A. magnusonii H3 exerted its growth-promoting effect over the negative effects of the two PGIB strains even when only a small amount was inoculated, probably due to its excellent competitive colonization ability. These experimental results demonstrate that there is a constant ecological equilibrium state involved in the bacterial colonization of aquatic plants.

Fast-growing willows significantly reduce invasive knotweed spread

Competitive interactions seem to play a major role in invasive plant success. However, they have mostly been addressed through the invader impacts on other species of the plant community and rarely through the way plant communities can contain alien species. Understanding such mechanisms would help in designing restoration projects using plant community competitive properties to control invasive populations. In this study, we looked at the role of competitive interactions in the success of Fallopia japonica (Houtt.) Ronse Decraene using a native willow frequently used in bioengineering techniques: Salix viminalis L. S. viminalis has a high growth rate and is, as such, a potential candidate to compete with F. japonica in restoration projects of invaded areas. Both species were grown in semi-controlled conditions in mesocosms (truck dumpsters), alone or in competition. Morphological traits (plant height, specific leaf area) as well as biomass (aboveground and underground) were measured on each species during two growing seasons. We also quantified spatial expansion of F. japonica. Even under a dense canopy of S. viminalis, F. japonica was able to survive and grow. However, its performance was significantly reduced compared to monocultures and its spatial colonization was less extended. Although S. viminalis biomass was affected by F. japonica, F. japonica expressed competitive stress through a modification of ramet density and height. There was no significant effect of F. japonica on S. viminalis height, enabling this species to dominate. Synthesis and applications: We conclude that S. viminalis succeeded in reducing F. japonica growth by developing a competitive canopy. Bioengineering techniques aiming at restoring a competitive neighborhood can control F. japonica. However, F. japonica's broad underground extension should be taken into account in any management strategy in order to successfully limit its development and spatial spread.

Disarming the gunslinger effect: Reaction beats intention for cooperative actions

According to the famous physicist Niels Bohr, gunfights at high noon in Western movies not only captivate the cinema audience but also provide an accurate illustration of a psychophysical law. He suggested that willed actions come with slower movement execution than reactions, and therefore that a film's hero is able to get the upper hand even though the villain normally draws first. A corresponding "gunslinger effect" has been substantiated by empirical studies. Because these studies used a markedly competitive setting, however, it is currently unclear whether the gunslinger effect indeed reflects structural differences between willed actions and reactive movements, or whether it is a by-product of the competitive setting. To obtain bullet-proof evidence for a true reactive advantage, we investigated willed and reactive movements during a cooperative interaction of two participants. A pronounced reactive advantage emerged, indicating that two independent systems indeed control willed and reactive movements.