Chronic pulmonary aspergillosis incidence in newly detected pulmonary tuberculosis cases during follow-up.

BACKGROUND: Chronic pulmonary aspergillosis (CPA) is known to complicate patients with post-tubercular lung disease. However, some evidence suggests that CPA might co-exist in patients with newly-diagnosed pulmonary tuberculosis (P.TB) at diagnosis and also develop during therapy. The objective of this study was to confirm the presence of CPA in newly diagnosed P.TB at baseline and at the end-of-TB-therapy. MATERIALS AND METHODS: This prospective longitudinal study included newly diagnosed P.TB patients, followed up at third month and end-of-TB-therapy with symptom assessment, anti-Aspergillus IgG antibody and imaging of chest for diagnosing CPA. RESULTS: We recruited 255 patients at baseline out of which 158 (62%) completed their follow-up. Anti-Aspergillus IgG was positive in 11.1% at baseline and 27.8% at end-of-TB-therapy. Overall, proven CPA was diagnosed in 7% at baseline and 14.5% at the end-of-TB-therapy. Around 6% patients had evidence of aspergilloma in CT chest at the end-of-TB-therapy. CONCLUSIONS: CPA can be present in newly diagnosed P.TB patients at diagnosis and also develop during anti-tubercular treatment. Patients with persistent symptoms or developing new symptoms during treatment for P.TB should be evaluated for CPA. Whether patients with concomitant P.TB and CPA, while receiving antitubercular therapy, need additional antifungal therapy, needs to be evaluated in future studies.

Cryptic diversity impacts model selection and macroevolutionary inferences in diversification analyses.

Species persist in landscapes through ecological dynamics but proliferate at wider spatial scales through evolutionary mechanisms. Disentangling the contribution of each dynamic is challenging, but the increasing use of dated molecular phylogenies opened new perspectives. First, the increasing use of DNA sequences in biodiversity inventory shed light on a substantial amount of cryptic diversity in species-rich ecosystems. Second, explicit diversification models accounting for various eco-evolutionary models are now available. Integrating both advances, we explored diversification trajectories among 10 lineages of freshwater fishes in Sundaland, for which time-calibrated and taxonomically rich phylogenies are available. By fitting diversification models to dated phylogenies and incorporating DNA-based species delimitation methods, the impact of cryptic diversity on diversification model selection and related inferences is explored. Eight clades display constant speciation rate model as the most likely if cryptic diversity is accounted, but nine display a signature of diversification slowdowns when cryptic diversity is ignored. Cryptic diversification occurs during the last 5 Myr for most groups, and palaeoecological models received little support. Most cryptic lineages display restricted range distribution, supporting geographical isolation across homogeneous landscapes as the main driver of diversification. These patterns question the persistence of cryptic diversity and its role during species proliferation.

Prevalence of hypertension among individuals with diabetes and its determinants: evidences from the National Family Health Survey 2015-16, India.

BACKGROUND: The incidence of diabetes mellitus (DM) has escalated in recent decades, and the risk of diabetes-related mortality has increased dramatically due to the co-existence of hypertension (HTN). DM and HTN, having similar aetiology and disease mechanisms, are influenced by lifestyle factors and greatly contribute to critical health complications. AIM: This study attempted to explore the co-existence of DM-HTN and the potential determinants considering the rapid upsurge of both these diseases. SUBJECTS AND METHODS: National Family Health Survey data were used, which included 7092 adult diabetic individuals, to find out the prevalence rate of HTN in diabetic persons in India. Appropriate statistical analyses were performed to accomplish the study objectives. RESULTS: Prevalence rate of HTN in diabetic individuals was approximately 37%. Higher body mass index (BMI) was associated with DM-HTN co-existence. In males, increased age, higher BMI, alcohol consumption, poorest wealth index, and non-smoking (tobacco) were the significant determinants of the co-existence of DM-HTN, while in females, they were increased age, higher BMI, and geographical region. CONCLUSIONS: This study unveiled the significance of healthy lifestyle maintenance and equitable health care services to prevent HTN among diabetics, along with promotion of the awareness and management of DM and HTN through appropriate pharmacological treatments.

Performance Analysis of Existing ITS Technologies: Evaluation and Coexistence.

