Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 56

Full-Text Articles in Life Sciences

Microhabitat Comparison Of Percina Roanoka (Roanoke Darter) And Percina Nevisense (Chainback Darter) In The Roanoke River, Dakota R. Spruill, Steven L. Powers Apr 2019

Microhabitat Comparison Of Percina Roanoka (Roanoke Darter) And Percina Nevisense (Chainback Darter) In The Roanoke River, Dakota R. Spruill, Steven L. Powers

Virginia Journal of Science

Snorkel observations of Percina roanoka and P. nevisense in the Roanoke River during summer months were followed by measuring current velocity, water depth, and substrate diameter at points of occupation. A total of 89 observations of P. roanoka and 81 observations of P. nevisense were compared using two-sample T-tests. Percina roanoka inhabited faster, shallower water than P. nevisense with the former found in a mean flow of 0.318 m/s and depth of 31.53 cm and the latter in a mean flow of 0.17 m/s and depth of 55.6 cm. Mean diameter of substrate at ...


Compositional Changes In Two Small Mammal Communities During Succession In Southeastern Virginia, Robert K. Rose, Robyn M. Nadolny, Jay Kiser, Stephen E. Rice, Heather Green Salamone, Jana Eggleston, Holly D. Gaff Jan 2018

Compositional Changes In Two Small Mammal Communities During Succession In Southeastern Virginia, Robert K. Rose, Robyn M. Nadolny, Jay Kiser, Stephen E. Rice, Heather Green Salamone, Jana Eggleston, Holly D. Gaff

Virginia Journal of Science

Changes in the composition of two small mammal communities were studied during 8 and 9 years of ecological succession in southern Chesapeake. Virginia. Using monthly live-trapping on grids of similar size and history since their abandonment as agricultural fields, we learned that house mice were early colonists on one grid but not the other. Two species of herbivorous rodent and the granivorous eastern harvest mouse were numerically dominant on both grids across the study. Some species disappeared early on one grid but persisted to the end at the other. The two arboreal small mammals, golden and white-footed mice, were most ...


Do Avian Blood Parasites Influence Hypoxia Physiology In A High Elevation Environment?, Farah Ishtiaq, Sahas Barve Jan 2018

Do Avian Blood Parasites Influence Hypoxia Physiology In A High Elevation Environment?, Farah Ishtiaq, Sahas Barve

Biological Sciences Faculty Publications

BACKGROUND: Montane birds which engage in elevational movements have evolved to cope with fluctuations in environmental hypoxia, through changes in physiological parameters associated with blood oxygen-carrying capacity such as haemoglobin concentration (Hb) and haematocrit (Hct). In particular, elevational migrants which winter at low elevations, encounter varying intensities of avian haemosporidian parasites as they traverse heterogeneous environments. Whilst high intensity parasite infections lead to anaemia, one can expect that the ability to cope with haemosporidian infections should be a key trait for elevational migrants that must be balanced against reducing the oxygen-carrying capacity of blood in response to high elevation. In ...


Review: Application Of Tick Control Technologies For Blacklegged, Lone Star, And American Dog Ticks, Alexis White, Holly Gaff Jan 2018

Review: Application Of Tick Control Technologies For Blacklegged, Lone Star, And American Dog Ticks, Alexis White, Holly Gaff

Biological Sciences Faculty Publications

Tick population control technologies have been studied for several decades but no method is successful in all situations. The success of each technology depends on tick species identity and abundance, host species identity and abundance, phenology of both ticks and hosts, geographic region, and a multitude of other factors. Here we review current technologies, presenting an overview of each and its effect on three common tick species in the eastern United States: blacklegged ticks (Ixodes scapularis (Say; Ixodida: Ixodidae)), lone star ticks (Amblyomma americanum (Linnaeus; Ixodida: Ixodidae)), and American dog ticks (Dermacentor variabilis (Say; Ixodida: Ixodidae)). Moreover, we assess the ...


