Updated 6 / 9 / 2004
Use the table below to jump to abstracts, alphabetized by first author
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Variation in Reproductive Investment in Two Species of Wolf Spider |
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Author
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Institution
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Christopher
Amaya
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Siena
College, Department of Biology
Loudonville, New York USA |
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Abstract: Patterns of reproductive investment have a profound influence on individual fitness as well as population and community dynamics. This study examined the variation in the life history traits of two sympatric species of wolf spider (Allocosa mokiensis and Pardosa dorsuncata) over a three-year period (1998-2000) and at three study sites in southeastern Arizona. The time frame examined corresponded with an El Nino/La Nina event (1997-2000), which had significant effects on the total precipitation during those years. It appears that the life histories of both P.dorsuncata and A. mokiensis appear to be significantly influenced by environmental factors. Both species follow similar patterns of reproduction across years. Females of both species were larger and heavier and produced lighter and bigger offspring in 1998 and females were small and light and produced heavier, though smaller offspring in 2000. There was also limited evidence of size-number tradeoffs. (posted 5-23-2004) |
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Predicting the Occurrence of Apomastus Species Across the Los Angeles Basin Using Geospatial Analyses |
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Authors
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Institution
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David
A. Beamer
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Department of Biology,
East Carolina University |
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Jason
E. Bond
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Abstract: Information regarding species distributions can have important implications for conservation, investigating historical demographic factors, or developing sampling strategies for systematic studies. Geographic information system (GIS) software provides a powerful analytical tool that can be used to predict and document species distributions. The mygalomorph genus Apomastus is distributed throughout the Los Angeles Basin and is primarily associated with oak woodlands. In order to better assess the fine-scale distribution of this genus, we developed a binary multiple logistic regression model (using Apomastus presence/absence information as the response variable) to predict the probability that Apomastus would occur at a given site. The following environmental variables were entered into the initial model to investigate their explanatory importance: land cover, gap vegetation, recent vegetation, elevation, slope, aspect, precipitation, and soil type. Only slope, elevation, and precipitation significantly (P < 0.05) contributed to the model. Our model suggests that additional populations of Apomastus remain to be discovered and that other populations have probably become extinct due to human-induced habitat modification. These data, when combined with phylogeographic information, provide insight into factors that have influenced the distribution of Apomastus populations and species. (posted 5 - 23 -2004) |
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The Californian Euctenizine Genus Apomastus: Species "Paraphyly", Biogeography, and Conservation |
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Author
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Institution
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Jason
E. Bond
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Department
of Biology, East Carolina University
Greenville, North Carolina USA |
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Abstract: The genus Apomastus is a relatively small group of mygalomorph spiders with a limited geographic distribution. Restricted to the Los Angeles Basin, San Juan Mountains, and San Joaquin Hills Apomastus occupies a fragile habitat rapidly succumbing to urban encroachment. Although originally described as monotypic, the genus was hypothesized to contain at least one additional species. However, females of the two reputed species are morphologically indistinguishable and the authors were unable to confidently assign specific status to populations for which they lacked male specimens. Using an approach that combines geographic, morphological and molecular data, all known populations are assigned to one of two hypothesized species. Mitochondrial DNA Cytochrome c Oxidase I sequences are used to infer population phylogeny, providing the evolutionary framework necessary to resolve population/species identity issues. Conflicts across analyses raise questions about species delineation, species paraphyly, and the application of molecular taxonomy to these taxa. Issues relevant to the conservation of Apomastus species are discussed in light of the substantive intraspecific species divergence observed in the mtDNA data.(posted 5-23-2004) |
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Proposal: Behavioral Assay to Identify the Important Sensory Cues Involved in Sand Scorpion Navigation to their Home Burrows |
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Authors
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Institution
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Karen
Bost
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Department of Zoology,
University of Oklahoma |
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Douglas
Gaffin
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Abstract: Sand scorpions leave their home burrows at night to hunt and mate. After a few hours of surface activity, they return to their home burrows. We are interested in the sensory cues that guide animals in this homing process. These animals present an ideal system for navigational study in that they live in ecologically simple dune environments; also, they are abundant, easily obtained, easily maintained in the laboratory, and fluorescent under ultraviolet light. Additionally, behavior observed in the laboratory is generally consistent with that observed in the field, allowing comparable laboratory and field study. To identify the stimuli that guide animals to their home burrows, we propose a series of directional choice tests, each quantifying the ability of scorpions to orient towards the direction of their burrow under a single stimulus modality (for example: chemical trails or polarized light). Potential cues under investigation include geomagnetism, starlight patterns, polarized light, humidity gradient, chemical trails, and direct vision of the burrow or surrounding landmarks. Stimuli that appear to affect sand scorpion navigation behavior in the laboratory will be re-examined in field experiments. We will discuss our behavioral assay, experimental design, and some of our preliminary findings. (posted 5 - 13 -2004) |
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The Spiders of Glen Helen Nature Preserve, Greene County, Ohio |
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Author
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Institution
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Richard
A. Bradley
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Department
of EEO Biology Ohio State University at Marion
Marion, Ohio USA |
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Abstract: Glen Helen Nature Preserve is located in rural Southeastern Ohio near the town of Yellow Springs. It is one of the oldest nature preserves in the region, having been protected continuously since 1929. The reserve area is 404.6 hectares, it is bounded on the southeast by John Bryan State Park and is also very near Clifton Gorge Nature Preserve. The primary habitat is mixed mesophytic hardwood forest. In addition to forested areas, spider sampling was conducted in old field and restored tall grass prairie habitats. Samples were collected between 4 November 1993 and 11 September 2001. Sampling techniques included pitfall traps, litter extraction, visual searches at ground level and in the understory, and sweep/beat samples. A total of 104 collections from 29 localities in the preserve produced 3,411 identified specimens. The spider fauna of Glen Helen is relatively diverse in the Ohio context. These specimens include representatives of 22 families and 173 species. Open habitats yielded more species (128) than forested sites (97).. (posted 5-23-2004) |
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Spiders in Grand Canyon 2001-2003: Ecological Associations with Vegetation and Vertebrates |
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Authors
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Institution
