Castaways: the Leeward Antilles endemic spider genus Papiamenta (Araneae: Pholcidae).

Ninetinae is a group of small to tiny short-legged spiders largely restricted to arid habitats. Among daddy-long-legs spiders (Pholcidae) this is by far the least diverse subfamily but this may partly be a result of inadequate collecting, poor representation in collections or scientific neglect. We build on a large recent collection of the ninetine genus Papiamenta Huber, 2000 from the Leeward Antilles and use cytochrome oxidase 1 (COI ) sequences, extensive scanning electron microscopy data, transmission electron microscopy data and karyotyping to analyse this geographically isolated and poorly known island genus. COI sequences support the split between the two morphologically distinct species on Curaçao but genetic distances between these are surprisingly low (7.4-9.8%; mean 8.6%). The type species P. levii (Gertsch, 1982) may include more than one species but COI and morphology suggest conflicting clade limits. A third species, P. bonay Huber sp. nov. is newly described from Bonaire. Our data on sperm ultrastructure and karyology are puzzling as these suggest different phylogenetic affinities of Papiamenta to other genera. Males transfer sperm as individual sperm (cleistosperm), agreeing with the putative closest relatives as suggested by molecular data, the North American genera Pholcophora and Tolteca . The sex chromosome system (X 1 X 2 X 3 Y ) of P. levii , however, is as in the South American Ninetinae genera Gertschiola and Nerudia but different from the putative closest relatives. ZooBank: urn:lsid:zoobank.org:pub:7A6A2E84-3A61-4637-AF6F-0E31A9FA79A8.

Enigmatic and extravagant genitalia in the spider genus Mastigusa (Araneae, Cybaeidae) - a taxonomic revision.

Mastigusa is a genus of small palearctic spiders that has recently been moved to the family Cybaeidae after the first inclusion of the genus in a phylogenetic matrix. Three species are currently recognised: M. arietina , M. lucifuga and M. macrophthalma . The status and delimitation, though, has always been problematic due to inconsistency in the characters used to discriminate between these, leading to great confusion in identity and distribution. We present a detailed morphological redescription of the genus and a taxonomic revision of the included species by the combined use of morphological data and molecular species-delimitation techniques based on the mitochondrial COI gene. The status of the three currently described species has been reevaluated and Mastigusa diversa was revalidated based on material from the Iberian Peninsula, North Africa and the United Kingdom. The distribution of Mastigusa species is updated based on novel taxonomic considerations, and comments on the natural history and ecological differences observed in the species are provided. ZooBank: urn:lsid:zoobank.org:pub:AAD3FAED-440F-4295-B458-455B1D913F81.

Heuristic test reveals little effect of learning and maturation on early prey capture experiences in a web-building spider.

Behaviors can vary throughout an animal's life and this variation can often be explained by changes associated with learning and/or maturing. Currently, there is little consensus regarding how these processes interact to affect behaviors. Here we proposed a heuristic approach to disentangle the effects of learning and maturation on behavior and applied it to the predatory behaviors of Physocyclus globosus spiderlings. We varied the degree of prey difficulty and familiarity spiderlings received along the first instar and across the molt to the second instar and quantified the time spiderlings spent wrapping prey, as a proxy for prey capture efficiency. We found no overall evidence for learning or maturation. Changes in efficiency were mainly due to the switch from difficult to easy prey, or vice versa. However, there was one treatment where spiderlings improved in efficiency before and after the molt, without a switch in prey type. This provides some indication that difficult prey may offer more opportunity for learning or maturation to impact behavior. Although we found little effect of learning or maturation on prey capture efficiency, we suggest that our heuristic approach is effective and could be useful in investigating these processes in other behaviors and other animals.

Venom-microbiomics of eight species of Neotropical spiders from the Theraphosidae family.

