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Abstracts2005 Annual Meeting
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Hosted by |
Maggie Hodge |
Todd Blackledge |
Sam Marshall |
Use the table below to jump to abstracts, alphabetized by first author
Screening of necrotizing arachnidism in Korea using sphingomyelinase assay |
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Authors |
Institution |
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Jeong-Su An |
Department of Biological Sciences |
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Yong-Seok Choi |
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Myung-Jin Moon |
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Abstract: While spider bites are not a major medical problem in Korea, it would be of great value to know which species of spiders pose a threat to human health. There are now more than 40,000 identified spider species in the world, and considered about 100 species as actually dangerous to human. Spider bites cause a range of symptoms from simple swellings to disfiguring necrotic lesions, and occasionally death. A middle molecular weight protein, sphingomyelinase D, has been identified in the venom of the brown recluse spider and strong evidence suggests that they have a major role in spider bite necrosis (Tambourgi et al., 1998). For the identification of necrotizing species, we have investigated using recently developed non-radioactive assay of sphingomyelinase for rapidly screening the necrotizing venoms. Here, we demonstrate the fetal toxicity of total 122 species among 622 identified spider species of Korea. It has been revealed that one species of the orb-weaving spider, Araneus ventricosus, and another species of wandering spider, Dolomedes sulfureus has the strongest positive activities among themselves. However comparing to that of the brown recluse spider, Loxosceles reclusa, in North America the necrotizing activities of these Korean species are still very low, so it seems to be little possibilities to create serious necrotizing arachnidism in Korean peninsula. (posted 5 - 24 - 2005) |
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Microstructure of the silk spinnerets in the lynx spider, Oxyopes licenti (Araneae: Oxyopidae) |
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Authors |
Institution |
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Jeong-Su An |
Department of Biological Sciences |
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Sung-Moon Yoe |
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Myung-Jin Moon |
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Abstract: Lynx spiders are one of free wandering spiders with long legs. They do not build web but hunt small insects on plants. In spite of the facts that the wandering spiders do not produce webs for prey-catching, they also have silk apparatus even though the functions are not fully defined. Here we describe the fine structural organization of the silk glands and its spinning apparatus in the lynx spider, Oxyopes licenti, revealed by the transmission electron microscope (TEM) and field emission scanning electron microscopes (FESEM). The silk glands of the adult female spider were located in four groups on the spinnerets including each pair of major and minor ampullates, tubuliforms, pyriforms and aciniforms. Each group of silk gland feed silk into one of the three pairs of spinnerets. Moreover, the tubuliform gland is only observed in female spiders, and the ampullate one is the most predominate gland in both sexes. However the flagelliform and the aggregate glands which had the function of adhesive thread production in orb-web spiders were not observed at both sexes of this spider. (posted 5 - 24 - 2005) |
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Fluorescence in spiders |
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Author |
Institution |
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| Kindra Andrews |
Department of Biology |
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Susan E. Masta |
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Abstract: Most studies of the color properties of organisms have focused on the portion of the light spectrum that is visible to humans. However, many animals are able to detect wavelengths in the ultraviolet range, and recent research with birds has uncovered some surprising patterns of ultraviolet reflectance. While examining the potential for ultraviolet reflectance in jumping spiders, we discovered that some spider setae also fluoresce when exposed to UV light. While the fluorescent properties of the scorpion cuticle have been well-documented, fluorescence in other arachnids has not been studied. Therefore, using an ultraviolet light and a digital camera, we have photographically documented the existence and distribution of fluorescence in spider setae and cuticles from diverse taxa. We present data from spiders from the families Antrodiaetidae, Theraphosidae, Gnaphosidae, Thomisidae, Clubionidae, Salticidae, Lycosidae, Araneidae, Agelenidae, and Theridiidae. |
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Evolution of habitat-use in a desert spider, Agelenopsis aperta |
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Author |
Institution |
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Nadia Ayoub |
Biology Department |
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Abstract: In the past, phylogeography has been primarily used to track historical events of species, such as colonization of islands or population fragmentation. A potentially powerful application of phylogeography is to trace the evolutionary history of adaptations to different habitats. The desert spider, Agelenopsis aperta, presents a unique opportunity to complete just such a study. An extensive background database exists for A. aperta on the genetic basis of adaptations to different habitats: arid and riparian. Furthermore, riparian patches are widely distributed throughout the spider's range of the desert southwest United States making migration between patches unlikely. In order to assess whether adaptations arose once and spread throughout the range of A. aperta or arose multiple times via recent natural selection, I used mitochondrial DNA sequences to examine population history of riparian patches and surrounding arid populations distributed across the range of A. aperta. Riparian patches exhibited identical mitochondrial DNA haplotypes to surrounding arid populations. On the other hand, geographically distant populations were genetically distinct. These population genetic patterns indicate that adaptations arose as a result of recent natural selection. (posted 5 - 24 - 2005) |
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An integrative approach to deciphering spider silk evolution |
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Authors |
Institution |
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Nadia Ayoub |
Biology Department |
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Cheryl Hayashi |
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Abstract: Spiders use silk for a variety of tasks throughout their lifetime. These tasks include safety draglines, prey capture nets, protective retreats, and coverings for eggs. Some lineages of spiders make only a few general-purpose silks while other lineages synthesize many specialized silks. Wide interest in spider silks has stemmed from the remarkable mechanical properties of some silks, which possess both extraordinary toughness and extensibility. Silks are composed of highly repetitive proteins that are encoded by a multi-gene family. To understand the structure, function, and evolution of spider silk genes, proteins, and fibers, the Hayashi research group takes a three-pronged approach. First, we quantify the biomechanic properties of silk fibers spun by a diversity of species. Second, we construct cDNA (gene expression) libraries from the silk glands of phylogenetically diverse species to determine the coding sequences of silk proteins. Third, we have built a genomic library (~3X genome coverage, ~40 kilobase insert size) from the Western black widow, Latrodectus hesperus. We are using this library to characterize silk gene architecture and regulatory regions. Our various silk genotypic and phenotypic data are integrated within a phylogenetic framework to trace the evolutionary steps that have led to the present diversity of spider silks. (posted 5 - 24 - 2005) |