Predation On Artificial Turkey Nests At Radford Army Ammunition Plant In Western Virginia, Shane Brandes, Karen E. Powers, Len L. Diioia Jr. Oct 2017

Predation On Artificial Turkey Nests At Radford Army Ammunition Plant In Western Virginia, Shane Brandes, Karen E. Powers, Len L. Diioia Jr.

Virginia Journal of Science

Because ground-nesting wild turkeys (Meleagris gallopavo) may sustain high incidences of nest predation in western Virginia, determining their predators is essential to understanding risk and managing the birds. Our study investigated potential predators of wild turkey nests at the Radford Army Ammunition Plant, New River Unit (RFAAP; Pulaski Co., in western Virginia). Here, we established 8 artificial nests during the breeding season for wild turkey (March-April, 2017), and documented predators via game cameras. Thirty-one species of mammals and birds visited the nests over the 31-day study. Nest predation was verified 56 times across 6 species, including coyotes (Canis latrans), a ...


An Erythristic Morph Of Red-Backed Salamander (Plethodon Cinereus) Collected In Virginia, Trevor L. Chapman, Brian G. Gall, Kari L. Spivey Aug 2017

An Erythristic Morph Of Red-Backed Salamander (Plethodon Cinereus) Collected In Virginia, Trevor L. Chapman, Brian G. Gall, Kari L. Spivey

Virginia Journal of Science

Eight different color polymorphisms of the Red-backed Salamander (Plethodon cinereus) have been described throughout its range. Among them, the erythristic phenotype is a mimetic morph with coloration patterns similar to that of toxic Eastern Newt efts (Notophthalmus viridescens). We describe an erythristic morph of P. cinereus collected at Mountain Lake Biological Station, Virginia. To our knowledge, there are no prior published records of this morph in Virginia.


Testing Alternative Hypotheses For The Cause Of Population Declines: The Case Of The Red-Headed Woodpecker, Walter D. Koenig, Eric L. Walters, Paul G. Rodewald Jan 2017

Testing Alternative Hypotheses For The Cause Of Population Declines: The Case Of The Red-Headed Woodpecker, Walter D. Koenig, Eric L. Walters, Paul G. Rodewald

Biological Sciences Faculty Publications

The Red-headed Woodpecker (Melanerpes erythrocephalus) has experienced strong population declines during the past 3 decades. Using North American Breeding Bird Survey (BBS) and Audubon Christmas Bird Count (CBC) data, we investigated 4 hypotheses that may explain this decline, including: (1) interspecific competition with native Red-bellied Woodpeckers (Melanerpes carolinus) and nonnative European Starlings (Sturnus vulgaris); (2) predation by Cooper's Hawks (Accipiter cooperii) and Sharp-shinned Hawks (Accipiter striatus); (3) climate change; and (4) changes in forested area within their range. In analyses of both the breeding and overwintering periods, our results indicated a role of increased accipiter populations in driving Red-headed ...


Reproductive Competency And Mitochondrial Variation In Aged Syrian Hamster Oocytes, Fang Li, Frank J. Castora, Wentia Ford, Khalid Alarid, Howard W. Jones Jr., R. James Swanson Jan 2017

Reproductive Competency And Mitochondrial Variation In Aged Syrian Hamster Oocytes, Fang Li, Frank J. Castora, Wentia Ford, Khalid Alarid, Howard W. Jones Jr., R. James Swanson

Biological Sciences Faculty Publications

The hamster is a useful model of human reproductive biology because its oocytes are similar to those in humans in terms of size and structural stability. In the present study we evaluated fecundity rate, ovarian follicular numbers, ova production, mitochondrial number, structure and function, and cytoplasmic lamellae (CL) in young (2–4 months) and old (12–18 months) Syrian hamsters (Mesocricetus auratus). Young hamsters had higher fertilisation rates and larger litters than old hamsters (100 vs 50% and 9.3 +/- 0.6 vs 5.5 +/- 0.6, respectively). Ovarian tissue from superovulated animals showed a 46% decrease in preantral follicles ...


