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Body coloration of orb-web spiders was previously hypothesized to be attractive to insects, luring potential prey, or associated with protection against visually oriented predators. We combined manipulative experiments with spectral reflectance analyses to test the prey attraction hypothesis, using the araneid spider Gasteracantha cancriformis as a model. The study was conducted in a shaded environment, within a forest fragment of the Atlantic forest located in Southeastern Brazil. Insect interception on web surfaces displaying the dorsal section of G. cancriformis opisthosoma, which emits blue fluorescence and reflects light in the ultraviolet wavelength region, was higher than on surfaces displaying the spider's ventral section, or in webs without spiders. This study supports the prey attraction hypothesis by providing evidence that the color patterns of G. cancriformis dorsum improve prey interception by their webs. Fluorescence and achromatic cues are probably important to lure and attract potential prey.

Conspicuous colours in animals are usually explained by mate attraction, predator avoidance and prey attraction. Predators may lure prey by mimicking food or other resources. Alternatively, some animals avoid predation by visually signalling unpalatability to predators. The evolution of a signal is affected by receiver processing mechanisms. Therefore, variation in sensory systems may explain the evolution of colour polymorphism of conspicuous species. We aimed to investigate the role of receivers in the evolution and maintenance of colour conspicuousness and polymorphism in Gasteracantha cancriformis (Araneidae). We tested two hypotheses: (1) conspicuous coloration is a prey lure strategy; (2) conspicuous coloration is a warning signal to predators. Furthermore, we identified the taxonomic order of prey captured and the type of predator (avian versus arthropod). To assess the role of prey, we conducted a field experiment in which webs were assigned to one of four treatments: yellow, red or black spider models, or no model. For each treatment, we counted the number of prey trapped on the webs and calculated the damaged area of the webs. To assess the role of predators, we conducted a second field experiment in which we attached yellow, red and black models to trees using nylon thread and observed the number of attack markings on each model. Our results did not corroborate the prey attraction hypothesis. In the predation experiment, black models had more attack markings, indicating that yellow and red models were less preferred. This suggests that spider coloration may play a role in predator avoidance. Colour polymorphism in this species is possibly a multifunctional attribute, where some morphs benefit from aposematism, whereas others may have alternative fitness advantages. Nonadaptive explanations should also be considered in future experiments of the evolution and maintenance of colour polymorphisms.

Spiders (order Araneae, class Arachnida) are an important group of predatory arthropods in terrestrial ecosystems that have been recently identified as an untapped reservoir of single-stranded (ss)DNA viruses. Specifically, spiders harbour a diversity of ssDNA viruses encoding a replication-associated protein (Rep) within a circular genome. However, little is known about the ecology of novel circular Rep-encoding ssDNA (CRESS DNA) viruses. Here we investigated two CRESS DNA viruses recently identified in spinybacked orbweavers (Gasteracantha cancriformis), namely spinybacked orbweaver circular virus (SpOrbCV) 1 and 2. SpOrbCV-1 was detected in the majority (> 65 %) of spider specimens from all life stages, including eggs, spiderlings and adults, demonstrating that this virus is active within spinybacked orbweavers. In contrast, SpOrbCV-2 was only detected in adults at a lower (36 %) prevalence. Since we also detected SpOrbCV-2 in other spider species and this virus has been reported from a dragonfly, we suggest that SpOrbCV-2 is accumulated in these predators through common insect prey. The prevalence of SpOrbCV-1 in collected specimens allowed us to design assays to characterize this virus, which represents a new group of CRESS DNA viruses, the ‘circularisviruses’. To our knowledge, SpOrbCV-1 is the first example of a vertically transmitted virus in spiders, which may explain its high prevalence in spinybacked orbweavers. Since vertically transmitted viruses infecting insects (class Insecta) can manipulate their host’s behaviour and physiology, future studies should investigate the ecological role of vertically transmitted viruses in spiders.