AIM: Tarantulas are one of the largest predatory arthropods in tropical regions. Tarantulas though not lethal to humans, their venomous bite kills small animals and insect upon which they prey. To understand the abiotic and biotic components involved in Neotropical tarantula bites, we conducted a venom-microbiomics study in eight species from Costa Rica. METHODS AND RESULTS: We determined that the toxin profiles of tarantula venom are highly diverse using shotgun proteomics; the most frequently encountered toxins were ω-Ap2 toxin, neprilysin-1, and several teraphotoxins. Through culture-independent and culture-dependent methods, we determined the microbiota present in the venom and excreta to evaluate the presence of pathogens that could contribute to primary infections in animals, including humans. The presence of opportunistic pathogens with hemolytic activity was observed, with a prominence of Stenotrophomonas in the venoms. Other bacteria found in venoms and excreta with hemolytic activity included members of the genera Serratia, Bacillus, Acinetobacter, Microbacterium, and Morganella. CONCLUSIONS: Our data shed light on the venom- and gut-microbiome associated with Neotropical tarantulas. This information may be useful for treating bites from these arthropods in both humans and farm animals, while also providing insight into the toxins and biodiversity of this little-explored microenvironment.

Bacteria inhabiting spider webs enhance host silk extensibility.

Spider silk is a promising material with great potential in biomedical applications due to its incredible mechanical properties and resistance to degradation of commercially available bacterial strains. However, little is known about the bacterial communities that may inhabit spider webs and how these microorganisms interact with spider silk. In this study, we exposed two exopolysaccharide-secreting bacteria, isolated from webs of an orb spider, to major ampullate (MA) silk from host spiders. The naturally occurring lipid and glycoprotein surface layers of MA silk were experimentally removed to further probe the interaction between bacteria and silk. Extensibility of major ampullate silk produced by Triconephila clavata that was exposed to either Microbacterium sp. or Novosphigobium sp. was significantly higher than that of silk that was not exposed to bacteria (differed by 58.7%). This strain-enhancing effect was not observed when the lipid and glycoprotein surface layers of MA silks were removed. The presence of exopolysaccharides was detected through NMR from MA silks exposed to these two bacteria but not from those without exposure. Here we report for the first time that exopolysaccharide-secreting bacteria inhabiting spider webs can enhance extensibility of host MA silks and silk surface layers play a vital role in mediating such effects.

Development and initial validation of an open-access online Behavioral Avoidance Test (BAT) for spider fear.

The behavioral avoidance test (BAT) is a well-known diagnostic tool assessing fear by directly measuring avoidance behavior. For instance, in spider phobia, participants or patients gradually approach a live spider until they feel too uncomfortable to continue. However, the use of different BAT protocols in various studies hampers the comparability of results. Moreover, conducting the test requires considerable preparation by researchers and clinicians. Thus, we have developed an open-access online BAT (vBATon). We validated its efficacy in measuring avoidance behavior and eliciting feelings of anxiety and disgust by comparing it to a real-life BAT (rl-BAT). Spider-fearful (N = 31) and nonfearful (N = 31) individuals completed a rl-BAT and vBATon on two separate dates within a 1-week interval. As expected, both tests successfully distinguished between spider-fearful and nonfearful individuals. Crucially, equivalence tests confirmed that vBATon captures avoidance behavior, anxiety, and disgust equal to the rl-BAT. Assessing validity, we found moderate to high correlations between vBATon and (a) the rl-BAT and (b) self-report measurements of spider fear (Spider Phobia Questionnaire, Fear of Spiders Questionnaire). Overall, our study displayed initial evidence of validity of vBATon and suggests that it is a standardized, efficient, and user-friendly alternative to rl-BATs for measuring spider fear. It can be utilized in both research and clinical practice. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Impact of pre-copulatory sexual cannibalism on genetic diversity and efficacy of selection.