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Sandra
L. Brantley
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Museum
of Southwestern Biology
University of New Mexico, Albuquerque USA |
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David
C. Lightfoot
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| Abstract: The impacts of dam construction and subsequent flow regulation on downstream ecosystems are complex, variable, and often indirect on native biodiversity or ecosystem function. We are developing an integrated monitoring program useful for dam operators and other stakeholders by documenting diversity as well as changes in ecological community structure. From 2001 to 2003 we visited 31 sites along the Colorado River, dividing each into a shore zone (SHOR), new high water zone (NHWZ) and old high water zone (OHWZ). Arthropods were sampled with 5 methods; here we discuss results from pitfall traps and sweep samples. Indicator species analysis revealed 17 ground-dwelling arthropod species (including 3 spiders) and 11 foliage species (including 2 spiders) that consistently defined the three zones. Ground-dwelling spiders were significantly correlated with vegetation height and volume in the NHWZ. Plant spiders were not correlated with these vegetation features in the NHWZ and were negatively correlated with vegetation in the OHWZ. Ground spiders were correlated strongly with other arthropods in the SHOR and NHWZ and with some vertebrates in the NHWZ. Plant spiders showed negative correlations with vertebrates in the NHWZ and OHWZ. Possible links underlying these correlations include predator/prey interactions, preferences for shade, open ground or soil type. We are now defining taxa for long-term monitoring; it is important to include arthropod taxa because of their high species numbers and varied interactions with other animals and vegetation. We expect these relationships to change over time in response to factors such as climate and river level. (posted 4-26-2004) | |
| An Investigation of the Mechanical Differences of Major Ampullate Silk Fibers from Nephila clavipes and Argiope aurantia | |
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Authors
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Institution
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Amanda
E. Brooks
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Department
of Molecular Biology
University of Wyoming Laramie, Wyoming USA |
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Shane
R. Nelson
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Holly
B. Steinkraus
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Justin
A. Jones
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Randolph
V. Lewis
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Abstract: Nephila clavipes and Argiope aurantia diverged from Macryphantes about 125 million years ago. Nephila is considered a derived araneoid; whereas, Argiope is an Araneida. Based on a cladogram, it would be expected that the silks of these two organisms would show distinct variations. Evolutionary divergence can be quantified by a comparison of the amino acid compositions of major ampullate silks from these two species. Major ampullate silk is the dominant constituent of dragline silk. It is composed of two distinct proteins, MaSp1 and MaSp2. Based on the proline content (as determined by amino acid analysis), Nephila clavipes major ampullate silk was calculated to consist of 19% MaSp2 and 81% MaSp1 while Argiope aurantia was calculated to have a significantly higher MaSp2 content of 59% (MaSp1 content 41%). To investigate the functional implications of the amino acid composition disparities, major ampullate silk fibers from Nephila clavipes and Argiope aurantia were mechanically tested and compared. Preliminary results, based on stress strain curves, show that there are substantial differences in a single major ampullate silk fiber from Nephila clavipes and Argiope aurantia. Despite the increased proline content (due to the increased MaSp2 content), which would be predicted to translate into a greater elastic capacity, Argiope aurantia major ampullate silk shows a similar elasticity after super contraction than that of the same kind of fiber from Nephila clavipes. Argiope aurantia silk is also able to withstand a higher peak load stress. Investigations are currently under way to understand the biological relevance of these findings. (posted 5 - 18 -2004) |
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Compensatory Growth in the Scorpion Centruroides vittatus |
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Author
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Institution
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Christopher
A. Brown
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Department
of Biology, Tennessee Tech University
Cookeville, TN USA |
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Abstract: In nature, many organisms are faced with a food supply that varies in space or time, and the ability to adjust growth rates to match food levels may be an important evolutionary adaptation. In particular, many organisms have the ability to grow at an accelerated rate when food levels increase following a period of low food availability; this process is termed compensatory growth. Compensatory growth has been little studied in arachnids, and there is no prior evidence for it in scorpions. In this study, I examined growth rates for two populations of Centruroides vittatus from Texas which differ in adult size and second instar size. I maintained juveniles on one of three feeding levels (fed every third, sixth, or ninth day) for six months, then fed all surviving juveniles every third day. Increased feeding rate during the initial six months led to higher survival, shorter instar duration, faster development (that is, more molts during this period), and a greater increase in length and mass. However, growth rates of surviving juveniles from the 6- and 9-day feeding treatments were significantly greater following transfer to a 3-day feeding treatment than were growth rates of juveniles maintained on the 3-day treatment continuously. This suggests that C. vittatus juveniles are capable of compensatory growth when food-limiting conditions are relaxed.(posted 5-14-2004) |
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Vibration Sensing in Sand Scorpions, Slit by Slit to the CNS |
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Authors
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Institutions
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Philip
Brownell
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Department of Zoology,
Oregon State University |
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Benedikt
Grothe
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Department
of Biologie II, University of Munich
Munich, Germany |
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Abstract: Sand scorpions (P. mesaensis) are exquisitely sensitive to nearby mechanical disturbances of dry sand substrates. Behavioral studies show they accurately locate the position and distance of moving objects from vibrational information detected by slit sensilla on their outstretched legs. We imaged the sensory neurons innervating each of 7 to 9 slits in each slit organ and measured their electrophysiological responses to controlled oscillation of the tarsal leg segments. For each slit, one or two neurons responded to broadband (<30 to >5000 Hz) vibrational input. At the threshold of stimulation these acceleration-sensitive neurons had peak sensitivity between 250 and 400 Hz, the dominant frequency band of surface wave signals conducted through sand. Individual slits showed differences in threshold correlated to their relative length and alignment to the leg axis. None of these spike responses were strongly phase-locked to the stimulus as previously predicted. Transmission EM and confocal microscopy of dye-filled slit organs showed at least two neurons (10-20 micron somata) innervating each slit, with an abundance of axo-axonic synapses between primary afferents. These findings contribute to a computational model of peripheral and central sensory processing proposed to explain vibration source localizing behavior.. (posted 5 - 24 -2004, modified 5-25-2004) |
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| Experiments Testing harvestmen as Agents of Biological Control | |
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Authors
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Institutions
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Alan
Cady
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Dept. of Zoology,
Miami Univ. |
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Sarah
Marchetti
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2990
Davis Road Apt. E 4
Fairbanks, AK USA |
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Ryan
Homsher
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Dept.
