109 results on '"ORB weavers"'
Search Results
2. Insight into the adaptive role of arachnid genome-wide duplication through chromosome-level genome assembly of the Western black widow spider.
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Miles, Lindsay S, Waterman, Hannah, Ayoub, Nadia A, Garb, Jessica E, Haney, Robert A, Rosenberg, Michael S, Krabbenhoft, Trevor J, and Verrelli, Brian C
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BIOLOGICAL evolution , *SPIDERS , *ORB weavers , *ARACHNIDA , *GENE families , *SENSORY perception , *CHROMOSOMES , *COMPARATIVE genomics , *GENOMES - Abstract
Although spiders are one of the most diverse groups of arthropods, the genetic architecture of their evolutionary adaptations is largely unknown. Specifically, ancient genome-wide duplication occurring during arachnid evolution ~450 mya resulted in a vast assembly of gene families, yet the extent to which selection has shaped this variation is understudied. To aid in comparative genome sequence analyses, we provide a chromosome-level genome of the Western black widow spider (Latrodectus hesperus)—a focus due to its silk properties, venom applications, and as a model for urban adaptation. We used long-read and Hi-C sequencing data, combined with transcriptomes, to assemble 14 chromosomes in a 1.46 Gb genome, with 38,393 genes annotated, and a BUSCO score of 95.3%. Our analyses identified high repetitive gene content and heterozygosity, consistent with other spider genomes, which has led to challenges in genome characterization. Our comparative evolutionary analyses of eight genomes available for species within the Araneoidea group (orb weavers and their descendants) identified 1,827 single-copy orthologs. Of these, 155 exhibit significant positive selection primarily associated with developmental genes, and with traits linked to sensory perception. These results support the hypothesis that several traits unique to spiders emerged from the adaptive evolution of ohnologs—or retained ancestrally duplicated genes—from ancient genome-wide duplication. These comparative spider genome analyses can serve as a model to understand how positive selection continually shapes ancestral duplications in generating novel traits today within and between diverse taxonomic groups. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. Reference genome of the long-jawed orb-weaver, Tetragnatha versicolor (Araneae: Tetragnathidae).
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Adams, Seira A, Graham, Natalie R, Holmquist, Anna J, Sheffer, Monica M, Steigerwald, Emma C, Sahasrabudhe, Ruta, Nguyen, Oanh, Beraut, Eric, Fairbairn, Colin, Sacco, Samuel, Seligmann, William, Escalona, Merly, Shaffer, H Bradley, Toffelmier, Erin, and Gillespie, Rosemary G
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ORB weavers , *GENOMES , *SPECIES distribution , *BUTTERFLIES , *JUMPING spiders - Abstract
Climate-driven changes in hydrological regimes are of global importance and are particularly significant in riparian ecosystems. Riparian ecosystems in California provide refuge to many native and vulnerable species within a xeric landscape. California Tetragnatha spiders play a key role in riparian ecosystems, serving as a link between terrestrial and aquatic elements. Their tight reliance on water paired with the widespread distributions of many species make them ideal candidates to better understand the relative role of waterways versus geographic distance in shaping the population structure of riparian species. To assist in better understanding population structure, we constructed a reference genome assembly for Tetragnatha versicolor using long-read sequencing, scaffolded with proximity ligation Omni-C data. The near-chromosome-level assembly is comprised of 174 scaffolds spanning 1.06 Gb pairs, with a scaffold N50 of 64.1 Mb pairs and BUSCO completeness of 97.6%. This reference genome will facilitate future study of T. versicolor population structure associated with the rapidly changing environment of California. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Increasing Information Content and Diagnosability in Family-Level Classifications.
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Kuntner, Matjaž, Čandek, Klemen, Gregorič, Matjaž, Turk, Eva, Hamilton, Chris A, Chamberland, Lisa, Starrett, James, Cheng, Ren-Chung, Coddington, Jonathan A, Agnarsson, Ingi, and Bond, Jason E
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COMPARATIVE biology , *ORB weavers , *BIODIVERSITY conservation , *CLASSIFICATION , *SPIDERS - Abstract
Higher-level classifications often must account for monotypic taxa representing depauperate evolutionary lineages and lacking synapomorphies of their better-known, well-defined sister clades. In a ranked (Linnean) or unranked (phylogenetic) classification system, discovering such a depauperate taxon does not necessarily invalidate the rank classification of sister clades. Named higher taxa must be monophyletic to be phylogenetically valid. Ranked taxa above the species level should also maximize information content, diagnosability, and utility (e.g. in biodiversity conservation). In spider classification, families are the highest rank that is systematically catalogued, and incertae sedis is not allowed. Consequently, it is important that family-level taxa be well defined and informative. We revisit the classification problem of Orbipurae, an unranked suprafamilial clade containing the spider families Nephilidae, Phonognathidae, and Araneidae sensu stricto. We argue that, to maximize diagnosability, information content, conservation utility, and practical taxonomic considerations, this "splitting" scheme is superior to its recently proposed alternative, which lumps these families together as Araneidae sensu lato. We propose to redefine Araneidae and recognize a monogeneric spider family, Paraplectanoididae fam. nov. to accommodate the depauperate lineage Paraplectanoides. We present new subgenomic data to stabilize Orbipurae topology which also supports our proposed family-level classification. Our example from spiders demonstrates why classifications must be able to accommodate depauperate evolutionary lineages, for example, Paraplectanoides. Finally, although clade age should not be a criterion to determine rank, other things being equal, comparable ages of similarly ranked taxa do benefit comparative biology. [Classification, family rank, phylogenomics, systematics, monophyly, spider phylogeny.] [ABSTRACT FROM AUTHOR]
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- 2023
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5. Web architecture, behavior, and predatory potential of Larinia chloris from rice fields (Araneae: Araneidae).
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Khan, Sozaina, Tahir, Hafiz Muhammad, Butt, Abida, and Khan, Abbas
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PADDY fields , *ORB weavers , *PREY availability , *DIPTERA , *HEMIPTERA - Abstract
Present study was carried out to investigate the variation in web architecture of Larinia chloris (Audouin 1826) in relation to seasonal differences and the biotic factors of the environment. In addition, relative abundance, behavior, and predatory potential of L. chloris were also recorded. For this purpose, 100 orb-webs of L. chloris were observed in rice fields (August–October, 2022) from 3 districts of Punjab (Lahore, Sheikhupura, and Kasur). Percent abundance of L. chloris was found to be highest in rice fields from Barki road, Lahore (39.53%). All the webs of L. chloris were vertical at height equal to the height of vegetation (115.2 ± 9.7 cm). Time required to complete the web was 45 ± 5 min. There was positive correlation between web architecture and vegetation height. Web capture area and average mesh height of L. chloris also showed positive correlation with carapace length. There was a significant difference in various web parameters (number of spirals, number of radii, capture area, average mesh height, upper radii, lower radii, left radii, and right radii) among different trapping months. A total of 1,326 insects were recorded from the 100 webs of L. chloris. The prey abundance was found to be highest in the fields from Barki Road, Lahore. The majority of the prey collected from webs of L. chloris belonged to order Diptera, Hemiptera, Coleoptera, and Lepidoptera. However, prey items recorded during different growth stages (from vegetative to ripening) varied significantly. This is the first ever report describing the ecology of L. chloris in rice fields from Punjab, Pakistan. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Chromosome-level genome and the identification of sex chromosomes in Uloborus diversus.
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Miller, Jeremiah, Zimin, Aleksey V, and Gordus, Andrew
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SEX chromosomes , *X chromosome , *GENETIC sex determination , *ORB weavers , *SPIDER silk , *GENOMES , *CHROMOSOMAL rearrangement - Abstract
The orb web is a remarkable example of animal architecture that is observed in families of spiders that diverged over 200 million years ago. While several genomes exist for araneid orb-weavers, none exist for other orb-weaving families, hampering efforts to investigate the genetic basis of this complex behavior. Here we present a chromosome-level genome assembly for the cribellate orb-weaving spider Uloborus diversus. The assembly reinforces evidence of an ancient arachnid genome duplication and identifies complete open reading frames for every class of spidroin gene, which encode the proteins that are the key structural components of spider silks. We identified the 2 X chromosomes for U. diversus and identify candidate sex-determining loci. This chromosome-level assembly will be a valuable resource for evolutionary research into the origins of orb-weaving, spidroin evolution, chromosomal rearrangement, and chromosomal sex determination in spiders. [ABSTRACT FROM AUTHOR]
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- 2023
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7. Stabilized Morphological Evolution of Spiders Despite Mosaic Changes in Foraging Ecology.