Factors that increase reproductive variance among individuals act to reduce effective population size (Ne), which accelerates the loss of genetic diversity and decreases the efficacy of purifying selection. These factors include sexual cannibalism, offspring investment and mating system. Pre-copulatory sexual cannibalism, where the female consumes the male prior to mating, exacerbates this effect. We performed comparative transcriptomics in two spider species, the cannibalistic Trechaleoides biocellata and the non-cannibalistic T. keyserlingi, to generate genomic evidence to support these predictions. First, we estimated heterozygosity and found that genetic diversity is relatively lower in the cannibalistic species. Second, we calculated dN/dS ratios as a measure of purifying selection; a higher dN/dS ratio indicated relaxed purifying selection in the cannibalistic species. These results are consistent with the hypothesis that sexual cannibalism impacts operational sex ratio and demographic processes, which interact with evolutionary forces to shape the genetic structure of populations. However, other factors such as the mating system and life-history traits contribute to shaping Ne. Comparative analyses across multiple contrasting species pairs would be required to disentangle these effects. Our study highlights that extreme behaviours such as pre-copulatory cannibalism may have profound eco-evolutionary effects.

Systematics, distribution patterns and historical biogeography of the Central America wandering spider genus Kiekie Polotow & Brescovit, 2018 (Araneae: Ctenidae).

Kiekie Polotow & Brescovit, 2018 is a Neotropical genus of Ctenidae, with most of its species occuring in Central America. In this study, we review the systematics of Kiekie and describe five new species and the unknown females of K. barrocolorado Polotow & Brescovit, 2018 and K. garifuna Polotow & Brescovit, 2018, and the unknown male of K. verbena Polotow & Brescovit, 2018. In addition, we described the female of K. montanense which was wrongly assigned as K. griswoldi Polotow & Brescovit, 2018 (both species are sympatric). We provided a modified diagnosis for previously described species based on the morphology of the newly discovered species and in situ photographs of living specimens. We inferred a molecular phylogeny using four nuclear (histone H3, 28S rRNA, 18S rRNA and ITS-2) and three mitochondrial genes (cytochrome c oxidase subunit I or COI, 12S rRNA and 16S rRNA) to test the monophyly of the genus and the evolutionary relationships of its species. Lastly, we reconstruct the historical biogeography and map diversity and endemism distributional patterns of the different species. This study increased the number of known species of Kiekie from 13 to 18, and we describe a new genus, Eldivo which is sister lineage of Kiekie. Most of the diversity and endemism of the genus Kiekie is located in the montane ecosystems of Costa Rica followed by the lowland rainforest of the Pacific side (Limon Basin). Kiekie originated in the North America Tropical region, this genus started diversifying in the Late Miocene and spread to Lower Central America and South America. In that region, Kiekie colonized independently several times the montane ecosystems corresponding to periods of uplifting of Talamanca and Central Cordilleras.

All-you-can-eat buffet: A spider-specialized bat species (Myotis emarginatus) turns into a pest fly eater around cattle.

Determining the dietary spectrum of European insectivorous bats over time is the cornerstone of their conservation, as it will aid our understanding of foraging behavior plasticity in response to plummeting insect populations. Despite the global decline in insects, a restricted number of arthropod pest species thrive. Yet past research has overlooked the potential of European bats to suppress pests harmful to woodlands or livestock, in spite of their economic relevance. Here we investigated the diet composition, its breeding season variations and pest consumption of an insectivorous bat species (Myotis emarginatus), at the northern edge of its range (Wallonia, Belgium). We also explored the prey ecology to gain insight into the hunting strategies and foraging habitats of this bat species. We used DNA metabarcoding to amplify two COI markers within 195 bat droppings collected in June, July and August, thereby identifying 512 prey taxa predominated by Diptera, Araneae and Lepidoptera. Overall, in 97% of the samples we detected at least one of the 58 potential pest taxa, 41 of which targeting trees. The June samples were marked by a diet rich in orb-weaver spiders, in accordance with the archetypal diet of M. emarginatus bats. However, during the highly energy demanding July-August parturition and lactation period, roughly 55% of the dropping samples contained two cattle fly pests (Stomoxys calcitrans and Musca domestica). Moreover, among the 88 Diptera species preyed upon by M. emarginatus in July and August, these flies accounted for around 50% of the taxa occurrences. This plasticity-the switch from a spider-rich to a fly-rich diet-seems providential considering the dramatic ongoing drop in insect populations but this involves ensuring bat-friendly cattle farming. Our results revealed that bats widely consume pest entomofauna, thereby highlighting their potential role as allies of forest managers and farmers.

