Tesi: "Alligator mississippiensis"

1

Rauschenberger, Richard Heath. "Developmental mortality in american alligators (alligator mississippiensis) exposed to organochlorine pesticides". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008223.

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Thesis (Ph.D.)--University of Florida, 2004.
Typescript. Title from title page of source document. Document formatted into pages; contains 233 pages. Includes Vita. Includes bibliographical references.

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2

Crawford, Jared Louis. "Seasonal variation in thyroxine in the American alligator (Alligator mississippiensis)". Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/303.

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Male and female alligators ranging from 58 cm to 361 cm in length (N=1054) were captured and their blood was sampled between 9 A.M. and midnight from June 2000 - June 2002 at the Rockefeller Wildlife Refuge in Grand Chenier, LA. Animals were captured in a variety of habitats including marsh, open water, canals, and ponds. Total thyroid hormones were measured by radioimmunoassay. Four criteria were used to evaluate changes in hormone levels: sex, total length, season, and time of day. Thyroxine (T4) varied over a wide range from 0.5 to 57 ng/mL. Triiodothyronine (T3) levels were below the sensitivity of the assay (<0.6ng/mL). A distinct seasonal peak in T4 was observed between December and April, peaking in March with highest mean T4 levels observed in the spring. Mean T4 declined significantly from the spring to an intermediate summer mean and declined significantly again in the winter. No T4 differences between the sexes were observed. Mean T4 was highest in juveniles, significantly lower in subadults, and significantly lower still in adults. Highest levels were found between 5 P. M. and midnight. With values up to 57 ng/ml in the spring, alligators exhibit T4 levels among the highest recorded for reptiles.

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3

Zweig, Christa L. "Body condition index analysis for the American alligator (Alligator mississippiensis)". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000836.

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4

Rice, Amanda Nicole. "Diet and condition of American alligators (Alligator mississippiensis) in three central Florida lakes". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004367.

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5

Membreno, Nelson Armando. "Effects of eggshell removal on embryonic skeletal development in the American alligator (Alligator mississippiensis)". CSUSB ScholarWorks, 2017. https://scholarworks.lib.csusb.edu/etd/529.

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The eggshell of reptiles is essential for not only protecting the embryo, but can also serve as source of calcium for embryonic skeletal development. Whereas embryonic lepidosaurs and chelonians rely on their yolk sac for calcium during development, embryonic archosaurs mobilise eggshell calcium supply to both the embryo and the yolk sac. By the time archosaurs hatch, their residual yolk sacs have a calcium content equal or greater than at time of oviposition, which is used to support post-hatching growth. To date, no study has looked into how removal of the calcareous eggshell affects embryonic development in archosaurs. I tested how the removal of the calcareous eggshell affects embryonic and hatchling growth and biomechanic function of the skeleton in embryos and hatchlings of the American alligator (Alligator mississippiensis). Experimental eggs had their eggshell manually peeled, while control eggs were sham handled but otherwise not altered. Sampling of eggs occurred on a weekly basis until the end of incubation. Embryos, yolk sacs, and eggshells were removed and analyzed for morphological, histological and biomechanical parameters. Results show that at the time of eggshell peeling yolk sac calcium reserves were sufficient for experimental embryos to develop, but animals hatched in diminutive state. Serial clearing and staining of embryos revealed that onset of bone mineralization was similar for both treatment groups. Growth trajectory of experimental hatchlings parallelled that of control animals, without compensatory growth. Experimental hatchlings were observed to have flexible lower jaws and produced a weaker bite force than control hatchlings. Cross-sections of the mandible and femoral mid-diaphysis had a significantly reduced cross-sectional area in experimental hatchlings. I conclude that loss of the calcareous eggshell during incubation leads to severe constraint on growth and biomechanics of the alligator skeleton.

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Bryan, Teresa A. "Morphological and constituent analyses of American alligator (Alligator mississippiensis) eggshells from contaminated and reference lakes". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010640.

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7

Strickland, Bradley Austin. "Spatial ecology and population estimation of the American alligator (Alligator mississippiensis) in inland systems of Mississippi". Thesis, Mississippi State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1596102.

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Wildlife management and conservation frequently rely on understanding mechanisms that influence distribution and abundance of animals. I quantified space use for a population of inland riverine adult male alligators in Mississippi. Results indicated habitat selection is a scale-dependent process and aquatic vegetation, water depth, and water temperature may be important factors influencing alligator foraging and thermoregulation. Apparent habitat suitability and low alligator density did not manifest in an observed body size-based dominance hierarchy. I also analyzed long-term Mississippi alligator spotlight survey data for trends and effects of environmental covariates on counts. Model results indicated alligator counts have increased over time. This response likely reflects benefits accrued from decades of protection and wetland conservation. Distance sampling does not appear to be a feasible monitoring technique for riverine alligator populations. Nevertheless, it is important that survey protocols and monitoring programs account for imperfect detection and model important covariates.

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8

Brandt, Laura A. "The status and ecology of the American alligator (Alligator mississippiensis) in Par Pond, Savannah River site". FIU Digital Commons, 1989. http://digitalcommons.fiu.edu/etd/1788.