The performance of vehicular communication technologies changes dynamically according to the application requirements considering data rate, communication ranges, latency, etc. These applications are evolving rapidly and should enhance intelligent transport systems (ITS) such as road safety and automated driving. However, to reach the required quality, these applications need many radio resources to carry the potential traffic load resulting from the environmental perception and data exchanged between the different entities. Therefore, an assessment of vehicular communication technologies' reliability and resilience under these conditions is required to address the multiple challenges of the ITS services. The paper's main contribution is to propose a comprehensive analysis model able to evaluate and compare the performances of ITS technologies according to different constraints related to environment-changing situations. This analysis examines the channel occupancy and provides simulation results which allow the identification of the suitable configurations and the most appropriate technology for a given use case. We also propose a coexistence solution between these technologies based on density-sharing according to the use case requirements and the availability of the technology. Finally, we present the challenge of adaptive configuration in vehicular networks, which helps to provide the optimal structure through road profiles and environment variability (infrastructure, data, etc.). Results show different trade offs and limitations between the considered ITS technologies, which are essential to understand their behaviour in a realistic environment.

DRiPLOF: An RPL Extension for Multi-Interface Wireless Sensor Networks in Interference-Prone Environments.

The Routing Protocol for Low-power and Lossy Networks (RPL) is a popular routing layer protocol for multi-hop Wireless Sensor Networks (WSNs). However, typical RPL configurations are based on decade-old assumptions, leading to a mismatch with: (1) advances in wireless hardware; and (2) growing wireless contention. To soften the impact of external stressors (i.e., jamming and interference), we extended RPL to exploit the capabilities of modern multi-interfaced wireless devices. More specifically, our main contribution is the design, development, and evaluation of a novel RPL Objective Function (OF) which, through simulations, is compared to traditional single-interface approaches and a state-of-the-art multi-interface approach. We examine two scenarios, with and without the injection of jamming, respectively. Our proposed OF is shown to outperform, or otherwise perform similar to, all alternatives considered. In normal conditions, it auto-selects the best interface whilst incurring negligible protocol overhead. In our jamming simulations, it provides stable end-to-end delivery ratios exceeding 90%, whereas the closest alternative averages 65% and is considerably less stable. Given we have open-sourced our development codebase, our solution is an ideal candidate for adoption by RPL deployments that expect to suffer interference from competing technologies or are unable to select the best radio technology a priori.

Mathematical model for the dynamics of Savanna ecosystem considering fire disturbances.

In this article, the stability of equilibrium solutions of a recently formulated mathematical model of Savanna ecosystem is analytically and numerically analyzed. The mathematical model is formulated by generalizing all plant life into three components; trees, tree saplings, and grass under ecologically valid effects of fire, rainfall and competition for space. Fire has a considerable effect on trees by delaying the recruitment of saplings to trees and the recruitment rate is a piecewise linear decreasing function of grass with a sigmoidal shape. This leads to there existing different equilibria in the plant community of a Savanna ecosystem. It is rigorously demonstrated that the local stability of equilibria depends on the slope and value of the recruitment function. Moreover, it is found that the composition of high grass cover and low tree cover or low grass cover and high tree cover are the stable equilibria, while intermediate cover results in unstable equilibria. In analyzing the global stability of solutions, it is found that the limit set is an equilibrium solution. Several numerical simulations are provided to validate the analytical studies of the behavior of the equilibrium solutions. The numerical solutions are generated using a Python ordinary differential equation(ODE) solver. The analytical and numerical solutions presented in this work are very important for further developments in the area of mathematical ecology.

The first report of co-existence of pulmonary tuberculosis and lung malignancy in a kidney transplant recipient: a case report and literature review.