Integrative species delimitation and five new species of lynx spiders (Araneae, Oxyopidae) in Taiwan.

An accurate assessment of species diversity is a cornerstone of biology and conservation. The lynx spiders (Araneae: Oxyopidae) represent one of the most diverse and widespread cursorial spider groups, however their species richness in Asia is highly underestimated. In this study, we revised species diversity with extensive taxon sampling in Taiwan and explored species boundaries based on morphological traits and genetic data using a two-step approach of molecular species delimitation. Firstly, we employed a single COI dataset and applied two genetic distance-based methods: ABGD and ASAP, and two topology-based methods: GMYC and bPTP. Secondly, we further analyzed the lineages that were not consistently delimited, and incorporated H3 to the dataset for a coalescent-based analysis using BPP. A total of eight morphological species were recognized, including five new species, Hamataliwa cordivulva sp. nov., Hamat. leporauris sp. nov., Tapponia auriola sp. nov., T. parva sp. nov. and T. rarobulbus sp. nov., and three newly recorded species, Hamadruas hieroglyphica (Thorell, 1887), Hamat. foveata Tang & Li, 2012 and Peucetia latikae Tikader, 1970. All eight morphological species exhibited reciprocally monophyletic lineages. The results of molecular-based delimitation analyses suggested a variety of species hypotheses that did not fully correspond to the eight morphological species. We found that Hamat. cordivulva sp. nov. and Hamat. foveata showed shallow genetic differentiation in the COI, but they were unequivocally distinguishable according to their genitalia. In contrast, T. parva sp. nov. represented a deep divergent lineage, while differences of genitalia were not detected. This study highlights the need to comprehensively employ multiple evidence and methods to delineate species boundaries and the values of diagnostic morphological characters for taxonomic studies in lynx spiders.

Interfacial interactions between spider silk protein and cellulose studied by molecular dynamics simulation.

CONTEXT: Due to their excellent biocompatibility and degradability, cellulose/spider silk protein composites hold a significant value in biomedical applications such as tissue engineering, drug delivery, and medical dressings. The interfacial interactions between cellulose and spider silk protein affect the properties of the composite. Therefore, it is important to understand the interfacial interactions between spider silk protein and cellulose to guide the design and optimization of composites. The study of the adsorption of protein on specific surfaces of cellulose crystal can be very complex using experimental methods. Molecular dynamics simulations allow the exploration of various physical and chemical changes at the atomic level of the material and enable an atomic description of the interactions between cellulose crystal planes and spider silk protein. In this study, molecular dynamics simulations were employed to investigate the interfacial interactions between spider silk protein (NTD) and cellulose surfaces. Findings of RMSD, RMSF, and secondary structure showed that the structure of NTD proteins remained unchanged during the adsorption process. Cellulose contact numbers and hydrogen bonding trends on different crystalline surfaces suggest that van der Waals forces and hydrogen bonding interactions drive the binding of proteins to cellulose. These findings reveal the interaction between cellulose and protein at the molecular level and provide theoretical guidance for the design and synthesis of cellulose/spider silk protein composites. METHODS: MD simulations were all performed using the GROMACS-5.1 software package and run with CHARMM36 carbohydrate force field. Molecular dynamics simulations were performed for 500 ns for the simulated system.

