Zoology Commons^™

Dietary Sequestration Of Defensive Steroids In Nuchal Glands Of The Asian Snake Rhabdophis Tigrinus, Deborah A. Hutchinson, Akira Mori, Alan H. Savitsky, Gordon M. Burghardt, Xiaogang Wu, Jerrold Meinwald, Frank C, Schroeder

Biological Sciences Faculty Publications

The Asian snake Rhabdophis tigrinus possesses specialized defensive glands on its neck that contain steroidal toxins known as bufadienolides. We hypothesized that R. tigrinus does not synthesize these defensive steroids but instead sequesters the toxins from toads it consumes as prey. To test this hypothesis, we conducted chemical analyses on the glandular fluid from snakes collected in toad-free and toad-present localities. We also performed feeding experiments in which hatchling R. tigrinus were reared on controlled diets that either included or lacked toads. We demonstrate that the cardiotonic steroids in the nuchal glands of R. tigrinus are obtained from dietary toads. …

Chemical Evidence For Dietary Toxin Sequestration In The Asian Snake Rhabdophis Tigrinus, Deborah A. Hutchinson

Biological Sciences Theses & Dissertations

Rhabdophis tigrinus (Colubridae: Natricinae) is an oviparous, bufophagous (toad-eating) snake from eastern Asia that possesses defensive integumentary glands on the neck known as nuchal glands. These glands are used in antipredator displays and typically contain bufadienolide toxins. Whereas toads are known to synthesize bufadienolide steroids from cholesterol precursors, we found that chemically undefended R. tigrinus must sequester bufadienolides from ingested toads in order to exhibit these compounds in their nuchal glands. Chemically defended females are capable of provisioning their embryos with these toxins so their unfed hatchlings possess defensive bufadienolides prior to consuming toads themselves. All of the hatchling R. …

Defensin Transcript Distribution In Tissues And Life Stages Of The Ixodid Ticks Amblyomma Americanum And Ixodes Scapularis, Stephanie M. Todd

Biological Sciences Theses & Dissertations

A number of bacterial, viral, and protozoan diseases are transmitted to humans via arthropods. Arthropods possess an innate immune system to destroy invading microorganisms. However, arthropods unable to rid their systems of pathogens function as disease vectors. The American dog tick, Dermacentor variabilis, destroys invading Borrelia burgdorferi spirochetes, preventing transmission. In contrast, the black-legged tick, Ixodes scapularis, which is unable to destroy acquired B. burgdorferi, successfully vectors the pathogen. The Lone Star tick, Amblyomma americanum, vectors a similar pathogen called Borrelia lonestari. The distribution of defensin, an antimicrobial peptide of the innate immune system, was examined in A. americanum and/. …

An Examination Of Seasonal Growth And Survivorship Of Sigmodon Hispidus In Southeastern Virginia, Heather Alyssa Green

Biological Sciences Theses & Dissertations

A reexamination of specific population dynamic aspects of Sigmodon hispidus, the hispid cotton rat, is necessary in order to gain additional knowledge and perspective on this species in its northernmost distribution on the east coast of the United States. Previous studies of Virginia cotton rats were based on data from necropsies, which do not allow for the determination of certain population characteristics, such as density, growth, and survival. General population trends and rates of growth and survival in males and females throughout the seasons in Virginia will also provide a basis for comparison with populations of cotton rats in …

The Adaptive Value Of Aggregation Among Juvenile Caribbean Spiny Lobster: An Evaluation Using Individual-Based Modeling, Thomas W. Dolan Iii, Mark J. Butler Iv

Biological Sciences Faculty Publications

Ontogenetic changes in gregariousness by pre-reproductive animals, like that observed in juvenile Caribbean spiny lobsters (Panulirus argus), may be adaptive and reflect size-specific changes in the effectiveness of aggregation in promoting survival. Alternatively, aggregation may simply result from changes in the distribution or availability of suitable habitat structure, or from other behaviors that enhance survival. There are currently two hypotheses explaining the potential benefits of gregarious behavior in juvenile spiny lobsters, both of which focus on increasing survivorship by reducing predation pressure: the group benefit hypothesis and the guide hypothesis. The group benefit hypothesis argues that aggregations of …

The Defensin Gene In Dermacentor Variabilis And Ixodes Scapularis, Katherine Corbett Seguin