BACKGROUND: Along with the medical development, organ transplant patients increase dramatically. Since these transplant patients take immunosuppressants for a long term, their immune functions are in a suppressed state, prone to all kinds of opportunistic infections and cancer. However, it is rarely reported that the kidney transplant recipients (KTRs) have pulmonary tuberculosis and lung cancer simultaneously. CASE PRESENTATION: A 60-year-old male was admitted because of persistent lung shadow for 2 years without any obvious symptom 8 years after renal transplant. T-SPOT test was positive but other etiological examinations for Mycobacterium tuberculosis were negative. Chest CT scan revealed two pulmonary lesions in the right upper and lower lobe respectively. 18F-fluorodesoxyglucose positron-emission tomography (FDG-PET) CT found FDG intake increased in both pulmonary consolidation lesions. CT-guided percutaneous transthoracic needle biopsy revealed lung adenocarcinoma and tuberculosis. The video-assisted thoracoscopic surgery was operated to resect the malignancy lesions. The patient received specific anti-tuberculosis therapy and was discharged. At the follow-up of 6 months post drug withdrawal, the patient was recovered very well. CONCLUSIONS: We for the first time reported co-existence of smear-negative pulmonary TB and lung adenocarcinoma in a KTR, which highlighted the clinical awareness of co-occurrence of TB and malignancy after renal transplant and emphasized the value of biopsy and 18F-FDG-PET in early diagnosis of TB and cancer.

Epilepsy in patients with focal cortical dysplasia may be associated with autism spectrum disorder.

INTRODUCTION: Patients with epilepsy associated with focal cortical dysplasia (FCD) may be associated with autism spectrum disorder (ASD). Therefore, the purpose of this study was to compare surgically treated patients with epilepsy secondary to FCD and normal volunteers without epilepsy and to review the neuropathological findings of patients with FCD. METHODS: This study involved 38 patients with medically intractable focal onset epileptic seizures who underwent epilepsy surgery (Group 1). All patients had epilepsy associated with FCD. These patients and 38 normal volunteers without epilepsy (Group 2) were administered the autism spectrum quotient (AQ) test, and the groups were compared. RESULTS: The 38 patients in Group 1 included 16 females and 22 males (age range 20-60, mean age, 33.0; standard deviation (SD), 11.8 years). The normal volunteers in Group 2 included 22 females and 16 males (age range 20-57, mean age, 30.6 years; SD, 8.8 years). Total AQ scores were significantly higher in Group 1 than Group 2 (p = 0.027). Patients with FCD I showed a higher AQ score than those with FCD II in the AQ test (p ≤ 0.001). CONCLUSION: Patients with epilepsy secondary to FCD were associated with higher ASD score than normal volunteers. This tendency was seen more strongly in patients with FCD I than FCD II.

Fishing within offshore wind farms in the North Sea: Stakeholder perspectives for multi-use from Scotland and Germany.

Offshore wind power generation requires large areas of sea to accommodate its activities, with increasing claims for exclusive access. As a result, pressure is placed on other established maritime uses, such as commercial fisheries. The latter sector has often been taking a back seat in the thrust to move energy production offshore, thus leading to disagreements and conflicts among the different stakeholder groups. In recognition of the latter, there has been a growing international interest in exploring the combination of multiple maritime activities in the same area (multi-use; MU), including the re-instatement of fishing activities within, or in close proximity to, offshore wind farms (OWFs). We summarise local stakeholder perspectives from two sub-national case studies (East coast of Scotland and Germany's North Sea EEZ) to scope the feasibility of combining multiple uses of the sea, such as offshore wind farms and commercial fisheries. We combined a desk-based review with 15 semi-structured qualitative interviews with key knowledge holders from both industries, regulators, and academia to aggregate key results. Drivers, barriers and resulting effects (positive and negative) for potential multi-use of fisheries and OWFs are listed and ranked (57 factors in total). Factors are of economic, social, policy, legal, and technical nature. To date, in both case study areas, the offshore wind industry has shown little interest in multi-use solutions, unless clear added value is demonstrated and no risks to their operations are involved. In contrast, the commercial fishing sector is proactive towards multi-use projects and acts as a driving force for MU developments. We provide a range of management recommendations, based on stakeholder input, to support progress towards robust decision making in relation to multi-use solutions, including required policy and regulatory framework improvements, good practice guidance, empirical studies, capacity building of stakeholders and improvements of the consultation process. Our findings represent a comprehensive depiction of the current state and key stakeholder aspirations for multi-use solutions combining fisheries and OWFs. We believe that the pathways towards robust decision making in relation to multi-use solutions suggested here are transferable to other international locations.

Assessing the Effectiveness of a Community-based Livestock Insurance Program.