Behavioural adjustments to changing environmental conditions are advantageous for spiders, as such adjustments likely allow spiders to remain in good hunting sites. Here, we describe the behavioural response of seven araneoid species to heavy rain in the neotropics. Five of the seven spiders drastically modified their position on the web, relative to the typical resting position. Four of these species (Allocyclosa bifurca, Argiope argentata, Cyrtophora citricola, and Leucauge mariana) hung from hub threads using their legs III and IV, oriented the anterior section of the prosoma downward, and moved legs I and II forward in front of the spider's eyes. Trichonephila clavipes had a similar response, but hung from only its legs IV. Two other species (Gasteracantha cancriformis and Micrathena duodecimspinosa) did not show an apparent response to heavy rain. The change in position reduces the spider's surface that heavy rain could impact, and speeds water drainage which may reduce pathogen infection. Universidad de Costa Rica/[833-C0-251]/UCR/Costa Rica UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET)

BackgroundModern molecular analyses are often inconsistent with pre-cladistic taxonomic hypotheses, frequently indicating higher richness than morphological taxonomy estimates. Among Caribbean spiders, widespread species are relatively few compared to the prevalence of single island endemics. The taxonomic hypothesisGasteracantha cancriformiscircumscribes a species with profuse variation in size, color and body form. Distributed throughout the Neotropics,G. cancriformisis the only morphological species ofGasteracanthain the New World in this globally distributed genus.MethodsWe inferred phylogenetic relationships across Neotropical populations ofGasteracanthausing three target genes. Within the Caribbean, we estimated genetic diversity, population structure, and gene flow among island populations.ResultsOur findings revealed a single widespread species ofGasteracanthathroughout the Caribbean,G. cancriformis, while suggesting two recently divergent mainland populations that may represent separate species, diverging linages, or geographically isolated demes. The concatenated andCOI(Cytochrome c oxidase subunit 1) phylogeny supported a Caribbean clade nested within the New World. Genetic variability was high between island populations for ourCOIdataset; however, gene flow was also high, especially between large, adjacent islands. We found structured genetic and morphological variation withinG. cancriformisisland populations; however, this variation does not reflect genealogical relationships. Rather, isolation by distance and local morphological adaptation may explain the observed variation.

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.

AimThe Andean uplift has played a major role shaping the current Neotropical biodiversity. However, in arthropods other than butterflies, little is known about how this geographic barrier has impacted species historical diversification. Here we examined the phylogeography of the widespread and color polymorphic spiderGasteracantha cancriformisto: (i) evaluate the effect of the northern Andean uplift on its divergence and, (ii) assess whether its diversification occurred in the presence of gene flow.LocationNorthern Andes and BrazilMethodsWe inferred phylogenetic relationships and divergence times inG. cancriformisusing mitochondrial and nuclear data from 105 individuals in northern South America. Genetic diversity, divergence and population structure were quantified. We also compared multiple demographic scenarios for this species using a model-based approach (PHRAPL) to establish divergence with or without gene flow. Finally, we evaluated the association between genetic variation and color polymorphism.ResultsBoth nuclear and mitochondrial data supported two well-differentiated clades, which correspond to populations occurring in opposite sides of the Eastern cordillera of the Colombian Andes. The splitting between these clades occurred in the early Pleistocene, around 2.13 million years ago (95% HPD = 0.98–3.93).Despite this vicariant event, there is shared genetic variation between the clades, which is better explained by a scenario of historical divergence in the face of gene flow. Color polymorphism was randomly scattered in both clades and is not statistically associated with the genetic variation studied here.Main ConclusionsThe final uplift of Eastern cordillera of the Colombian Andes was identified as the major force that shaped the diversification ofG. cancriformisin Northern South America, resulting in acis- andtrans-Andean phylogeographic structure for the species. The divergence in the face of gene flow betweencis- andtrans-Andean populations found for this spider has been likely facilitated by the presence of low-elevation passes across the Eastern Colombian cordillera. Our work constitutes the first example where the Andean uplift coupled with gene flow influenced the evolutionary history of an arachnid lineage.