Diversity and Functionality of Bacteria Associated with Different Tissues of Spider Heteropoda venatoria Revealed through Integration of High-Throughput Sequencing and Culturomics Approaches.

Spiders host a diverse range of bacteria in their guts and other tissues, which have been found to play a significant role in their fitness. This study aimed to investigate the community diversity and functional characteristics of spider-associated bacteria in four tissues of Heteropoda venatoria using HTS of the 16S rRNA gene and culturomics technologies, as well as the functional verification of the isolated strains. The results of HTS showed that the spider-associated bacteria in different tissues belonged to 34 phyla, 72 classes, 170 orders, 277 families, and 458 genera. Bacillus was found to be the most abundant bacteria in the venom gland, silk gland, and ovary, while Stenotrophomonas, Acinetobacter, and Sphingomonas were dominant in the gut microbiota. Based on the amplicon sequencing results, 21 distinct cultivation conditions were developed using culturomics to isolate bacteria from the ovary, gut, venom gland, and silk gland. A total of 119 bacterial strains, representing 4 phyla and 25 genera, with Bacillus and Serratia as the dominant genera, were isolated. Five strains exhibited high efficiency in degrading pesticides in the in vitro experiments. Out of the 119 isolates, 28 exhibited antibacterial activity against at least one of the tested bacterial strains, including the pathogenic bacteria Staphylococcus aureus, Acinetobacter baumanii, and Enterococcus faecalis. The study also identified three strains, GL312, PL211, and PL316, which exhibited significant cytotoxicity against MGC-803. The crude extract from the fermentation broth of strain PL316 was found to effectively induce apoptosis in MGC-803 cells. Overall, this study offers a comprehensive understanding of the bacterial community structure associated with H. venatoria. It also provides valuable insights into discovering novel antitumor natural products for gastric cancer and xenobiotic-degrading bacteria of spiders.

The Andes as a semi-permeable geographical barrier: Genetic connectivity between structured populations in a widespread spider.

Geographical barriers like mountain ranges impede genetic exchange among populations, promoting diversification. The effectiveness of these barriers in limiting gene flow varies between lineages due to each species' dispersal modes and capacities. Our understanding of how the Andes orogeny contributes to species diversification comes from well-studied vertebrates and a few arthropods and plants, neglecting organisms unable to fly or walk long distances. Some arachnids, such as Gasteracantha cancriformis, have been hypothesized to disperse long distances via ballooning (i.e. using their silk to interact with the wind). Yet, we do not know how the environment and geography shape its genetic diversity. Therefore, we tested whether the Andes contributed to the diversification of G. cancriformis acting as an absolute or semi-permeable barrier to genetic connectivity between populations of this spider at opposite sides of the mountain range. We sampled thousands of loci across the distribution of the species and implemented population genetics, phylogenetic, and landscape genetic analyses. We identified two genetically distinct groups structured by the Central Andes, and a third less structured group in the Northern Andes that shares ancestry with the previous two. This structure is largely explained by the altitude along the Andes, which decreases in some regions, possibly facilitating cross-Andean dispersal and gene flow. Our findings support that altitude in the Andes plays a major role in structuring populations in South America, but the strength of this barrier can be overcome by organisms with long-distance dispersal modes together with altitudinal depressions.