Diet And Foraging Behaviors Of Timber Rattlesnakes, Crotalus Horridus, In Eastern Virginia, Scott M. Goetz, Christopher E. Petersen, Robert K. Rose, John D. Kleopfer, Alan H. Savitzky Jan 2016

Diet And Foraging Behaviors Of Timber Rattlesnakes, Crotalus Horridus, In Eastern Virginia, Scott M. Goetz, Christopher E. Petersen, Robert K. Rose, John D. Kleopfer, Alan H. Savitzky

Biological Sciences Faculty Publications

During a 17-yr telemetry study, we examined the diet and ambush behavior of a population of Crotalus horridus in southeastern Virginia. Forty dietary items were identified from 37 fecal samples. We documented 722 instances of snakes in an ambush posture, 61 of which were in a vertical-tree posture, as if hunting arboreal prey at the base of a tree. The most common prey items were Eastern Gray Squirrels (Sciurus carolinensis), which accounted for 45 of all dietary items and represented an estimated 78 of total biomass consumed by C. horridus. Prey was not consumed in proportion to availability, based on ...


The Population Dynamics Of Two Rodents In Two Coastal Marshes In Virginia, Robert K. Rose, John A. March Jan 2013

The Population Dynamics Of Two Rodents In Two Coastal Marshes In Virginia, Robert K. Rose, John A. March

Virginia Journal of Science

The communities of small mammals were evaluated for 13 months with capture-mark-recapture methods in two Spartina-Juncus marshes of the Atlantic coast in Northampton County, Virginia. Small mammals were trapped for three days each month using live traps placed on floats on two study grids. Two rodents were numerically dominant (~90% of small mammals) there: marsh rice rat, Oryzomys palustris, and meadow vole, Microtus pennsylvanicus. Monthly estimates of population density were greater for rice rats (peak: 45/ha) than for those of meadow voles (peak: 30/ha). Survival rates were generally low, especially for rice rats, indicating highly vagile populations. Both ...


First Record Of Pond Sliders (Trachemys Scripta Scripta And T. S. Elegans) At Fredericksburg, Virginia With Observations On Population Size, Age And Growth, Werner Wieland, Yoshinori Takeda Jan 2013

First Record Of Pond Sliders (Trachemys Scripta Scripta And T. S. Elegans) At Fredericksburg, Virginia With Observations On Population Size, Age And Growth, Werner Wieland, Yoshinori Takeda

Virginia Journal of Science

We conducted a turtle mark-recapture program within a 160 m stretch of the Fredericksburg Canal with standard, baited hoop nets from May to July 2012 to determine if a population of the introduced Red-eared Slider (Trachemys scripta elegans) and Yellow-bellied Slider (Trachemys s. scripta) are established in this area. We captured and marked nine Red-eared Sliders (1 male, 8 females) and estimated a population size of 23 individuals. Most were reproductively mature. The established population in the canal may be a source of introduction into the Rappahannock River.


Chemical Defense Of An Asian Snake Reflects Local Availability Of Toxic Prey And Hatchling Diet, D. A. Hutchinson, A. H. Savitzky, G. M. Burghardt, C. Nguyen, J. Meinwald, F. C. Schroeder, A. Mori Jan 2013

Chemical Defense Of An Asian Snake Reflects Local Availability Of Toxic Prey And Hatchling Diet, D. A. Hutchinson, A. H. Savitzky, G. M. Burghardt, C. Nguyen, J. Meinwald, F. C. Schroeder, A. Mori

Biological Sciences Faculty Publications

Species that sequester toxins from prey for their own defense against predators may exhibit population-level variation in their chemical arsenal that reflects the availability of chemically defended prey in their habitat. Rhabdophis tigrinus is an Asian snake that possesses defensive glands in the skin of its neck (nuchal glands'), which typically contain toxic bufadienolide steroids that the snakes sequester from consumed toads. In this study, we compared the chemistry of the nuchal gland fluid of R.tigrinus from toad-rich and toad-free islands in Japan and determined the effect of diet on the nuchal gland constituents. Our findings demonstrate that captive-hatched ...