The Andean uplift has played a major role in shaping the current Neotropical biodiversity. However, in arthropods other than butterflies, little is known about how this geographic barrier has impacted species historical diversification. Here, we examined the phylogeography of the widespread color polymorphic spider Gasteracantha cancriformis to evaluate the effect of the northern Andean uplift on its divergence and assess whether its diversification occurred in the presence of gene flow. We inferred phylogenetic relationships and divergence times in G. cancriformis using mitochondrial and nuclear data from 105 individuals in northern South America. Genetic diversity, divergence, and population structure were quantified. We also compared multiple demographic scenarios for this species using a model‐based approach (phrapl) to determine divergence with or without gene flow. At last, we evaluated the association between genetic variation and color polymorphism. Both nuclear and mitochondrial data supported two well‐differentiated clades, which correspond to populations occurring on opposite sides of the Eastern cordillera of the Colombian Andes. The final uplift of this cordillera was identified as the most likely force that shaped the diversification of G. cancriformis in northern South America, resulting in a cis‐ and trans‐Andean phylogeographic structure for the species. We also found shared genetic variation between the cis‐ and trans‐Andean clades, which is better explained by a scenario of historical divergence in the face of gene flow. This has been likely facilitated by the presence of low‐elevation passes across the Eastern Colombian cordillera. Our work constitutes the first example in which the Andean uplift coupled with gene flow influenced the evolutionary history of an arachnid lineage.

A teoria de “sensory drive” prediz que sinais, sistemas sensoriais e comportamentos de sinalização devem coevoluir. Variação no sistema sensorial de presas ou predadores pode explicar a diversidade de colorações existentes e polimorfismos de cores. A aranha de teia orbicular Gasteracantha cancriformis apresenta padrões de coloração conspícuos e polimorfismo de cor. A evolução e manutenção de tal variação cromática pode ser influenciada por presas e predadorescom sistemas visuais diferentes, já que um mesmo morfo é percebido distintamente por potenciais presas e predadores. A coloração conspícua, entretanto, não se assemelha à coloração de flores. Tampouco influencia na captura de presas, visto que modelos dessa aranhas apresentaram números similares de presas nas teias. Portanto, ao contrário de outras aranhas de teia orbicular, para as quais a coloração chamativa é atribuída ao mimetismo floral, para G. cancriformis, esta hipótese não é corroborada. Os morfos amarelo e vermelho apresentam coloração típica de organismos aposemáticos e são conspícuos para a visão de uma ave. O morfo vermelho apesar de não ser conspícuo na visão de vespas, ainda assim poderia estar protegido de predação por camuflagem. Dessa forma, esses morfos poderiam ser mantidos na população devido à pressão de diferentes predadores, morfos vermelhos sinalizariam impalatabilidade para aves, enquanto morfos amarelos, para vespas. Porém, essas diferenças não foram observadas experimentalmente. Em campo, modelos pretos de aranha apresentaram mais marcas de predação do que modelos amarelos e vermelhos, também sugerindo que em G. cancriformis a coloração chamativa pode ser um sinal de advertência para predadores. Porém, a multiplicidade de predadores por si só não explica a variação cromática em populações dessa espécie de aranha. Consequentemente, o polimorfismo de cor em G. cancriformis pode ser uma característica multi-funcional, onde morfos não aposemáticos seriam mantidos nas populações devido a outras funções adaptativas, como camuflagem ou termorregulação. The sensory drive theory predicts that signals, sensory systems, and signaling behavior should coevolve. Variation in the sensory systems of prey and predators may explain the diversity of color signals, such as color polymorphism. The spider Gasteracantha cancriformis (Araneidae) possesses several conspicuous color morphs. The aim of the present study was to assess whether the color polymorphism of G. cancriformis may be maintained by pressure from multiple signal receivers, such as prey and predators with distinct color vision systems. In orb-web spiders, the prey attraction hypothesis states that conspicuous colors are prey lures that increase spider foraging success via flower mimicry. However, in highly defended species, conspicuous colors could also be a warning signal to predators. We used color vision modelling to estimate chromatic and achromatic contrast of G. cancriformis morphs as perceived by potential prey and predator taxa. To assess the role of prey, we conducted a prey capture experiment in the field, in which webs were assigned to four treatments: yellow, red, and black models, or no model. For each treatment, we counted the number of prey trapped on the webs and the calculated webs damaged area. To assess the role of predators on the evolution of conspicuous color patterns and polymorphism, we conducted a second field experiment, allocating yellow, red and black spider models in nylon threads along the vegetation, and observed the number of attack markings for each of them. Our results revealed that individual prey and predator taxa perceive the conspicuousness of morphs differently. Therefore, the multiple prey and multiple predator hypotheses may explain the evolution of color polymorphism in G. cancriformis. The results of prey capture experiment did not corroborate the prey attraction hypothesis nor the prey specific adaptation of color polymorphism. On the predation experiment, we found that black spider models presented more markings, which indicates that yellow and red models were less preferred, possibly suggesting that spider coloration may play a role on predator avoidance. Our results, however, do not corroborate the hypothesis that multiple predators influence polymorphism evolution. Color polymorphism in this species is possibly a multi-functional attribute, where some morphs benefits from aposematism, whereas others may alternative fitness advantages. Non-adaptive explanation should also be considered in future experiments of the evolution and maintenance of color polymorphisms. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES

The sensory drive theory predicts that signals, sensory systems, and signaling behavior should coevolve. Variation in the sensory systems of prey and predators may explain the diversity of color signals, such as color polymorphism. The spider Gasteracantha cancriformis (Araneidae) possesses several conspicuous color morphs. The aim of the present study was to assess whether the color polymorphism of G. cancriformis may be maintained by pressure from multiple signal receivers, such as prey and predators with distinct color vision systems. Although, the multiple receivers world is a more realistic scenario, it has received little attention. In orb-web spiders, the prey attraction hypothesis states that conspicuous colors are prey lures that increase spider foraging success via flower mimicry. However, in highly defended species, conspicuous colors could also be a warning signal to predators. We used color vision modelling to estimate chromatic and achromatic contrast of G. cancriformis morphs as perceived by potential prey and predator taxa. Our results revealed that individual prey and predator taxa perceive the conspicuousness of morphs differently. For instance, the red morph is perceived as quite conspicuous to lepidopteran prey and avian predators, but not by other insects. Therefore, the multiple prey and predator hypotheses may explain the evolution of color polymorphism in G. cancriformis. However, flower mimicry hypothesis was weakly corroborated. Other parameters that are not evaluated by color vision models, such as distance, shape, angle, and pattern geometry could also affect the perception of color morphs by both prey and predators and thereby influence morph survival.

Se estudió la composición de parasitoides y depredadores de la mosca blanca en espiral Aleurodicus dispersus así como la abundancia relativa de las primeras diez fincas productoras de banano, durante 1997 y 1998 en Matina, Limón, Costa Rica. Se recuperaron cuatro especies de parasitoides de ninfas de mosca blanca Encarsiella noyesi Hayat, E. aleurodici (Girault), Encarsiella probo nsp. y Encarsia guadeloupae Viggiani. Los depredadores de ninfas y adultos de mosca blanca más comunes fueron dos especies de ácaros pertenecientes a la familia Phytoseiidae, Nephaspis sp. (Coleoptera: Coccinelidae), Scymnus sp. (Coleoptera: Coccinelidae), y tres especies de arañas: Plesiometa argyra (Araneida), Gasteracantha cancriformis (Araneida), y Chrysso sp. (Araneida). El porcentaje de parasitismo difirió significativamente entre fincas y fue mayor en AGRODISA>SEMDEL> Anabel.

The presence of conspicuous colouration in predators is puzzling because natural selection is expected to favour cryptic or disruptive colouration, making predators less detectable by prey. However, the prey attraction hypothesis proposes that conspicuous colour patterns in spiders increase their foraging success by luring prey. Using manipulative experiments we tested the prey attraction hypothesis for the three most common colour morphs of the orb-weaver Gasteracantha cancriformis (yellow, white, and black and white), as well as individuals painted black and individuals painted yellow. Contrary to our predictions, the black painted spiders had the highest number of damaged areas in webs (an indirect measure of foraging success). Black painted spiders were also observed more often consuming prey and with prey remains in the web, although the trend was not significant. Furthermore, there was no difference in the number of prey intercepted by webs of each spider colour and, in the laboratory, Drosophila me...