Biological Sciences Theses & Dissertations

In response to microbial challenge, invertebrates rely on their innate immune response to recognize and destroy harmful pathogens. One of the primary proteins produced by the response and that has been observed in many invertebrates, including insects, mussels, and ticks, is defensin. These proteins are responsible for forming pores in the membranes of invading microbes thereby destroying them. This study examined the gene coding region for defensin in two important tick disease vectors, Dermacentor variabilis and Ixodes scapularis. PCR amplification of the genes from tick chromosomal DNA resulted in the amplification of a 225 base pair amplicon. Sequencing of …

New Species Of Amphipod Crustaceans In The Genera Tegano And Melita (Hadzioidea : Melitidae) From Subterranean Groundwaters In Guam, Palau, And The Philippines, Thomas R. Sawicki, John R. Holsinger, Thomas M. Iliffe

Biological Sciences Faculty Publications

Three new species of Tegano are described, two from caves on Panglao Island, Bohol, Philippines, and one from a cave on Peleliu Island, Palau. Sriha vagabunda from Sri Lanka is reassigned to the genus Tegano based primarily on the high degree of similarity between Sriha vagabunda and species of Tegano and the fact that these species exhibit a great deal of variation in the reduction of the mandibular palp. A new species of Melita with characters intermediate between those defining the genera Abludomelita, Melita, and Paraniphargus is described from a spring on Guam. The characters of the new …

Mechanical Properties Of The Integument Of The Common Gartersnake, Thamnophis Sirtalis (Serpentes: Colubridae), Gabriel Rivera, Alan H. Savitzky, Jeffrey A. Hinkley

Biological Sciences Faculty Publications

The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies examining the morphological consequences of macrophagy have concentrated on modifications of the skull and cephalic musculature. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. We examined mechanical properties of skin along the body axis in Thamnophis sirtalis (Colubridae). Data were collected from tensile tests and were analyzed using a multivariate analysis of variance (MANOVA) and post-hoc multiple comparison …

A Staging Sequence And Analysis Of Growth In Postovipositional Embryos Of Lamprophis Fulignosus, Angela Renee Vogel Rivera

Biological Sciences Theses & Dissertations

The brown house snake, Lamprophis fuliginosus, is a small, oviparous snake found throughout much of Africa. This lamprophiine colubrid reproduces rapidly; captive females can lay clutches every three to four months for a sustained period. Thus, L. fuliginosus is an excellent model for developmental studies requiring large numbers of embryos. In addition, the embryos of oviparous species are more suitable for some procedures than are those of viviparous forms. The most widely used system for staging embryonic snakes was developed for the common gartersnake, Thamnophis sirtalis, a viviparous natricine colubrid (Zehr, 1962). Based on the examination of 135 …

Comparative Systematics Of Subterranean Amphipod Crustaceans (Hadzioidea), Thomas R. Sawicki

Biological Sciences Theses & Dissertations

The research project presented in this doctoral dissertation is a compilation of six published papers. Therefore, instead of being a single comprehensive project, it is composed of a number of sub-projects. Introductory and summary sections provide structure for the compilation of papers.

The research for this dissertation investigates the systematics of genera within the amphipod families Hadziidae Karaman, 1943 and Melitidae Bousfield, 1973. In the family Hadziidae, Bahadzia patilarga is described from an anchialine cave on the southern coast of Cuba, B. caymanensis is described from a weakly brackish-water pool in a small cave on Grand Cayman Island in the …

Characterization Of Association Patterns Of Coastal Migratory Bottlenose Dolphins, Tursiops Truncatus, In The Nearshore Waters Of Virginia Beach, Virginia, Holly Fearnbach

Biological Sciences Theses & Dissertations

Bottlenose dolphins, Tursiops truncatus, commonly occur in fission-fusion social systems. For this study, I analyzed photo-identification data from 1994 to 1999 to describe association patterns of bottlenose dolphins in the nearshore waters of Virginia Beach, Virginia. Bottlenose dolphins are present seasonally (late April until early November) in these waters and individuals are considered to be members of the North Atlantic coastal migratory stock. I selected 78 individuals for detailed analyses from the 972 dolphins identified in the study area. Those chosen as “select” dolphins had been sighted at least five times in three of the six study years; all …

Metabolic Rate Models And The Substitutability Of Predator Populations, David R. Chalcraft, William J. Resetarits Jr.

