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1. Lambek pregroups are Frobenius spiders in preorders

   Pavlovic, Dusko ( November 2021 , Compositionality)

   "Spider" is a nickname of special Frobenius algebras, a fundamental structure from mathematics, physics, and computer science. Pregroups are a fundamental structure from linguistics. Pregroups and spiders have been used together in natural language processing: one for syntax, the other for semantics. It turns out that pregroups themselves can be characterized as pointed spiders in the category of preordered relations, where they naturally arise from grammars. The other way around, preordered spider algebras in general can be characterized as unions of pregroups. This extends the characterization of relational spider algebras as disjoint unions of groups. The compositional framework that emerged with the results suggests new ways to understand and apply the basis structures in machine learning and data analysis. 

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2. Spider webs, stable isotopes and molecular gut content analysis: Multiple lines of evidence support trophic niche differentiation in a community of Hawaiian spiders

   https://doi.org/10.1111/1365-2435.13361  

   Kennedy, Susan ; Lim, Jun Ying ; Clavel, Joanne ; Krehenwinkel, Henrik ; Gillespie, Rosemary G. ; Godoy, ed., Oscar ( June 2019 , Functional Ecology)

   Adaptive radiations are typically characterized by niche partitioning among their constituent species. Trophic niche partitioning is particularly important in predatory animals, which rely on limited food resources for survival.

   We test for trophic niche partitioning in an adaptive radiation of HawaiianTetragnathaspiders, which have diversified in situ on the Hawaiian Islands. We focus on a community of nine species belonging to two different clades, one web‐building and the other actively hunting, which co‐occur in wet forest on East Maui. We hypothesize that trophic niches differ significantly both: (a) among species within a clade, indicating food resource partitioning, and (b) between the two clades, corresponding to their differences in foraging strategy.

   To assess niches of the spider species, we measure: (a) web architecture, the structure of the hunting tool, and (b) site choice, the physical placement of the web in the habitat. We then test whether differences in these parameters translate into meaningful differences in trophic niche by measuring (c) stable isotope signatures of carbon and nitrogen in the spiders’ tissues, and (d) gut content of spiders based on metabarcoding data.

   We find significant interspecific differences in web architecture and site choice. Importantly, these differences are reflected in stable isotope signatures among the five web‐building species, as well as significant isotopic differences between web‐builders and active hunters. Gut content data also show interspecific and inter‐clade differences. Pairwise overlaps of web architecture between species are positively correlated with overlaps of isotopic signature.

   Our results reveal trophic niche partitioning among species within each clade, as well as between the web‐building and actively hunting clades. Based on the correlation between web architecture and stable isotopes, it appears that the isotopic signatures of spiders’ tissues are influenced by architectural differences among their webs. Our findings indicate an important link between web structure, microhabitat preference and diet in the HawaiianTetragnatha.

   A freePlain Language Summarycan be found within the Supporting Information of this article.

    

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3. Endosymbiont diversity across native and invasive brown widow spider populations

   https://doi.org/10.1038/s41598-024-58723-2  

   Mowery, Monica A. ; Rosenwald, Laura C. ; Chapman, Eric ; Lubin, Yael ; Segoli, Michal ; Khoza, Thembile ; Lyle, Robin ; White, Jennifer A. ( April 2024 , Scientific Reports)

   The invasive brown widow spider,Latrodectus geometricus(Araneae: Theridiidae), has spread in multiple locations around the world and, along with it, brought associated organisms such as endosymbionts. We investigated endosymbiont diversity and prevalence across putative native and invasive populations of this spider, predicting lower endosymbiont diversity across the invasive range compared to the native range. First, we characterized the microbial community in the putative native (South Africa) and invasive (Israel and the United States) ranges via high throughput 16S sequencing of 103 adult females. All specimens were dominated by reads from only 1–3 amplicon sequence variants (ASV), and most individuals were infected with an apparently uniform strain ofRhabdochlamydia. We also foundRhabdochlamydiain spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variantRhabdochlamydiastrains and severalWolbachia,Spiroplasmaand Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically forRhabdochlamydiaandWolbachia.We foundRhabdochlamydiain 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate ofL. geometricus. Wolbachiawas found at lower overall prevalence (14%) and was represented in all countries, but not all populations. In addition, we found evidence for geographic variation in endosymbiont prevalence: spiders from Israel were more likely to carryRhabdochlamydiathan those from the US and South Africa, andWolbachiawas geographically clustered in both Israel and South Africa. Characterizing endosymbiont prevalence and diversity is a first step in understanding their function inside the host and may shed light on the process of spread and population variability in cosmopolitan invasive species.

