Complex Relationships between Competing Guilds along Large-Scale Environmental Gradients

Despite much research over the past 30 years there is still little general understanding of how the outcomes of interactions vary along environmental gradients, particularly at large geographic scales. A simple expectation is that decreasing environmental quality should reduce densities of competitors and hence the effects of competition should weaken in poorer environments. A counter-intuitive consequence is that associations between densities of competitors might change from negative to positive as environments decrease in quality. Here we test these predictions in a set of vascular plant communities where perennial species share space and resources with less competitive annuals. We surveyed nine grey dune communities annually for 5 years along a cross-European latitudinal gradient of habitat quality. We find that densities of annual and perennial species are negatively correlated at the high-quality end of the gradient, while at the low-quality end guild densities are uncorrelated or positively correlated, consistent with a weakening of competition linked to increasing environmental limitations. Our results suggest that even simple interactions can give rise to non-obvious changes in species associations along environmental gradients. They highlight that understanding the outcome of species interactions may require explicit characterization of their changing intensity with environmental quality, and that the factors limiting species’ co-distribution can vary along environmental gradients

The Evolution of Functionally Redundant Species; Evidence from Beetles

While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world’s 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10–20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect

Developing hierarchical density‐structured models to study the national‐scale dynamics of an arable weed

Population dynamics can be highly variable in the face of environmental heterogeneity, and understanding this variation is central in the study of ecology. Robust management decisions require that we understand how populations respond to management at a range of scales, and under a broad suite of conditions. Population models are potentially valuable tools in addressing this challenge. However, without adequate data, models can fail to produce useful results. Populations of arable weeds are particularly problematic in this respect, as they are widespread and their dynamics are extremely variable. Owing to the inherent cost of collecting data, most studies of plant population dynamics are derived from localized experiments under a small range of environmental conditions, limiting the extent to which variance in population dynamics can be measured. Density‐structured models provide a route to rapid, large‐scale analysis of population dynamics, and can expand the scale of ecological models that are directly tied to data. Here we extend previous density‐structured models to include environmental heterogeneity, variation in management, and to account for inter‐population variation. We develop, parameterize, and test hierarchical density‐structured models for a common agricultural weed, black‐grass (Alopecurus myosuroides). We model the dynamics of this species in response to crop management, using survey data gathered over 4 yr from 364 fields across a network of 45 UK farms. We show that hierarchical density‐structured models provide a substantial improvement over their nonhierarchical counterparts. Using these models, we demonstrate that several alternative crop rotations are effective in reducing weed densities. Rotations with high wheat prevalence exhibit the most severe infestations, and diverse rotations generally have lower weed densities. However, a key outcome is that in many cases the effect of crop rotation is small compared to the high variability arising from spatiotemporal heterogeneity. This result highlights the need to monitor and model population dynamics across large spatial and temporal scales in order to account for variation in the drivers of plant dynamics. Our framework for data collection and modeling provides a means to achieve this

Electromagnetic navigation bronchoscopy in the European cohort of the prospective, multicenter NAVIGATE study

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Optimisation and molecular signalling of apoptosis in sequential cryotherapy and chemotherapy combination in human A549 lung cancer xenografts in SCID mice

We define the optimal parameters for combination of cryotherapy (nitrous oxide) with chemotherapy (vinorelbine ditartrate, VNB) treatment and characterise some of the signals involved for apoptosis activation. No advantage appeared when cryotherapy and VNB were combined simultaneously compared to cryosurgery alone. In contrast, tumour volumes were reduced after a sequential treatment schedule, where each individual treatment was separated by 48 h. No significant benefit appeared when the sequential treatment was separated by 24 h, although some individual mice showed a good response. The sequence of treatment had no impact on the observed tumour growth inhibition in mice. The number of apoptotic cells was significantly augmented in the sequential treatment schedule where VNB was administered 48 h before cryotherapy. In this sequential treatment, the number of apoptotic cells correlated with heightened expression of the BH3-only Puma, Noxa and Bim-EL, at both the mRNA and protein levels. No significant change in Bax, Bcl-xL and Bcl-2 mRNA expression was apparent, whereas Mcl-1 expression increased only slightly to a much lower level than BH3-only mRNAs. Our data indicate that 48 h sequential rather than simultaneous cryotherapy with VNB in future cancer cryochemotherapy schedules will enhance the tumour response, and argue that VNB administration, 48 h before cryotherapy, will provoke apoptosis more efficiently

Functional, size and taxonomic diversity of fish along a depth gradient in the deep sea

