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Mycorrhizal response is the most common metric for characterizing how much benefit a plant derives from mycorrhizal symbiosis. Traditionally, ecologists have used these metrics to generalize benefit from mycorrhizal symbiosis in plant species, ignoring the potential for plant intraspecific trait variation to alter the outcome of the mutualism. In order for mean trait values to be useful as a functional trait to describe a species, as has been attempted for mycorrhizal response traits, interspecific variation must be much larger than intraspecific variation. While the variation among species has been extensively studied with respect to mycorrhizal response traits, variation within species has rarely been examined. We conducted a systematic review and analyzed how much variation for mycorrhizal growth and nutrient response typically exists within a plant species. We assessed 28 publications that included 60 individual studies testing mycorrhizal response in at least five genotypes of a plant species, and we found that intraspecific trait variation for mycorrhizal response was generally very large and highly variable depending on study design. The difference between the highest and lowest growth response in a study ranged from 10% to 350% across studies, and 36 of the studies included species for which both positive and negative growth responses to mycorrhizae were observed across different genotypes. The intraspecific variation for mycorrhizal growth response in some of these studies was larger than the variation documented among species across the plant kingdom. Phosphorus concentration and content was measured in 17 studies and variation in phosphorus response was similar to variation in growth responses. We also found that plant genotype was just as important for predicting mycorrhizal response as the effects of fungal inoculant identity. Our analysis highlights not only the potential importance of intraspecific trait variation for mycorrhizal response, but also the lack of research that has been done on the scale of this variation in plant species. Including intraspecific variation into research on the interactions between plants and their symbionts can increase our understanding of plant coexistence and ecological stability.

Quantifying community-level trait shifts, driven by species turnover and intraspecific trait variation (ITV), is essential for understanding environmental filtering and elucidating community assembly and species coexistence. While well-studied in seed plants, the relative roles of these processes in ferns-a key component of forest understories-remain poorly understood. Here, we evaluated how topographic, soil, and overstory biotic factors influence the functional traits of understory fern communities at a local scale in a subtropical forest. We measured six key functional traits across 45 fern species in 121 plots of 10 m × 10 m. We found that trait-environment models based on species turnover alone (CWM_fixed) had consistently higher explanatory power than models that included ITV (CWM_specific) (mean pseudo-R² = 0.56 vs. 0.23). Variance partitioning revealed that trait-environment relationships were primarily driven by the unique effects of environmental factors rather than their shared variance, identifying soil properties and overstory biotic structure as distinct, independent drivers of community functional composition (explaining 23.0% and 17.7% of variance for plant growth and resource-use strategies, respectively). Our results highlight two key insights: (1) the understory fern community responds to environmental filters primarily through species turnover (compositional shifts) rather than widespread intraspecific trait variation; (2) soil phosphorus and forest structure act as critical filters that together shape community-level functional traits of ferns.

Theoretical and empirical ecology have recently explored the role of intraspecific trait variation (ITV) in structuring ecological communities. Such trait variation may be correlated with high environmental variability within a site or across a species' range. Here we explore the relationship between ITV, spatial and temporal environmental heterogeneity, and the breadth of species' environmental distributions for 33 tree species across eight sites occurring along marked environmental gradients in Puerto Rico. Specifically, we asked (1) If within‐site ITV is positively correlated with site‐level temporal and spatial environmental variation, and (2) How across‐site ITV relates to the breadth of species' environmental distributions on the island. Two key plant traits, leaf mass per area (LMA) and wood density, were used to understand the association between ITV and environmental variation. We examined ITV across species and sites using statistical models to assess the relationship between (1) within‐site ITV and site‐level spatial (topography) and temporal (rainfall) environmental variability; (2) across‐site ITV and environmental variation across the species geographic range on the island. We also assessed the relationship between across‐site mean trait values and island‐wide environmental ranges. (1) Across all species, we did not find any significant associations between within‐site ITV and site‐level temporal or spatial variability. (2) Greater ITV values of LMA and wood density were associated with larger environmental ranges. We also found that species with high wood density, a trait associated with a conservative growth strategy, had narrower ranges across climatic conditions, but this pattern was not evident for LMA. Our findings emphasize the complexity of the relationships between ITV and species distributions with respect to environmental heterogeneity at different spatial and temporal scales. These complexities are important for research on species distributions and range‐shift dynamics. Here we explore the relationship between ITV, spatial and temporal environmental heterogeneity, and the breadth of species' environmental distributions for 33 tree species across eight sites across marked environmental gradients in Puerto Rico. Species with greater across‐site ITV in wood density and LMA occurred over broader ranges of potential evapotranspiration but lower elevation ranges. We also found that species with high wood density, a trait associated with a conservative growth strategy, had narrower ranges across climatic conditions, while there were no consistent patterns for species with high LMA.