of Zoology, Miami Univ.
Middletown, OH USA |
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Abstract:Harvestmen (Opiliones) are common inhabitants of vegetable gardens. They are an endemic Generalist Predatory Arthropod (=GPA; e.g. spiders, harvestmen predaceous beetles, ants) with potential biological control abilities. Harvestman natural history is poorly known, especially how they may contribute to biocontrol effects within GPA assemblages. Opilionids are abundant, ubiquitous, and are active scavengers and predators. They will feed on pest species (leafhoppers, beetles, and lepidopetrans and their eggs), sometimes impacting pest populations. The gregarious nature of harvestmen would permit coexistence at higher densities than for other GPAs having interpredatory tendencies (e.g. spiders). Experiments have indicated that the presence of these predators in experimental enclosures protected young brussels sprouts plants from damage by early instars of common lepidopteran and aphid pests. Plants in enclosures holding harvestmen had greater growth, less damage, and more biomass than did controls. Energy supplements (chopped earthworms or mealworms) enhanced plant protection. A second year of experiments tested the influence of lowered harvestman densities and of small lean-to shelters within the experimental enclosures. Similar to the previous year, brussels sprouts with harvestmen present tended to have less damage and greater biomass, and dry cucumber weights tended to be higher. Results this year probably were less definitive due to reduced harvestman densities. Early in the season, more harvestmen were found in shelters during daylight, and they gradually moved to the plants for diurnal refuge as the foliage area expanded. These simple shelters placed in vegetable gardens could persuade harvestmen to remain there during the day, an important aspect relative to biocontrol. . (posted 5 - 24 -2004) |
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Responses of Burrowing Wolf Spiders in Florida Scrub to Wildfires: A Long-Term Study |
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Author
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Institution
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James
E. Carrel
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Division
of Biological Sciences, University of Missouri
Columbia, MO USA |
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Abstract: Florida scrub, a relictual habitat restricted to ancient sand dunes, is replete with endemic plants and vertebrates that require periodic fires for their persistence. I hypothesized that subterranean spider species found primarily in sandy gaps in the scrub matrix also might benefit from wildfires. To evaluate this idea, since 1987 I have monitored the densities of two burrowing wolf spiders (Geolycosa xera archboldi and G. hubbelli), both endemic to the Lake Wales Ridge in central Florida. I performed spider censuses annually in February on fifteen 100-m2 quadrats located in oak scrub at the Archbold Biological Station. All sites were burned in May 1989 and again in February 2001 by wildfires during my 17-year study. Most Geolycosa survived a burn because they were deep in the soil. I found a significant increase in density of burrowing wolf spiders within 1 year of each burn, relative to pre-burn values, then spider densities declined rapidly as gaps of open sand disappeared due to sprouting of woody shrubs from underground stems and accumulation of leaf litter. Additional measurements using bowl traps and aerial interception traps indicated that insect prey was less diverse and less abundant in burned scrub for 4-8 months after the fire event, relative to unburned control sites. Hence, increases in Geolycosa densities after a fire appear to be driven primarily by habitat modification (gap creation) rather than an increase in prey. (posted 5-5-2004) |
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| Modular Measured Elements in Ochyroceratid Webs | |
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Author
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Institution
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Jonathan Coddington
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Smithsonian Institution |
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Abstract: Very few spider lineages have evolved the ability to measure, that is, to place threads in a regularly repeating pattern, although exactly what constitutes "regularity" remains ambiguous. Orbwebs are an obvious example, of which there are several specialized sub-categories. Synotaxids, psechrids, and at least one tropical theridiid also measure. This report describes a fifth instance of regular thread spacing in ochyroceratid web "modules". Although the internal structure of these modules is regular, their orientation to each other is not. Neither the function nor the building behavior is known.. (posted 4-24-2004) |
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| Spiders of North America: An Identification Guide | |
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Authors
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Institutions
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Paula
E. Cushing
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Denver
Museum of Nature & Science
Denver, CO USA |
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Darrell Ubick
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California
Academy of Sciences
San Francisco, CA USA |
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Pierre Paquin
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Abstract:In September 2001, a team of taxonomists and interested arachnologists proposed to the American Arachnological Society Executive Committee that the Spider Genera of North America guide by Vince Roth be revised. The Spider Genera of North America Revision Team, or SGNART was formed. The new manual, entitled Spiders of North America: an identification guide, (first edition) is scheduled for publication by early 2005. The manual will contain a key to spider families of North America, north of Mexico; well illustrated keys to genera in each of these families; a chapter on the etymology of generic names; a fully illustrated glossary and pronunciation guide; and a complete bibliography. We will provide an overview of the contents and information on how to purchase the guide. (posted 5-7-2004) |
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| Distribution of Zinc and Manganese in Spider Cuticle | |
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Author
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Institution
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Bruce
