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Articles 1 - 14 of 14
Full-Text Articles in Animal Sciences
The Role Of Natural And Sexual Selection In The Origin And Maintenance Of Divergence Within And Between The Mexican Sailfin Mollies, Poecilia Velifera And P. Petenensis, Shala Hankison
All Dissertations
Understanding speciation remains a holy grail of evolutionary biology. One useful approach is studying the evolutionary mechanisms important in population divergence to infer the mechanisms important in speciation. This method is especially useful when closely related species can be compared to determine whether intraspecific differences parallel interspecific differences. I studied population divergence in two species of Mexican sailfin mollies, Poecilia velifera and P. petenensis. These closely related species are particularly useful for this type of study, as they live in habitats that may differ in the importance of natural selection. In addition, these species may differ in the importance …
Physical And Behavioral Development Of Nursing Harbor Seal (Phoca Vitulina) Pups In Maine, John P. Skinner
Physical And Behavioral Development Of Nursing Harbor Seal (Phoca Vitulina) Pups In Maine, John P. Skinner
Electronic Theses and Dissertations
Compared to other phocids seals, the maternal investment strategy of the small bodied female harbor seal (Phoca vitulina) is complex. Females are unable to fast for the entire duration of pup rearing and are therefore reliant on resources in the vicinity of the pupping aggregation to continue provisioning their pup by mid-lactation. At the same time, harbor seal pups are highly active during lactation which increases energetic costs to the female but also offers an opportunity for females to influence the behavioral development of her pup. To understand how females maximize their pup's survival it is important to …
Defensin Transcript Distribution In Tissues And Life Stages Of The Ixodid Ticks Amblyomma Americanum And Ixodes Scapularis, Stephanie M. Todd
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/. …
Chemical Evidence For Dietary Toxin Sequestration In The Asian Snake Rhabdophis Tigrinus, Deborah A. Hutchinson
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. …
Habitat Utilization And Salinity Tolerance Of The Sandbar Shark, Carcharhinus Plumbeus, In Virginia, Leonard Pace
Habitat Utilization And Salinity Tolerance Of The Sandbar Shark, Carcharhinus Plumbeus, In Virginia, Leonard Pace
Dissertations, Theses, and Masters Projects
No abstract provided.
Movement Patterns And Habitat Usage Of Shark Bay Dugongs, David K. Holley
Movement Patterns And Habitat Usage Of Shark Bay Dugongs, David K. Holley
Theses: Doctorates and Masters
In order to define small and large scale spatial and temporal individual movement patterns of dugongs (Dugong dugon) within the Shark Bay World Heritage Property (SBWHP) a total of 19 dugongs were fitted with remote location recording and transmitting devices. Combined locations from all units totalled over 10,000 locations. This spatial and temporal data was used to define movement patterns of dugongs within Shark Bay as well as areas of high use deemed to be indicative of foraging activity. Platform Transmitting Terminals (PTT?s) using the ARGOS location collection system tracked animals over large temporal scales with 4 animals tracked up …
Sources Of Mortality, Movements And Behavior Of Sea Turtles In Virginia, Katherine Lamont. Mansfield
Sources Of Mortality, Movements And Behavior Of Sea Turtles In Virginia, Katherine Lamont. Mansfield
Dissertations, Theses, and Masters Projects
Aerial surveys are commonly used to evaluate in-water sea turtle abundances. A correction is applied to account for turtles diving below the observed surface. Historically, observations of summer/fall surfacing behavior were used for this correction, assuming constant behavior among seasons. Using radio/acoustic telemetry, seasonal differences in sea turtle surfacing behavior were determined among Kemp's ridleys and loggerheads. Mean time spent at surface in the spring ranged between 9.9%-30.0% with significant differences among individuals. Observed surfacing times were higher than historic summer/fall observations (Byles 1988; 5.3%), indicating that historic springtime abundances were overestimated by 50%-80%. Aerial surveys (2001-2004) indicated a 65%-75% …
Ecology And Conservation Of Virginia Shark Species: Analysis Of Thirty Years Of Virginia Long-Line Shark Census Data, 1974--2004, Daniel Stuart Ha
Ecology And Conservation Of Virginia Shark Species: Analysis Of Thirty Years Of Virginia Long-Line Shark Census Data, 1974--2004, Daniel Stuart Ha
Dissertations, Theses, and Masters Projects
Sharks of the Atlantic coast of the United States have suffered increased fishing pressure in last three decades. Commercial and recreational catches jumped in the mid to late 1980's, leading to regulation by the National Marine Fisheries Service in the early 1990's. The Virginia Institute of Marine Sciences' shark long-line survey, begun in 1974, and continuing to the present day, is thus well positioned to look at the effects of this fishing mortality on sharks. Using GAM modelling, six of ten shark species analyzed, including the most common species, Carcharhinus plumbeus, suffered declines of from 98-99% of early abundances in …
Migratory And Spawning Behavior Of American Shad In The James River, Virginia, Aaron W. Aunins
Migratory And Spawning Behavior Of American Shad In The James River, Virginia, Aaron W. Aunins
Dissertations, Theses, and Masters Projects
No abstract provided.