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A morphometric analysis of mygalomorph carapace shape and its efficacy as a phylogenetic character |
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Authors |
Institution |
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David Beamer |
Department of Biology |
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Jason E. Bond |
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Abstract: Despite the fact that shape features are often used as characters in cladistic analyses they are seldom delineated in an objective, repeatable fashion. Carapace shape is one such character that is often used in analyses of mygalomorph spider relationships. For example, most analyses (Raven 1985, Goloboff 1993, Bond & Opell 2002) use cephalic region morphology (e.g., steeply arched vs. flat or sloping) as a key feature that delineates (in part) some major clades. In practice carapace shapes at the extremes are relatively easy to identify; however, intermediate carapace shapes have proven to be much more difficult to objectively score in one of three shape categories. In this study carapace shape is used as an exemplar characteristic to evaluate the utility of shape features in phylogenetic analyses and to evaluate our ability to effectively score discrete character states. We digitally photographed 173 spider carapaces from specimens sampled across all 15 nominal mygalomorph families and traced outlines and pseudo-landmarks. An Elliptic Fourier Analysis was then employed in an attempt to both delineate and assess character states. (posted 5- 19 - 2005) |
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The effects of wolf spider communities on soybean herbivory |
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Authors |
Institution |
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Ryan D. Bell |
Biology Department |
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Michael V. Cole |
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Matthew H. Persons |
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Alissa A. Packer |
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Abstract: Wolf spiders are common generalist predators in agricultural systems and could potentially have direct or indirect effects on plant herbivory. Many wolf spiders are also significant intraguild predators that may result in complex interactions between spiders, herbivores, and plants. We conducted a field study using three commonly occurring wolf spiders, Pardosa milvina, Trochosa ruricola, and Rabidosa spp. with soybean as our model agricultural plant. Nine treatments were created by planting the soybean during the summer growing season within enclosures of different wolf spider communities. The treatments were: 1) Rabidosa only, 2) Pardosa only, 3) Trochosa only, 4) Pardosa and Rabidosa, 5) Pardosa and Trochosa, 6) Trochosa and Rabidosa, 7) no enclosure, 8) no spiders, and 9) Pardosa, Rabidosa, and Trochosa (N= 17/treatment). Enclosures were checked on a weekly basis, various vegetative and reproductive measurements were taken. The presence of spiders was recorded, and any non-treatment species were removed. Plants were harvested at the end of the summer and leaves, pods, and root nodules were counted and plant biomass was weighed. Spider treatments were not shown to have a significant impact on any vegetative or reproductive plant traits, but intraguild interactions did impact spider number and body condition, particularly for Pardosa milvina.(posted 5 - 18 - 2005) |
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Molecular phylogenetic analyses of Sicariid species relationships and sphingomyelinase D gene family evolution |
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Authors |
Institution |
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Greta J. Binford |
Department of Biology |
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Chris Ellison |
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Kate Baldwin |
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Melissa Bodner |
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Melissa Callahan |
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Abstract: Loxosceles and Sicarius spiders are well known for the dermonecrotic effects of their venoms on mammalian tissues. The toxic enzyme sphingomyelinase D (SMase D) is sufficient for causing lesion formation after bites from these species. Inspired by a desire to understand the molecular evolution of SMase D we are using sequence data from mitochondrial markers ND1/16s, CO1, and nuclear 28s to estimate relationships among species representing their native distribution. Analyses to date consistently support: (1) North American Loxosceles as monophyletic and their presence on the continent predating the most recent connection of North and South America by the Isthmus of Panama; (2) South African species as basal lineages within both genera. Interestingly, species relationships within Loxosceles do not match the gene tree for SMase D. Patterns of relationships among SMaseD cDNAs make it clear that SMase D evolution includes processes that homogenize paralogs within lineages. We propose differential paralog homogenization as an explanation for the gene tree - species tree mismatch. l.(posted 5 - 18 - 2005) |
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Spider silk: a 400 million year experiment in materials science |
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Author |
Institution |
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Todd A. Blackledge |
Department of Biology |
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Abstract: Silk plays an integral role in many aspects of the lives of spiders including protection against predators or the environment, capture of prey, dispersal, communication, and reproduction. Thus, the mechanical performance of spider silk is likely to have been shaped by natural selection and can provide insight into how spiders interact with their environment. The material properties of spider silk result from how the constituent proteins of silk fibers are assembled and interact with one another. Therefore, the biomechanical study of spider silk can potentially link together research ranging from the evolution of silk genes through the ecological function of webs or other silk structures. Here, I discuss some of my recent research on the biomechanics of orb-weaving spider silk. In particular, I demonstrate that Argiope argentata spins a diverse toolkit of silks, including five different fibrous silks each of which has its own unique mechanical characteristics. (posted 5 - 24 - 2005) |
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Light wavelength biases of the desert grassland scorpion |
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Authors |
Institution |
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Greg R.C. Blass |
Department of Zoology |
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Douglas D. Gaffin |
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Abstract: Desert grassland scorpions, Paruroctonus utahensis, are nocturnal animals that typically emerge from their burrows within a few hours after sunset. Scorpions are negatively phototactic, and physiological data suggest that scorpion photoreceptors are differentially sensitive to light wavelengths ranging from red to ultraviolet. However, behavioral differences to wavelengths have not been firmly established. Responses of animals were monitored in circular (8.9 cm diameter) arenas. Half of each arena received infrared light, while the other half received one of four treatments: red, green, UV, or no light. The three light treatments were matched for intensity. We ran three trials of sixteen animals each (48 total animals) with each animal experiencing the full set of randomized treatments; each treatment lasted 1 h for a total filming time of 64 h. Each animal was monitored for periods of movement into and out of the treated side, and these periods were averaged within a 10 min sampling window for each treatment. Scorpions spent significantly less time in areas exposed to UV than those exposed to green light (P=0.01) or red light (P<0.01). This does not correlate directly with reported physiological spectral sensitivity of the median and lateral eyes, which indicate peak sensitivity in the green with a lesser but pronounced shoulder in the UV. These observations may relate to extraocular regions of light sensitivity and/or the green fluorescence of scorpion cuticle under UV.(posted 5- 19 - 2005) |