Cutler
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University of Kansas |
| Abstract: It has been known for about 25 years that terrestrial arthropods have high concentrations of metallic elements in specialized cuticular structures. For those with electron microscopes, a readily available technique for elemental determination is electron induced X-ray emission particularly EDS (energy dispersive X-ray spectroscopy). The distribution of zinc and manganese in selected cuticle areas in 18 different spider families was examined by EDS. Studies from the 1980s and 90s on a few genera indicated significant levels of zinc in the surface layer of fang cuticle, and manganese in the cheliceral teeth and tarsal claws. This was confirmed in this study, but some genera differ. Anyphaena, Frontinella, Herpyllus, Thiodina and Titanoeca lack manganese in the cheliceral teeth. In Argyrodes and Metaltella zinc replaced manganese in cheliceral teeth, and in Dysdera and Metaltella zinc replaced manganese in tarsal claws. Fang serrulae have zinc, however in Herpyllus manganese replaces zinc. Manganese and zinc never co-occur at the same site. The only clear familial difference seen is that theridiids (3 genera) either lack or have very low manganese levels in tarsal claws. At this point no other higher category pattern of spider elemental distribution emerges. In arachnids the only similar survey was done on scorpions. Buthids had a different pattern of cuticle element distribution that is concordant with its isolated position within the order. (posted 4-23-2004) | |
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Subnivean Spiders of Green Bay, Wisconsin: Survey and Evaluation of a New Trapping Device |
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Authors
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Institutions
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Michael L. Draney
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Department of Natural
& Applied Sciences |
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Christopher
M. Buddle
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Department of Natural
Resource Sciences, McGill University |
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Abstract: Winter active spiders and other invertebrates were surveyed during two winters at five distinct habitats (old field, restored prairie, eastern red cedar, forested seep wetland, and deciduous woods) in east-central Wisconsin. An additional objective of the survey was to evaluate the effectiveness of a subnivean pitfall trap designed by the second author and David P. Shorthouse, which allows samples to be collected without disturbing the overlying snow layers. Three snow-pitfall/regular roofed pitfall pairs were operated in each of the five habitats during December through March. Snow pitfall traps captured more spiders and more species of spiders than the regular traps, but the difference was of marginal significance (Wilcoxon signed rank test, p between 0.05 and 0.10). Overall lack of significant differences between the performance of the snow traps and regular roofed traps indicates the new trap does function properly, but is not advantageous in areas with relatively thin average snow cover, such as east-central Wisconsin. 77% of the spiders trapped were adults, belonging to just 14 species. Preliminary evidence suggests that regions both south (South Carolina) and even north (Manitoba) of Green Bay harbor a richer winter-active spider fauna. Further research is needed to determine whether thin, inconsistent snow cover and cold winter temperatures explain this geographic pattern. The red cedar stand yielded about six times more spiders than the average of the other four habitats. This was mainly due to late winter dominance of two species, Cicurina brevis and Lepthyphantes (Tenuiphantes) zebra. Centromerus sylvaticus dominated the non-forested habitats. (posted 5-23-2004) |
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Eye Characters Support Sister Group Placement of Salticidae with Thomisidae |
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Author
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Institution
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GB
Edwards
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Florida
State Collection of Arthropods
Gainesville, FL USA |
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Abstract: Old World Thomisidae of the genus Amyciaea are atypical in body shape and leg proportion for crab spiders, instead having characters of this type that resemble jumping spiders. The eye arrangement of this genus is also very nearly like that of Salticidae, with the PME advanced forward and moved laterally. Examination of the eyes of typical thomisids reveals that these also have eyes in three rows, rather than two rows as has been assumed. This realization has been obscured by the presence of large rings of pigment surrounding the small eye lenses of thomisids. Salticids also have their eyes surrounded by large rings of pigment. One hypothesis for the presence of heavy pigment rings would be to shield the retinae from light penetrating through the cuticle in diurnal hunters. (posted 5 - 23 -2004) |
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Observations on the Life History of Monoblemma muchmorei Shear |
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Author
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Institution
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Robert
L. Edwards
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Woods
Hole, MA USA
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Abstract:
Monoblemma muchmorei is a diminutive orange-red species of
the armoured spider family Tetrablemmidae. Adults average 0.8 mm
in length. There are least 30 recognized genera and a very large
number of species found in tropical regions around the world. There
is virtually no life history information available for any of these
species. In Puerto Rico, in the area around El Yunque, M. muchmorei
occurs uniquely in bamboo litter at elevations of 100 meters or
less. |
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A Comparison of Ventral Mesosomal Changes in Scorpion Embryos |
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Author
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Institution
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Roger
D. Farley
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Department
of Biology, University of California
Riverside, CA USA |
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Abstract:
The SEM was used to compare embryogenesis in species with katoikogenic
(Pandinus imperator, Scorpionidae) and apoikogenic development.