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Wolff, Jonas O, Wierucka, Kaja, Paterno, Gustavo B, Coddington, Jonathan A, Hormiga, Gustavo, Kelly, Michael B J, Herberstein, Marie E, and Ramírez, Martín J
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ANIMAL habitations , *ORB weavers , *BROWNIAN motion , *SPIDER webs , *BODY size , *ARACHNIDA , *PREDATION - Abstract
A prominent question in animal research is how the evolution of morphology and ecology interacts in the generation of phenotypic diversity. Spiders are some of the most abundant arthropod predators in terrestrial ecosystems and exhibit a diversity of foraging styles. It remains unclear how spider body size and proportions relate to foraging style, and if the use of webs as prey capture devices correlates with changes in body characteristics. Here, we present the most extensive data set to date of morphometric and ecological traits in spiders. We used this data set to estimate the change in spider body sizes and shapes over deep time and to test if and how spider phenotypes are correlated with their behavioral ecology. We found that phylogenetic variation of most traits best fitted an Ornstein–Uhlenbeck model, which is a model of stabilizing selection. A prominent exception was body length, whose evolutionary dynamics were best explained with a Brownian Motion (free trait diffusion) model. This was most expressed in the araneoid clade (ecribellate orb-weaving spiders and allies) that showed bimodal trends toward either miniaturization or gigantism. Only few traits differed significantly between ecological guilds, most prominently leg length and thickness, and although a multivariate framework found general differences in traits among ecological guilds, it was not possible to unequivocally associate a set of morphometric traits with the relative ecological mode. Long, thin legs have often evolved with aerial webs and a hanging (suspended) locomotion style, but this trend is not general. Eye size and fang length did not differ between ecological guilds, rejecting the hypothesis that webs reduce the need for visual cue recognition and prey immobilization. For the inference of the ecology of species with unknown behaviors, we propose not to use morphometric traits, but rather consult (micro-)morphological characters, such as the presence of certain podal structures. These results suggest that, in contrast to insects, the evolution of body proportions in spiders is unusually stabilized and ecological adaptations are dominantly realized by behavioral traits and extended phenotypes in this group of predators. This work demonstrates the power of combining recent advances in phylogenomics with trait-based approaches to better understand global functional diversity patterns through space and time. [Animal architecture; Arachnida; Araneae; extended phenotype; functional traits; macroevolution; stabilizing selection.] [ABSTRACT FROM AUTHOR]
- Published
- 2022
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8. Population level variation in silk chemistry but not web architecture in a widely distributed orb web spider.
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Henneken, Jessica, Blamires, Sean J, Goodger, Jason Q D, Jones, Therésa M, and Elgar, Mark A
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ORB weavers , *SPIDER webs , *PREDATION , *SILK - Abstract
Spider webs are iconic examples of extended phenotypes that are remarkably plastic across different environments. Orb webs are not only effective traps for capturing prey, but can also provide information to potential mates and, in some cases, potential predators and prey through silk-based chemicals. As with regular phenotypic traits, variability in the properties of spider webs is thought to be mediated by a combination of genetic and environmental effects. Here, we examined variation in several key features of the webs of the orb-weaving spider Argiope keyserlingi across five geographically disparate populations. We documented variation in web architecture and chemical properties of webs collected directly from the field. We then probed the potential for the underlying environmental driver of local insect abundance to explain this variation, by analysing the properties of orb webs constructed by the spiders from these different populations, but under identical laboratory conditions. We found no evidence of variation across populations in the architecture of webs constructed in the laboratory, despite the large geographic distances. Nonetheless, we discovered between population variation in the composition of chemicals found on the surface of silk and in the taxonomic distribution of available prey. Furthermore, there was a positive correlation between the quantity of nitrogenous compounds in web silks and female body condition. When combined, these findings suggest that environmental mechanisms can drive variation in web traits across spider populations. [ABSTRACT FROM AUTHOR]
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- 2022
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9. Identification of sex chromosomes using genomic and cytogenetic methods in a range-expanding spider, Argiope bruennichi (Araneae: Araneidae).
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Sheffer, Monica M, Cordellier, Mathilde, Forman, Martin, Grewoldt, Malte, Hoffmann, Katharina, Jensen, Corinna, Kotz, Matěj, Král, Jiří, Kuss, Andreas W, Líznarová, Eva, and Uhl, Gabriele
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X chromosome , *SEX chromosomes , *ORB weavers , *SPIDERS , *GENOME size , *POLYMERASE chain reaction , *CHROMOSOME duplication - Abstract
Differences between sexes in growth, ecology and behaviour strongly shape species biology. In some animal groups, such as spiders, it is difficult or impossible to identify the sex of juveniles based on external morphology. This information would be useful for field surveys, behavioural experiments and ecological studies, such as those on sex ratios and dispersal. In species with sex chromosomes, sex can be determined based on the specific sex chromosome complement. Additionally, information on the sequence of sex chromosomes provides the basis for studying sex chromosome evolution. We combined cytogenetic and genomic data to identify the sex chromosomes in the sexually dimorphic spider Argiope bruennichi and designed quantitative real-time polymerase chain reaction sex markers. We found that the genome size and GC content of this spider fall into the ranges reported for the majority of araneids. The male karyotype is formed by 24 acrocentric chromosomes with an X1X20 sex chromosome system, with little similarity between X chromosomes, suggesting an origin of these chromosomes by X chromosome fission or early duplication of an X chromosome and subsequent independent differentiation of the copies. Our data suggest X chromosomes of similar sizes in A. bruennichi. They are smaller chromosomes of the complement. Our findings open the door to new directions in spider evolutionary and ecological research. [ABSTRACT FROM AUTHOR]
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- 2022
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10. Captivating color: evidence for optimal stimulus design in a polymorphic prey lure.
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Kemp, Darrell J, Edwards, Will, and White, Thomas E
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COLOR , *DIPTERA , *ORB weavers , *PREDATION - Abstract
Many species – humans included – employ color as an instrument of deception. One intriguing example of this resides in the conspicuous abstract color patterns displayed on the bodies of female orb weaving spiders. These displays increase prey interception rates and thereby function at least as visual lures. Their chromatic properties however vary extensively, both across and within species, with discrete forms often co-existing in the manner of a stable polymorphism. Variation is principally expressed in terms of signal hue (color per se), but it is unclear how attractiveness scales with this property and if extant morphs are maximally attractive relative to a graded range of potential alternatives. We examined these questions by assessing catch rates among color-manipulated females of the dimorphic jeweled spider Gasteracantha fornicata in their natural webs. The manipulation altered dorsal appearance in a manner akin to adding six new variants of their existing white/yellow phenotypes. This magnified the natural variation in stimulus hue independently of chroma (saturation) across a range spanning most of the color spectrum. Catch rate varied across treatments in simple accordance with how greatly stimulus hue deviated from either of the two extant spider phenotypes. Predictions based on fly-perceived chromatic and achromatic background contrast were clearly unsupported despite dipterans constituting ~60 % of identifiable prey. This study supports the importance of signal coloration per se in G. fornicata and suggests that extant lure phenotypes reside in a broadly optimal spectral range for stimulating their aggregate prey community. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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11. Correlated evolution between orb weaver glue droplets and supporting fibres maintains their distinct biomechanical roles in adhesion.
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Kelly, Sean D., Opell, Brent D., and Correa‐Garwhal, Sandra M.
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ORB weavers , *FIBERS , *SPIDER silk , *GLUE , *MECHANICAL properties of condensed matter , *ELASTIC modulus - Abstract
Orb weaving spiders employ a 'silken toolkit' to accomplish a range of tasks, including retaining prey that strike their webs. This is accomplished by a viscous capture spiral thread that features tiny glue droplets, supported by a pair of elastic flagelliform fibres. Each droplet contains a glycoprotein core responsible for adhesion. However, prey retention relies on the integrated performance of multiple glue droplets and their supporting fibres, with previous studies demonstrating that a suspension bridge forms, whose biomechanics sum the adhesive forces of multiple droplets while dissipating the energy of the struggling insect. While the interdependence of the droplet's glycoprotein and flagelliform fibres for functional adhesion is acknowledged, there has been no direct test of this hypothesized linkage between the material properties of each component. Spider mass, which differs greatly across orb weaving species, also has the potential to affect flagelliform fibre and glycoprotein material properties. Previous studies have linked spider mass to capture thread performance but have not examined the relationship between spider mass and thread material properties. We extend earlier studies to examine these relationships in 16 orb weaving species using phylogenetic generalized least squares. This analysis revealed that glycoprotein stiffness (elastic modulus) was correlated with flagelliform fibre stiffness, and that spider mass was related to the glycoprotein volume, flagelliform fibre cross‐sectional area and droplets per unit thread length. By shaping the elastic moduli of glycoprotein adhesive and flagelliform fibres, natural selection has maintained the biomechanical integration of this adhesive system. [ABSTRACT FROM AUTHOR]
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- 2022
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12. Limitations of sperm transfer in the complex reproductive system of spiders.
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Dharmarathne, Wijayamuni Dewage Sanjaya Chathuranga and Herberstein, Mariella Elisabeth
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GENITALIA , *SPERMATOZOA , *ORB weavers , *SPERM competition , *SEMEN , *SEXUAL intercourse , *CANNIBALISM - Abstract
In spiders, sperm transfer from the male to the female is indirect via secondary copulatory structures, the pedipalps. At the time of transfer the sperm are not mobile and the ejaculate needs to move through narrow male and female ducts to the female sperm storage organ. In addition, copulation duration can be very short, often limited to just a few seconds. Finally, sexual cannibalism and genital damage limits male life-time mating opportunities. These features of the reproductive biology in spiders are likely to result in sperm transfer constraints. Here we review the intrinsic and extrinsic sperm transfer limitations and conduct a meta-analysis on sperm transfer data from published data. Most of the information available relates to orb-web spiders, but our meta-analysis also includes non-orb-web spiders. Our review identifies some of the behavioural factors that have been shown to influence sperm transfer, and lists several morphological and physiological traits where we do not yet know how they might affect sperm transfer. [ABSTRACT FROM AUTHOR]
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- 2022
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13. Relationship between body colour and microhabitat breadth in an orb-web spider.