Biodiversity is well studied in ecology and the concept has been developed to include traits of species, rather than solely taxonomy, to better reflect the functional diversity of a system. The deep sea provides a natural environmental gradient within which to study changes in different diversity metrics, but traits of deep-sea fish are not widely known, hampering the application of functional diversity to this globally important system. We used morphological traits to determine the functional richness and functional divergence of demersal fish assemblages along the continental slope in the Northeast Atlantic, at depths of 300–2,000 m. We compared these metrics to size diversity based on individual body size and species richness. Functional richness and size diversity showed similar patterns, with the highest diversity at intermediate depths; functional divergence showed the opposite pattern, with the highest values at the shallowest and deepest parts of the study site. Species richness increased with depth. The functional implications of these patterns were deduced by examining depth-related changes in morphological traits and the dominance of feeding guilds as illustrated by stable isotope analyses. The patterns in diversity and the variation in certain morphological traits can potentially be explained by changes in the relative dominance of pelagic and benthic feeding guilds. All measures of diversity examined here suggest that the deep areas of the continental slope may be equally or more diverse than assemblages just beyond the continental shelf

Lung Volume Reduction Coil Treatment vs Usual Care in Patients With Severe Emphysema: The REVOLENS Randomized Clinical Trial:

IMPORTANCE: Therapeutic options for severe emphysema are limited. Lung volume reduction using nitinol coils is a bronchoscopic intervention inducing regional parenchymal volume reduction and restoring lung recoil. OBJECTIVE: To evaluate the efficacy, safety, cost, and cost-effectiveness of nitinol coils in treatment of severe emphysema. DESIGN, SETTING, AND PARTICIPANTS: Multicenter 1:1 randomized superiority trial comparing coils with usual care at 10 university hospitals in France. Enrollment of patients with emphysema occurred from March to October 2013, with 12-month follow-up (last follow-up, December 2014). INTERVENTIONS: Patients randomized to usual care (n = 50) received rehabilitation and bronchodilators with or without inhaled corticosteroids and oxygen; those randomized to bilateral coil treatment (n = 50) received usual care plus additional therapy in which approximately 10 coils per lobe were placed in 2 bilateral lobes in 2 procedures. MAIN OUTCOMES AND MEASURES: The primary outcome was improvement of at least 54 m in the 6-minute walk test at 6 months (1-sided hypothesis test). Secondary outcomes included changes at 6 and 12 months in the 6-minute walk test, lung function, quality of life as assessed by St George's Respiratory Questionnaire (range, 0-100; 0 being the best and 100 being the worst quality of life; minimal clinically important difference, ≥4), morbidity, mortality, total cost, and cost-effectiveness. RESULTS: Among 100 patients, 71 men and 29 women (mean age, 62 years) were included. At 6 months, improvement of at least 54 m was observed in 18 patients (36%) in the coil group and 9 patients (18%) in the usual care group, for a between-group difference of 18% (1-sided 95% CI, 4% to ∞; P = .03). Mean between-group differences at 6 and 12 months in the coil and usual care groups were +0.09 L (95% CI, 0.05 L to ∞) (P = .001) and +0.08 L (95% CI, 0.03 L to ∞) (P = .002) for forced expiratory volume in the first second, +21 m (95% CI, -4 m to ∞) (P = .06) and +21 m (95% CI, -5 m to ∞) (P = .12) for 6-minute walk distance, and -13.4 points (95% CI, -8 points to ∞) and -10.6 points (95% CI, -5.8 points to ∞) for St George's Respiratory Questionnaire (1-sided P < .001 for both). Within 12 months, 4 deaths occurred in the coil group and 3 in the usual care group. The mean total 1-year per-patient cost difference between groups was $47,908 (95$47,879-$48,073) (P < .001); the incremental cost-effectiveness ratio was$782,598 per additional quality-adjusted life-year. CONCLUSIONS AND RELEVANCE: In this preliminary study of patients with severe emphysema followed up for 6 months, bronchoscopic treatment with nitinol coils compared with usual care resulted in improved exercise capacity with high short-term costs. Further investigation is needed to assess durability of benefit and long-term cost implications. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01822795.Comment in : *Lung Volume Reduction Coils for Severe Emphysema--Reply. [JAMA. 2016] *Coils implanted into lungs show promise for emphysema. [BMJ. 2016] *Lung Volume Reduction Coils for Severe Emphysema. [JAMA. 2016] *Bronchoscopic Lung Volume Reduction in COPD: Lessons in Implementing Clinically Based Precision Medicine. [JAMA. 2016

Emergent neutrality leads to multimodal species abundance distributions

Recent analyses of data sampled in communities ranging from corals and fossil brachiopods to birds and phytoplankton suggest that their species abundance distributions have multiple modes, a pattern predicted by none of the existing theories. Here we show that the multimodal pattern is consistent with predictions from the theory of emergent neutrality. This adds to the observations, suggesting that natural communities may be shaped by the evolutionary emergence of groups of similar species that coexist in niches. Such self-organized similarity unifies niche and neutral theories of biodiversity