The Small Mammals Of Two Dune Communities In Southeastern Virginia, Robert K. Rose, Justin L. Sweitzer Jan 2013

The Small Mammals Of Two Dune Communities In Southeastern Virginia, Robert K. Rose, Justin L. Sweitzer

Virginia Journal of Science

Small mammals were surveyed using live and pitfall traps between the primary and secondary dunes at two locations on the shores of the Chesapeake Bay near the Atlantic Ocean: Little Creek Amphibious Base in Norfolk and Joint Expeditionary Base Fort Story in Virginia Beach, Virginia. Captures were dominated by house mice (Mus musculus) in interdunal habitats with sparse grass, whereas white-footed mice (Peromyscus leucopus) were found primarily in shrubby live-oak thickets on the tops of dunes. Hispid cotton rats (Sigmodon hispidus) were present only at Fort Story, and then only in patches of dense herbaceous vegetation just above the wrack ...


Unusually High Body Mass In Virginia Meadow Voles, Sara B. Longtin, Robert K. Rose Jan 2012

Unusually High Body Mass In Virginia Meadow Voles, Sara B. Longtin, Robert K. Rose

Biological Sciences Faculty Publications

We used monthly capture-mark-recapture information to determine growth rates and life spans for 2 populations of meadow voles studied for 28 and 29 months in eastern Virginia in order to learn whether the exceptionally large body masses of some voles were due to rapid growth, long lives, or both. On 1 study grid, 64 males (19%) and 43 nonpregnant females (11%) were ≥70 g, with the largest male being 89 g. Mostly positive growth rates (averaging 1.1-3.9 g/month) were recorded, even in autumn and winter months, times when meadow voles are losing mass in northern populations, where ...


Effects Of Gypsy Moth Outbreaks On North American Woodpeckers, Walter D. Koenig, Eric L. Walters, Andrew M. Liebhold May 2011

Effects Of Gypsy Moth Outbreaks On North American Woodpeckers, Walter D. Koenig, Eric L. Walters, Andrew M. Liebhold

Biological Sciences Faculty Publications

We examined the effects of the introduced gypsy moth (Lymantria dispar) on seven species of North American woodpeckers by matching spatially explicit data on gypsy moth outbreaks with data on breeding and wintering populations. In general, we detected modest effects during outbreaks: during the breeding season one species, the Red-headed Woodpecker (Melanerpes erythrocephalus), increased over pre-outbreak levels, while during the winter one species, the Yellow-bellied Sapsucker (Sphyrapicus varius), increased and one, the Downy Woodpecker (Picoides pubescens), decreased from pre-outbreak levels. Responses following outbreaks were similarly variable, and in general we were unsuccessful at predicting population responses to outbreaks from a ...


A New Species Of The Subterranean Amphipod Crustacean Genus Stygobromus (Crangonyctidae) From A Cave In Nevada, Usa, Steven J. Taylor, John R. Holsinger Jan 2011

A New Species Of The Subterranean Amphipod Crustacean Genus Stygobromus (Crangonyctidae) From A Cave In Nevada, Usa, Steven J. Taylor, John R. Holsinger

Biological Sciences Faculty Publications

Stygobromus albapinus, a new stygobiotic amphipod crustacean species in the family Crangonyctidae, is described from two pools in Model Cave in Great Basin National Park, White Pine County, Nevada, USA. The type specimens were collected on two different visits to the cave. The new species is assigned to the hubbsi group, bringing the number of described species in this group to 45, but many other provisionally recognized species assigned to this group remain undescribed. With exception of a single species from deep wells in southeastern Wisconsin, all other members of the hubbsi group are recorded from a wide variety of ...