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Nakata, Kensuke
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ECOLOGICAL niche , *ORB weavers , *SPIDER webs , *PREY availability , *DARKNETS (File sharing) , *ANIMAL coloration - Abstract
Habitat use often differs among intraspecific individuals, and the degree to which individual animals use specific habitats, i.e. microhabitat breadth, can also vary. Variation in body colour sometimes emerges as dark vs. bright coloration, which can be related to habitat selectivity. The aim of this study was to examine whether darker animals prefer shady sites to avoid overheating from direct sunlight exposure, whereas brighter animals would use both shady and open sites. Orb-web spiders, Cyclosa argenteoalba , have a silver dorsal abdomen with black markings; the proportion of these black markings varies between 20 and 100% among individuals. In summer, there was less variation in the duration of direct sunlight hitting the webs of darker spiders compared with that of brighter spiders. This indicated a narrower microhabitat range for darker spiders, which preferred shady sites. This pattern was not observed in spring and autumn, when thermal conditions were less severe. These results are consistent with the hypothesis that when the temperature is high, darker animals are microhabitat specialists, whereas brighter animals are generalists. A previous study found that darker spiders capture more prey than brighter spiders, and the amount of black markings is considered to be a trade-off between foraging success and microhabitat availability. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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14. Discoid decorations function to shield juvenile Argiope spiders from avian predator attacks.
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Wang, Bingjun, Yu, Long, Ma, Nina, Zhang, Zengtao, Liu, Qian, Fan, Wenrui, Rong, Yu, Zhang, Shichang, and Li, Daiqin
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ORB weavers , *SPIDER webs , *NEOPHOBIA , *CHICKS , *PREDATORY animals , *ANIMAL species - Abstract
Decorating behavior is common in various animal taxa and serves a variety of functions from camouflage to communication. One predominant function cited for decoration is to avoid predators. Conspicuous, disc-like (discoid) silk decorations spun by orb-web Argiope juvenile spiders are hypothesized, among others, to defend spiders against visual predators by concealing spider outlines on the web, deflecting attacks, shielding them from view, or masquerading as bird-droppings. However, the direct evidence is limited for a specific mechanism by which discoid decorations may deter predators. Here we evaluate the mechanisms by which discoid decorations may defend Argiope juveniles against naïve chicks. Using visual modeling, we show that avian predators are able to distinguish spiders from discoid decorations. Using chick predation experiments, we found that the naïve chicks readily pecked any objects, ruling out the possibility of their neophobia. Significantly more chicks attacked spiders when they were exposed to chicks, regardless of whether their webs had discoid decorations, but few chicks attacked spiders when they were behind the decorations. We also found that significantly few chicks attacked decorations when spiders were absent or behind the decorations. We thus conclude that discoid decorations function to deter avian predators by shielding the spider from view or distracting, not by deflecting attacks, concealing the spider's outline, or masquerading as bird-droppings. This study sheds light on the study of other similar anti-predator strategies, in a wide range of spider species and other animals that use decorating strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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15. Web wars: males of the golden orb-web spider invest more in fights for mated females.
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Silva, Amanda Vieira da, Oliveira, Reisla, and Peixoto, Paulo Enrique Cardoso
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SPERM competition , *FEMALES , *MALES , *ORB weavers , *ADULTS - Abstract
In addition to resource value, the cost of finding mates may affect how much males invest in fights for females. The cost of finding females may be imposed through natural factors extrinsic to males, such as female spatial distribution and predation pressure, which can be challenging to simulate in laboratory conditions. Therefore, studies under natural conditions may be suitable for understanding how the costs of finding mating partners affect male investment in fights. We used the spider Trichonephila clavipes to evaluate the hypotheses that males in field conditions invest more in contests for access to 1) unmated and 2) more fecund females and 3) when access to females is harder. To test these hypotheses, we recorded the occurrence, duration, and escalation of induced contests between males located in webs of females that differed in reproductive status (estimated by female life stage), fecundity (estimated by female abdominal area), and spatial distribution (i.e. isolated or aggregated with webs of other females). The occurrence and duration of contests were unrelated to female value or search costs. However, the probability for escalation was higher when males were fighting for adult (and probably mated) females. We also found that males tended to start a contest more often in aggregated webs. These results indicate that males of T. clavipes adjust investment in contests but contrarily to what we expected. We suggest that males invest more in contests for adult females because they are defending females that they previously fertilized to avoid sperm competition. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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16. Golden orb-weaving spider (Trichonephila clavipes) silk genes with sex-biased expression and atypical architectures.
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Correa-Garhwal, Sandra M., Babb, Paul L., Voight, Benjamin F., and Hayashi, Cheryl Y.
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ORB weavers , *GENE expression , *SPIDER silk , *SPIDER venom , *SILK , *GENES , *GENE families , *AMINO acid sequence - Abstract
Spider silks are renowned for their high-performance mechanical properties. Contributing to these properties are proteins encoded by the spidroin (spider fibroin) gene family. Spidroins have been discovered mostly through cDNA studies of females based on the presence of conserved terminal regions and a repetitive central region. Recently, genome sequencing of the golden orb-web weaver, Trichonephila clavipes, provided a complete picture of spidroin diversity. Here, we refine the annotation of T. clavipes spidroin genes including the reclassification of some as non-spidroins. We rename these non-spidroins as spidroin-like (SpL) genes because they have repetitive sequences and amino acid compositions like spidroins, but entirely lack the archetypal terminal domains of spidroins. Insight into the function of these spidroin and SpL genes was then examined through tissue- and sex-specific gene expression studies. Using qPCR, we show that some silk genes are upregulated in male silk glands compared to females, despite males producing less silk in general. We also find that an enigmatic spidroin that lacks a spidroin C-terminal domain is highly expressed in silk glands, suggesting that spidroins could assemble into fibers without a canonical terminal region. Further, we show that two SpL genes are expressed in silk glands, with one gene highly evolutionarily conserved across species, providing evidence that particular SpL genes are important to silk production. Together, these findings challenge long-standing paradigms regarding the evolutionary and functional significance of the proteins and conserved motifs essential for producing spider silks. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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17. Orb-weaving spiders show a correlated syndrome of morphology and web structure in the wild.
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Fisher, David N, Pruitt, Jonathan N, and Yeager, Justin
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ORB weavers , *SPIDER webs , *BODY size , *MORPHOLOGY , *JUMPING spiders - Abstract
Extended phenotypes are traits that exist outside the physical body of organisms. Despite their role in the lives of the organisms that express them and other organisms influenced by extended phenotypes, the consistency and covariance with morphological and behavioural traits of extended phenotypes has rarely been evaluated. We repeatedly measured an extended phenotype involved in prey acquisition (web structure) of wild orb-weaving spiders (Micrathena vigorsii), which re-build their webs daily. We related web structure to behaviours and spider body length. Web diameter and web density were repeatable among individuals, reaction to a predation threat was very marginally so, and response to a prey stimulus and web evenness were not repeatable. Larger spiders spun wider webs, had webs with increased thread spacing, and the spider possibly tended to react more slowly to a predation threat. When a spider built a relatively larger web it was also a relatively less dense and less even web. The repeatability of web construction and relationship with spider body size we found may be common features of intra-population variation in web structure in spiders. By estimating the consistency and covariances of extended phenotypes we can begin to evaluate what maintains their variation and how they might evolve. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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18. Phylogeography of the 'cosmopolitan' orb-weaver Argiope trifasciata (Araneae: Araneidae).
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Abel, Christoph, Schneider, Jutta M, Kuntner, Matjaž, and Harms, Danilo
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ORB weavers , *BIOLOGICAL classification , *GEOGRAPHIC boundaries , *JUMPING spiders , *PHYLOGEOGRAPHY , *PALEARCTIC - Abstract
Few spider species show truly cosmopolitan distributions. Among them is the banded garden spider Argiope trifasciata , which is reported from six continents across major climatic gradients and geographical boundaries. In orb-weaver spiders, such global distributions might be a result of lively dispersal via ballooning. However, wide distributions might also be artefactual, owing to our limited understanding of species taxonomy. To test the hypothesis that A. trifasciata might be a complex of cryptic species with more limited geographical ranges, we investigated the biogeographical structure and evolutionary history of A. trifasciata through a combination of time-calibrated phylogenetic analyses (57 terminals and three genes), ancestral range reconstruction and species delimitation methods. Our results strongly suggest that A. trifasciata as currently defined is not a single species. Its populations fall into five reciprocally monophyletic clades that are genetically distinct and have evolutionary origins in the Plio-Pleistocene. These clades are confined to East Asia, temperate Australia, Hawaii, the New World and the Old World (Africa and most of the Palaearctic). Our results provide the basis for future investigation of morphological and/or ecological disparity between the populations that are likely to represent species, in addition to examinations of the attributes and dispersal modes of these species. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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19. Tachinobia repanda (Hymenoptera: Eulophidae) From Egg Sacs of a Colonial Spider, Cyrtophora moluccensis (Araneae: Araneidae) in Papua New Guinea.