Las barreras geográficas como las cordilleras montañosas impiden el intercambio genético entre poblaciones, promoviendo la diversificación. La efectividad de estas barreras para limitar el flujo genético varía entre linajes debido a los modos y capacidades de dispersión de cada especie. Nuestra comprensión de cómo la orogenia de los Andes contribuye a la diversificación de especies proviene de vertebrados y algunos artrópodos y plantas bien estudiados, descuidando a los organismos incapaces de volar o caminar grandes distancias. Se ha hipotetizado que algunas arañas, como Gasteracantha cancriformis, se dispersan a grandes distancias mediante la técnica de "ballooning" (es decir, utilizando su seda para interactuar con el viento). Sin embargo, no sabemos cómo el entorno y la geografía han dado forma a su diversidad genética. Por lo tanto, probamos si los Andes contribuyeron a la diversificación de G. cancriformis actuando como una barrera absoluta o permeable para la conectividad genética entre poblaciones de esta araña en lados opuestos de la cordillera. Muestreamos miles de loci a través de la distribución de la especie e implementamos análisis de genética de poblaciones, filogenéticos y de genética del paisaje. Identificamos dos grupos genéticamente distintos estructurados por los Andes Centrales, y un tercer grupo menos estructurado en los Andes del Norte que comparte ascendencia con los dos anteriores. Esta estructura se explica en gran medida por la altitud a lo largo de los Andes, que disminuye en algunas regiones, posiblemente facilitando la dispersión y el flujo genético a través de los Andes. Nuestros hallazgos apoyan que la altitud en los Andes juega un papel importante en la estructuración de las poblaciones en América del Sur, pero la fuerza de esta barrera puede ser superada por organismos con modos de dispersión a larga distancia junto con depresiones altitudinales.

From genome to proteome: Comprehensive identification of venom toxins from the Chinese funnel-web spider (Macrothelidae: Macrothele yani).

Macrothelidae is a family of mygalomorph spiders containing the extant genera Macrothele and Vacrothele. China is an important center of diversity for Macrothele with 65 % of the known species occurring there. Previous work on Macrothele was able to uncover several important toxin compounds including Raventoxin which may have applications in biomedicine and agricultural chemistry. Despite the importance of Macrothele spiders, high-quality reference genomes are still lacking, which hinders our understanding and application of the toxin compounds. In this study, we assembled the genome of the Macrothele yani to help fill gaps in our understanding of toxin biology in this lineage of spiders to encourage the future study and applications of these compounds. The final assembled genome was 6.79 Gb in total length, had a contig N50 of 21.44 Mb, and scaffold N50 of 156.16 Mb. Hi-C scaffolding assigned 98.19 % of the genome to 46 pseudo-chromosomes with a BUSCO score of 95.7 % for the core eukaryotic gene set. The assembled genome was found to contain 75.62 % repetitive DNA and a total of 39,687 protein-coding genes were annotated making it the spider genome with highest number of genes. Through integrated analysis of venom gland transcriptomics and venom proteomics, a total of 194 venom toxins were identified, including 38 disulfide-rich peptide neurotoxins, among which 12 were ICK knottin peptides. In summary, we present the first high-quality genome assembly at the chromosomal level for any Macrothelidae spider, filling an important gap in our knowledge of these spiders. Such high-quality genomic data will be invaluable as a reference in resolving Araneae spider phylogenies and in screening different spider species for novel compounds applicable to numerous medical and agricultural applications.

Diversity and complexity of arthropod references in haiku.

Haiku are short poems, each composed of about 10 words, that typically describe moments in nature. People have written haiku since at least the 17th century, and the medium continues to be popular with poets, amateurs, educators, and students. Collectively, these poems represent an opportunity to understand which aspects of nature-e.g., which taxa and biological traits-resonate with humans and whether there are temporal trends in their representation or the emotions associated with these moments. We tested this potential using a mix of linguistic and biological methods, in analyses of nearly 4,000 haiku that reference arthropods. We documented the taxa and the life history traits represented in these poems and how they changed over time. We also analyzed the poems for emotion and tone. Our results reveal a mix of predictable trends and compelling surprises, each of which stand to potentially inform engagement strategies. At least 99 families of arthropods, in 28 orders, are represented in these haiku. The eight most commonly referenced taxa, from highest to lowest number of references, include: Lepidoptera, Hymenoptera, Diptera, Coleoptera, Araneae, Orthoptera, Hemiptera, and Odonata. Several common, conspicuous orders were never referenced, including Trichoptera, Plecoptera, and Megaloptera. The most commonly referenced traits relate to ecology (especially habitat, phenology, time of day), behavior (especially sound production), phenotype (especially color), and locomotion (especially flight). The least common traits in haiku relate to arthropod reproduction and physiology. Our analyses revealed few obvious temporal trends in the representations of taxa, biological traits, or emotion and tone. The broader implications of these results and possible future directions are discussed.