Financial mechanisms to mitigate the costs of negative human-carnivore interactions are frequently promoted to support human coexistence with carnivores. Yet, evidence to support their performance in different settings is scarce. We evaluated a community-based livestock insurance program implemented as part of a broader snow leopard conservation effort in the Tost Tosonbumba Nature Reserve, South Gobi, Mongolia. We assessed program efficiency and effectiveness for snow leopard conservation using a results-based evaluation approach. Data sources included program records from 2009 to 2018, as well as surveys conducted in 2016 and 2017, which allowed us to compare key indicators across communities that participated in the insurance program and control communities. Program coverage and number of livestock insured rapidly increased over the years to reach 65% of households and close to 11,000 livestock. Participants expressed satisfaction with the program and their contributions increased over time, with an increasing proportion (reaching 64% in 2018) originating from participant premiums, suggesting strong community ownership of the program. Participants were less likely to report the intention to kill a snow leopard and reported fewer livestock losses than respondents from control communities, suggesting increased engagement in conservation efforts. These results together suggest that the insurance program achieved its expected objectives, although it is challenging to disentangle the contributions of each individual conservation intervention implemented in intervention communities. However, in the first three years of the program, snow leopard mortalities continued to be reported suggesting that additional interventions were needed to reach impact in terms of reducing retaliatory killings of large carnivores.

Prevalence and co-existence of locomotive syndrome, sarcopenia, and frailty: the third survey of Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study.

This study aimed to estimate the prevalence of locomotive syndrome, sarcopenia, and frailty and clarify their co-existence in a population-based cohort. The third survey of Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study was conducted between 2012 and 2013, examining 963 subjects (aged ≥ 60 years; 321 men, 642 women). Locomotive syndrome, sarcopenia, and frailty were defined using three tests proposed by Japanese Orthopaedic Association, Asian Working Group for Sarcopenia criteria, and Fried's definition, respectively. Prevalence of locomotive syndrome stages 1 and 2 were 81.0% (men, 80.4%; women, 81.3%) and 34.1% (men, 30.5%; women, 35.8%), respectively, and those of sarcopenia and frailty were 8.7% (men, 9.7%; women, 8.3%) and 4.5% (men, 2.8%; women, 5.3%), respectively. Locomotive syndrome stage 1, sarcopenia, and frailty co-existed in 2.1%; 6.5% had locomotive syndrome stage 1 and sarcopenia, 2.4% had locomotive syndrome stage 1 and frailty, while none had sarcopenia and frailty. Locomotive syndrome stage 1 presented alone in 70.0%, sarcopenia in 0.1%, and no frailty. The remaining 18.9% had none of these conditions. Co-existence of locomotive syndrome stage 2, sarcopenia, and frailty was observed in 2.0%; 5.0% had locomotive syndrome stage 2 and sarcopenia, 2.2% had locomotive syndrome stage 2 and frailty, and 0.1% had sarcopenia and frailty. Locomotive syndrome stage 2, sarcopenia, and frailty alone, presented in 24.9%, 1.7%, and 0.2%, respectively. The remaining 64.0% had none of these conditions. Most subjects with sarcopenia and/or frailty also had locomotive syndrome. Preventing locomotive syndrome may help prevent frailty and sarcopenia and subsequent disability.

Co-existence of GM, conventional and organic crops in developing countries: Main debates and concerns.

The co-existence approach of GM crops with conventional agriculture and organic farming as a feasible agricultural farming system has recently been placed in the center of hot debates at the EU-level and become a source of anxiety in developing countries. The main promises of this approach is to ensure "food security" and "food safety" on the one hand, and to avoid the adventitious presence of GM crops in conventional and organic farming on the other, as well as to present concerns in many debates on implementing the approach in developing countries. Here, we discuss the main debates on ("what," "why," "who," "where," "which," and "how") applying this approach in developing countries and review the main considerations and tradeoffs in this regard. The paper concludes that a peaceful co-existence between GM, conventional, and organic farming is not easy but is still possible. The goal should be to implement rules that are well-established proportionately, efficiently and cost-effectively, using crop-case, farming system-based and should be biodiversity-focused ending up with "codes of good agricultural practice" for co-existence.

Heterospecific plant-soil feedback and its relationship to plant traits, species relatedness, and co-occurrence in natural communities.