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Yefremova, Zoya A and Lubin, Yael
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EGG cases (Zoology) , *ORB weavers , *EULOPHIDAE , *HYMENOPTERA , *SPIDERS , *JUMPING spiders , *ICHNEUMONIDAE - Abstract
We report the discovery of the wasp Tachinobia repanda Bouček collected from egg sacs of the colonial spider Cyrtophora moluccensis (Doleschall) in Morobe Province, Papua New Guinea (PNG) by Lubin, Y.D. in 1980. This is the first record of T. repanda from egg sacs of a colonial spider. The likely host of this eulophid wasp was the larvae of a sarcophagid fly that parasitizes the egg sacs of these spiders. The 67 T. repanda collected were all females and varied little in body size. We suggest that this species is a gregarious hyperparasitoid. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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20. Friend or Foe? Orb-Weaver Spiders Inhabiting Ant–Acacias Capture Both Herbivorous Insects and Acacia Ant Alates.
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Ledin, Anna E, Styrsky, John D, and Styrsky, Jennifer Nesbitt
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INSECTS , *ORB weavers , *ACACIA , *JUMPING spiders , *ANTS , *SPIDER webs , *PLANT defenses - Abstract
The orb-weaver spiders Eustala oblonga (Chickering) and Eustala illicita (O. Picard-Cambridge) (Araneae: Araneidae) inhabit the ant-defended acacias Vachellia melanocerus (Beurling) and Vachellia collinsii (Safford) (Fabales: Fabaceae), respectively, in Panama. These spiders do not capture patrolling Pseudomyrmex ants but exploit their plant-protection services to escape predation. What effect the spiders have on the ant-acacia mutualisms is unknown. They may provide an additional layer of plant defense by capturing flying herbivorous insects in their webs. Alternatively, the spiders may disrupt the ant–acacia mutualisms by capturing alate acacia ants during nuptial flights. We evaluated these two hypotheses by sampling insects flying through acacia foliage and by identifying prey remains in webs. The proportions of insects captured on sticky card traps and in webs varied with taxonomic order and ecological role. Herbivorous insects greatly outnumbered other groups captured on sticky cards and were captured in spiders' webs in both acacia species but made up a minority of prey remains in webs. Instead, insect predators and parasitoids made up the majority of prey remains and were comprised primarily by alate ant mutualists of the host acacias. These results provide indirect support for both hypotheses and suggest that the spiders potentially both benefit and harm their host ant-acacia mutualisms. The net effect of spider exploitation, however, is unclear and is likely based on both the effectiveness of plant protection from herbivory provided by the spiders relative to that provided by acacia ants, as well as the overall proportion of the ant reproductive caste the spiders actually capture. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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21. Exploring the impact of morphology, multiple sequence alignment and choice of optimality criteria in phylogenetic inference: a case study with the Neotropical orb-weaving spider genus Wagneriana (Araneae: Araneidae).
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Cabra-García, Jimmy and Hormiga, Gustavo
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ORB weavers , *SEQUENCE alignment , *JUMPING spiders , *CASE studies - Abstract
We present a total evidence phylogenetic analysis of the Neotropical orb-weaving spider genus Wagneriana and discuss the phylogenetic impacts of methodological choices. We analysed 167 phenotypic characters and nine loci scored for 115 Wagneriana and outgroups, including 46 newly sequenced species. We compared total evidence analyses and molecular-only analyses to evaluate the impact of phenotypic evidence, and we performed analyses using the programs POY, TNT, RAxML, GARLI, IQ-TREE and MrBayes to evaluate the effects of multiple sequence alignment and optimality criteria. In all analyses, Wagneriana carimagua and Wagneriana uropygialis were nested in the genera Parawixia and Alpaida , respectively, and the remaining species of Wagneriana fell into three main clades, none of which formed a pair of sister taxa. However, sister-group relationships among the main clades and their internal relationships were strongly influenced by methodological choices. Alignment methods had comparable topological effects to those of optimality criteria in terms of 'subtree pruning and regrafting' moves. The inclusion of phenotypic evidence, 2.80–3.05% of the total evidence matrices, increased support irrespective of the optimality criterion used. The monophyly of some groups was recovered only after the addition of morphological characters. A new araneid genus, Popperaneus gen. nov. , is erected, and Paraverrucosa is resurrected. Four new synonymies and seven new combinations are proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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22. Color lures in orb-weaving spiders: a meta-analysis.
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Ximenes, Nathalia G, Moraes, Vinicius De Souza, Ortega, Jean C G, and Gawryszewski, Felipe M
- Subjects
- *
ORB weavers , *EYE , *FORECASTING , *SPIDER webs , *COLORS , *META-analysis , *JUMPING spiders - Abstract
Lures are deceptive strategies that exploit sensory biases in prey, usually mimicking a prey's mate or food item. Several predators exploit plant–pollinator systems, where visual signals are an essential part of interspecific interactions. Many diurnal, and even nocturnal, orb-web spiders present conspicuous body coloration or bright color patches. These bright colors are regarded as color-based lures that exploit biases present in insect visual systems, possibly mimicking flower colors. The prey attraction hypothesis was proposed more than 20 years ago to explain orb-web spider coloration. Although most data gathered so far has corroborated the predictions of the prey attraction hypothesis, there are several studies that refute these predictions. We conducted a multilevel phylogenetic meta-analysis to assess the magnitude of the effect of conspicuous orb-web spider body coloration on prey attraction. We found a positive effect in favor of the prey attraction hypothesis; however, there was substantial heterogeneity between studies. Experimental designs comparing conspicuous spiders to painted spiders or empty webs did not explain between-studies heterogeneity. The lack of theoretical explanation behind the prey attraction hypothesis makes it challenging to address which components influence prey attraction. Future studies could evaluate whether color is part of a multicomponent signal and test alternative hypotheses for the evolution of spider colors, such as predator avoidance and thermoregulation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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23. Monophyly, Taxon Sampling, and the Nature of Ranks in the Classification of Orb-Weaving Spiders (Araneae: Araneoidea).
- Author
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Kallal, Robert J, Dimitrov, Dimitar, Arnedo, Miquel A, Giribet, Gonzalo, and Hormiga, Gustavo
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- *
ORB weavers , *BIOLOGICAL classification , *SEXUAL dimorphism , *CLASSIFICATION , *JUMPING spiders - Abstract
We address some of the taxonomic and classification changes proposed by Kuntner et al. (2019) in a comparative study on the evolution of sexual size dimorphism in nephiline spiders. Their proposal to recircumscribe araneids and to rank the subfamily Nephilinae as a family is fundamentally flawed as it renders the family Araneidae paraphyletic. We discuss the importance of monophyly, outgroup selection, and taxon sampling, the subjectivity of ranks, and the implications of the age of origin criterion to assign categorical ranks in biological classifications. We explore the outcome of applying the approach of Kuntner et al. (2019) to the classification of spiders with emphasis on the ecribellate orb-weavers (Araneoidea) using a recently published dated phylogeny. We discuss the implications of including the putative sister group of Nephilinae (the sexually dimorphic genus Paraplectanoides) and the putative sister group of Araneidae (the miniature, monomorphic family Theridiosomatidae). We propose continuation of the phylogenetic classification put forth by Dimitrov et al. (2017) , and we formally rank Nephilinae and Phonognathinae as subfamilies of Araneidae. Our classification better reflects the understanding of the phylogenetic placement and evolutionary history of nephilines and phonognathines while maintaining the diagnosability of Nephilinae. It also fulfills the fundamental requirement that taxa must be monophyletic, and thus avoids the paraphyly of Araneidae implied by Kuntner et al. (2019). [ABSTRACT FROM AUTHOR]
- Published
- 2020
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24. The Bugs of America 1826–1838.
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Wagner, James
- Subjects
- *
STINKBUGS , *ARTISTIC collaboration , *ART collecting , *ORB weavers , *PASSERIFORMES - Published
- 2019
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25. Females of a cannibalistic spider control mutilation of their genitalia by males.
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Mouginot, Pierick and Uhl, Gabriele
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- *
MALE reproductive organs , *VULVA , *ORB weavers , *FEMALE reproductive organs , *FEMALES - Abstract
When females can mate multiply, the interests of both sexes over female remating may not coincide, leading to selection for adaptations and counteradaptations in males and females. In several orb-weaving spiders, males damage external structures of the female genitalia during copulation, which hinders the female from remating. We investigated whether females have control over the mutilation of their genitalia in the orb-weaving spider Larinia jeskovi. We found that female sexual cannibalism during copulation reduced the number of insertions a male was able to perform and hence limited the probability of genital mutilation by the male. Genital mutilation did not differ between treatments in which females experienced different availabilities of other males before the mating trial: males absent, males near the female ("vicinity group"), and males in the female's web ("web group"). However, traits of the mating male (size, condition) were significantly correlated with the occurrence of cannibalism during mating in "web" and "vicinity" treatments. These results suggest that females have control over mutilation by an early termination of mating, can respond to the availability of potential mates and can alter the probability of mutilation according to certain male traits. Female sexual cannibalism may represent a counteradaptation to genital mutilation allowing females to mate multiply. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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26. Prey and predators perceive orb-web spider conspicuousness differently: evaluating alternative hypotheses for color polymorphism evolution.