Biological Sciences Faculty Publications

1. Much of the debate surrounding the consequences of biodiversity loss centres around the issue of whether different species are functionally similar in their effects on ecological processes. In this study, we examined whether populations consisting of smaller, more abundant individuals are functionally similar to populations of the same species with larger, fewer individuals.
2. We manipulated the biomass and density of banded sunfish (Enneacanthus obesus) and measured their impact on populations of Southern leopard frog (Rana sphenocephala) larvae. We also evaluated the ability of models relating metabolic rate to body size to predict the relative …

Comparative Life Histories Of Georgia And Virginia Cotton Rats, Bradley J. Bergstrom, Robert K. Rose

Biological Sciences Faculty Publications

Adult hispid cotton rats (Sigmodon hispidus) were collected from the field monthly for >2 years from populations near the northern edge of their range in Virginia and contemporaneously from south-central Georgia. Body measurements and weights were taken at capture, and after dissection embryos, corpora lutea, and placental scars were counted and measured; testes and seminal vesicles were dissected out, measured, and weighed. This allowed comparison of several life-history parameters between the populations and tests of several life-history hypotheses. The breeding season was up to 2 months longer in Georgia than in Virginia, where there was typically a 3-month …

Mechanical Properties Of The Integument Of The Common Gartersnake, Thamnophis Sirtalis (Serpentes: Colubridae), Gabriel Rivera

Biological Sciences Theses & Dissertations

The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies examining the morphological consequences of macrophagy have concentrated on modifications of the skull and cephalic musculature. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. I examined mechanical properties of skin along the body axis in male Thamnophis sirtalis (Colubridae). From each of 11 specimens, I examined nine circumferential strips of skin, each spanning 10 ventral scales, spaced at …

Geographic Variation In The Morphology Of Crotalus Horridus (Serpentes: Viperidae), John Robert Allsteadt

Biological Sciences Theses & Dissertations

The Timber Rattlesnake (Crotalus horridus) occurs in discontinuous populations throughout the eastern and central United States. The species exhibits high levels of polymorphism in morphological traits, especially in coloration and pattern. Previous studies recognized either distinct northern and southern subspecies or three regional morphs (northern, southern, and western), but conflicting data sets and limited geographic sampling of previous studies have left the relationships among those regional variants unclear. In this study, univariate and multivariate statistics, together with a geographic information system, were used to analyze geographic variation in 36 morphological characters recorded from 2,420 specimens of C. horridus …

An Unusually Colored Red-Backed Salamander (Plethodon Cinerus) From Northern Virginia, Joseph C. Mitchell, Thomas K. Pauley, C. Todd Georgel

Virginia Journal of Science

We describe an orange-pink, patternless, translucent morph of the Red-backed Salamander (Plethodon cinereus) found in northern Virginia on 27 September 2001. This is the first description of this unusual phenotype in this terrestrial salamander.

Hybridization Between The Watersnakes Nerodia Sipedon And Nerodia Fasciata, In The Carolinas: A Morphological And Molecular Approach, Konrad Mebert

Biological Sciences Theses & Dissertations

A few traditionally applied diagnostic characters of color pattern were compared with an additional set of morphological and genetic characters to evaluate differences between Nerodia sipedon and N. fasciata and to study the dynamics across their hybrid zone in the Carolinas. Many of the morphological characters exhibited significant interspecific differences, although only the number of dorsally complete crossbands (CBa) was diagnostic by itself. A discriminant function analysis of morphological characters was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression …

Keys To The Mammals And Mammal Skulls Of The Northern Coastal Plain Of Virginia, John F. Pagels, A. Scott Bellows, Joseph C. Mitchell

Virginia Journal of Science

This publication is designed to function as a tool for the identification of mammal species that occur on the Coastal Plain of northern Virginia. We provide whole-body and skull keys to the 40 species that occur in this region. Baseline data for this work were collected during several studies conducted on Fort A.P. Hill, Caroline County. The intended audience includes interested naturalists, teachers, students, field biologists, and natural resource managers.