Plant-soil feedback is one of the mechanisms affecting co-existence of species, ecological succession, and species invasiveness. However, in contrast to conspecific plant-soil feedback, general patterns in heterospecific feedback are mostly unknown. We used a meta-analysis to search for correlations between heterospecific feedback and species relatedness, functional traits, and field co-occurrence patterns. We searched published literature and compiled a data set of 618 PSF interactions. We gathered data on species traits reflecting plant size and growth rate (height, specific leaf area, and life span), co-occurrence in habitats and phylogenetic distance between species pairs. We found that species grew better in soil conditioned by (i) close relatives than in conspecific soil, whereas there was no relationship with phylogeny for distantly related species, (ii) species of greater plant height (but there was no relationship with species SLA or life span), and (iii) species more frequently co-occurring in the field. The results show that heterospecific plant-soil feedback can be explained by plant traits (height) and is reflected in co-occurrence patterns. Phylogeny was a significant predictor of feedbacks over short phylogenetic distance, suggesting fast evolution of traits related to feedback. The low variability explained by the models, however, indicates that other factors such as environmental conditions possibly alter plant-soil feedback responses.

Sexual selection, speciation and constraints on geographical range overlap in birds.

The role of sexual selection as a driver of speciation remains unresolved, not least because we lack a clear empirical understanding of its influence on different phases of the speciation process. Here, using data from 1306 recent avian speciation events, we show that plumage dichromatism (a proxy for sexual selection) does not predict diversification rates, but instead explains the rate at which young lineages achieve geographical range overlap. Importantly, this effect is only significant when range overlap is narrow (< 20%). These findings are consistent with a 'differential fusion' model wherein sexual selection reduces rates of fusion among lineages undergoing secondary contact, facilitating parapatry or limited co-existence, whereas more extensive sympatry is contingent on additional factors such as ecological differentiation. Our results provide a more mechanistic explanation for why sexual selection appears to drive early stages of speciation while playing a seemingly limited role in determining broad-scale patterns of diversification.

Mutation in the S gene of hepatitis B virus and anti-HBs subtype-nonspecificity contributed to the co-existence of HBsAg and anti-HBs in patients with chronic hepatitis B virus infection.

The mechanism for the co-existence of hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs) in chronic HBV infected patients remains controversial. This study aimed to explore the role of HBV S gene mutation and anti-HBs subtype-nonspecificity in patients with simultaneous HBsAg/anti-HBs positivity. Chronic HBV infections with (n = 145, group I) and without (n = 141, group II) anti-HBs were included. The S gene was amplified and sequenced. The neutralization experiment was used in group I patients' sera to determine the specificity of anti-HBs. Additionally, the HBV vaccinated persons' sera were used to estimate the neutralize capacity of anti-HBs against HBsAg in group I patients. Results showed that 2.63% (145/5513) chronic HBV infected patients had positive results for anti-HBs. HBsAg amino acid (aa) substitution rate in 35 patients of group I was significantly higher than that in 58 patients of group II (1.89% vs 0.95%, P < 0.05), especially within "a" determinant (4.05% vs 1.22%, P < 0.05). In group I patients, anti-HBs in (74.29%, 26/35) patients was not directed to the subtypes of the co-existing HBsAg. Besides, some HBsAg variations in group I patients, sG145R mutation, inserted mutations, and continuous aa mutations within the major hydrophilic region (MHR), decreased the neutralized capacity of anti-HBs from HBV vaccinated persons. In conclusion, both of HBsAg mutation and anti-HBs subtype-nonspecificity contributed to the co-existence of HBsAg and anti-HBs in chronic HBV infection. HBV vaccine recipients may still have a risk of HBV infection when exposure to patients with simultaneous HBsAg/anti-HBs positivity.

The conserved phylogeny of blood microbiome.

The proliferation and intensification of diseases have forced every researcher to take actions for a robust understanding of the organisms. This demands deep knowledge about the cells and tissues in an organ and its entire surroundings, more precisely the microbiome community which involves viruses, bacteria, archaea, among others. They play an important role in the function of our body, and act both as a deterrent as well as shelter for diseases. Therefore, it is pertinent to study the relation within the microbiome in a human body. In this work, we analyze the sequence data provided through the Human Microbiome Project to explore evolutionary relations within blood microbiome. The objective is to analyze the common proteins present in the different microbes in the blood and find their phylogeny. The analysis of the phylogenetic relation between these species provides important insights about the conservedness of phylogeny of blood microbiome. Interestingly, the co-existence of five of those common proteins is observed in human too.