- Author
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Ximenes, Nathalia G and Gawryszewski, Felipe M
- Subjects
- *
PREDATION , *EYE , *COLOR vision , *HYPOTHESIS , *ORB weavers , *COLORS - Abstract
Color polymorphisms have been traditionally attributed to apostatic selection. The perception of color depends on the visual system of the observer. Theoretical models predict that differently perceived degrees of conspicuousness by two predator and prey species may cause the evolution of polymorphisms in the presence of anti-apostatic and apostatic selection. The spider Gasteracantha cancriformis (Araneidae) possesses several conspicuous color morphs. In orb-web spiders, the prey attraction hypothesis states that conspicuous colors are prey lures that increase spider foraging success via flower mimicry. Therefore, polymorphism could be maintained if each morph attracted a different prey species (multiple prey hypothesis) and each spider mimicked a different flower color (flower mimicry hypothesis). Conspicuous colors could be a warning signal to predators because of the spider's hard abdomen and spines. Multiple predators could perceive morphs differently and exert different degrees of selective pressures (multiple predator hypothesis). We explored these 3 hypotheses using reflectance data and color vision modeling to estimate the chromatic and achromatic contrast of G. cancriformis morphs as perceived by several potential prey and predator taxa. Our results revealed that individual taxa perceive the conspicuousness of morphs differently. Therefore, the multiple prey hypothesis and, in part, the multiple predator hypothesis may explain the evolution of color polymorphism in G. cancriformis , even in the presence of anti-apostatic selection. The flower mimicry hypothesis received support by color metrics, but not by color vision models. Other parameters not evaluated by color vision models could also affect the perception of morphs and influence morph survival and polymorphism stability. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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27. Golden Orbweavers Ignore Biological Rules: Phylogenomic and Comparative Analyses Unravel a Complex Evolution of Sexual Size Dimorphism.
- Author
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Kuntner, Matjaž, Hamilton, Chris A, Cheng, Ren-Chung, Gregorič, Matjaž, Lupše, Nik, Lokovšek, Tjaša, Lemmon, Emily Moriarty, Lemmon, Alan R, Agnarsson, Ingi, Coddington, Jonathan A, and Bond, Jason E
- Subjects
- *
SEXUAL dimorphism , *ORB weavers , *COMPARATIVE biology , *LIFE sciences , *MATHEMATICAL complex analysis , *ALLOMETRY - Published
- 2019
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28. Toward Spider Glue: Long Read Scaffolding for Extreme Length and Repetitious Silk Family Genes AgSp1 and AgSp2 with Insights into Functional Adaptation.
- Author
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Stellwagen, Sarah D. and Renberg, Rebecca L.
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ORB weavers , *GENE families , *SILK fibroin , *AMINO acid sequence , *GLUE , *VISCOELASTIC materials - Abstract
An individual orb weaving spider can spin up to seven different types of silk, each with unique functions and material properties. The capture spiral silk of classic two-dimensional aerial orb webs is coated with an amorphous glue that functions to retain prey that get caught in a web. This unique modified silk is partially comprised of spidroins (spider fibroins) encoded by two members of the silk gene family. The glue differs from solid silk fibers as it is a viscoelastic, amorphic, wet material that is responsive to environmental conditions. Most spidroins are encoded by extremely large, highly repetitive genes that cannot be sequenced using short read technology alone, as the repetitive regions are longer than read length. We sequenced for the first time the complete genomic Aggregate Spidroin 1 (AgSp1) and Aggregate Spidroin 2 (AgSp2) glue genes of orb weaving spider Argiope trifasciata using error-prone long reads to scaffold for high accuracy short reads. The massive coding sequences are 42,270 bp (AgSp1) and 20,526 bp (AgSp2) in length, the largest silk genes currently described. The majority of the predicted amino acid sequence of AgSp1 consists of two similar but distinct motifs that are repeated ~40 times each, while AgSp2 contains ~48 repetitions of an AgSp1-similar motif, interspersed by regions high in glutamine. Comparisons of AgSp repetitive motifs from orb web and cobweb spiders show regions of strict conservation followed by striking diversification. Glues from these two spider families have evolved contrasting material properties in adhesion (stickiness), extensibility (stretchiness), and elasticity (the ability of the material to resume its native shape), which we link to mechanisms established for related silk genes in the same family. Full-length aggregate spidroin sequences from diverse species with differing material characteristics will provide insights for designing tunable bio-inspired adhesives for a variety of unique purposes. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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29. Systematics, phylogeny and biogeography of the Australasian leaf-curling orb-weaving spiders (Araneae: Araneidae: Zygiellinae), with a comparative analysis of retreat evolution.
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Kallal, Robert J and Hormiga, Gustavo
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- *
ORB weavers , *BIOGEOGRAPHY , *SPECIES diversity , *BIODIVERSITY , *ARACHNIDA - Abstract
We revise and monograph the Australasian clade of the araneid subfamily Zygiellinae F.O. Pickard-Cambridge. Several members of this clade construct conspicuous leaf retreats at the hub of their webs. We gathered and analyzed a matrix of 95 taxa of zygiellines and close relatives with sequence data from six genetic markers (12S rRNA, 16S rRNA, 18S rRNA, 28S rRNA, cytochrome oxidase c subunit I, and histone H3), in addition to 235 morphological and behavioral characters. Analyses conducted using parsimony, maximum likelihood, and Bayesian methods indicate that Phonognatha Simon is paraphyletic as currently circumscribed, which we accommodate by erecting the genus Artifex gen. nov. Our analyses support Zygiellinae as the earliest diverging araneid subfamily. Biogeographic analyses using BioGeoBEARS support multiple colonizations of zygiellines to New Caledonia from Australia, congruent with the island's geology. Furthermore, analysis of the retreat types show using leaf retreats integrated with the hub to have arisen at least three times independently. We describe one new species, Phonognatha tanyodon sp. nov. redescribe three species of Phonognatha, three species of Deliochus Simon, and two species of Artifex gen. nov. Three species of Araneus Clerck and Phonognatha are synonymized with these taxa, and four species are misplaced in Zygiellinae. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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30. Natural Compounds as Spider Repellents: Fact or Myth?
- Author
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Fischer, Andreas, Ayasse, Manfred, and Andrade, Maydianne C. B.
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REPELLENTS ,PEST control ,ORB weavers ,ARANEUS diadematus ,SPIDERS - Abstract
Although some spiders are globally invasive, found at high densities, and may be considered pests (particularly those that are toxic to humans), there are few pest management methods based on experimental data. 'Common wisdom' and advertisements on internet websites assert that a number of natural substances repel spiders. We tested whether the three substances cited most frequently (lemon oil, peppermint oil, and chestnut-fruits) effectively repelled female spiders or whether these were myths. We presented each of the putative repellents versus a control in a two-choice assay and tested responses of females of three invasive spider species in two different families: theridiids, Latrodectus geometricus C. L. Koch (Araneae: Theridiidae) and Steatoda grossa C. L. Koch (Araneae: Theridiidae) and the araneid, Araneus diadematus Clerck . Chestnuts (Araneae: Araneidae) and mint oil strongly repelled L. geometricus and A. diadematus. S. grossa was less sensitive to these chemicals but had a slight tendency to avoid chestnuts. However, lemon oil, the substance most likely to be cited as a repellent (over 1,000,000 hits on Google), had no effect on any of these spiders. We conclude that volatiles released by mint oil and chestnuts may be effective in deterring spider settlement in two different families of spiders, but lemon oil as a repellent is a myth. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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31. Systematics and natural history of Uaitemuri, a new genus of the orb-weaving spider family Uloboridae (Araneae: Deinopoidea) from south-eastern Brazil.
- Author
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SANTOS, ADALBERTO J. and GONZAGA, MARCELO O.
- Subjects
- *
ORB weavers , *ULOBORIDAE , *EGG cases (Zoology) , *MOUNTAIN forests - Abstract
We describe a new genus and two new species of the spider family Uloboridae Thorell, 1869 from south-eastern Brazil. Uaitemurigen. nov. can be distinguished by the peculiar shape of the opisthosoma, the presence of flattened setae on the patella and tibia of all legs, the flattened embolus, presence of a tegular plate in the male palpus, and female genitalia with flattened copulatory ducts associated with inflated hyaline copulatory atria. The type species, Uaitemuri rupicolasp. nov., is described from males and females from lowland and montane forests throughout south-eastern Brazil. A second species, Uaitemuri demariaisp. nov., is based on a single male from a coastal forest in the state of São Paulo. Morphological and behavioural data support the monophyly of the genus and suggest it is closely related to Orinomana Strand, 1934, Polenecia Lehtinen, 1967, Hyptiotes Walckenaer, 1837, and Miagrammopes O. Pickard-Cambridge, 1870. Uaitemuri rupicola builds vertical orb webs with a spiral-free sector, as observed in some species of Araneidae and Tetragnathidae, but recorded here for the first time in Uloboridae. The pteromalid wasp Arachnopteromalus dasys Gordh, 1976 was observed attacking egg sacs in a population of U. rupicola. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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32. Body-colour variation in an orb-web spider and its effect on predation success.