Those studied with the latter developmental mode are: Paruroctonus
mesaensis (Vaejovidae), Vaejovis spinigerus (Vaejovidae),
Hadrurus arizonensis (Iuridae), Centruroides exilicauda
(Buthidae) and |
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| The Platypus of a Scorpion: Genus Pseudochactas (Scorpiones: Pseudochactidae) | |
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Authors
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Institutions
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Victor Fet
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Department
of Biological Sciences, Marshall University
Huntington, WV USA |
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Michael E. Soleglad
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Borrego
Springs, CA USA
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Alexander
V. Gromov
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Institute
of Zoology, Almaty, 480060 Kazakhstan
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Abstract: A unique monotypic scorpion genus Pseudochactas was described from southern Uzbekistan and Tajikistan by Gromov (1998). New material, collected by V. Fet and A. Gromov in 2002 during the field expedition sponsored by the National Geographic Society, allowed confirming and further studying a relict position of this taxon. It belongs to a separate family, superfamily, and parvorder (Soleglad & Fet 2003), and represents the most basal lineage of extant scorpions (data from both morphology and DNA). A separate trichobothrial pattern was introduced for Pseudochactas (Soleglad & Fet 2001). This parvorder could have been established in Permian/Triassic. The relict character of Pseudochactas could be due to its preservation in mild-climate, low-mountain depressions with desert surroundings. Ecologically, Pseudochactas is not a desert scorpion: it forages on wet mud, and likely spends most of dry season in hibernation. It could represent one of the few remnants of the Mesozoic littoral fauna of the receded Tethys Ocean, elevated by Tertiary tectonic uplift. (posted 5 - 14 -2004) |
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| The Euroscorpion: Genus Euscorpius (Scorpiones: Euscorpiidae) | |
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Authors
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Institutions
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Victor Fet
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Department
of Biological Sciences, Marshall University
Huntington, WV USA |
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Michael E. Soleglad
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Borrego
Springs, CA USA
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Benjamin
Gantenbein
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Department
of Genetics, University of Cambridge
Cambridge UK |
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Abstract: The genus Euscorpius Thorell, 1876 includes the most common scorpions in Europe and the Mediterranean area. Multiple specific and subspecific forms have been described, but their validity is not clear. A wealth of information is scattered in the literature but a comprehensive modern revision of the entire genus has never been done. We studied numerous available material from many European museums, starting with the Linnaean type specimen of E. carpathicus. Our ongoing comparative studies in 1998-2004 on morphology (especially trichobothrial patterns), mitochondrial DNA and nuclear gene (allozymes) variation (Gantenbein et al. 1999a, 1999b, 2000, 2001, 2002 etc.; Fet & Soleglad 2002; Fet et al. 2001, 2002, 2003, etc.) revealed unprecedented variability and active speciation process in several delineated species complexes. Currently, 15 species are recognized; status of many populations is still under investigation. Especially interesting are: Alpine refugial relicts E. germanus and E. alpha; high-mountain Balkan species E. hadzii; relict complex of E. sicanus (Italy, Malta, Greece); isolated E. tauricus (Crimea) and E. koschevnikovi (Greek Macedonia); and widespread but genetically impoverished E. italicus. (posted 5 - 14 -2004, revised 5-23-2004) |
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| Systematics and Molecular Phylogeny of Euscorpius from the Julian Alps of Slovenia (Scorpiones: Euscorpiidae) | |
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Authors
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Institutions
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Victor Fet
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Department
of Biological Sciences, Marshall University
Huntington, WV USA |
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Michael E. Soleglad
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Borrego
Springs, CA USA
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Benjamin
Gantenbein
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Department
of Genetics, University of Cambridge
Cambridge UK |
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Elizabeth
V. Fet
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Department
of Biological Sciences, Marshall University
Huntington, WV USA |
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Abstract: The scorpion genus Euscorpius is common in Europe, including high mountains (up to 2,400 m). An mtDNA study by Gantenbein et al. (2000) defined the Alpine refugial relict species E. germanus (C. L. Koch) from Italy, Switzerland, Austria, and Slovenia. Fet et al. (2001) reviewed fauna of scorpions from Slovenia, including the most southeastern populations of E. germanus in the Julian Alps. New data from both morphology and mtDNA confirm the separate position of Slovenian populations (known as subspecies E. g. marcuzzii Valle et al., 1971). Especially important is (an unprecedented for the genus) reduction in trichobothrial number from 4 to 3 in the external suprabasal (eba) series on pedipalp patella, which can be interpreted as a reversal to an ancestral character state. Taxonomy, morphology, and biogeography of Slovenian populations are discussed as compared to E. germanus from Italy, Switzerland, and Austria, and other related taxa. We thank Prof. Boris Sket (University of Ljubljana, Slovenia) and Matjaz Kuntner (Smithsonian Institution) for their enormous help in loaning scorpion collections. (posted 5 - 14 -2004) |
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| Tarsal Spinule Clusters and Evolution of the Superfamily Iuroidea (Scorpiones) | |
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Authors
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Institutions
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Victor Fet
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Department
of Biological Sciences, Marshall University Huntington, WV USA
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Michael E. Soleglad
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Borrego
Springs, CA USA
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David
P. A. Neff
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Department
of Chemistry, Marshall University
Huntington, WV USA |
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Iasmi Stathi
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Natural
History Museum of Crete, University of Crete
Irakleio, Crete, Greece |
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Abstract: Five scorpion genera of superfamily Iuroidea exhibit ancient disjunct ranges (South America, North America, Mediterranean), and are an important object in the study of scorpion phylogeny. They have an exceptional variety of tarsal leg setation/spination (Soleglad & Fet 2003). New SEM data from all five genera and two families: Caraboctonidae (Caraboctonus, Hadruroides, Hadrurus) and Iuridae (Iurus, Calchas) are characterized in detail. We demonstrate two major patterns: (1) an irregular median row of grouped spinule clusters, found in juvenile to subadult but reduced in adult (Calchas); or (2) a median row of highly concentrated spinule clusters. Pattern (2) is either forming “spinule tufts” (Caraboctonus, Hadruroides, Iurus), or individual “spinule-looking: protuberances (Hadrurus). We suggest that the latter are a derived feature as a result of fusion of separate spinules into a solid structure. (posted 5 - 14 -2004) |
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The Adaptive Value of the Scorpion’s Sting |