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Evolutionary origin and loss of sphingomylinase D in the Sicarius and Loxosceles lineages |
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Authors |
Institution |
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Melissa R. Bodner |
Department of Biology |
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Melissa Callahan |
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Greta J. Binford |
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Abstract: The enzyme sphingomyelinase D (SMaseD) found in the venoms of brown spiders (Loxosceles) causes dermonecrotic lesions in mammalian tissues. Bites from some species of the related genus Sicarius cause similar lesions. Previous comparative venom/tissue analyses of representatives from eight families of haplogyne spiders found SMaseD activity only from a worldwide representation of Loxosceles and two South African Sicarius species, supporting evidence of evolutionary origin of SMaseD in the most recent common ancestor of Loxosceles and Sicarius. This analysis did not include New World representatives of Sicarius. We report SMaseD assays of venoms of the Costa Rican species Sicarius rugosus and the Argentine species S. patagonicus, S. rupestris and S. terrosus. Unlike Old World congenerics, all New World Sicarius species showed a reduction or loss of SMaseD activity, yet had proteins of the molecular weight corresponding to SMaseD. To test whether the differences in New World venom represented an ancestral or derived state, molecular phylogenetic analyses of the relationships among the genera Loxosceles, Sicarius, Drymusa and Scytodes where carried out using a roughly 1.8 kb fragment of 28S. All analyses placed New World Sicarius as derived from SMaseD bearing ancestors, indicating the apparent loss of SMaseD activity in New World Sicarius is a derived state. A more thorough survey of Sicarius species will determine whether the reduction or loss of SMaseD activity is universal in and exclusive to the New World lineage. (posted 5 - 20 - 2005) |
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Molecular phylogeny of the Mygalomorphae |
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Authors |
Institutions |
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Jason E. Bond |
Department of Biology |
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Marshal Clinton Hedin |
Department of Biology San Diego State University San Diego, CA USA |
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Abstract: Mygalomorph spiders, which include the tarantulas, trapdoor spiders, and their kin, represent one of three main spider lineages. Current estimates of mygalomorph diversity place roughly 2,500 species into approximately 280 genera and 15 families. Published phylogenies of mygalomorph relationships, based almost exclusively on morphological data, reveal areas of both conflict and congruence, suggesting the need for additional phylogenetic research. As part of a combined evidence study of global mygalomorph relationships, we have gathered ~ 4.2 kb of rDNA data (18S and 28S) for a sample of 80 genera, representing all 15 mygalomorph families. The following primary results are supported by both Bayesian and parsimony analyses of the combined matrices: 1) the Atypoidina, including Atypidae, Antrodiaetidae and Mecicobothriidae, are basal, 2) diplurids and hexathelids form a paraphyletic grade at the base of the remaining tree, but neither family is recovered as monophyletic, 3) sampled nemesiids form a clade, but include Microstigmata and the Australian cyrtaucheniid Kiama, 4) other sampled cyrtaucheniids are separated into two clades, including a North American Euctenizinae and a South African clade, 5) of the Domiothelina, only idiopids are consistently recovered as monophyletic, while (surprisingly) migids and ctenizids are not. The Domiothelina themselves are not monophyletic. Overall, the molecular results are more consistent with Goloboff (1993), less consistent with Raven (1985). (posted 5- 25 - 2005) |
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Combining genetic and geospatial analyses to infer population extinction in mygalomorph spiders endemic to the Los Angeles region |
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Authors |
Institutions |
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Jason E. Bond |
Department of Biology |
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David Beamer |
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Marshal Clinton Hedin |
Department of Biology San Diego State University San Diego, CA USA |
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Abstract: Although hyperdiverse groups like terrestrial arthropods are almost certainly severely impacted by habitat fragmentation and destruction, relatively few studies have formally documented such effects. We summarize a multifaceted research approach to assessing the magnitude and importance of anthropogenic population extinction on the narrowly endemic trapdoor spider genus Apomastus (Mygalomorphae: Cyrtaucheniidae). We use GIS (Geographical Information Systems) modeling to reconstruct the likely historical distribution of Apomastus, and use molecular phylogeographic data to understand population genetic structure and detect genetic signatures of population extinction. In combination, these complementary lines of inference support direct observations of population extinction, and lead us to conclude that population extinction via urbanization has played an important role in defining the modern-day distribution of Apomastus species. This population loss implies coincident loss of genetic and adaptive diversity within this genus, and more generally, suggests a loss of ground-dwelling arthropod population diversity throughout the LA Basin. Strategies for minimizing this loss are proposed. (posted 5- 18 - 2005) |
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The Balkan and Aegean Euscorpius (Scorpiones: Euscorpiidae): new data for mitochondrial DNA phylogeny |
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Authors |
Institutions |
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Michael Brewer |
Department of Biological Sciences |
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Victor Fet |
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Elizabeth V. Fet |
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Jan Ove Rein |
Norwegian University of Science & Technology |
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Marco Colombo |
Busto Arsizio |