    

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4. Temporal Diversification and Evolutionary History of the Cribellum in Marronoid Spiders

   Mottershead, S. D. ; Riquelme, F. C. ; Esposito, L. A. ; Gorneau, J. A. ( October 2023 , Society for the Advancement of Chicanos/Hispanics and Native Americans in Science - 2023 NDiSTEM)

   Webs play many essential roles in spider biology, including communication, prey capture, locomotion, and reproduction. One interesting morphological feature of many spiders is the cribellum, a plate located near the silk-producing structures called spinnerets, and used to create a special type of matted silk that captures prey mechanically, instead of with glue droplets used by many orb-weaving spiders. The cribellum is hypothesized to have been present in the ancestor of all araneomorph spiders, but lost multiple times over the course of spider evolution. One group of spiders, the ‘marronoids’, shows a pattern of repeated loss and gain of this structure, placing them at a transitional position in the evolution of spider webs, with further implications for the web capture strategy, and other ecological conditions such as water-associated habitat. Studying the timing of the loss of the cribellum may yield insight to the cryptic ecology and morphology of the marranoid clade, and more broadly, araneomorph spiders. We use comparative phylogenetic methods to identify ancestral states of morphological and behavioral characters, and examine divergence dates with fossil calibrations. To do this, 98 representative spiders from the marronoid clade were coded by zoogeographic region, distribution proximity to a body of water and type, web type, and observed aquatic behavior. The morphology of the cribellum and spinnerets was assessed using 42 characters with multiple states. We identified patterns of evolution of the cribellum and aquatic habitat associations in the context of phylogeny, and geologic time. 

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5. Impacts of female body size on cannibalism and juvenile abundance in a dominant arctic spider

   https://doi.org/10.1111/1365-2656.13230  

   Koltz, Amanda M. ; Wright, Justin P. ; O'Gorman, ed., Eoin ( May 2020 , Journal of Animal Ecology)

   Body size influences an individual's physiology and the nature of its intra‐ and interspecific interactions. Changes in this key functional trait can therefore have important implications for populations as well. For example, among invertebrates, there is typically a positive correlation between female body size and reproductive output. Increasing body size can consequently trigger changes in population density, population structure (e.g. adult to juvenile ratio) and the strength of intraspecific competition.

   Body size changes have been documented in several species in the Arctic, a region that is warming rapidly. In particular, wolf spiders, one of the most abundant arctic invertebrate predators, are becoming larger and therefore more fecund. Whether these changes are affecting their populations and role within food webs is currently unclear.

   We investigated the population structure and feeding ecology of the dominant wolf spider speciesPardosa lapponicaat two tundra sites where adult spiders naturally differ in mean body size. Additionally, we performed a mesocosm experiment to investigate how variation in wolf spider density, which is likely to change as a function of body size, influences feeding ecology and its sensitivity to warming.

   We found that juvenile abundance is negatively associated with female size and that wolf spiders occupied higher trophic positions where adult females were larger. Because female body size is positively related to fecundity inP. lapponica, the unexpected finding of fewer juveniles with larger females suggests an increase in density‐dependent cannibalism as a result of increased intraspecific competition for resources. Higher rates of density‐dependent cannibalism are further supported by the results from our mesocosm experiment, in which individuals occupied higher trophic positions in plots with higher wolf spider densities. We observed no changes in wolf spider feeding ecology in association with short‐term experimental warming.

   Our results suggest that body size variation in wolf spiders is associated with variation in intraspecific competition, feeding ecology and population structure. Given the widespread distribution of wolf spiders in arctic ecosystems, body size shifts in these predators as a result of climate change could have implications for lower trophic levels and for ecosystem functioning.

    

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