Independent Evolution of Leaf and Root Traits within and among Temperate Grassland Plant Communities

In this study, we used data from temperate grassland plant communities in Alberta, Canada to test two longstanding hypotheses in ecology: 1) that there has been correlated evolution of the leaves and roots of plants due to selection for an integrated whole-plant resource uptake strategy, and 2) that trait diversity in ecological communities is generated by adaptations to the conditions in different habitats. We tested the first hypothesis using phylogenetic comparative methods to test for evidence of correlated evolution of suites of leaf and root functional traits in these grasslands. There were consistent evolutionary correlations among traits related to plant resource uptake strategies within leaf tissues, and within root tissues. In contrast, there were inconsistent correlations between the traits of leaves and the traits of roots, suggesting different evolutionary pressures on the above and belowground components of plant morphology. To test the second hypothesis, we evaluated the relative importance of two components of trait diversity: within-community variation (species trait values relative to co-occurring species; α traits) and among-community variation (the average trait value in communities where species occur; β traits). Trait diversity was mostly explained by variation among co-occurring species, not among-communities. Additionally, there was a phylogenetic signal in the within-community trait values of species relative to co-occurring taxa, but not in their habitat associations or among-community trait variation. These results suggest that sorting of pre-existing trait variation into local communities can explain the leaf and root trait diversity in these grasslands

Plant interactions are unimportant in a subarctic-alpine plant community

We investigated whether plant interaction intensity in a subarctic-alpine meadow is important for determining community structure and species abundance. Using two common species as phytometers, we measured interaction intensity using a neighbor removal approach. Eight biotic and abiotic variables known to influence species abundance and community structure were measured, with regression trees used to examine how plant interactions and the biotic and abiotic variables were related to species evenness, richness, and phytometer spatial cover. A range of interactions was present, with both strong competition and facilitation present over small-scale abiotic and biotic gradients. Despite the variation in interaction intensity, it was generally unrelated to either community structure or phytometer cover. In other words, plant interactions were intense in many cases but were not important to community structure. This may be due to the prevalence of clonal species in this system and the influence of previous year's interactions on plant survival and patterns of community structure. These results also suggest how conflicting theories of the role of competition in unproductive environments may be resolved. Our findings suggest that plant interactions may be intense in reducing individual growth, while simultaneously not important in the context of community structure. Plant interactions need to be viewed and tested relative to other factors and stresses to accurately evaluate their importance in plant communities, with continued differentiation between the intensity of plant interactions and their relative importance in communities

Interspecific differences in root foraging precision cannot be directly inferred from species' mycorrhizal status or fine root economics

Nutrient acquisition in plants can be represented by a suite of intercorrelated root traits such as root diameter, nitrogen content, root tissue density and specific root length. However, it is unclear how a plant's ability to precisely forage for nutrients in a heterogeneous soil environment (i.e. the precision of placing roots into nutrient-rich areas) relates to these traits. Mycorrhizal symbiosis also affects the relationship between the fine root traits and root foraging precision because fungal hyphae may be used for foraging instead of roots. Hypotheses matching high root foraging precision with low mycorrhizal colonization or ‘fast' acquisitive strategies of plants have been raised based either on data from tree species or a limited number of herbaceous species. To test these hypotheses, we compiled data quantifying the experimentally measured degree to which root biomass responded to patchy substrate nutrient concentrations (i.e. root foraging precision) for 123 herbaceous grassland species using a partial meta-analysis. We tested root foraging precision relationship with root traits involved in nutrient acquisition and mycorrhizal symbiosis (root diameter, specific root length, root tissue density, root tissue nitrogen content and mycorrhizal colonization). The root foraging precision data came from four different pot experiments, and the trait data were extracted from publicly available trait databases. We used a phylogenetically informed approach in order to detect the degree of conservation of the relationships. We found that root foraging precision was not significantly correlated with other fine root traits and mycorrhizal colonization. Thus, it appears unrelated to the main dimensions of the nutrient acquisition space of herbaceous species, namely acquisitive–conservative strategy and outsourcing of acquisition to the fungi. Also, we found only a very weak phylogenetic signal in root foraging precision of 123 species. Our results suggest that root foraging precision constitutes another distinct, evolutionarily independent dimension in herbaceous species' trait space.acceptedVersio

Large-scale insect outbreak homogenizes the spatial structure of ectomycorrhizal fungal communities