There is controversy about the function of silk stabilimenta, also called silk decorations, oil spiders' webs. Most of the proposed hypotheses have been tested using indirect methods. Protection against predators, advertisement for vertebrates to avoid web damage, and increasing prey attraction are the most popular hypotheses. In this study, I tested the prey attraction hypothesis oil the silk decorations of the araneid Argiope savignyi using a trial tunnel built ill the field, ill which 1 exposed stingless bees Tetragonisca angustula to decorated and undecorated webs placed oil wooden frames. I carried out two experiments: 1) a three-frame choice, consisting of a frame bearing it decorated web, one bearing an undecorated web and a control frame without web and spider; 2) a two-frame choice, in which the bees were exposed to only two frames consisting or "decorated web vs. control," "decorated web vs. undecorated web," and "undecorated web vs. control". In favor of the prey attraction function, I found that decorated webs intercepted more bees that) webs deprived of the decoration or controls with no webs. Argiope savignyi's decorations might lure prey to the web by UV-reflectance as it has been suggested for other Argiope species.

Several orb-web spiders build conspicuous decorations in their webs. The prey attraction hypothesis proposes that decorations increase spider foraging success by attracting prey, and that attraction is linked to UV reflectance. Alternatively, the web advertisement hypothesis proposes that decorations are a signal that advertises the presence of the web to large animals. We tested both hypotheses for the web silk tufts of Gasteracantha cancriformis. Even though tufts are UV reflective, we did not find support for the prey attraction hypothesis. In the field, when webs with tufts painted black and control webs were compared, there were no differences in the number of prey captured, number of damaged areas in webs and type of prey captured. In the laboratory, Drosophila melanogaster did not demonstrate preference for tufted silk lines versus non-tufted silk lines. Our data also did not give support for the web advertisement hypothesis. The proportion of web destruction was similar between web with tufts painted black and control webs during four days of experimentation. Therefore, two of the most favoured hypotheses that attempt to explain decorations do not apply for web silk tufts in our study system. Instead we propose that silk tufts might be an aposematic signal.

Both the uloborid Philoponella vicina and the araneid Gasteracantha cancriformis spiders sometimes placed silk stabilimenta on non-orb “resting webs” that consisted of only one or a few lines. These webs completely lacked sticky silk, so their stabilimenta could not function to attract prey. Some non-orbs were built by spiders when their orb webs are damaged. These observations contradict the prey attraction camouflage hypothesis for stabilimentum function, but are compatible with the spider camouflage and web advertisement to avoid web destruction hypotheses.