Advertisement Call And Distribution Of The Treefrogs Hyla Chrysoscelis And Hyla Versicolor In Virginia, Joseph C. Mitchell, Christopher A. Pague Jan 2011

Advertisement Call And Distribution Of The Treefrogs Hyla Chrysoscelis And Hyla Versicolor In Virginia, Joseph C. Mitchell, Christopher A. Pague

Virginia Journal of Science

The gray treefrog complex consists of two sibling species that are indistinguishable morphologically, the diploid Hyla chrysoscelis and the tetraploid Hyla versicolor. Identification is possible in the field only by audio recognition of male advertisement call trill rates (pulses/second). During 1979-1983 we evaluated taped calls of these two species taken from 89 populations from throughout Virginia to map their respective ranges and to evaluate differences in call parameters. Hyla chrysoscelis occurs in the Coastal Plain, eastern and southern Piedmont, and in southwestern Virginia. Hyla versicoloroccurs in the Piedmont, Blue Ridge, and Ridge and Valley regions south to Wythe ...


The Impact Of Conservation On The Status Of The World's Vertebrates, Michael Hoffmann, Craig Hilton-Taylor, Ariadne Angulo, Monika Böhm, Thomas M. Brooks, Stuart H. M. Butchart, Kent E. Carpenter, Janice Chanson, Beth A. Polidoro, Jonnell C. Sanciangco Jan 2010

The Impact Of Conservation On The Status Of The World's Vertebrates, Michael Hoffmann, Craig Hilton-Taylor, Ariadne Angulo, Monika Böhm, Thomas M. Brooks, Stuart H. M. Butchart, Kent E. Carpenter, Janice Chanson, Beth A. Polidoro, Jonnell C. Sanciangco

Biological Sciences Faculty Publications

Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to ...


Morphological Differences Among Eyeless Amphipods In The Genus Stygobromus Dwelling In Different Subterranean Habitats, David C. Culver, John R. Holsinger, Mary C. Christman, Tanja Pipan Jan 2010

Morphological Differences Among Eyeless Amphipods In The Genus Stygobromus Dwelling In Different Subterranean Habitats, David C. Culver, John R. Holsinger, Mary C. Christman, Tanja Pipan

Biological Sciences Faculty Publications

The amphipod genus Stygobromus occurs in a variety of subterranean habitats in North America, including caves, phreatic (groundwater) lakes, and superficial subterranean habitats (seeps and epikarst). The habitats share the absence of light but differ in other features, such as pore size of the habitat, available food, and degree of seasonality. Measurements of body size, antennal size, and antennal segment number of type specimens were compared for 56 species occurring in the eastern United States. Except for differences in body size, differences among species in the four different habitats were not significant. Body size was related to relative pore size ...


Growth And Survival In A Northern Population Of Hispid Cotton Rats, Heather A. Green, Robert K. Rose Jan 2009

Growth And Survival In A Northern Population Of Hispid Cotton Rats, Heather A. Green, Robert K. Rose

Biological Sciences Faculty Publications

Using data from a 28-month capture–mark–recapture study that included 3 winters, we compared rates of body growth and survival for a population of hispid cotton rats (Sigmodon hispidus) in eastern Virginia with another marginal population in eastern Kansas, and where possible, with southern populations in coastal Texas and central Florida. Patterns of seasonal growth were similar in Virginia and Kansas, being low, often near 0, in winter but moderate in other seasons, unlike the uniform seasonal growth rates in Texas. Survival rates were similar between the sexes in both Virginia and Kansas but the overall monthly survival rate ...


Induction Of Winter Breeding In Small Mammals By 6-Mboa, Robert K. Rose, Roger K. Everton, Gregory E. Glass Oct 2008

Induction Of Winter Breeding In Small Mammals By 6-Mboa, Robert K. Rose, Roger K. Everton, Gregory E. Glass

Virginia Journal of Science

A plant-derived cyclic carbamate, 6-methoxybenzoxazolinone (6-MBOA), is

known to initiate reproductive activity in Microtus montanus. We studied

overwintering populations of four other rodent species, and observed increased

reproduction in experimental populations of two herbivorous species, Microtus

pennsylvanicus and Sigmodon hispidus, but not in two omnivorous species,

Oryzomys palustris and Mus musculus. These results suggest that low

concentrations of 6-MBOA may trigger seasonal breeding primarily in

herbivorous small mammals.