Endosymbiont diversity across native and invasive brown widow spider populations.

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 of Rhabdochlamydia. We also found Rhabdochlamydia in spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variant Rhabdochlamydia strains and several Wolbachia, Spiroplasma and Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically for Rhabdochlamydia and Wolbachia. We found Rhabdochlamydia in 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate of L. geometricus. Wolbachia was 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 carry Rhabdochlamydia than those from the US and South Africa, and Wolbachia was 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.

Chemical species recognition in an adaptive radiation of Hawaiian Tetragnatha spiders (Araneae: Tetragnathidae).

Studies of adaptive radiations have played a central role in our understanding of reproductive isolation. Yet the focus has been on human-biased visual and auditory signals, leaving gaps in our knowledge of other modalities. To date, studies on chemical signals in adaptive radiations have focused on systems with multimodal signalling, making it difficult to isolate the role chemicals play in reproductive isolation. In this study we examine the use of chemical signals in the species recognition and adaptive radiation of Hawaiian Tetragnatha spiders by focusing on entire communities of co-occurring species, and conducting behavioural assays in conjunction with chemical analysis of their silks using gas chromatography-mass spectrometry. Male spiders significantly preferred the silk extracts of conspecific mates over those of sympatric heterospecifics. The compounds found in the silk extracts, long chain alkyl methyl ethers, were remarkably species-specific in the combination and quantity. The differences in the profile were greatest between co-occurring species and between closely related sibling species. Lastly, there were significant differences in the chemical profile between two populations of a particular species. These findings provide key insights into the role chemical signals play in the attainment and maintenance of reproductive barriers between closely related co-occurring species.

Establishing superfine nanofibrils for robust polyelectrolyte artificial spider silk and powerful artificial muscles.

Spider silk exhibits an excellent combination of high strength and toughness, which originates from the hierarchical self-assembled structure of spidroin during fiber spinning. In this work, superfine nanofibrils are established in polyelectrolyte artificial spider silk by optimizing the flexibility of polymer chains, which exhibits combination of breaking strength and toughness ranging from 1.83 GPa and 238 MJ m-3 to 0.53 GPa and 700 MJ m-3, respectively. This is achieved by introducing ions to control the dissociation of polymer chains and evaporation-induced self-assembly under external stress. In addition, the artificial spider silk possesses thermally-driven supercontraction ability. This work provides inspiration for the design of high-performance fiber materials.

Hot and scared: how do heatwaves and predation risk impact resource acquisition and allocation?

Heatwaves are increasingly prevalent and can constrain investment into important life-history traits. In addition to heatwaves, animals regularly encounter threats from other organisms in their environments, such as predators. The combination of these two environmental factors introduces a decision-making conflict-heat exposure requires more food intake to fuel investment into fitness-related traits, but foraging in the presence of predators increases the threat of mortality. Thus, we used female variable field crickets (Gryllus lineaticeps) to investigate the effects of heatwaves in conjunction with predation risk (exposed food and water sources, and exposure to scent from black widow spiders, Latrodectus hesperus) on resource acquisition (food intake) and allocation (investment into ovarian and somatic tissues). A simulated heatwave increased food intake and the allocation of resources to reproductive investment. Crickets exposed to high predation risk reduced food intake, but they were able to maintain reproductive investment at an expense to investment into somatic tissue. Thus, heatwaves and predation risk deprioritized investment into self-maintenance, which may impair key physiological processes. This study is an important step towards understanding the ecology of fear in a warming world.