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Abstract: The systematic composition of the genus Euscorpius Thorell, 1876 (Scorpiones: Euscorpiidae) in the Balkans is unclear. This especially refers to so-called "carpathicus complex" (Fet & Soleglad, 2002). New material obtained in 1999-2004 from Greece and Bulgaria has been used for DNA extraction and PCR amplification of ca. 400 bp of the mitochondrial gene for 16S rRNA, followed by sequence comparison of 26 DNA sequences via PAUP* 4b10. New data for mitochondrial DNA phylogeny allow to outline several independent lineages, some of which could have species status. A separate Greek lineage is formed by populations from Crete ("E. candiota" Birula, 1903) grouping closely with Kithyra, Peloponnese, and western Greece (Corfu and Parga in Epiros). Among other Aegean islands, Thassos population is very different from Paros; the latter shows affinity to E. tauricus (C.L. Koch, 1837) from Crimea, Ukraine. Another cluster is formed by populations from Rhodope Mts. (Xanthi in Northern Greece; Trigrad, Kovachevitsa, and Melnik in Southern Bulgaria). Olympus and Ossa (Thessaly, Eastern Greece) refer to "E. carpathicus ossae" Caporiacco, 1950. Sliven (Stara Planina Mts., Bulgaria) forms a separate lineage, not close to Romanian E. carpathicus (L., 1767); the latter shows affinity to the western Balkan (Slovenia, Croatia)/Italian E. tergestinus (C.L. Koch, 1837). Separate status of the Balkan E. hadzii Caporiacco, 1950 (Croatia, Herzegovina) and E. sicanus (C.L.Koch, 1837) (Thessaly) is confirmed. In total, Greece could house over 10 species of Euscorpius, and Bulgaria, at least four. (posted 5 - 6 - 2005) |
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Arachnological concerns of USDA, APHIS and PPQ (talk) |
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Author |
Institution |
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Susan Broda |
USDA, APHIS, PPQ |
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Abstract: A preliminary general overview will be given of arachnological groups which are of concern to USDA, APHIS, PPQ, as well as the Homeland Security Department. I will then describe in more detail the problems with exotic ticks (Acarina: Metastigmata) being brought in on exotic pets introduced to the USA. (posted 5 - 16 - 2005) |
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I smell a femme fatale: can males chemically detect a cannibalistic prospective mate? |
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Authors |
Institutions |
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Joshua M. Cattell |
Biology Department, Susquehanna University |
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Ann L. Rypstra |
Department of Zoology, Miami University |
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Matthew H. Persons |
Biology Department, Susquehanna University Selinsgrove, Pennsylvania USA |
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Abstract: Virgin female Hogna helluo wolf spiders cannibalize prospective mates in 13-20% of encounters with courting males. Males may therefore benefit by possessing the ability to detect and avoid cannibalistic females. We tested if prior cannibalistic experience alters female behavior toward males and if males can detect cannibalistic females based on either direct interactions with females or indirectly through cues from female silk and excreta. We reared 36 female spiders on entomophagic diets consisting of house crickets (Acheta domesticus) and an additional 34 females on araneophagic diets consisting of two Hogna feedings at adulthood prior to testing. We then measured male and female mating behavior across the following treatments (14-20 replicates/treatment): 1) cannibalistic female on cannibalistic chemical cues, 2) cannibalistic female on non-cannibalistic chemical cues, 3) non-cannibalistic female on non-cannibalistic chemical cues, and 4) non-cannibalistic female on cannibalistic chemical cues. Male Hogna were placed with females and cannibalism events, courtship duration, courtship latency, mating success, and courtship intensity were recorded. Males significantly decreased courtship duration in the presence of cannibalistic females and significantly increased courtship intensity when encountering silk from females that had cannibalized previously. Cannibalistic females showed higher numbers of leg taps, a putative receptive response, toward males than non-cannibals but we found no significant difference in mating success or cannibalism frequency across treatments. Results suggest that males discriminate between females who have eaten conspecifics and those who have not based on information in silk, but female cannibalism frequency and male mating success is unrelated to recent female cannibalism experiences. (posted 5 - 13 - 2005) |
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Influences of Environmental Variation on Courtship Behavior in the Wolf Spider Schizocosa ocreata |
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Authors |
Institutions |
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David L. Clark |
Dept. of Biology |
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George W. Uetz |
Dept. of Biology |
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J. Andrew Roberts |
Department of EEOB |
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Meghan Rector |
Dept. of Biology, Alma College |
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Abstract: During the breeding season, male wolf spiders (Schizocosa ocreata) expend considerable energy searching for females and run a risk of predation by exposing themselves to potential predators. In the leaf litter there is considerable variation in temperature and ambient light characteristics on leaf surfaces. In this study, we examined; 1) variation in leaf litter temperature and compared these to locations where courting males were found; and 2) reflectance patterns of male spider body parts were compared to the spectra of leaf litter. There was no significant difference between the location temperatures of courting males (22.47 C) and non-courting males (22.56 C) (students t-test, t=0.139; DF=114; P>0.05). Interestingly, the mean location temperature of male spiders was between the means of leaves found in the sun and leaves found in the shade at 22.52 C. Spectral analysis of spider body parts showed that some parts of the spider appear exceptionally dark (e.g., the lateral view of leg tufts), while other aspects (dorsal median stripe) appear to closely match to the spectra of leaf litter. This revealed that leg tufts contrast with the lighter background of leaf litter, but that dorsal coloration contrasted less with the litter background. These results suggest that wolf spiders maximize contrast and exposure when viewed from the side (by female spiders), while minimizing potential for detection from above (predators) by cryptic coloration. (posted 5 - 4 - 2005) |
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Spider species diversity in some dry forest plants of western Mexico |
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Authors |
Institutions |
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Pablo Corcuera |
Departamento de Biología |
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María Luisa Jiménez |
Centro de Investigaciones Biológicas del Noroeste S.C., MÉXICO |
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Abstract: Spiders were collected from eight tree and three shrub species in each of two sites in a Mexican dry forest thorough June, July, September, October and November of 1999, and january and abril 2000. A total of 1349 adult specimens, belonging to 21 species were obtained. Plant arquitecture and foliage type have been related to spider species richness, abundance and diversity. We measured relative cover, foliar area, and leaf type and disposition for each plant species in order to determine their influence on the spider community structure. Number of adults, species richness, dominance (Simpson index) and equitability (Pielou index) were measured for the spiders. In both sites, small-leaved bipinnate trees and shrubs, particularly the shrub Acacia cymbispina and the tree Prosopis juliflora, had more species as well as higher spider abundances. Foliar area was negatively correlated with spider abundance in both sites, and to species richness in one of them. Dominance was particularly high for Croton ciliatoglanduliferus, a widespread shrub typical of disturbed sites in the region, in which the Green Lynx spider Peucetia viridans was abundant. (posted 5- 19 - 2005) |
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The suctorial organ of the Solifugae (Arachnida, Solifugae) |
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Authors |
Institutions |
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Paula E. Cushing |
Department of Zoology, |
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Jack O. Brookhart |