Pusimos a prueba tres hipótesis concernientes a la función de los estabilimentos en la araña Gasteracantha cancriformis: 1) advertencia a animales grandes que podrı´an destruir accidentalmente la red; 2) atracción de presas; y 3) camuflaje. Se cumplió una predicción de la hipótesis de advertencia (pero no de las demás) de que las redes menos expuestas deberı´an presentar menos estabilimentos: se observaron muy pocos estabilimentos en las líneas periféricas de redes pequeñas. Por otra parte, la predicción de la hipótesis de atracción de presas, de que redes con más estabilimentos deberían presentar más presas capturadas, solo se cumplió en una submuestra y análisis posteriores mostraron que el tamaño de la araña y no el número de estabilimentos explicó mejor la presencia de presas. Otra observación que no apoya la hipótesis de atracción de presas fue haber encontrado redes de descanso, las cuales carecieron de un espiral de captura, con un importante número de estabilimentos. Finalmente, el número de estabilimentos fue menor en las redes de arañas blancas (en relación a las amarillas o las anaranjadas), contradiciendo la predicción de la hipótesis de camuflaje. Nuestros resultados apoyan la hipótesis de advertencia y no la de atracción de presas. We tested three hypotheses concerning the function of stabilimenta in the orb weaver Gasteracantha cancriformis: 1) warning to large animals that might accidentally destroy the web; 2) prey attraction; and 3) camouflage. One prediction of the warning hypothesis (but not of the others), that less exposed webs should have fewer stabilimentum tufts, was verified: very few tufts occurred on the peripheral lines of small webs. On the other hand, a prediction of the prey attraction hypothesis, that webs with more stabilimentum tufts should also have more captured prey, was only confirmed in one sub sample, and further analysis indicated that spider size rather than number of stabilimentum tufts best explained the presence of prey. An additional observation not in accord with prey attraction was that resting webs, which lacked sticky silk for prey capture, nevertheless had abundant stabilimentum tufts. Finally, the number of stabilimentum tufts was lower in the webs of white (as opposed to yellow or orange) spiders, contradicting a prediction of the camouflage hypothesis. The strongest conclusions from our results are support for the warning function, and lack of support for the prey attraction function. Fil: Jaffé, Rodolfo. Martin-Luther-Universität Halle-Wittenberg; Alemania Fil: Eberhard, William. Universidad de Costa Rica; Costa Rica Fil: de Angelo, Carlos Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Fundación Vida Silvestre; Argentina Fil: Eusse, Diana. Universidad del Valle; Colombia Fil: Gutierrez, Adrián. Universidad Autónoma de México; México Fil: Quijas, Sandra. Universidad Autónoma de México; México Fil: Rodríguez, Antonio. Universidad de La Habana; Cuba Fil: Rodríguez, Mayanin. Universidad de los Andes; Venezuela

Female spiders have two separate reproductive tracts, one on each side of the body, which receive and store sperm. Thus, females may be virgin or nonvirgin on both sides, or virgin on one side and nonvirgin on the other side. To examine whether male orb-weaving spiders, G. cancriformis, respond differentially to females based on mating history, we presented males to (1) virgin females, (2) females that had previously mated with one of their two tracts and (3) females that had mated previously with both reproductive tracts. Prior to copulation, males showed no differential responses in terms of latency to courtship, number of courtship bouts, number of insertion attempts, or latency to copulation. Female mating history influenced copulatory frequency and sperm release by the male, but not duration of copulation. Nearly all males copulated twice with virgin females, once with each reproductive tract. They released nearly all sperm contained in their palps. Males that encountered nonvirgin reproductive tracts were more likely to depart after a single copulation without attempting a second. Such males rarely released sperm, but the few that did released as many as males mating with virgin tracts. Thus, sperm were released in an all-or-none fashion. Female mating history did not influence the frequency of intersexual cannibalism. This suggests that differential response by males is more likely related to female patterns of sperm use than to high levels of intersexual killing.

This study focuses on the predatory capacity of four sympatric species of web- building spiders that inhabit coffee plantations in Southern Mexico: Gasteracantha cancriformis, Cyclosa caroli , and the morphologically similar species pair Leucauge marianaand L. venusta which were considered as one species group. The retention capabilities of the webs of these species and the incidence of prey capture and consumption were measured using eight types of insect prey belonging to the orders Coleoptera (1 species), Hymenoptera (3), Diptera (2) Lepidoptera (1) and Homoptera (1). The different characteristics of each prey such as body weight, body size, defensive behaviour, etc., were recorded. The incidence of prey retention, capture and consumption were significantly higher in G. cancriformis than in any of the other species. The lowest rates of retention, capture and consumption were observed in C. caroli, while L. mariana/venustawere intermediate in their predatory capabilities. Significant negative correlations between prey size and percent consumption were detected in L. mariana/venustaand in G. cancriformis; in both cases, large prey were less likely to be immediately consumed than small prey items. The results can be interpreted in the light of the morphological characteristics of the spiders. G. cancriformispossesses long legs and a carapace and appeared to have few difficulties to manipulate all types of prey. In contrast, C. caroli showed lesser abilities to manipulate and subdue aggressive prey items, perhaps due to the short leg length and unprotected body of this species. The consumption of prey items may be related to the predatory strategy of each spider. G. cancriformis constructs a new web every morning and prey storage was never observed. The absence of prey storage behaviour could explain why this species consumes prey soon after capture. In contrast, C. caroli constructs a permanent web and stores captured prey on a stabilimentum that may explain the very low incidence of immediate consumption of prey observed in this species.