- Author
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Nakata, Kensuke and Shigemiya, Yusuke
- Subjects
- *
ORB weavers , *PREDATION , *ANIMAL coloration , *BODY temperature regulation , *ANIMAL species - Abstract
Animal body coloration serves several functions such as thermoregulation, camouflage, aposematism, and intraspecific communication. In some orb-web spiders, bright and conspicuous body colours are used to attract prey. On the other hand, there are other species whose body colour does not attract prey. Using a spider species showing individual body-colour variation, the present study aimed to determine whether or not the variation in body colour shows a correlation with predation rates. We studied the orb-web spider ( Cyclosa argenteoalba) using both field observations and T-maze experiments, in which the prey were exposed to differently coloured spiders. Cyclosa argenteoalba has silver- and black-coloured areas on its dorsal abdomen, with the ratio of these two colours varying continuously among individuals. The bright and conspicuous silver area reflects ultraviolet light. Results of both field observations and colour choice experiments using Drosophila flies as prey showed that darker spiders have a greater chance of capturing prey than silver spiders. This indicates that body-colour variation affects predation success among individuals and that the bright silver colour does not function to attract prey in C. argenteoalba. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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33. Phylogenetic position and composition of Zygiellinae and Caerostris, with new insight into orb-web evolution and gigantism.
- Author
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Gregorič, Matjaž, Agnarsson, Ingi, Blackledge, Todd A., and Kuntner, Matjaž
- Subjects
- *
ORB weavers , *INVERTEBRATE evolution , *INVERTEBRATE phylogeny , *ANIMAL species , *MOLECULAR phylogeny , *BIOMECHANICS , *ARACHNIDA classification - Abstract
Orb-weaving spiders are good objects for evolutionary research, but phylogenetic relationships among and within orb-weaving lineages are poorly understood. Here we present the first species-level molecular phylogeny that includes the enigmatic orb weavers ' Zygiellidae' and Caerostris. Zygiellidae is interesting for the evolution of the sector web, and Caerostris is noteworthy for web gigantism and extraordinary silk biomechanics. We assembled a molecular data set using mitochondrial ( COI, 16S) and nuclear ( H3, 18S, 28S, ITS2) gene fragments for 112 orbicularian exemplars, focusing on taxa with diverse web architecture and size. We show that ' Zygiellidae' contains the Holarctic Zygiella genus group ( Leviellus, Parazygiella, Stroemiellus, and Zygiella) and the Australasian Phonognatha and Deliochus. As this clade is placed with Araneidae in all analyses we treat it as a subfamily, Zygiellinae. Using the new phylogeny, we show that the sector web evolved eight times, and coevolved with the silk tube retreat, but that these features are not zygielline synapomorphies. Zygiellinae, Caerostris, and some other araneids form a basal grade of araneids that differ from 'classical' araneids in web-building and preying behaviour. We also confirm that Caerostris represents the most striking case of spider-web gigantism. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]
- Published
- 2015
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34. Vertical asymmetries in orb webs.
- Author
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Zschokke, Samuel and Nakata, Kensuke
- Subjects
- *
SYMMETRY (Biology) , *ORB weavers , *CENTROID , *BIOLOGICAL adaptation , *CYCLOSA , *ANIMAL species - Abstract
In almost all vertical orb webs the hub is above the geometric centre and consequently, the extent of the capture area is larger below the hub than above. In addition to this vertical web-extent asymmetry, orb webs show vertical asymmetries in number of spiral loops, mesh widths, and angles between radii. However, it was unknown whether these asymmetries are adaptations to the web-extent asymmetry or whether they are linked to gravity in a different way than through web-extent asymmetry. We reviewed known vertical asymmetries of orb webs, and we analysed the asymmetries of webs built by four different Cyclosa species, which show large intra- and inter-specific variation in web-extent asymmetry. We found all analysed structural asymmetries to be linked both to web-extent asymmetry and to gravity: Larger web extents below the hub and gravity both led to more sticky-spiral loops and to smaller angles between radii below the hub, whereas web-extent asymmetry and gravity had opposing effects on mesh width (mean and peripheral). Independent of web-extent asymmetry, almost all analysed webs had narrower peripheral meshes and smaller angles between radii below the hub than above. We interpret the narrow peripheral meshes along the web's lower edge as an adaptation to prevent tumbling prey from escaping, and the small angles between radii as an adaptation to prevent the sticky-spiral lines in these narrow meshes to come into contact with each other. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 659-672. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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35. Individual differences in boldness positively correlate with heart rate in orb-weaving spiders of genus Larinioides.
- Author
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SHEARER, Taylor A. and PRUITT, Jonathan N.
- Subjects
- *
INDIVIDUAL differences , *HEART beat , *ORB weavers , *SPIDER behavior , *ECOLOGISTS , *BIOLOGISTS - Abstract
Recent years have seen a dramatic increase in the number of studies devoted to consistent individual differences in behavior, termed "behavioral syndromes" or animal "personality". In particular, ecologists and evolutionary biologists alike seek to explore the functional consequences of individuals' personalities and explanations for their general maintenance. Understanding the mechanistic underpinnings to personality is arguably key to a deeper understanding of their functional consequences and maintenance. In particular, consistent individual differences in metabolic rate have been proposed as a general explanation for the maintenance of consistent individual differences in boldness, aggressiveness, and activity level. In this paper we explore whether consistent individual differences in boldness are associated with heat rate, a proxy for metabolic rate, in two species of orb-weaving spider: Larinioides cornutus and L. patagiatus. We first documented consistent individual differences in boldness in L. cornutus but not L. patagiatus, as estimated by individuals' latency to resume movement following an aversive stimulus. We also measured individuals' heart rate twice in a separate situation. We then tested for an association between individuals' boldness and their heart rate during these two events. We found that increased boldness was associated with increased heart. Thus, individuals that resumed movement quickly following an aversive stimulus also exhibited faster heart rates. Our studies provide further evidence that consistent individual differences in key physiological attributes, like metabolic rate, might be a general mechanism underlying consistent individual differences in behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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36. A new view of orb webs: multiple trap designs in a single structure.
- Author
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Eberhard, William G.
- Subjects
- *
ORB weavers , *NEPHILA pilipes , *SPIDER webs - Abstract
Spider orb webs are impressive for their apparently uniform geometric patterns. There are, however, consistent, substantial and taxonomically widespread periphery-to-hub differences in the distances between both adjacent radii and between sticky spiral lines. Radii in typical orbs were on average about 4-5 times farther apart at the outer edge than the inner edge of the area covered by sticky lines. Distances between sticky spiral loops were on average about two times larger near the outer edge than in more inner portions. This pattern in sticky spiral spacing was absent in the modified orbs of Nephila clavipes, in which distances between radii varied less. Thus, patterns in sticky spiral spacing may be related to inter-radial spacing; there is, however, probably no single explanation for all of the different patterns of sticky spiral spacing. The patterned differences in radius and sticky spiral spacing have important consequences for understanding orb function, because the lines in a prey's immediate vicinity largely determine whether it will be stopped and then retained, and elementary physics dictates that contact with more lines will tend to increase prey being stopped and retained. Rather than being a unit trap with a single set of prey capture properties, an orb has locally different trapping properties in different sectors. Abandoning the previous typological style of discussion of 'the' ability of a given design to stop and retain prey promises to lead to improved understanding of orb web designs. Published 2014. This article is a U.S. Government work and is in the public domain in the USA, Biological Journal of the Linnean Society, 2014, 111, 437-449. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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37. Systematic review of a new orb-weaving spider genus (Araneae: Araneidae), with special reference to the Australasian-Pacific and South-East Asian fauna.
- Author
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JOSEPH, MATHEW M. and FRAMENAU, VOLKER W.
- Subjects
- *
ORB weavers , *PEDIPALP , *ANIMAL species , *PHYLOGENY , *ANIMAL morphology , *META-analysis - Abstract
The Australasian-Pacific and South-East Asian species of the new orb-weaving spider genus Plebs with Plebs eburnus (Keyserling, 1886) as type species are revised. Following this study, Plebs includes a total of 22 species of which seven are here described new. Seven species are found in Australia, two in the Pacific region (New Caledonia, Vanuatu), and two in South-East Asia (Papua New Guinea, The Philippines). Eleven Asian species are transferred to the new genus . Plebs represent comparatively small orb-weaving spiders of c. 1.2-15.0 mm body length with a slightly elongated abdomen and humeral (shoulder) humps. Males of most species have two to three stout setae on the ventral side of their fourth coxae. Male pedipalps are characterized by the presence of a single macroseta on the patella, the presence of a paramedian apophysis as basal extension of the conductor, and an apical tegular protrusion. The female epigyne has a scape that is generally much longer than wide. It does not have a terminal pocket and is frequently broken off in a number of species. A phylogenetic analysis of 15 species of Plebs (those for which both sexes are known), 13 Australian/Pacific orb-weaving spider species representing the most commonly collected clades with paramedian apophysis, three species of Nearctic Eriophora Simon, 1864, and Araneus diadematus Clerck, 1758, as outgroup, identified a single synapomorphy of Plebs based on 35 morphological and three behavioural characters: a distinct, inverted U-shaped light pattern on the ventral side of the abdomen with two additional white spots anterolateral to the spinnerets. This analysis recovered a monophyletic clade of all Asian Plebs, suggesting a single colonization event of the genus that putatively originated in Australia. Most Plebs species appear to be active during the day. They build a regular orb-web with vertical stabilimentum in grass and low shrubs. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166, 279-341. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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38. Phylogenetic analysis of Micrathena and Chaetacis spiders (Araneae: Araneidae) reveals multiple origins of extreme sexual size dimorphism and long abdominal spines.
- Author
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Magalhães, Ivan L. F. and Santos, Adalberto J.