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Author
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Institution
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Daniel
R. Formanowicz, Jr.
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Department
of Biology
University of Texas at Arlington USA |
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Abstract:
Animal venoms function as defensive mechanisms against potential
predators and are important in prey capture, particularly of relatively
large prey. The importance of venoms to success of species that
utilize them has proven difficult to assess experimentally. This
is the result of the problem of isolating the effects of manipulating
envenomation capability without impairing feeding structures and
behavior. Scorpions are actively venomous animals that are unique
in that the venom delivery system is divorced from feeding structures.
Data from a population of Centruroides vittatus from North
Texas indicate that stinger damage does occur naturally (3% of individuals
have stinger damage that precludes them from envenomating prey or
predators). I examined the importance of the ability of C. vittatus
to envenomate on prey capture and survival with predators in a series
of laboratory and field enclosure experiments. |
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Scorpion Peg Sensilla: Are They the Same or Are They Different? |
|
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Authors
|
Institution
|
|
Douglas Gaffin
|
Department
of Zoology, University of Oklahoma
Norman, OK USA |
|
Paul McGowan
|
|
|
Mark Walvoord
|
|
|
Abstract: Thousands of seemingly identical peg sensilla adorn the ground-facing surfaces of the elaborate chemosensory organs of scorpion called pectines. The answer to the question of whether or not all sensilla behave identically could enhance our understanding of the overall behavior of this chemosensory system. Identical sensilla would suggest a parallel sampling scheme, lending support to an “information enhancement” hypothesis. Conversely, an observation that sensilla do not behave identically would support a “segmentation” hypothesis, similar to the decomposition of sensory elements in the well-studied mammalian visual processing system. We are using a newly developed chemical delivery approach to test peg response patterns to consistent, repeatable stimulation. We will report our findings based on electrophysiological recordings of stimulated peg sensilla of desert grassland scorpions (Paruroctonus utahensis, Scorpiones: Vaejovidae). We will also report on other relevant characteristics, including the nature and time course of a typical pecten “sniff” and the density of peg sensilla relative to substrate particle size from the animals’ natural sand habitat. (posted 5 - 13 - 2004) |
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Seismic Communication and Mate Choice in a Wolf Spider |
|
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Authors
|
Institution
|
|
Jeremy
S. Gibson
|
Department of Biological
Sciences |
|
George
W. Uetz
|
|
|
Abstract: Male multimodal courtship displays in the wolf spider, Schizocosa ocreata (Hentz), consist of two components - visual and vibratory/seismic - which are behaviorally coupled. Females use these multimodal signals in mate choice. Previous research demonstrated that the visual component of male courtship behavior influences female mate choice and that some visual signals (e.g. foreleg tufts) correlate with male condition. However, it has not yet been shown whether the seismic component also conveys information used in mate choice. Central to understanding the adaptive function and evolution of communication in this system is whether male multimodal courtship displays are more effective because they are redundant, or because they contain different information. To address this question, the multi-sensory signals were broken down into their individual components and studied separately. Males and females were paired in a cue isolation apparatus which blocked visual cues but allowed seismic communication. Analysis of female behavior indicated that male seismic signals influence female receptivity, as components of seismic communication differed between successful and unsuccessful males in their rate, total number, and total duration. Despite these differences between successful and unsuccessful males, no morphological measurements correlated with male success. These results suggest that visual and seismic signals may contain different information. Further investigation will be necessary to identify what information is being sent via the seismic channel. (posted 5 - 11 -2004) |
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Tarantula Sericophily |
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Authors
|
Institutions
|
|
Tim
Guiher
|
Department of Biology,
J. H. Barrow Field Station |
|
Samuel
D. Marshall
|
J.
H. Barrow Field Station, Environmental Studies Program
Hiram College, Hiram, Ohio USA |
|
Abstract: We studied the effect of prior residency cues on retreat-site selection in an arboreal tarantula, Avicularia avicularia (Araneae, Theraphosidae, Aviculariinae). We presented Avicularia with a choice of an artificial retreat that it been confined to for one week and an artificial retreat that had never been used. We also presented Avicularia with the choice of a different individual’s artificial retreat and an artificial retreat that had never been used. We constructed artificial ‘trees’ that consisted of a 1.27 cm diameter 77.0 cm tall PVC tubing trunk with two 3.81 cm diameter, 13.5 cm long PVC tubing retreats oriented vertically on each side of the top of the vertical support. The test trees were anchored in water-filled trashcans enclosed in a mosquito netting tent to deter the spiders from leaving the test apparatus. Each of 50 test Avicularia were confined to each retreat tube for five days by fiberglass mesh secured with rubber bands. After the five-day period the Avicularia were removed from the tube and the used tube was placed at the top of the apparatus along with a new tube. The Avicularia were placed into open cups at water level at the base of the trunk. The following morning the retreat selected by the Avicularia was noted. Based on a prior study we expect to find that the Avicularia will show a preference for their own retreats, but not for a strange retreat. The results will be presented at the meeting. (posted 5 - 26 -2004) |
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| Studies on the Brain Modulation of Circadian Rhythms in the Scorpion Heterometrus swammerdami | |
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Author
|
Institution
|
|
Mohammad
Habibulla
|
Human
Services Fund
Schaumburg Township Illinois USA |
| Abstract:
The first air breathing
land animal scorpion evolved 430 million years ago along with the
first vascular plants and the land plants. This was long before the
appearance of the mighty dinosaurs. The environmental conditions at
that time were different than now. Physiological rhythms are coordinated
with the external environmental conditions through the evolution of
internal biological clocks. This ensures the success of survival.