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Hans-Joachim Kleebe |
Colorado School of Mines |
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Gary Zito |
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Peter Payne |
Department of Pathology & Laboratory Medicine |
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Abstract: The ability of members of the arachnid order Solifugae to climb smooth, vertical surfaces and the organs involved in this behavior are investigated. Macroscopic, microscopic, and scanning electron microscopic observations are made of a palpal organ called the suctorial organ. Observations of the behavior but not the microstructure have been made in the past. Histological examination illustrates the internal gross anatomy of this structure and scanning electron microscopy demonstrates the fine structure in adults of four genera: Eremobates (Eremobatidae), Eremochelis (Eremobatidae), Eremorhax (Eremobatidae), Ammotrechula (Ammotrechidae), as well as an unidentified late stage immature and third stage instar. The suctorial organ is most likely primarily used for prey capture in the wild. (posted 5 - 15 - 2005) |
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Metals in cuticular structures of Palpigrada, Ricinulei and Schizomida (Arachnida) |
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Authors |
Institutions |
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Bruce Cutler |
Microscopy & Analytical Imaging Laboratory and Department of Ecology & Evolutionary Biology |
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Lynn McCutchen |
Biology Department |
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Abstract: Specimens of Palpigrada, Ricinulei and Schizomida were examined by energy dispersive x-ray spectroscopy for the presence of metallic elements in cuticular structures. Manganese was found in the largest tooth of the fixed cheliceral finger in a ricinuleid. Zinc was found in the chelicerae, leg and palpal claws and in the palpal tarsal spur of a schizomid. Zinc was also found in the chelicerae and leg claws of a palpigrade. When presence or absence of zinc is added to a cladogram of arachnid orders, the absence of zinc in the Acaromorpha (Acari + Ricinulei) appears to be derived. Similarly the absence of manganese in the Uropygi (Schizomida + Thelyphonida) may be derived also. (posted 5- 6 - 2005) |
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Unnatural castration in a spider: are environmental pollutants to blame? |
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Author |
Institution |
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Anne Danielson-François |
Ecology and Evolutionary Biology Dept. |
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Abstract: With the 1962 publication of Rachel Carson's Silent Spring, the public began to appreciate more fully the dangers of environmental pollution from pesticides and other anthropogenic chemicals. A particular class of such chemicals, endocrine disruptors, function as sex hormones in vitro and/or in vivo. Environmental estrogens have been implicated in the feminization of male vertebrates, and androgens contribute to imposex in neogastropods. Despite the importance of arthropods in many ecosystems, studies of the effects of these compounds on arthropod species are scarce and there is currently no information available for arachnid taxa. Here, I report the first evidence that anthropogenic chemicals may affect male spiders similarly. Males collected from a polluted site in Louisiana exhibit palp abnormalities that prevent sperm transfer, effectively castrating these individuals. Field-collected adults show a nearly 2:1 ratio of affected to normal males. Lab-reared penultimate-stage males exhibit a 5:1 ratio -- a substantial increase that has profound implications for population dynamics. Possible consequences could include affected populations exhibiting (1) a decreased ability to recover from environmental catastrophes, and (2) increased sensitivity of the population to further exposure by new pollutants, possibly resulting in local population extinction. Future work will include characterizing the specific chemicals involved by mass spectrometry and high performance liquid chromatography. (posted 5 - 26 - 2005) |
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The spider species of the Great Lakes States |
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Authors |
Institutions |
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Michael Draney |
Department of Natural and Applied Sciences and Cofrin Center for Biodiversity |
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Petra Sierwald |
Zoology Department |
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Thomas Prentice |
Department of Entomology University of California Riverside, California USA |
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Abstract: Critical analysis of existing spider species lists for Wisconsin, Michigan, Ohio, Indiana and Illinois reveal 899 species recorded from the five-state region (284 genera, 40 families). Illinois currently has the highest recorded total with 622 species, followed by 571 from Ohio,563 from Michigan, 477 from Wisconsin, and 385 from Indiana. All non-native, non-established, or otherwise questionable species records were scrutinized and their status is discussed. The most speciose families in the region are Linyphiidae (almost 24% of species), Salticidae (10.3%), Theridiidae (8.9%), Lycosidae (8.8%), and Araneidae (7.7%). The configuration of the five states, as well as the topography and glacial history of the region enabled us to generate predictions of over 400 new state species occurrences based on their known presence within each of the five states, and to produce higher minimum estimates of the actual fauna in each state. Richness among states is analyzed and found to be primarily dependent on varying degrees of sampling effort. We feel this work shows that much remains to be learned about the fauna of the Great Lakes region, and we hope this encourages basic faunistic research. We have created a searchable online database which allows access to all published data, returning currently valid taxa starting from any names previously published from this region. (posted 5 - 26 - 2005) |
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Responsivity of male Dolomedes triton to dragline silk from females |
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Authors |
Institution |
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Amber Elaine Ehlman |
Department of Biology |
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Nancy Kreiter |
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Abstract: Activities that increase an organism's survival and reproduction are important energetic expenditures for every species. Low density, wandering species must travel long distances in order to locate potential mates. Mechanisms that increase the success of the search and decrease the energetic costs to the animal should be selected for through the evolutionary process. Energy should be allocated where it is most likely to be repaid; in this case in the form of copulation and successful reproduction. We investigated male search tactics in the non-webbuilding spider Dolomedes triton, or fishing spider, which inhabits vegetations around freshwater lakes and ponds in North America. Female D. triton are less active than their male counterparts, which exert considerable time and energy locating and courting females. We tested the hypothesis that males uses cues bound to female dragline silk to locate stationary females. Silk from virgin and mated adult females was extracted from the spinnerets and presented to virgin and mated adult males and the subsequent courtship behaviors including various waves and taps with the legs demonstrated by males were recorded. It was expected that (1) males would expend an approximately equal amount of time and energy courting dragline silk as they would true female spiders (2) males would exhibit preference towards unmated, adult females as this should increase probability of copulation as well as reduce the chance of sexually-induced cannibalism and (3) males cue in on factors among the dragline rather than the presence of silk itself. Variance tests indicate males conserve courtship to pads containing female silk but do not appear to discriminate between virgin or mated silk. (posted 5 - 25 - 2005) |