Ectomycorrhizal fungi (plant symbionts) are diverse and exist within spatially variable communities that play fundamental roles in the functioning of terrestrial ecosystems. However, the underlying ecological mechanisms that maintain and regulate the spatial structuring of ectomycorrhizal fungal communities are both complex and remain poorly understood. Here, we use a gradient of mountain pine beetle (Dendroctonus ponderosae) induced tree mortality across eleven stands in lodgepole pine (Pinus contorta) forests of western Canada to investigate: (i) the degree to which spatial structure varies within this fungal group, and (ii) how these patterns may be driven by the relative importance of tree mortality from changes in understory plant diversity, productivity and fine root biomass following tree death. We found that the homogeneity of the ectomycorrhizal fungal community increased with increasing tree death, aboveground understory productivity and diversity. Whereas, the independent effect of fine root biomass, which declined along the same gradient of tree mortality, increased the heterogeneity of the ectomycorrhizal fungal community. Together, our results demonstrate that large-scale biotic disturbance homogenizes the spatial patterns of ectomycorrhizal fungal communities

Not a melting pot: Plant species aggregate in their non-native range

Aim Plant species continue to be moved outside of their native range by human activities. Here, we aim to determine whether, once introduced, plants assimilate into native communities or whether they aggregate, thus forming mosaics of native- and alien-rich communities. Alien species might aggregate in their non-native range owing to shared habitat preferences, such as their tendency to establish in high-biomass, species-poor areas. Location Twenty-two herbaceous grasslands in 14 countries, mainly in the temperate zone. Time period 2012-2016. Major taxa studied Plants. Methods We used a globally coordinated survey. Within this survey, we found 46 plant species, predominantly from Eurasia, for which we had co-occurrence data in their native and non-native ranges. We tested for differences in co-occurrence patterns of 46 species between their native (home) and non-native (away) range. We also tested whether species had similar habitat preferences, by testing for differences in total biomass and species richness of the patches that species occupy in their native and non-native ranges. Results We found the same species to show different patterns of association depending on whether they were in their native or non-native range. Alien species were negatively associated with native species; instead, they aggregated with other alien species in species-poor, high-biomass communities in their non-native range compared with their native range. Main conclusions The strong differences between the native (home) and non-native (away) range in species co-occurrence patterns are evidence that the way in which species associate with resident communities in their non-native range is not species dependent, but is instead a property of being away from their native range. These results thus highlight that species might undergo important ecological changes when introduced away from their native range. Overall, we show origin-dependent associations that result in novel communities, in which alien-rich patches exist within a mosaic of native-dominated communities

Effectiveness of an Interprofessional Education Event for Graduate Health Professional Students

ABSTRACT Purpose: The purpose of this study was to investigate the impact of a single, optional, half-day, interprofessional education (IPE) event for a myriad of graduate-level health professional students (n=44) at a university in Illinois, USA. Methods: The researchers in this study examined students’ performance on two out of six of the domains on the Interprofessiomnal Collaborator Assessment Rubric (ICAR): Roles and Responsibilities and Communication Strategies. This study also investigated quantitative and qualitative findings related to student perceptions regarding this IPE opportunity. Results: Results indicated that students met or exceeded the minimum competency for the ranking of “developing” for all 6 of the behaviors evaluated. Results also revealed that this half-day extracurricuricular IPE event was viewed favorably by health-professional students and created a venue whereby students belonging to different health professional programs can enter into discussions and learn about each others’ respective roles and responsibilities in patient care. Conclusion: The creation and implementation of short term extracurricular IPE events may be a valuable alternative for healthcare programs that are unable to implement IPE activities due to some of the common barriers impacting the development, implementation, or continuation of IPE opportunities

Unsupervised Domain Adaptation for Automated Knee Osteoarthritis Phenotype Classification

Purpose: The aim of this study was to demonstrate the utility of unsupervised domain adaptation (UDA) in automated knee osteoarthritis (OA) phenotype classification using a small dataset (n=50). Materials and Methods: For this retrospective study, we collected 3,166 three-dimensional (3D) double-echo steady-state magnetic resonance (MR) images from the Osteoarthritis Initiative dataset and 50 3D turbo/fast spin-echo MR images from our institute (in 2020 and 2021) as the source and target datasets, respectively. For each patient, the degree of knee OA was initially graded according to the MRI Osteoarthritis Knee Score (MOAKS) before being converted to binary OA phenotype labels. The proposed UDA pipeline included (a) pre-processing, which involved automatic segmentation and region-of-interest cropping; (b) source classifier training, which involved pre-training phenotype classifiers on the source dataset; (c) target encoder adaptation, which involved unsupervised adaption of the source encoder to the target encoder and (d) target classifier validation, which involved statistical analysis of the target classification performance evaluated by the area under the receiver operating characteristic curve (AUROC), sensitivity, specificity and accuracy. Additionally, a classifier was trained without UDA for comparison. Results: The target classifier trained with UDA achieved improved AUROC, sensitivity, specificity and accuracy for both knee OA phenotypes compared with the classifier trained without UDA. Conclusion: The proposed UDA approach improves the performance of automated knee OA phenotype classification for small target datasets by utilising a large, high-quality source dataset for training. The results successfully demonstrated the advantages of the UDA approach in classification on small datasets.Comment: Junru Zhong and Yongcheng Yao share the same contribution. 17 pages, 4 figures, 4 table