- Subjects
- *
PHYLOGENY , *MICRATHENA , *DIMORPHISM in animals , *SPIDERS , *ORB weavers , *SEXUAL behavior in insects , *INSECT morphology , *INSECTS - Abstract
The phylogenetic relationships amongst the New World spiny orb-weaving spiders Micrathena and Chaetacis were assessed through parsimony and Bayesian analyses of morphological characters. A total of 146 characters was scored for ten outgroup taxa and 37 Micrathena and four Chaetacis species. The results indicate that Chaetacis nests within Micrathena and we propose Chaetacis as a junior synonym of Micrathena. Twelve subgeneric species groups of Micrathena are recognized and diagnosed. Species with extremely long spines evolved at least eight times in the genus and we suggest that this may be related to antipredator defences. Micrathena is primitively sexually monomorphic and extreme sexual size dimorphism has arisen at least six times in the genus. Most of these events are because of enlargement of the female in relation to the ancestral size, although in two cases sexual dimorphism was attained through male reduction, adding more data to the 'giant females' vs. 'dwarf males' controversy. The genus is probably of South American origin and has repeatedly invaded Central and North America. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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39. Body spot coloration of a nocturnal sit-and-wait predator visually lures prey.
- Author
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Blamires, Sean J., Lai, Cheng-Hui, Cheng, Ren-Chung, Liao, Chen-Pan, Shen, Pao-Sheng, and Tso, I-Min
- Subjects
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PROTECTIVE coloration (Biology) , *ORB weavers , *NOCTURNAL animals , *PREDATOR management , *SPIDER physiology - Abstract
Many nocturnal spiders have paired conspicuous yellow ventral spots that contrast against their black and brown abdomens. A previous experiment, manipulating the coloration of the spots of the spider Neoscona punctigera, suggested that the spots lure prey. We conducted a field experiment in which we placed spider dummies that either mimicked an adult female N. punctigera in coloration, size, and shape (standard dummies) or mimicked N. punctigera but with the coloration of their ventral spots manipulated onto orb webs in the field at night and monitored them with infrared video cameras. Spectrophotometry confirmed that the coloration of the dummies resembled spider bodies, with the exception of the spots of the gray spotted dummies, where chromatic and achromatic contrast differences from spider spots were found. We used entirely yellow dummies to assess whether the spots represent a compromise between prey attraction and predator avoidance. We found that the standard dummies, mimicking adult female N. punctigera in coloration, size, and shape, attracted more prey than the dummies with gray spots, the entirely black dummies, and webs without spiders. The entirely yellow dummies attracted fewer prey than the standard dummies. These results show that the coloration of nocturnal spider ventral spots lures prey, although whether chromatic or achromatic cues are used could not be identified. The entirely yellow dummies did not lure more prey than standard dummies, so the spots are unlikely to represent a compromise between prey attraction and predator avoidance, in contrast to the coloration of certain diurnal orb web spiders. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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40. Modeling male reproductive strategies and optimal mate number in an orb-web spider.
- Author
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Rittschof, Clare C., Hilber, Samantha A., Tudor, M. Scarlett, and St Mary, Colette M.
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ORB weavers , *ANIMAL sexual behavior , *COMPETITION (Biology) , *REPRODUCTION , *SPIDER behavior - Abstract
It is widely accepted that males maximize their reproductive success by maximizing their number of mates. However, empirical evidence shows that males, like females, may use complex strategies to allocate their reproductive investment, and optimize, rather than maximize, their mate number. We use a dynamic state model to evaluate male mating strategies and mate number in the golden orb-web spider Nephila clavipes. In this spider, males move among female webs and compete to copulate with the web owner. Pre- and postcopulatory competition for fertilizations is a function of female age and mated status. Thus, males experience a heterogeneous mating environment. In addition, because males have very limited sperm, there is strong selection on males to optimize their mating strategies. We determine the major factors that limit male mate number and assess whether males use size-based strategies to maximize their reproductive success. Results suggest that there is more than one mate number optimum for males. Male reproductive success from mating monogynously with a virgin female is similar to reproductive success from mating promiscuously. Mean reproductive success decreases over the course of the season. Mate guarding and mating multiply are traded-off by males depending on potential reproductive rate and male size. Variation in female quality favors multiple mating but not choosiness unless the costs of reproduction are extreme. Finally, males of different sizes achieve similar reproductive success but employ size-dependent strategies [ABSTRACT FROM AUTHOR]
- Published
- 2012
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41. Microhabitat preferences drive phylogeographic disparities in two Australian funnel web spiders.
- Author
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BEAVIS, AMBER S., SUNNUCKS, PAUL, and ROWELL, DAVID M.
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ECOLOGICAL niche , *PHYLOGEOGRAPHY , *ORB weavers , *POPULATION genetics , *COMPARATIVE studies , *SAPROXYLIC insects - Abstract
Comparative phylogeography is underpinned by the assumption that sympatrically-distributed taxa will have experienced similar environmental histories, resulting in broadly congruent spatial structuring of phylogenetic lineages, particularly if they inhabit similar niches. However, divergent local conditions, specifically those related to microhabitat, may produce significantly divergent systematic signatures of demographic histories. In the present study, we compare the phylogenetic and population genetic spatial patterns displayed by two species of niche-separated (but sympatrically distributed) Australian funnel web spiders (Mygalomorphae: Hexathelidae). We demonstrate that an apparently minor disparity in habitat niche has led to divergent experiences of a common environmental history in the saproxylic Hadronyche cerberea and the ground-burrowing Atrax sutherlandi. Furthermore, we take a crucial first step in documenting the molecular systematics of a group that has traditionally suffered from a dearth of research interest. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 805-819. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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42. Morphological and phylogenetic atlas of the orb-weaving spider family Tetragnathidae (Araneae: Araneoidea).
- Author
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ÁLVAREZ-PADILLA, FERNANDO and HORMIGA, GUSTAVO
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ORB weavers , *INSECT morphology , *PHYLOGENY , *TETRAGNATHIDAE , *NUCLEOTIDE sequence , *CLADISTIC analysis , *INSECT evolution , *SCANNING electron microscopy - Abstract
The present atlas documents the morphology of representative species of 22 tetragnathid genera, with emphasis on nontetragnathines. It includes approximately 960 scanning electron micrographs, morphological drawings and web photographs. The 213 characters used in the phylogenetic analyses are described and illustrated. We discuss the optimal cladograms obtained by the analysis of the morphological and behavioural data, and compare our results to a recent hypothesis of tetragnathid phylogenetic relationships that combined similar data with multigene DNA sequences. Based on the cladistic hypothesis that results from the total evidence analysis, we study the evolution of six morphological character systems within Tetragnathidae: spinneret spigots, respiratory structures, trichobothria, chelicerae, and male and female genitalia. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 713-879. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
43. Behavioural and biomaterial coevolution in spider orb webs.
- Author
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SENSENIG, A., AGNARSSON, I., and BLACKLEDGE, T. A.
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SPIDER webs , *ORB weavers , *TENDONS , *MUSCLES , *BIODIVERSITY , *FERTILITY - Abstract
Mechanical performance of biological structures, such as tendons, byssal threads, muscles, and spider webs, is determined by a complex interplay between material quality (intrinsic material properties, larger scale morphology) and proximate behaviour. Spider orb webs are a system in which fibrous biomaterials—silks—are arranged in a complex design resulting from stereotypical behavioural patterns, to produce effective energy absorbing traps for flying prey. Orb webs show an impressive range of designs, some effective at capturing tiny insects such as midges, others that can occasionally stop even small birds. Here, we test whether material quality and behaviour (web design) co-evolve to fine-tune web function. We quantify the intrinsic material properties of the sticky capture silk and radial support threads, as well as their architectural arrangement in webs, across diverse species of orb-weaving spiders to estimate the maximum potential performance of orb webs as energy absorbing traps. We find a dominant pattern of material and behavioural coevolution where evolutionary shifts to larger body sizes, a common result of fecundity selection in spiders, is repeatedly accompanied by improved web performance because of changes in both silk material and web spinning behaviours. Large spiders produce silk with improved material properties, and also use more silk, to make webs with superior stopping potential. After controlling for spider size, spiders spinning higher quality silk used it more sparsely in webs. This implies that improvements in silk quality enable ‘sparser’ architectural designs, or alternatively that spiders spinning lower quality silk compensate architecturally for the inferior material quality of their silk. In summary, spider silk material properties are fine-tuned to the architectures of webs across millions of years of diversification, a coevolutionary pattern not yet clearly demonstrated for other important biomaterials such as tendon, mollusc byssal threads, and keratin. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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- View/download PDF