Understanding the relationship between intraspecific trait variability (ITV) and its biotic and abiotic drivers is crucial for advancing population and community ecology. Despite its importance, there is a lack of guidance on how to effectively sample ITV and reduce bias in the resulting inferences. In this study, we explored how sample size affects the estimation of population‐level ITV, and how the distribution of sample sizes along an environmental gradient (i.e., sampling design) impacts the probabilities of committing Type I and II errors. We investigated Type I and II error probabilities using four simulated scenarios which varied sampling design and the strength of the ITV‐environment relationships. We also applied simulation scenarios to empirical data on populations of the small mammal, Peromyscus maniculatus across gradients of latitude and temperature at sites in the National Ecological Observatory Network (NEON) in the continental United States. We found that larger sample sizes reduce error rates in the estimation of population‐level ITV for both in silico and Peromyscus maniculatus populations. Furthermore, the influence of sample size on detecting ITV‐environment relationships depends on how sample sizes and population‐level ITV are distributed along environmental gradients. High correlations between sample size and the environment result in greater Type I error, while weak ITV–environmental gradient relationships showed high Type II error probabilities. Therefore, having large sample sizes that are even across populations is the most robust sampling design for studying ITV‐environment relationships. These findings shed light on the complex interplay among sample size, sampling design, ITV, and environmental gradients. Linking organismal traits to environmental gradients reveals mechanisms underlying patterns of biodiversity, from individual adaptations to ecosystem‐scale dynamics. This study provides much‐needed guidance for optimizing sampling strategies to improve the accuracy of population‐level characterization of intraspecific trait variability (ITV) and estimation of ITV‐environment relationships, thereby significantly advancing ecological understanding.

Background Stereotactic body radiotherapy (SBRT) is an established local treatment method for patients with hepatic oligometastasis or oligoprogression. Liver metastases often occur in close proximity to radiosensitive organs at risk (OARs). This limits the possibility to apply sufficiently high doses needed for optimal local control. Online MR-guided radiotherapy (oMRgRT) is expected to hold potential to improve hepatic SBRT by offering superior soft-tissue contrast for enhanced target identification as well as the benefit of gating and daily real-time adaptive treatment. The MAESTRO trial therefore aims to assess the potential advantages of adaptive, gated MR-guided SBRT compared to conventional SBRT at a standard linac using an ITV (internal target volume) approach. Methods This trial is conducted as a prospective, randomized, three-armed phase II study in 82 patients with hepatic metastases (solid malignant tumor, 1–3 hepatic metastases confirmed by magnetic resonance imaging (MRI), maximum diameter of each metastasis ≤ 5 cm (in case of 3 metastases: sum of diameters ≤ 12 cm), age ≥ 18 years, Karnofsky Performance Score ≥ 60%). If a biologically effective dose (BED) ≥ 100 Gy (α/β = 10 Gy) is feasible based on ITV-based planning, patients will be randomized to either MRgRT or ITV-based SBRT. If a lesion cannot be treated with a BED ≥ 100 Gy, the patient will be treated with MRgRT at the highest possible dose. Primary endpoint is the non-inferiority of MRgRT at the MRIdian Linac® system compared to ITV-based SBRT regarding hepatobiliary and gastrointestinal toxicity CTCAE III or higher. Secondary outcomes investigated are local, locoregional (intrahepatic) and distant tumor control, progression-free survival, overall survival, possible increase of BED using MRgRT if the BED is limited with ITV-based SBRT, treatment-related toxicity, quality of life, dosimetric parameters of radiotherapy plans as well as morphological and functional changes in MRI. Potential prognostic biomarkers will also be evaluated. Discussion MRgRT is known to be both highly cost- and labor-intensive. The MAESTRO trial aims to provide randomized, higher-level evidence for the dosimetric and possible consecutive clinical benefit of MR-guided, on-table adaptive and gated SBRT for dose escalation in critically located hepatic metastases adjacent to radiosensitive OARs. Trial registration The study has been prospectively registered on August 30th, 2021: Clinicaltrials.gov, “Magnetic Resonance-guided Adaptive Stereotactic Body Radiotherapy for Hepatic Metastases (MAESTRO)”, NCT05027711.

Biological invasions provide a unique window into community assembly. While classic theory predicts that native species must differentiate their niches to coexist with an invader, the actual outcomes under intense pressure are complex. Our study examines community reassembly under extreme pressure from the invasive ant Solenopsis invicta. We found that while native species do differentiate themselves from the invader, the overwhelming competition constrains this process, forcing survivors into a narrow, shared functional space. This constrained niche differentiation produces a pattern of community-level functional convergence, a process where functionally dissimilar communities become more similar under intense environmental filtering, as survivors are forced into a narrow, shared niche space. The capacity for these rapid, adaptive niche shifts is rooted in intraspecific trait variation (ITV). We also identified a dynamic feedback loop through density-dependent phenotypic plasticity in the invader. By showing how the foundational process of niche differentiation leads to a convergent outcome under extreme pressure, our work clarifies the rules of community assembly in an increasingly invaded world.