The Effects Of Serotonin On The Courtship Behavior Of Drosophilia Melanogaster, Nicholas James Brandmeir
The Effects Of Serotonin On The Courtship Behavior Of Drosophilia Melanogaster, Nicholas James Brandmeir
Electronic Theses and Dissertations
In Drosophila, the male courtship ritual is stereotyped and under the control of several genes including fruitless. In previous studies, it has been show that various fruitless alleles cause phenotypic abnormalities in the D. melanogaster courtship ritual. It is also known that there is a high level of co-expression of both the fruitless gene product and serotonin in specific neurons of the Drosophila CNS. This study examines the role of serotonin in the Drosophila male courtship ritual by using a mutant strain, Ddc^ts1,in which the production of serotonin is blocked above 30°C. In this study an increase in temperature caused …
Phenotypic Divergence Of Indigenous And Translocated Arctic Charr (Salvelinus Alpinus) Populations In Maine, Wendy K. Michaud
Phenotypic Divergence Of Indigenous And Translocated Arctic Charr (Salvelinus Alpinus) Populations In Maine, Wendy K. Michaud
Electronic Theses and Dissertations
Selection on traits related to trophic ecology is recognized as an important contributing factor in adaptive divergence and speciation. For several freshwater fish species, including Arctic charr (Salvelinus alpinus), such selection is commonly reflected in relationships between diet, habitat use and phenotypic divergence. Trophic specializations that emerge have been extensively studied among sympatric forms, but much less is known of the extent of this type of divergence in allopatry. Trait differences among these forms are also thought to reflect thousands of years of evolution, making it difficult to examine root causes of such divergence in natural populations. Here, I address …
Sexual Dimorphic Social Development And Female Intrasexual Chemical Signaling Of African Elephants (Loxodonta Africana), Jordana M. Meyer
Sexual Dimorphic Social Development And Female Intrasexual Chemical Signaling Of African Elephants (Loxodonta Africana), Jordana M. Meyer
Electronic Theses and Dissertations
Author's abstract: African elephants are a polygynous species in which males and females carry out dimorphic lifestyles. Males search and compete for reproductively active females, while females care for offspring and facilitate group cohesion. The objectives of this study was a) to compare the development of sexually dimorphic behaviors and developmental trends between young male and female wild African elephants and b) to determine the ability of captive female African elephants to discern between the follicular and luteal phase of conspecifics through trunk-tip contacts and the investigation of urine, and whether the reproductive phase of the receiver affected the response …
Development Of Generalized Index-Removal Models, With Particular Attention To Catchability Issues, Thomas F. Ihde
Development Of Generalized Index-Removal Models, With Particular Attention To Catchability Issues, Thomas F. Ihde
Dissertations, Theses, and Masters Projects
The index-removal method estimates abundance, exploitation and catchability coefficient, given surveys conducted before and after a known removal. The method assumes a closed population between surveys. Index-removal has seldom been applied due to its strong assumption of constant survey catchabilities. This work generalizes the method to allow multiple years of data to be incorporated, and the assumptions of the original model to be relaxed. If catchability is constant across years, precision can be improved by analyzing multi-year data simultaneously. Two multiple-year models were developed: the first, 1qIR, assumes constant catchability within and among years; the second, 2qIR, allows catchability to …
An Examination Of Seasonal Growth And Survivorship Of Sigmodon Hispidus In Southeastern Virginia, Heather Alyssa Green
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 …