In Heterometrus swammerdami the biological clock is located
in the brain. Rhythmic brain protein variations in the scorpion with respect to time indicate, that, the then day-night length was different from now. The biological clock was adapted to that environment. Change in the light dark conditions disturbs the rhythms in the proteins. In DD the rhythm curve is monophasic and in the LL it ges attenuated. Heterometrus spends most of its time in burrows and is not affected much by the darkness. The night peak in serotonin (5-HT) suggests the light suppression. When dark, the endogenous peak is generated. The metabolite of serotonin, 5-HIAA varies with day night cycle, maximal being at midnight and minimal bein g at around 4 in the morning. Histamine rhythm in the brain is similar to that of 5-HIAA. Entrainment by light is necessary for its rhythmic stability. Electrophoresis brain protein analysis suggests that 41 K Da protein (product of clock gene) is a probable agent for clock similar to the period like protein in suprachiasmatic nuclei of mammals. This shows that the so called “mammalian biological clock” has been in existence long before the actual mammals evolved. Perhaps, a generalized model based on this study could be successfully formulated. (posted 5- 5-2004) |
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| Correlation of Population Density of Arctosa sanctaerosae to Human Impact on Native Beaches Along the Northern Rim of the Gulf of Mexico | |
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Authors
|
Institution
|
|
Drew
Hataway
|
Department
of Biology Samford University
Birmingham, AL USA |
|
Ron
L. Jenkins
|
|
|
W.
Mike Howell
|
|
|
Kristen
Ramsey
|
|
|
Abstract: Arctosa sanctaerosae is a wolf spider, existing only on the white beaches of the northern Gulf of Mexico. A. sancterosae was first described by Gertsch and Wallace in 1935 on Santa Rosa Island, FL. Dondale and Redner (1983) described its range eastward from the Mississippi through the panhandle of Florida. McNatt, et al (2000)described the specific habitat preference of this spider to native secondary dunes. They suspected populations of A. sanctaerosae to be very sensitive to commercial encroachment. According to the Alabama Beach Management Plan natural beaches on the northern rim of the Gulf of Mexico have been cut by one third between 1970 and 1997 by commercial development. The objective of the present study was to assess the current ecological status of A. sanctaerosae populations in the spider’s range and to evaluate the impact of commercial expansion on healthy populations of the spider. A. sanctaerosae were counted inside 40-foot square quadrants in 21 locations from the western border of Mississippi to St. George Island, FL. The 21 sites were categorized as a (1) native beach, (2) partial commercial development, or (2) extensive commercial development. All counts were made on secondary dunes during clear warm summer nights due to the spider’s specific nocturnal preferences. Mean population densities of A. sanctaerosae on native beaches were significantly greater (p<.002) than on beaches with extensive commercial development. There was also a significant difference (p <0.01) between population densities on the native beaches and those only moderately impacted beaches. (posted 5 - 14 -2004) |
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| Preliminary Study of Spiders of Lick Creek Park in Texas | |
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Authors
|
Institution
|
|
Takesha
Henderson
|
Department
of Entomology, Texas A&M University
College Station, TX USA |
|
Allen
Dean
|
|
|
Marvin
Harris
|
|
|
Alejandro Calixto
|
|
|
Abstract: Lick Creek Park is a local nature park acquired in 1987 by the city of College Station, Texas. It is comprised of 515 acres. The site has a variety of plant and animal species indigenous to the area with several miles of trails. 965 species of spiders are recorded from Texas with 213 in Brazos Co. Reviewing previously collected material and small collections this spring, 70 species are presently known from Lick Creek Park with 25 new records for Brazos Co. and one new species to Texas. The spider collection was made using pitfalls and tree band traps distributed evenly throughout different habitats; such as tall grass, short grass, sandy, and sandy with water area. Results illustrate generalized populations of different spider families and species found in pitfalls and tree band traps. Little was known about the spiders in Lick Creek Park before this study. Many additional species can be expected to be found in this habitat with additional collecting. This area merits its attention for conservation for the enjoyment and education of future generations, annually Bioblitz takes place on this important area attracting many hundreds of people that join biologists to learn and shared experiences about the fauna and flora of this particular ecosystem, a long-term commitment to inventory the natural park annually to monitor the changes as our urban community expands to surround the park.. (posted 5 - 24 -2004) |
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Assessing Species Boundaries in the Antrodiaetus unicolor Species Complex (Araneae: Mygalomorphae: Antrodiaetidae) |
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Authors
|
Institution
|
|
Brent
E. Hendrixson
|
Department of Biology,
East Carolina University |
|
Jason
E. Bond
|
|
|