Characterized by distinctive evolutionary adaptations, spiders provide a comprehensive system for evolutionary and developmental studies of anatomical organs, including silk and venom production. Here we performed cDNA sequencing using massively parallel sequencers (454 GS-FLX Titanium) to generate ~80,000 reads from the spinning gland of Actinopus spp. (infraorder: Mygalomorphae) and Gasteracantha cancriformis (infraorder: Araneomorphae, Orbiculariae clade). Actinopus spp. retains primitive characteristics on web usage and presents a single undifferentiated spinning gland while the orbiculariae spiders have seven differentiated spinning glands and complex patterns of web usage. MIRA, Celera Assembler and CAP3 software were used to cluster NGS reads for each spider. CAP3 unigenes passed through a pipeline for automatic annotation, classification by biological function, and comparative transcriptomics. Genes related to spider silks were manually curated and analyzed. Although a single spidroin gene family was found in Actinopus spp., a vast repertoire of specialized spider silk proteins was encountered in orbiculariae. Astacin-like metalloproteases (meprin subfamily) were shown to be some of the most sampled unigenes and duplicated gene families in G. cancriformis since its evolutionary split from mygalomorphs. Our results confirm that the evolution of the molecular repertoire of silk proteins was accompanied by the (i) anatomical differentiation of spinning glands and (ii) behavioral complexification in the web usage. Finally, a phylogenetic tree was constructed to cluster most of the known spidroins in gene clades. This is the first large-scale, multi-organism transcriptome for spider spinning glands and a first step into a broad understanding of spider web systems biology and evolution. Made available in DSpace on 2013-04-02T23:33:43Z (GMT). No. of bitstreams: 1 spinningjournal.pone.0021634.pdf: 1140596 bytes, checksum: 76fd13b774c83ae57842557cf8eda437 (MD5) Previous issue date: 2011-10-04

This study tested predictions regarding male mating preferences which were based on some aspects of female reproductive morphology which may influence sperm precedence patterns in six species of spiders. Males of two species, whose 'conduit' spermathecal design has been associated in previous studies with first male sperm precedence, showed the predicted preference for associating with immature females about to moult to maturity rather than mature females. Those of a third species, however, associated indiscriminately with mature and penultimate instar females. As predicted, males of three other species with 'cul-de-sac' spermathecal morphology did not associate preferentially with immature females. Immature females were avoided in two of the species, but not in the third. One of the species with cul-de-sac spermathecae showed, as predicted, lack of a strong first male advantage in sperm precedence. These data give only limited confirmation of the predictions.

This study investigates the relationship between extinction rate and temporal variability in population size for 174 populations of seven orb spider species on 106 subtropical islands. Evidence for all population time series with at least two nonzero values supports either a negative (inverse) relationship or no relationship at all; this result is robust over a wide variety of statistical treatments. This perhaps unexpected result can be interpreted mainly as reflecting the inability of populations frequently going extinct ever to achieve large enough population sizes to attain even large relative variances (such as coefficient of variation), as well as reflecting the very erratic trajectories of boom-and-bust-type populations that seldom reach resource carrying capacities. Removal of zero counts from time series is also probably involved, and skewness of population-size values may have an effect as well. One type of data preparation, however-that including zero values of the population series and using a...