Advancing Epidemiological Science Through Computational Modeling: A Review With Novel Examples, Scott M. Duke-Sylvester, Eli N. Perencevich, Jon P. Furuno, Leslie A. Real, Holly Gaff Jan 2008

Advancing Epidemiological Science Through Computational Modeling: A Review With Novel Examples, Scott M. Duke-Sylvester, Eli N. Perencevich, Jon P. Furuno, Leslie A. Real, Holly Gaff

Biological Sciences Faculty Publications

Computational models have been successfully applied to a wide variety of research areas including infectious disease epidemiology. Especially for questions that are difficult to examine in other ways, computational models have been used to extend the range of epidemiological issues that can be addressed, advance theoretical understanding of disease processes and help identify specific intervention strategies. We explore each of these contributions to epidemiology research through discussion and examples. We also describe in detail models for raccoon rabies and methicillin-resis-tant Staphylococcus aureus, drawn from our own research, to further illustrate the role of computation in epidemiological modeling.


Oviposition Behavior Partitions Aquatic Landscapes Along Predation And Nutrient Gradients, C. A. Binckley, W. J. Resetarits Jr. Jan 2008

Oviposition Behavior Partitions Aquatic Landscapes Along Predation And Nutrient Gradients, C. A. Binckley, W. J. Resetarits Jr.

Biological Sciences Faculty Publications

That individuals attempt to minimize the ratio of mortality risk/growth rate (μ/g) when foraging within individual habitat patches is well established. Do species partition among spatially discrete communities embedded in complex landscapes in a similar manner? We investigated how 3 ovipositing species (2 Hyla treefrogs and a hydrophilid beetle, Tropisternus lateralis) responded to simultaneous gradients of nutrients and predation risk. Species partitioned our experimental metacommunity primarily by reducing oviposition with fish. Tropisternus positively responded to increased nutrients, but the effect decreased with increasing risk, as predicted by μ/g theory. Use of fish habitats by Tropisternus was unrelated ...


Swimming Dynamics And Propulsive Efficiency Of Squids Throughout Ontogeny, Ian K. Bartol, Paul S. Krueger, Joseph T. Thompson, William J. Stewart Jan 2008

Swimming Dynamics And Propulsive Efficiency Of Squids Throughout Ontogeny, Ian K. Bartol, Paul S. Krueger, Joseph T. Thompson, William J. Stewart

Biological Sciences Faculty Publications

Synopsis Squids encounter vastly different flow regimes throughout ontogeny as they undergo critical morphological changes to their two locomotive systems: the fins and jet. Squid hatchlings (paralarvae) operate at low and intermediate Reynolds numbers (Re) and typically have rounded bodies, small fins, and relatively large funnel apertures whereas juveniles and adults operate at higher Re and generally have more streamlined bodies, larger fins, and relatively small funnel apertures. These morphological changes and varying flow conditions affect swimming performance in squids. To determine how swimming dynamics and propulsive efficiency change throughout ontogeny, digital particle image velocimetry (DPIV) and kinematic data were ...


Low-Density Rodent Communities In Eastern Virginia, Robert K. Rose, Jean F. Stankavich Jan 2008

Low-Density Rodent Communities In Eastern Virginia, Robert K. Rose, Jean F. Stankavich

Virginia Journal of Science

Two communities of small mammals were live trapped every other week for 15 months in linear oilfield habitat bordered by forested swampland in eastern Virginia. All nine species of the rodent community were present, mostly in low numbers and often intermittently. All species were characterized by high transiency, with a minority of marked animals becoming resident. Despite high trappability, all but two species in these communities had extremely low densities, suggesting that most species could not sustain populations via in situ reproduction.


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 Jan 2007

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 Jul 2006

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 ...


The Adaptive Value Of Aggregation Among Juvenile Caribbean Spiny Lobster: An Evaluation Using Individual-Based Modeling, Thomas W. Dolan Iii, Mark J. Butler Iv Jan 2006

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 juvenile lobsters ...


An Examination Of Seasonal Growth And Survivorship Of Sigmodon Hispidus In Southeastern Virginia, Heather Alyssa Green Jan 2006

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 other ...


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 Jan 2005

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 species and ...