The use of surface electromyography (sEMG) signals gains importance in rehabilitation and sports science because it provides a noninvasive and convenient way to analyze the activities of muscles. Since sEMG signals are weak, nonstationary electrical signals mixed with baseline noise, motion artifacts, power line interference, and many other types of noise, these signals need to be denoised for the extraction of useful information. This paper presents a method of denoising sEMG signals based on the combination of complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and interval total variation (ITV). First, we devised the CEEMDAN method to decompose an sEMG signal into several intrinsic mode functions (IMFs). Next, we categorized the IMFs into signal-dominant and noise-dominant IMFs according to energy entropy and frequency-domain transform. Then, we separately denoised these signal-dominant IMFs using the ITV method. Finally, we reconstructed the denoised signal-dominant IMFs to obtain a denoised sEMG signal. Extensive comparisons conducted on both synthetic noisy and real sEMG signals demonstrate the effectiveness of the CEEMDAN-ITV method.

Introduction The detailed anatomy visualization with magnetic resonance (MR)‐guided radiotherapy is particularly attractive for abdominal treatments, but patient respiratory motion can compromise image quality. The “navigator technique” produces high‐quality 3D images, triggered by diaphragm displacement, in exhale phase only. The gold standard for planning is 4D imaging, which visualizes the lesion for all breathing phases. When 4D imaging is not available, an alternative is using 3D imaging combined with motion information from cine‐MR. Methods This work investigates two alternative internal target volume (ITV) generation methods and compares them with the original treatment 4DCT imaging ITV. Datasets were analyzed from 10 upper abdominal patients that originally had been treated with a 4DCT‐based ITV. In addition to the 4DCT, these patients received an exhale MR and cine‐MR scans prior to treatment. An MR‐CT‐compatible motion phantom was also used to compare the two alternative ITV methods with the clinical 4DCT method. The first ITV method uses “margins expansion” (ME method) asymmetrically. The second method duplicates the exhale gross tumor volume (GTV) and shifts it to the positions of the average inhale GTV and mid‐position GTV. The ITV is the “Boolean combine” (BC method) of the three displaced GTVs. The ME and BC methods were compared with the clinical 4DCT method using the Dice similarity coefficient (DSC) to determine the impact of approximating the true GTV trajectory and neglecting deformation. Results The ITV DSC ranges were 73%–96% for the ME method and 76%96% for the BC method. The BC approach created smaller treatment volumes than the ME method and more closely resembled the 4DCT margin for cases with larger motion and a significant component in the anterior–posterior direction. Conclusions An exhale MR combined with cine‐MR can be used to simply create an ITV for adaptive MR‐guided radiotherapy. For small lesions with larger anterior motion, the Boolean Combine method is the more accurate method.

Background The internal target volume (ITV) approach and the mid-ventilation (MidV) concept are the two main respiratory motion-management strategies under free breathing. The purpose of this work was to compare the actual in-treatment target coverage during volumetric modulated arctherapy (VMAT) delivered through both ITV-based and MidV-based planning target volume (PTV) and to provide knowledge in choosing the optimal PTV for stereotactic body radiotherapy (SBRT) for lung lesions. Methods and materials Thirty-two lung cancer patients treated by a VMAT technique were included in the study. For each fraction, the mean time-weighted position of the target was localized by using a 4-dimensional cone-beam CT (4D-CBCT)-based image guidance procedure. The respiratory-correlated location of the gross tumor volume (GTV) during treatment delivery was determined for each fraction by using in-treatment 4D-CBCT images acquired concurrently with VMAT delivery (4D-CBCT in-treat ). The GTV was delineated from each of the ten respiratory phase-sorted 4D-CBCT in-treat datasets for each fraction. We defined target coverage as the average percentage of the GTV included within the PTV during the patient’s breathing cycle averaged over the treatment course. Target coverage and PTVs were reported for a MidV-based PTV (PTV MidV ) using dose-probabilistic margins and three ITV-based PTVs using isotropic margins of 5 mm (PTV ITV + 5mm ), 4 mm (PTV ITV + 4mm ) and 3 mm (PTV ITV + 3mm ). The in-treatment baseline displacements and target motion amplitudes were reported to evaluate the impact of both parameters on target coverage. Results Overall, 100 4D-CBCT in-treat images were analyzed. The mean target coverage was 98.6, 99.6, 98.9 and 97.2% for PTV MidV , PTV ITV + 5mm , PTV ITV + 4mm and PTV ITV + 3mm , respectively. All the PTV margins led to a target coverage per treatment higher than 95% in at least 90% of the evaluated cases. Compared to PTV ITV + 5mm , PTV MidV , PTV ITV + 4mm and PTV ITV + 3mm had mean PTV reductions of 16, 19 and 33%, respectively. Conclusion When implementing VMAT with 4D-CBCT-based image guidance, an ITV-based approach with a tighter margin than the commonly used 5 mm margin remains an alternative to the MidV-based approach for reducing healthy tissue exposure in lung SBRT. Compared to PTV MidV , PTV ITV + 3mm significantly reduced the PTV while still maintaining an adequate in-treatment target coverage.