Abstract: Spider species have typically been delineated solely on the basis of morphology. However, species constructs are seldom investigated using multiple lines of evidence (e.g., morphology, molecules, ecology). Antrodiaetus unicolor is a highly variable and widespread mygalomorph species, and has been used as a “catch-all” name for all specimens of Antrodiaetus from the southern and central Appalachian Mountains. Based on museum material and our extensive fieldwork, a novel species has been described from southwestern North Carolina and surrounding areas. This new species is diagnosed in the traditional sense (i.e., by morphology), but we have also implemented a phylogenetic approach to test for genealogical exclusivity. Based on 28S rDNA and COI mtDNA, the new species is strongly supported in parsimony and Bayesian analyses; however, it is nested within A. unicolor, rendering the latter species paraphyletic. This pattern (i.e., gene-tree/species-tree incongruence) may be explained by incomplete lineage sorting, sexual selection by female choice, erroneous taxonomic decisions, or is most likely indicative of a “cryptic species complex”. These data further indicate that species boundaries based exclusively on morphological criteria may be potentially misleading. In addition, the resulting phylogenetic analysis has shed some light on interpreting the vast amount of morphological variation first observed by Fred Coyle within the A. unicolor complex. Hence, we advocate a total-evidence approach (within a phylogenetic context) to delineating species boundaries. (posted 5 - 23 -2004) |
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| Scorpion Diversity of Two Desert Islands in the Northern Chihuahuan Desert | |
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Author
|
Institution
|
|
Richard
Henson
|
Appalachian
State University
Boone, NC USA |
|
Abstract: One thousand seven hundred thirty five scorpions representing 16 of Texas' 19 known species and three families were collected within Texas' two mountainous National Parks(Big Bend and Guadalupe Mountains) between 1986 and 2003. These scorpions were found in various habitats ranging from loose shifting sand to rocky substrates with some being highly specialized to habitat and others being generalists and less habitat specific. Both of these desert islands with large elevation changes possess varied life zones and the most diverse scorpion populations in Texas. Big Bend is represented by 16 species and Guadalupe Mountains by seven species (17 ot Texas' 19 species). The spatial distribution of these scorpions is partially dependent on several abiotic factors including temperature, precipitation, soil and substrate characteristics. (posted 5 - 14 -2004) |
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Genetic Structure of Nephila clavipes Populations in Mexico (Araneae: Tetragnathidae) |
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Authors
|
Institutions
|
|
Linden
E. Higgins
|
Dept.
of Biology, University of Vermont
Burlington, VT USA |
|
Jesus
Vargas
|
Instituto
de Ecología
Universidad Nacional Autonoma de México Mexico City, Mexico |
|
Juan
Nuñez Farfán
|
|
|
Abstract:
The large orb-weaving spider Nephila clavipes is very broadly
distributed: found from the southeastern US to Misiones Argentina,
populations inhabit environments ranging from mid-altitude deserts
to tropical rainforests. Previous studies have shown that these
populations vary in many aspects of life history and juvenile development,
and that much of this variation is environmentally induced (phenotypic
plasticity). |
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Tick and Cliff Swallow Associations in the Caddo Canyons of West-Central Oklahoma |
|
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Author
|
Institution
|
|
Cluff E. Hopla
|
Department of Zoology,
University of Oklahoma |
|
Abstract: Ticks associated with the cliff swallows in Caddo canyons are Ixodes baergi and Ornithodoros concanensis. I. baergi is host specific associated only with cliff swallows. The life history may be prolonged, usually is not completed within one calendar year, but requires three to four years. Female I. baergi engorge primarily upon the young nestlings. The larvae nymphs feed mainly on the adult birds. The adult birds transport all stages of I. baergi between colonies especially when seeking a colony site prior to nesting. Ornithodoros concanensis is not restricted to cliff swallows but also feeds on rodents and other mammals associated with the cliff face in the swallow nesting colonies. Ornithodoros concanensis is often classified as a “bat tick” and is frequently found wandering on the surface of the cliff at night within the swallow colonies during nesting season. Ornithodoros concanensis may be found readily under the superficial rock scale within the colony site, usually throughout the year. (posted 6-3-2004) |
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Comparison of Palps in Geolycosa Wolf Spiders; Development of Affordable Methods for Observing Three Dimensional Structures |
|
|
Authors
|
Institution
|
|
Ryan
Huber
|
Dept.
of Biology, University of Mississippi,
University, MS USA |
|
Gail
Stratton
|
|
|
Abstract: Meaningful comparison of complex structures such as male spider palps is hindered when dissecting scopes can only display one portion of the structure sharply in focus due to limited depth of field. Although commercial hardware and software have been developed to generate a fully focused image from multiple images with different depths of view (Syncroscopy, 2004), it remains impractical for many researchers due to high cost. Generating a fully focused image of a structure can be accomplished, however, using relatively inexpensive and commercially available Adobe Photoshop software with no additional hardware. This technique makes it possible to measure structures with greater precision and to more accurately describe morphological relationships between multiple structures. Although similar techniques have been used and described elsewhere (Colloff, 1997), this appears to be the first application of this technique to spiders. Another inexpensive and fairly simple technique yet to be utilized for spider imaging is the creation of Quicktime Virtual Reality (QTVR) Object movies using digital images and free software. QTVR Object movies allow the researcher to scale and rotate the specimen on the screen by clicking and dragging. (posted 5-5-2004) |
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The Responses of Jumping Spiders to Simplified Visual Stimuli |
|
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Authors
|
Institution
|
|
Elizabeth
M. Jakob
|
University
of Massachusetts
Amherst, Massachusetts USA |
|
Cristian
Gazmuri
|
|
|
Michael
Whalen
|
|
|
Christa
D. Skow
|
|
|
Abstr | |