44. Ladder webs in orb-web spiders: ontogenetic and evolutionary patterns in Nephilidae.
- Author
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KUNTNER, MATJAŽ, KRALJ-FIŠER, SIMONA, and GREGORIČ, MATJAŽ
- Subjects
- *
ORB weavers , *SPIDERS , *MACROEVOLUTION , *ONTOGENY , *PHYLOGENY - Abstract
Spider web research bridges ethology, ecology, functional morphology, material science, development, genetics, and evolution. Recent work proposes the aerial orb web as a one-time key evolutionary innovation that has freed spider-web architecture from substrate constraints. However, the orb has repeatedly been modified or lost within araneoid spiders. Modifications include not only sheet- and cobwebs, but also ladder webs, which secondarily utilize the substrate. A recent nephilid species level phylogeny suggests that the ancestral nephilid web architecture was an arboricolous ladder and that round aerial webs were derived. Because the web biology of the basalmost Clitaetra and the derived Nephila are well understood, the present study focuses on the webs of the two phylogenetically intervening genera, Herennia and Nephilengys, to establish ontogenetic and macroevolutionary patterns across the nephilid tree. We compared juvenile and adult webs of 95 Herennia multipuncta and 143 Nephilengys malabarensis for two measures of ontogenetic allometric web changes: web asymmetry quantified by the ladder index, and hub asymmetry quantified by the hub displacement index. We define a ‘ladder web’ as a vertically elongated orb exceeding twice the length over width (ladder index ≥ 2) and possessing (sub)parallel rather than round side frames. Webs in both genera allometrically grew from orbs to ladders, more so in Herennia. Such allometric web growth enables the spider to maintain its arboricolous web site. Unexpectedly, hub asymmetry only increased significantly in heavy-bodied Nephilengys females, and not in Herennia, challenging the commonly invoked gravity hypothesis. The findings obtained in the present study support the intrageneric uniformness of nephilid webs, with Herennia etruscilla webs being identical to H. multipuncta. The nephilid web evolution suggests that the ancestor of Nephila reinvented the aerial orb web because the orb arises at a much more inclusive phylogenetic level, and all intervening nephilids retained the secondarily acquired substrate-dependent ladder web. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 849–866. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
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45. First fossil Molinaranea Mello-Leitão, 1940 (Araneae: Araneidae), from middle Miocene Dominican amber, with a phylogenetic and palaeobiogeographical analysis of the genus.
- Author
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SAUPE, ERIN E., SELDEN, PAUL A., and PENNEY, DAVID
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SPIDERS , *FOSSILS , *ORB weavers , *PHYLOGENY - Abstract
The first fossil Molinaranea is described, from middle Miocene Dominican amber. This record extends the known range of the genus back 16 million years; it also extends the geographical range of the genus through time, with extant species known only from Chile, Argentina, the Falkland Islands, and Juan Fernandez Island. A parsimony-based phylogenetic analysis was performed, which indicates that the fossil species, Molinaranea mitnickii sp. nov., is nested with Molinaranea magellanica Walckenaer, 1847 and Molinaranea clymene Nicolet, 1849 . A modified Brooks parsimony analysis was conducted in order to examine the biogeography and origins of the fossil species in the Dominican Republic; the analysis suggests that M. mitnickii sp. nov. arrived in Hispaniola from South America as a result of a chance dispersal event. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158, 711–725. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
46. Effects of Grassland Succession on Communities of Orb-Weaving Spiders.
- Author
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Richardson, M. L. and Hanks, L. M.
- Subjects
SPECIES diversity ,HABITATS ,ANIMAL-plant relationships ,GRASSLAND plants ,ORB weavers ,PLANT succession ,PLANT communities ,ANIMAL communities - Abstract
Native grasslands are among the most imperiled of the North American ecosystems, but abandoned agricultural areas may provide suitable habitat for animal taxa that are endemic to grasslands. We studied how species diversity of orb-weaving spiders was influenced by secondary succession of a grassland plant community by monitoring the abundance and species diversity in study plots that were cultivated at 6-yr intervals and left uncultivated in the interim. We tested the hypothesis that local abundance and species diversity of spiders would be positively associated with time since cultivation because plant communities in older habitats would be more architecturally complex. Local abundance of spiders in general was not associated with time since cultivation, but abundance of Mangora gibberosa (Hentz) was positively associated with the abundance of perennial plants. Species richness and diversity of spiders also were positively associated with the abundance of perennial plants and reached a threshold a few years after cultivation. Species diversity of orb-weaving spiders seems to be strongly influenced by species composition of the plant community. Therefore, effective restoration of the structure and function of endemic communities of orb-weaving spiders may depend on preserving endemic grassland plant communities. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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47. Partitioning of Niches Among Four Species of Orb-Weaving Spiders in a Grassland Habitat.
- Author
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Richardson, M. L. and Hanks, L. M.
- Subjects
ECOSYSTEM management ,ORB weavers ,ECOLOGICAL niche ,INSECT societies ,SPIDER physiology ,ANIMAL morphology ,HABITATS ,GRASSLANDS ,ECOLOGY ,GRASSLAND animals - Abstract
Partitioning of niches can play an important role in structuring fauna! communities. We tested the hypothesis that differences between four species of orb-weaving spiders (Araneidae) in body size and the structure and position of their webs resulted in their partitioning the available prey. The study species are sympatric in a grassland habitat and included Argiope trifasciata (Forskål), Cyclosa turbinata (Walckenaer), Mangora gibberosa (Hentz), and Neoscona arabesca (Walckenaer). The spider species differed in body size, web diameter, height of web above the ground, spacing of mesh within webs, and the type of plant to which the web was attached. The spider species had a generalist diet and captured prey of multiple trophic levels. Nevertheless, the hypothesis was supported: the spider species differed in the types of prey that they captured. Partitioning of the available prey was influenced by body size, with larger spiders capturing larger prey, but not by the structure or position of their webs. Differences between spider species in niche may reduce competitive interactions and allow them to coexist in sympatry. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
48. Wrap attack activates web-decorating behavior in Argiope spiders.
- Author
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Walter, André, Elgar, Mark A., Bliss, Peter, and Moritz, Robin F.A.
- Subjects
- *
SPIDER webs , *SILK , *ARGIOPE , *SPIDER behavior , *ORB weavers , *PREDATION , *BEHAVIOR - Abstract
Various orb-weaving spiders add extra silk structures—“web decorations”—to their webs. The adaptive value of these web decorations is still unclear, and the suite of functional hypotheses remains controversial. Spiders in the genus Argiope decorate their webs with densely woven zigzag ribbons made of fibrous aciniform silk. This type of silk is also used by the spiders for “wrap attacks” to immobilize the prey by wrapping it with a dense silk cover. Previous studies suggested that the spiders use accumulated excess silk for building web decorations due to a constant secretion in the aciniform glands. We test if this hypothesis holds for 3 species, which construct different types of web decorations: linear in Argiope bruennichi, irregular in Argiope sector, and cruciate in Argiope keyserlingi. We show that depletion of aciniform silk has a stimulating effect on web-decorating behavior in 3 species of Argiope. The aciniform glands apparently readily overcompensated experimentally induced silk losses, and so silk depletion may result in the activation of the according glands. We suggest that the aciniform gland activation might be an important mechanism for Argiope’s wrap attack to ensure sufficient wrapping of silk under high prey density and repeated wrapping events. The web decorations might function as a mechanism to maintain high gland activity, thereby maximizing the efficiency of the wrap attack strategy of Argiope. [ABSTRACT FROM PUBLISHER]
- Published
- 2008
- Full Text
- View/download PDF
49. Size-dependent mating strategies and the risk of cannibalism.
- Author
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ELGAR, MARK A. and JONES, THERÉSA M.
- Subjects
- *
NEPHILA , *ORB weavers , *SPERM competition , *SEXUAL dimorphism in animals , *ANIMAL sexual behavior , *ANIMAL paternity - Abstract
The role of sexual selection in determining the nature and direction of sexual size dimorphism may depend upon the timing of sexual selection, and this may also influence the variation in male size. For example, selection through sperm competition favours smaller males in the highly sexually size dimorphic orb-weaving spider Nephila edulis, whereas larger males are better able to exclude their smaller rivals from the central hub of the web where mating takes place. We investigate experimentally the role of body size and hub tenure in determining male fertilization success when males of different sizes compete for a single female over a 24-h period that includes a period of darkness. Our results confirm that small and large males obtain similar paternity share but that, in contrast with previous studies, hub tenure does not translate into greater paternity share. Unexpectedly, smaller males are at greater risk of postmating sexual cannibalism than larger males, suggesting that natural selection through sexual cannibalism may place a lower limit on male size. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 355–363. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
50. Why cross the web: decoration spectral properties and prey capture in an orb spider ( Argiope keyserlingi) web.
- Author
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BLAMIRES, SEAN J., HOCHULI, DIETER F., and THOMPSON, MICHAEL B.
- Subjects
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ANIMAL sounds , *BLUE light , *ULTRAVIOLET radiation , *SPIDER webs , *ARGIOPE , *ORB weavers , *INSECTS - Abstract
An effective visual signal elicits a strong receiver response. The visual receptors of most insects are sensitive to ultraviolet (UV), blue and green light. The decorations of certain orb web spiders may be described as a type of visual signal, a sensory trap, as they exploit visual biases in insects. We filtered UV and blue light from the decorations of Argiope keyserlingi, under field conditions, using plastic sheets to test if the UV and blue light reflected affects the type of prey caught. We found that houseflies, blowflies, stingless bees, honeybees and vespid wasps were caught more frequently in webs with decorations than webs without, while ichneumonid wasps were caught less frequently. Blowflies, stingless bees, honeybees and vespid wasps were caught more often in unfiltered decorated webs. These insects also have receptor sensitivities in the blue and UV. We showed that exploiting visual sensory biases plays an integral role in attracting insects to orb web decorations. Whether UV light, blue light, or both, are the most important cue, however, requires further study. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 221–229. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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