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Distribution and relations of ground spider's genus Taieria (Araneae, Gnaphosidae) in Australasia |
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Authors |
Institutions |
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Mariya Fedoryak |
Department of General and Experimental Ecology |
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Vladimir Ovtcharenko |
Department of Natural Sciences |
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Boris Zakharov |
Division of Invertebrate Zoology American Museum of Natural History New York, New York USA |
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Abstract: The genus Taieria was described by R. Forster in 1979. Earlier, two species were described by L. Koch (1873) as Drassus erebus and Drassus achropus from New Zealand. R. Forster (1979) showed that those two species were male and female of one species and chose as the valid name Taieria erebus (L. Koch). Additionally, R. Forster described four new species of the genus Taieria from New Zealand: T. elongata, T. kaituna, T. obtusa and T. miranda. Recently we found one new species of Taieria in New Zealand. Also we found T. erebus and T. kaituna on the Southern Island (both species were recorded before only from the Northern Island) and T. elongata on the Northern Island (earlier known only from the Southern Island). Our revision of Taieria in Australasia showed that this genus is also very common in Australia. We found 16 new species of Taieria in Australia and two in New Guinea. The distribution of Taieria in Australia has an interesting pattern, which shows Eastern Australia more populated and represented by seven species of Taieria. Western Australia is represented by six species, two species of Taieria related to the southern part of Australia and Tasmania. One species is widely distributed across all Australia. It is important to underline that there is no common species of Taieria for New Zealand, Australia and New Guinea. (posted 5 - 25 - 2005, corrected 6 - 8 - 2005) |
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A morphology-based phylogeny of the Habronattus tarsalis species complex and its inconsistency with a molecular phylogeny |
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Authors |
Institution |
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Steven E. Foldi |
Department of Biology, Evolutionary Biology Program Area |
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Marshal Hedin |
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Abstract: Males of the six species of jumping spiders (Salticidae) belonging to the Habronattus tarsalis group are highly variable morphologically throughout their range in California and surrounding states. These morphological differences have been used to derive a "species tree" of the relationships between both populations and species. Neighboring populations in continuous habitat are morphologically more similar to each other than more isolated populations. Therefore, male morphology appears to be a good tool for examining the relationships of these species and the species tree agrees with typical phylogeographic patterns for California. However, a gene tree derived from mitochondrial evidence shows divergence only for isolated desert and island populations, but is unable to resolve even some species relationships. This has lead to the hypothesis that gene flow between neighboring populations in contiguous habitats has caused shared mtDNA sequences, while strong sexual selection has preserved the phylogenetic signal for morphological divergence. Thus, the Habronattus tarsalis group could be a clear example of why different data sets provide variable results. (posted 5- 15 - 2005) |
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Static and dynamic components of male seismic signals reflect influence of past and current condition in the wolf spider Schizocosa ocreata (Araneae: Lycosidae) |
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Authors |
Institution |
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Jeremy S. Gibson |
University of Cincinnati |
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George W. Uetz |
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Abstract: Courtship displays of male Schizocosa ocreata (Hentz) are multimodal, consisting of visual and seismic signals. Previous research has shown that male secondary sexual characters (foreleg tufts) are condition-dependent visual signals used in female mate choice. Here we test the hypothesis that seismic signals are also condition-dependent, through two different approaches. In the first study, a test of the effect of rearing environment, seismic signals were compared between spiders raised under 3 different conditions: completely in the laboratory (LR), completely in the field (FR) or partially in the field then the laboratory (FL). A second experimental study tested the effects of current condition on seismic signals. Adult spiders were collected from the field and placed into two treatment groups, then fed to satiation or starved. Spiders were recorded 3 times over the course of the experiment. Rearing environment affected static (e.g. fundamental frequency of signal) and dynamic (e.g. duration of signal) components of seismic signals differently. Static traits were similar between LR and FR but both differed from FL. Dynamic traits were similar for FL and FR but differed from LR. Moreover, static traits did not change over time in response to food availability; however, all dynamic traits did. These findings suggest that lifetime foraging history and/or habitat and experience contribute to static features of seismic signals, while dynamic features change with current body condition. This experiment demonstrates that seismic signals in this species are condition-dependent, and contain information that females may be able to use to asses male mate quality. (posted 5- 18 - 2005) |
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Wolf spiders reduce aggression toward conspecifics after repeated encounters |
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Authors |
Institutions |
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Ryan J. Gifford |
Department of Zoology |
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Jill DeVito |
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Matthew H. Persons |
Department of Biology Susquehanna University Selinsgrove, Pennsylvania USA |
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Ann L. Rypstra |
Department of Zoology Miami University Oxford, Ohio USA |
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Abstract: The "dear enemy" phenomenon suggests that territorial species should exhibit less aggressive behavior toward familiar neighbors as compared to strangers that they encounter. We examined whether this phenomena could be operating in populations of the large burrowing wolf spider, Hogna helluo (Araneae, Lycosidae). In a laboratory experiment, we monitored the repeated interactions between adult field-caught females over four consecutive days. On the fifth day we exposed them to unfamiliar animals and observed that interaction. There was an increase in the total number of encounters between spiders after repeated exposure but the frequency with which they approached one another with legs raised decreased as did the likelihood of physical contact during encounters. Thus their interactions appeared much less aggressive after repeated exposure with a conspecific. However, there was no evidence of a neighbor effect as their behavior toward an unfamiliar animal on day five was similar to their reactions to the familiar animal on day four. We conclude that, although Hogna females appear to learn to reduce their overall aggression level toward conspecifics in high-density situations, they do not discriminate between individuals they have encountered repeatedly and unfamiliar individuals. (posted 5 - 19 - 2005) |
