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1. Reconstruction of the Crossing Type of a Point Set from the Compatible Exchange Graph of Noncrossing Spanning Trees

   https://doi.org/10.1007/978-3-030-14085-4_19  

   Marcos Oropeza, Csaba D. (February 2019, International Conference on Discrete Geometry for Computer Imagery)

   Let P be a set of n points in the plane in general position. The order type of P specifies, for every ordered triple, a positive or negative orientation; and the x-type (a.k.a. crossing type) of P specifies, for every unordered 4-tuple, whether they are in convex position. Geometric algorithms on P typically rely on primitives involving the order type or x-type (i.e., triples or 4-tuples). In this paper, we show that the x-type of P can be reconstructed from the compatible exchange graph G1(P) of noncrossing spanning trees on P. This extends a recent result by Keller and Perles (2016), who proved that the x-type of P can be reconstructed from the exchange graph G0(P) of noncrossing spanning trees, where G1(P) is a subgraph of G0(P) . A crucial ingredient of our proof is a structure theorem on the maximal sets of pairwise noncrossing edges (msnes) between two components of a planar straight-line graph on the point set P. 

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2. 2-Adic point counting on K3 surfaces

   https://doi.org/10.1007/s40993-022-00378-x  

   Elsenhans, Andreas-Stephan; Jahnel, Jörg (December 2022, Research in Number Theory)

   Abstract This article reports on an approach to point counting on algebraic varieties over finite fields that is based on a detailed investigation of the 2-adic orthogonal group. Combining the new approach with a p -adic method, we count the number of points on some K 3 surfaces over the field $$\mathbb {F}_{\!p}$$ F p , for all primes $$p < 10^8$$ p < 10 8 . 

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3. Spider and caterpillar abundance, tree size, and canopy closure metrics in a tree diversity experiment

   https://doi.org/10.6084/m9.figshare.20997910.v1  

   Burghardt, Karin; Butz, Elizabeth; Schmitt, Lauren; Parker, John (January 2023, figshare)

   This data set includes spider abundances recorded on focal trees in a large-scale forest diversity manipulation at the Smithsonian Environmental Research Center in Edgewater, MD, USA. We repeatedly sampled spiders on 540 trees of 15 species planted in single or mixed species combinations (4 or 12) in June and August of 2019 and 2021. We took caterpillar abundance data, measured tree height, and took canopy closure measurements on each tree in 2021. Data associated with the paper: Positive tree diversity effects on arboreal spider abundance are tied to canopy cover in a forest experiment published in Ecology 

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4. The interactive effects of heat stress, parasitism and host plant quality in a host–parasitoid system

   https://doi.org/10.1111/1365-2435.14498  

   Parker, Anna L.; Kingsolver, Joel G. (January 2024, Functional Ecology)

   Abstract Species interactions are expected to change in myriad ways as the frequency and magnitude of extreme temperature events increase with anthropogenic climate change.The relationships between endosymbionts, parasites and their hosts are particularly sensitive to thermal stress, which can have cascading effects on other trophic levels.We investigate the interactive effects of heat stress and parasitism on a terrestrial tritrophic system consisting of two host plants (one common, high‐quality plant and one novel, low‐quality plant), a caterpillar herbivore and a specialist parasitoid wasp.We used a fully factorial experiment to determine the bottom‐up effects of the novel host plant on both the caterpillars' life history traits and the wasps' survival, and the top‐down effects of parasitism and heat shock on caterpillar developmental outcomes and herbivory levels.Host plant identity interacted with thermal stress to affect wasp success, with wasps performing better on the low‐quality host plant under constant temperatures but worse under heat‐shock conditions.Surprisingly, caterpillars consumed less leaf material from the low‐quality host plant to reach the same final mass across developmental outcomes.In parasitized caterpillars, heat shock reduced parasitoid survival and increased both caterpillar final mass and development time on both host plants.These findings highlight the importance of studying community‐level responses to climate change from a holistic and integrative perspective and provide insight into potential substantial interactions between thermal stress and diet quality in plant–insect systems. Read the freePlain Language Summaryfor this article on the Journal blog. 

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5. Mechanistic links between biodiversity effects on ecosystem functioning and stability in a multi‐site grassland experiment

   https://doi.org/10.1111/1365-2745.13725  

   Yan, Ying; Connolly, John; Liang, Maowei; Jiang, Lin; Wang, Shaopeng (July 2021, Journal of Ecology)

   Abstract Although the positive effects of biodiversity on ecosystem functioning and stability have been extensively documented in the literature, previous studies have mostly explored the mechanisms of functioning and stability independently. It is unclear how biodiversity effects on functioning may covary with those on stability.Here we developed an integrated framework to explore links between mechanisms underlying biodiversity effects on functioning and those on stability. Specifically, biodiversity effects on ecosystem functioning were partitioned into complementarity effects (CE) and selection effects (SE), and those on stability were partitioned into species asynchrony and species stability. We investigated howCEandSEwere linked to species asynchrony and stability and how their links might be mediated by species evenness, using a multi‐site grassland experiment.Our mixed‐effects models showed that a higher community productivity was mainly due toCEand a higher community stability was mainly due to species asynchrony. Moreover,CEwas positively related to species asynchrony, thus leading to a positive association between ecosystem productivity and stability.We used a structural equation model to illustrate how species evenness might mediate links between the various mechanisms. Communities with a higher evenness exhibited a higherCEand species asynchrony, but a lowerSEand species stability. These evenness‐mediated associations enhanced the positive relationship betweenCEand species asynchrony, but blurred that betweenSEand species asynchrony.Synthesis. Our findings demonstrate mechanistic links between biodiversity effects on ecosystem functioning and stability. By doing so, our study contributes a novel framework for understanding ecological mechanisms of the functioning–stability relationship, which has important implications for developing management plans focused on strengthening synergies between ecosystem functioning and stability over the long term. 

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