Plasticity in nitrogen uptake among plant species with contrasting nutrient acquisition strategies in a tropical forest.

Nitrogen (N) availability influences the productivity and distribution of plants in tropical montane forests. Strategies to acquire soil N, such as direct uptake of organic compounds or associations with root symbionts to enhance N acquisition in exchange for carbon (C), may facilitate plant species coexistence and ecosystem N retention. Alternatively, rapid microbial turnover of soil N forms in tropical soils might promote flexible plant N-uptake strategies and mediate species coexistence. We tested whether sympatric plant species with different root symbiont associations, and therefore potentially different nutrient acquisition strategies, partition chemical forms of N or show plasticity in N uptake in a tropical pre-montane forest in Panama. We traced the movement of three 15 N forms into soil pools, microbes, and seedlings of eleven species differing in root traits. Seedlings were grown in a split-plot field transplant experiment, with plots receiving equimolar mixtures of ammonium, nitrate, and glycine, with one form isotopically labeled in each block. After 48 h, more 15 N was recovered in microbes than in plants, while all pools (extractable organic and inorganic N, microbial biomass, and leaves) contained greater amounts of 15 N from nitrate than from ammonium or glycine. Furthermore, 13 C from dual-labeled glycine was not recovered in the leaves of any seedling, suggesting the studied species do not directly take up organic N or transform organic N prior to translocation to leaves. Nitrogen uptake differed by root symbiont group only for nitrate, with greater 15 N recovery in plants with arbuscular mycorrhizal (AM) associations or proteoid roots compared to orchids. Some root trait groups differed in 15 N recovery among N forms, with greater nitrate uptake than ammonium or glycine by AM-associated and N2 -fixing plants. However, only five of eleven species showed differences in uptake among N forms. These results indicate flexibility in uptake of N forms in tropical plants across root trait groups, with only a few species displaying weak preferences for a specific N form.

Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics.

Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures and their abundance in sewage sludge collected from wastewater treatment plants were analysed. Results indicated that ANAMMOX and DAMO bacteria co-existed in sewage sludge in different seasons and their abundance was positively correlated (P < 0.05). The high abundance of ANAMMOX and DAMO bacteria in autumn and winter indicated that these seasons were the preferred time to favour the growth of ANAMMOX and DAMO bacteria. The community structure of ANNAMOX and DAMO bacteria could also shift with seasonal changes. The "Candidatus Brocadia" genus of ANAMMOX bacteria was mainly recovered in spring and summer, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion. The redundancy analysis revealed that pH and nitrate were the most significant factors affecting community structures of these two groups (P < 0.01). This study reported the diversity of ANAMMOX and DAMO in wastewater treatment plants that may be the basis for new nitrogen removal technologies.

Arbuscular mycorrhizal fungi alter the competitive hierarchy among old-field plant species.

Inoculation with arbuscular mycorrhizal (AM) fungi is known to increase the species diversity of plant communities. One mechanism that can increase the likelihood of species co-existence, and thus species diversity, is a trade-off between competitive ability and the magnitude of plant growth response to AM fungal inoculation. By suppressing the growth of strong competitors while simultaneously enhancing the growth of weak competitors, this trade-off would cause the competitive hierarchy to be less pronounced in soil inoculated with AM fungi relative to non-inoculated conditions. To test whether such a trade-off exists, we quantified competitive abilities and mycorrhizal growth response (MGR) among 21 species that co-occur in old fields in southern Ontario. Competitive ability was determined by calculating competitive effect (CE), or the degree to which each species suppressed the biomass of a common phytometer species, Plantago lanceolata. Higher CE values represent stronger competitive ability. Old-field species varied in their ability to suppress the biomass of the phytometer and MGR was generally positive. There was a statistically significant negative correlation between CE in non-inoculated soil and MGR (r = -0.49, P = 0.02). In addition, variance in CE was 73% lower in soil inoculated with AM fungi compared to non-inoculated soil (P = 0.0023). These findings support the hypothesis that AM fungi weaken strong competitors while enhancing the performance of weak competitors. Because this trade-off compressed the competitive hierarchy among old-field species in soil inoculated with AM fungi, it may be a mechanism by which mycorrhizal fungi enhance species evenness and diversity.