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Genetic diversity within colonial aggregations of the North American tarantula Aphonoplema hentzi (Theraphosidae) in Texas populations |
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Authors |
Institutions |
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D.E. Hamilton |
Department of Biological Science |
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M.E. Janowski-Bell |
Department of Biology |
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N.E. McIntyre |
Department of Biological Science Texas Tech University Lubbock, TX USA |
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L.D. Densmore |
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Abstract: The Theraphosid genus Aphonopelma belongs to the infraorder Mygalomorphae, a group thought to be relatively primitive and highly conserved morphologically. Adult females and sub-adult males live in subterranean burrows in informal aggregations commonly referred to as colonies although analysis of aggregations of Aphonopelma hentzi (Girard 1852) in Wilbarger Co., TX showed the burrows to be over rather than under-dispersed indicating the aggregations may simply be the result of habitat condition and not a reflection of behavior (Janowski-Bell 2001). However, the aggregations may still be matriarchal in nature since although some mygalomorphs have been found to disperse by ballooning (Coyle 1983), theraphosids are not known to do so and this may cause their dispersal distances to be limited in immaturity. Upon maturity, the males disperse, walking from their burrows in search of a mature female, presumably unrelated to the male. Radio-telemetry work suggests that the dispersal range of Aphonopelma males may be limited to 1-3 km, at least with A. hentzi (Janowski-Bell and Horner 1999). We tested the hypothesis of familial aggregations using two molecular markers from the mitochondrial genome, CO1 and 16S. Although both showed relatively low levels of diversity the results do not support familial aggregations and instead suggest an ad-hoc assemblage based probably on habitat availability. (posted 5 - 26 - 2005) |
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Molecular evolution and phylogenetic utility of hemocyanin blood protein gene sequences in mygalomorph spiders (Araneae: Mygalomorphae) |
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Authors |
Institutions |
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Marshal Hedin |
Department of Biology |
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Cheryl Hayashi |
Department of Biology |
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Abstract: Hemocyanins are hemolymph proteins that facilitate oxygen transport in all major arthropod lineages. The likely basal condition in spiders includes a protein of 620-660 amino acids, duplicated into seven paralogous loci (subunits) that combine to form a 24-mer (4 X 6) quaternary structure. Although paralog structure is fairly conserved in spiders, some lineages reveal dynamic changes in patterns of molecular evolution (e.g., paralog loss and duplication in the RTA clade). To more fully explore patterns of molecular evolution, and assess the phylogenetic utility of this gene family, we have conducted phylogenetic analyses on hemocyanin exon 4 data for a diverse sample of mygalomorphs, and several araneomorphs. Results can be summarized as follows: 1) Mygalomorph sequences fall into seven distinct clades that correspond to the seven well-studied subunits of Aphonopelma. Although not all mygalomorph taxa are represented in each paralog group, this is probably evidence for PCR bias, rather than paralog loss; 2) Trees reconstructed using concatenated and combined (molecules + morphology) matrices recover some expected clades (e.g., Atypoidina), but other larger clades (e.g., Domiothelina) and some families are not recovered as monophyletic; 3) Sequences from taxa representing the RTA clade (Habronattus, Zorocrates, Allocosa, and Cupiennius) are restricted to the subunit g clade. The loss of all paralogs except g, and subsequent duplication within this paralog group, may represent a molecular synapomorphy for this spider clade; 4) Hemocyanins represent, in effect, up to seven independent loci that might be used for molecular phylogenetic analysis in spiders. With development, this gene family has considerable phylogenetic promise. (posted 5 - 13 - 2005) |
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Phylogeography of the Antrodiaetus unicolor species complex (Araneae: Mygalomorphae: Antrodiaetidae) |
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Authors |
Institution |
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Brent E. Hendrixson |
East Carolina University |
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Jason E. Bond |
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Abstract: Antrodiaetus unicolor (sensu lato) is the most abundant and widespread mygalomorph species in the eastern United States. Given the dynamic geological history of this region (including orogeny, coastal plain inundation, and glaciation cycles) and the interesting life history characteristics of these spiders (fossorial burrowers, limited dispersal ability), spatial patterns of genetic variation are expected to be diverse and complex. We investigated the phylogeography of this species complex by sampling over 300 individuals from 100+ populations. Preliminary assessment of these analyses (based upon COI mtDNA and 28S rRNA; ~1800 bp) suggests a complicated history consisting of recent range expansions, vicariance events, and prolonged periods of isolation and divergence in situ. Some northern populations (IN, OH, VA, WV) display a genetic signature indicative of recent range expansion into areas previously uninhabitable during the Pleistocene. Furthermore, there have been multiple independent invasions of these spiders to the coastal plains (i.e., coastal populations are not monophyletic). Closely related lineages are sometimes disjunct, indicating that ancestral populations became fragmented; this subsequently allowed the sundered populations to diverge substantially from each other. No mitochondrial haplotypes are shared between populations, and most populations exhibit substantial divergence and genealogical exclusivity. Secondary contact between distantly related lineages is extremely common and provides strong evidence for multiple codistributed species. Future research will focus on testing specific biogeographical hypotheses and delimiting species boundaries. (posted 5- 19 - 2005) |
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The rich spider fauna of the Hocking Hills region, Ohio |
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Authors |
Institution |
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William Hickman |
Department of EEO Biology |
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Richard Bradley |
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Abstract: The Hocking Hills region is located in Hocking and Fairfield Counties of unglaciated south central Ohio. The system of hills and valleys were, nevertheless, strongly influenced by the glaciers. Glaciers to the north formed a dam that blocked the northwestward flow of the historic Teays River. The region's drainage was redirected southeast into the relatively newer Ohio River, in the Mississippi drainage. This history is revealed in the vegetation, which is very diverse, incorporating southern elements characteristic of the western Allegheny plateau and northern remnants from glacial times. This scenic region is dominated by the Black Hand Sandstone which has eroded to form numerous caverns, arches, and recess-caves. The region is clothed in mature second-growth mixed hardwood forest, hemlock coves, farm fields and pasturelands. The spider fauna of the Hocking hills is similarly diverse. A total of 265 species have been documented for the region to date. Historical collections were made by William Barrows, primarily between 1914 and 1924. Collections of the Ohio Spider Survey were made between 1994 and 2004. Only 37% of the spider species were found by both collection efforts; 43% were found exclusively in our recent work and 20% only in the earlier Barrows work. It is not clear whether or not these differences are due to different sampling methods or possibly actual changes in the spider fauna.(posted 5- 19 - 2005) |