The Effect Of A Predator Gradient On Female Oviposition Site Selection And Larval Performance, Josef F. Rieger

Biological Sciences Theses & Dissertations

Patterns of larval amphibian distribution and abundance have historically been ascribed to direct predation. However, adult oviposition site selection is an alternative mechanism that can produce identical patterns and significantly influence community assembly. Although such behavioral habitat selection has been documented in several amphibian species whose larvae lack particular anti-predator defenses, the sensitivity of adult amphibians in detecting predator cues and avoiding these habitats has not yet been determined. If larval survivorship is greatly reduced in sites containing predatory fish, selection to detect and avoid habitats with low fish densities should be strong. I conducted three experiments which, (1) evaluated …

Anting Behavior In Birds: Ant Selection And Effect Of Ant Chemistry On Feather Ectoparasites, Hannah Carrington Revis

Biological Sciences Theses & Dissertations

Active anting behavior occurs when songbirds apply ants to their feathers. During anting displays, a bird draws its wings forward in front of the head and swings its tail around to the far right or left. Both wing and tail feathers are then rubbed with ants held in the bird's beak. The potential associations among ants, feather ectoparasites and birds make anting behavior an important community-level interaction. Although this behavior is cosmopolitan in distribution and occurs in a wide variety of passerine birds, it remains poorly understood. This dissertation tested hypotheses about anting behavior through controlled experiments with captive songbirds …

Evidence For Infanticide In Bottlenose Dolphins Of The Western North Atlantic, Dale G. Dunn, Susan G. Barco, D. Ann Pabst, William A. Mclellan

Biological Sciences Faculty Publications

Nine bottlenose dolphin (Tursiops truncatus) calves that stranded in Virginia in 1996 and 1997 died of severe blunt-force trauma. Injuries were concentrated on the head and chest and multiple rib fractures, lung lacerations, and soft tissue contusions were prominent. Skeletal and/or soft tissue trauma occurred bilaterally in all of the calves. One had a bite wound across the left mandible that exhibited deep punctures consistent with the tooth placement in an adult bottlenose dolphin. The lesions were not compatible with predation, boat strike, fisheries interactions, rough-surf injury, or blast injury. However, they were similar to traumatic injuries described in stranded …

Mammals Of Fort A. P. Hill, Caroline County, Virginia And Vicinity, A. Scott Bellows, Joseph C. Mitchell, John F. Pagels, Heather N. Mansfield

Virginia Journal of Science

Fort A.P. Hill (APH) is a 30,329 ha military training installation (U.S. Army) located in the upper Coastal Plain of Caroline County, Virginia. It was formed in 1941 and named in honor of Civil War Confederate Lt. General Ambrose Powell Hill. The current landscape includes a mosaic of habitats that range from old fields to hardwood forests. Forty species of mammals are known to exist on or near the installation. These include one marsupial, five insectivores, 9 chiropterans, one lagomorph, 12 rodents, 10 carnivores, and one cervid. We have studied many of the species on APH since 1997. In this …

Investigations Into The Innate Resistance Of The Tick, Dermacentor Variabilis, When Challenged With The Bacterium, Escherichia Coli, Shane Michael Ceraul

Biological Sciences Theses & Dissertations

In addition to the soluble response, many invertebrates control bacterial infections by means of phagocytosis or melanotic encapsulation. In some insects, Escherichia coli growth is reported to be inhibited by aggregation/encapsulation. Soluble and phagocytic responses to bacterial challenge have been reported in ticks, but evidence of an aggregation/encapsulation response was reported only for inanimate (araldite) implants. This study was done to determine how ticks control infection by E. coli. Ticks were challenged by direct inoculation of bacteria into the hemocoel cavity. Using plate counts, no viable E. coli were detected I hour post-inoculation. A direct fluorescence assay (DF A) …

Twenty-Five Years Of Population Fluctuations Of Microtus Ochrogaster And M-Pennsylvanicus In Three Habitats In East-Central Illinois, Lowell L. Getz, Joyce E. Hofmann, Betty Mcguire, Thomas W. Dolan Iii

Biological Sciences Faculty Publications

Populations of 2 species of arvicoline rodents, the prairie vole (Microtus ochrogaster) and meadow vole (M. pennsylvanicus), were monitored monthly in alfalfa, bluegrass, and tallgrass prairie habitats in east-central Illinois from 1972 through 1997. Alfalfa provides very highquality preferred food and poor vegetative cover for both vole species, whereas bluegrass provides intermediate food and vegetative cover. Preferred food resources were very low, especially for M. ochrogaster, and vegetative cover was very dense in tallgrass prairie. Maximum and mean population densities of M. ochrogaster were highest in alfalfa, intermediate in bluegrass, and lowest in tallgrass prairie. …

Small Mammal Communities In Riparian And Upland Habitats On The Upper Coastal Plain Of Virginia, A. Scott Bellows, Joseph C. Mitchell