Argyrodes globosus (Keyserling, 1884) is a small kleptoparasite spider that steals prey from the web of web-building spiders. In coffee plantations in the south of Mexico it was observed to parasitize five species: Gasteracantha cancriformis (Linnaeus, 1785) and Verrucosa arenata (Walckenaer, 1841) (Araneidae), Leucauge mariana (Keyserling, 1881) and Leucauge venusta (Walckenaer, 1841) (morphologically indistinguishable species) and Leucauge argyra (White, 1841) (Tetragnathidae). G. cancriformis was more frequently parasitized than the other hosts. An analysis of web diameter for each host species indicated that for L. mariana/venusta, L. argyra and V. arenata the kleptoparasite was associated with webs of a certain size range (23-33cm diameter) although a far larger range of web sizes was available (17-50cm diameter). The average size of the web of G. cancriformis (~23cm) appeared to be close to the preferred size for the kleptoparasite and this, together with an apparent absence of host aggression, may ...

Spiders were collected from various habitats in the banana plantation at Changuinola, Panama. Vertical stratification of the 47 species collected was very marked; 2 were collected only from the ground, 14 only from ground-cover vegetation, 10 only from pseudostems and hanging leaves, 3 only from webs suspended between leaf petioles, and 3 only from extended banana leaves. Fifteen species were collected from more than 1 stratum. Immature spiders outnumbered adults 3.5 to 1 on extended banana leaves, but the 2 stages were in equal abundance on older, hanging leaves, and the immatures were much less abundant on pseudostems. The family Argiopidae was represented in collections by the largest number of species, and of the 14 species collected, 7 have extensive geographical distributions ranging northward into the United States. Three of the other species collected also range into the United States. Gasteracantha cancriformis (L.) was studied more extensively than other species collected and some of its predators and parasites were observed and recorded as well as the degree of parasitization. Several species of spiders were observed feeding on larvae of lepidopterous banana pests in the field.

One of the more colorful spiders in Florida is a spiny orb weaver, Gasteracantha cancriformis (Linnaeus) 1767. Although not as large as some of the other common orb weavers (e.g., Argiope, Levi 1968; Neoscona, Edwards 1984), the combination of color, shape, and web characteristics make G. cancriformis one of the most conspicuous of spiders. The colloquial name for this spider in parts of Florida is "crab spider", although it is not related to any of the families of spiders commonly called crab spiders, e.g., Thomisidoe. This species belongs to a pantropical genus which contains many species in the Old World. With the possible exception of the West Indian G. tetracantha (L.) (which may be only a geographic race), G. cancriformis is the only species of its genus to occur in the New World, ranging from the southern United States to northern Argentina (Levi 1978). The bite of this common species is not known to cause serious effects to humans. This document is EENY-167 (originally published as DPI Entomology Circular 308), one of the Featured Creatures series of the Entomology andNematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: October 2000. EENY-167/IN324: Spiny Orb Weaver Spider, Gasteracantha cancriformis (Linnaeus) (Arachnida: Araneae: Araneidae) (ufl.edu)

Observations and experiments on the common, citrus grove-inhabiting, spiny-bellied orb-weaver, Gasteracantha cancriformis (L.), have demonstrated that the spider completes a life cycle in 1 year, maturing in the late fall and early winter. The characteristic webs vary in size and position and are reconstructed daily. Prey includes whiteflies, flies, moths and beetles. The tiny males accomplish sperm induction just prior to the 1 hour courtship and copulation. The ovate green-striped egg cases are constructed and filled in 1 to 2 hours. Eggs incubate in less than 2 weeks, deutova and first instar spiderlings hatch and molt within the case. Spiderlings do not disperse for 2 to 5 weeks.

Predation of 216 egg cases of Gasteracantha cancriformis (L.) collected from more than 20 groves involved 48.2% of the cases: 43.7% by the phorid, Phalacrotophora epeirae (Brues), 3.2% by the eupelmid, Arachnophaga ferruginea Gahan, and 1.3% by unidentifiable predators. The phorid completed development in 2 to 4 weeks with a mean attack rate of 17 larvae per egg case. The eupelmid completed development in 3 to 6 weeks with a mean attack rate of 12 larvae per egg case. A hyperparasitic eulophid, Tetrastichus sp., emerged from the pupae of the phorid. The attack rate of this hyperparasite was not determined but 70% of the spider egg cases attacked by the phorid also produced the eulophid. Spider egg destruction was not always complete in predated cases but the predator-parasite complex unquestionably reduces populations of this spider.