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Variation in the flag gene among Nephila clavipes in Mexico |
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Authors |
Institutions |
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Linden E. Higgins |
Department of Biology |
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Sheryl White |
Department of Anatomy and Neurobiology University of Vermont Burlington VT USA |
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Juan Nuñez-Farfán |
Instituto de Ecología |
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Jesus Vargas |
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Abstract: The gene coding for the spider flagelliform silk, Flag, is one of the more recently characterized silk genes, and codes for one of the more recently evolved silks. Like many silk genes in spiders and other arthropods, the Flag gene has a nested structure: small glycine and proline rich motifs repeat within larger motifs. In Flag, the larger motifs are ensemble repeats of up to 61 small motifs on either side of a non-repetitive glycine-poor spacer. Each ensemble repeat corresponds to an individual exon. Many authors have speculated that the repeating motifs of silk genes may evolve like "minisatellite" DNA, with misalignment during recombination generating variation upon which selection could then act. This misalignment could also lead to homogenization of the sequences across the repeats, or gene conversion. The most effective way to test these models is to investigate variation among individuals within a species, but the majority of silk genes that have been sequenced have only been sequenced once for a particular species. Here, we present a comparison of sequences of one exon from eight individuals from four populations in Mexico. (posted 5 - 20 - 2005) |
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Activity cycles and vertical stratification of spiders in cornfields |
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Authors |
Institution |
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Ryan Homsher |
Miami University |
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Alan Cady |
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Abstract: Spider distributions and abundances across the diel period have been investigated in various row crops but are not well-studied in corn. Furthermore, it is unknown if certain families of spiders prefer specific locations on corn plants, as has been found in other crops. Plants near discrete habitat refugia (small straw piles) in soy and corn fields have been shown to have less insect damage and increased crop yield, but the mechanism behind this "refugia effect" is not clear. One hypothesis is that spider assemblages associated with refugia help protect plants from herbivory. Thus, a nine-week observational study of spiders on and around plants in six one-half hectare conventionally-tilled corn fields was conducted to determine daily spider activity cycles, their positions on corn plants, and the composition of spider assemblages. Most variability of spider numbers and their community compositions appeared to be related to spider phenology and corn growth stages. There was a well-defined stratification of spider families on the corn plants. The Lycosidae dominated the ground layer while the Salticidae were most prevalent on the plant tops throughout the season. Other spider families occupying different areas on the plants shifted during the summer. There was an inverse relationship between salticid and thomisid numbers on the plants. Most spiders tended to be active at night, with lycosids and salticids showing a mid-day spike in activity. No significant effects from the presence of refugia were found on spider numbers, but more cursorial spiders tended to be near plants associated with refugia. (posted 5- 24 - 2005) |
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Spiders as conservation indicators at two oases in Baja California, Mexico |
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Authors |
Institution |
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María-Luisa Jiménez |
Centro de Investigaciones Biológicas del Noroeste (CIBNOR) |
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Miguel Correa |
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Gisela Nieto |
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Carlos Palacios |
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Abstract: Geomorphologic and evolutionary changes in the Baja California Peninsula created many mesic oases. In these habitats, the spider fauna is almost unknown. Two oases were surveyed every two months during 2002-3 to develop an ecological index. Pitfall traps, foliage nets, and hand collections were made along three transects set perpendicular to the oases streams. Of 184 species (138 at San Isidro and 143 at San José de Comondú), 92 were common to both localities. About 45% have nearctic and 22% have neotropical affinity. About 34% are exclusive to Baja California. Diversity of both communities were similar (H' = 3.73 at San Isidro and H' = 3.94 at San José). Morisita's Index was 0.55%. About 6.5% of the species at San Isidro and 6.3% at San José were dominant; whereas rare species represented about 41% at the first locality and 35% at the second. Previously undescribed species numbered 29, as well as one undescribed genus. In mesic areas, about 18% of the species were abundant; in xeric areas, about 39% were abundant. Anyphaena sp. nov. and Hamataliwa grisea were the most abundant species. The many spider species at these oases show that this environment conserves diversity, perhaps from geographic isolation and low anthropogenic impact. The spider species associated with mesic vegetation are probably relict populations of the Pleistocene because they are found in the highland oak-pine forest of the Sierra de la Laguna on the peninsula and highland mesic locations on the mainland of Mexico. (posted 5 - 11 - 2005) |
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Love Bites: Evidence of Coercive Mating in the Brush-Leg Wolf Spider Schizocosa ocreata (Hentz) |
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Authors |
Institution |
Julianna L. Johns |
University of Cincinnati |
George W. Uetz |
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Abstract: Coercive mating is defined as forced copulation when the female is not receptive, (at any point during the interaction or just prior to being mounted), and has been noted in many animals, especially arthropods. Obvious benefits to males who coercively mate include reduced energy cost from prolonged courtship, and an increase in the number of offspring sired. Adult male Brush-legged wolf spiders, Schizocosa ocreata (Hentz), exhibit elaborate courtship displays when presented with adult females and their silk. In response, females exhibit receptivity behaviors that in most cases determine whether copulation occurs. However, in trials where females are not receptive, mounting and subsequent copulation sometimes happens. Upon re-review of videotapes from previous studies of mating in this species, several instances of coercive mating were identified (in 12 out of 92 [13%] of mating trials). In several of these trials, the females were receptive at some point but not directly prior to mounting, and males often physically pulled down non-receptive females (attempting escape from the side of the arena) and copulated with them. Inspection of several male-female pairs in which mating was apparently coercive revealed that during copulation, males used fangs to maintain position in copula. Subsequent examination revealed cuticular wounds oozing hemolymph, which were not seen | |