Virginia Journal of Science

We compared small mammal communities between riparian (stream corridor) and nearby upland habitats in a hardwood forest ecosystem on Fort A.P. Hill, Caroline County, Virginia. We used a combination of small-scale drift fence/pitfall trap arrays and snap traps to capture small mammals during April – October 1998, with an additional winter sample in January 1999. We captured seven small mammal species at 14 sites (7 pairs). Numbers of species were not significantly different between habitat types. Bray-Curtis polar ordinations showed that plant and small mammal community compositions were similar in upland sites and that these communities were most varied in …

Observations On Amphibians And Reptiles In Burned And Unburned Forests On The Upper Coastal Plain Of Virginia, Joseph C. Mitchell

Virginia Journal of Science

I evaluate the results of a short-term study on the effects of prescribed burning on terrestrial amphibians and reptiles on Fort A.P. Hill, Caroline County, Virginia. Six species of amphibians and reptiles were observed in unburned sites and eight species were observed in burned sites. More individual amphibians (46) were observed in unburned stands than in burned stands (15). Adults of two species (Bufo americanus, Plethodon cinereus) were found dead under logs in the still smoldering prescribed burn. The results of this study suggest that prescribed burning may have some negative effects on amphibians and reptiles. Because …

An Analysis Of Migratory Behavior Physiological Condition And Life History Strategy In The Salamanders Ambystoma Mabeei And A. Opacum In Southeastern Virginia, Michael W. Mccoy

Biological Sciences Theses & Dissertations

Ambystoma mabeei is listed as threatened in Virginia due to its rarity and susceptibility to urbanization and poor forestry practices. The goal of this study was to identify factors that may affect the persistence of A. mabeei in Virginia by studying the life history and ecology of A. mabeei and its syntopic congener A. opacum. This information will contribute to the knowledge of life history variation within Ambystomatidae and will be critical for the development of a comprehensive management plan for A. mabeei. Population sizes of the two species and the proximate factors responsible for initiating breeding migrations were determined …

Comparative Systematics Of Subterranean Amphipod Crustaceans In The Families Crangonyctidae And Bogidiellidae, Stefan Koenemann

Biological Sciences Theses & Dissertations

The research project presented in this doctoral dissertation deals with the systematics of two different taxonomic groups of subterranean amphipods (Crustacea). Therefore, rather than being a single project, this study is divided into several sub-projects. Altogether, the chapters for the sub-projects are composed of five publications. An introductory chapter and a summarizing discussion are added to provide a structural unit for the collection of papers and to compare the results of the individual projects.

The thesis investigates the systematics of the amphipod families Bogidiellidae Hertzog, 1936, and Crangonyctidae Bousfield, 1973. Based on descriptive taxonomy according to modern standards, revisions are …

An Ultrastructural Survey Of The Nuchal Glands Of Rhabdophis Tigrinus (Serpentes: Colubridae), Kathleen A. Roberts

Biological Sciences Theses & Dissertations

Rhabdophis tigrinus, an Asian natricine snake, possesses a series of integumentary glands located in the nuchal skin. Previous studies indicated that the nuchal glands are of mesodermal origin, contain cardiac steroids analogous to bufotoxins found in the parotoid glands of toads, which are included in the snake's diet. The nuchal glands are defensive in function. Preliminary histological studies revealed differences in quality of the gland tissue compared to previous studies, and difference in fixation techniques were suspected. Seven specimens of R. tigrinus were fixed by perfusion using a conservative fixation process standard for electron microscopy. The nuchal gland series …

Conservation Status Of The Southern Appalachian Herpetofauna, Joseph C. Mitchell, Thomas K. Pauley, David I. Withers, Steven M. Roble, Brian T. Miller, Alvin L. Braswell, Paul V. Cupp Jr., Christopher S. Hobson

Virginia Journal of Science

Seventy one species of amphibians (55 salamanders, 16 anurans) and 46 species of reptiles (15 turtles, 8 lizards, 23 snakes) inhabit a five state area (Kentucky, North Carolina, Tennessee, Virginia, West Virginia) in the southern Appalachian region bordered by the Potomac River, the Blue Ridge Mountains, and the western margin of the Appalachian Plateau. Of these, 47.9 % of the amphibian fauna and 52.2 % of the reptilian fauna are listed as being of conservation concern by federal, state, and Natural Heritage programs in all or a portion of their ranges of this region. The Shenandoah salamander (Plethodon Shenandoah …