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Par Pond is a man-made 1120 ha cooling reservoir located on the Savannah River Site near Aiken, South Carolina. From 1972-1978 a detailed study on the status of the alligator in Par Pond was conducted by Tom Murphy (unpub. MS thesis Univ. of GA, 1977). Murphy estimated that approximately 110 alligators inhabited Par Pond with an adult (> 1.8 m) to juvenile (< 1.8 m) ratio of (1.8:1), an overall sex ratio of 3.2:1, and an average of only 2.3 nests/yr. The purpose of this study (1986-1989) was to determine the current population size and structure, determine how the population has changed in the last 15 years and to examine growth and survival of juvenile alligators. Data were collected by monthly night-time eyeshine counts aerial surveys, capturing animals, and locating and following the fate of nests. There was a strong positive correlation between water temperature and the number of alligators observed during eyeshine counts. Both eyeshine counts and aerial surveys were highest in spring and varied seasonally. A total of 184 different non-hatchling and 157 hatchling alligators were captured between May 1986 and November 1988. Population estimates and size distributions based on capture data indicate that over the last 15 years the population has increased from approximately 110 to 200 alligators, and the size distribution has shifted from one dominated by large adults to one that has a higher proportion of juveniles. The current sex ratio (2.6:1) is not significantly different from that reported by Murphy (1977, 3.2:1). However, the average number of nests/yr has increased from 2.3 to 4.0. Data on juvenile growth and survival show that the growth rate of hatchlings (32.9 cm/yr total length) is greater than that of animals age 1-3 (21.6 cm/yr total length) and survival of all ages is variable between years and between clutches. Results from this study indicate that from 1972-988 the population has increased ac an average exponential rate of 6 % per year. If conditions in Par Pond do not change, the population size should continue to increase.

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9

Temsiripong, Yosapong. "Growth and survival rates of wild and repatriated hatchling American alligators (Alligator mississippiensis) in central Florida lakes". [Florida] : State University System of Florida, 1999. http://etd.fcla.edu/etd/uf/1999/amp7407/temsiripong.pdf.

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Thesis (M.S.)--University of Florida, 1999.
Title from first page of PDF file. Document formatted into pages; contains xi, 55 p.; also contains graphics (some colored). Vita. Includes bibliographical references (p. 49-54).

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10

Rosenblatt, Adam. "Factors Influencing Movements and Foraging Ecology of American Alligators (Alligator mississippiensis) in a Dynamic Subtropical Coastal Ecosystem". FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/900.

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Top predators can have large effects on community and population dynamics but we still know relatively little about their roles in ecosystems and which biotic and abiotic factors potentially affect their behavioral patterns. Understanding the roles played by top predators is a pressing issue because many top predator populations around the world are declining rapidly yet we do not fully understand what the consequences of their potential extirpation could be for ecosystem structure and function. In addition, individual behavioral specialization is commonplace across many taxa, but studies of its prevalence, causes, and consequences in top predator populations are lacking. In this dissertation I investigated the movement, feeding patterns, and drivers and implications of individual specialization in an American alligator (Alligator mississippiensis) population inhabiting a dynamic subtropical estuary. I found that alligator movement and feeding behaviors in this population were largely regulated by a combination of biotic and abiotic factors that varied seasonally. I also found that the population consisted of individuals that displayed an extremely wide range of movement and feeding behaviors, indicating that individual specialization is potentially an important determinant of the varied roles of alligators in ecosystems. Ultimately, I found that assuming top predator populations consist of individuals that all behave in similar ways in terms of their feeding, movements, and potential roles in ecosystems is likely incorrect. As climate change and ecosystem restoration and conservation activities continue to affect top predator populations worldwide, individuals will likely respond in different and possibly unexpected ways.

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11

Beyeler, Patrick Marcel. "Protein requirements of juvenile Nile crocodiles (Crocodylus niloticus) in an intensive production system". Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/29554.

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The objective of this study was to determine the dietary protein requirements of the Nile crocodile (Crocodylus niloticus) between the ages of 5 – 8 months, and to compare the results with documented protein requirements of the American alligator (Alligator mississippiensis). This was achieved by feeding the crocodiles 4 diets with varying amounts of crude protein (CP), including 62%, 56.6%, 51.6% and 46%. All four diets were iso-energetic with a metabolisable energy to protein ratio of 25.85KJ/g. The highest protein diet contained 44% raw minced chicken and 46.9% fish meal with minimal contribution (of 6.4%) made from vegetable protein sources (full fat soya). The lowest protein diet was made up of a majority of vegetable protein (30% soya bean oilcake, 9.8% full fat soya and 17.2% maize meal) and some contribution from protein of animal origin (4.3% carcass meal and 35% fish meal). This study was carried out for 12 weeks during the crocodiles first year of life. Body mass, total body length, head length and snout to vent length were measured five times at 3 weekly intervals. Twenty representative crocodiles in a pen of 200 were individually tagged for the duration of the trial. As there were 3 replicates for each of the 4 treatment diets, 240 crocodiles in 12 pens were tagged. During the early phase of the study, it was observed that crocodiles on the 46% CP treatment diet were not performing well, and that most of the crocodiles on this diet were losing mass. This treatment diet was discontinued at 9 weeks into the trial for both financial and ethical reasons. The remaining three diets were tested for the full 12 weeks. Chromium oxide was mixed into the diets at two time periods during the trial to determine the protein, energy and dry matter digestibility. It was determined that the 46%, the 51.6%, the 56.6% and the 62% CP diets had a digestible protein (DP) content of 246.44 g/kg, 294.80 g/kg, 381.32 g/kg and 468.65 g/kg and a digestibility coefficient of 53.50%, 57.00%, 69.15% and 75.65% respectively. Performance of crocodiles on the 46% CP treatment diet was found to be lower in all measurement categories than crocodiles on the three higher protein diets. However, crocodiles on the 62% CP treatment diet outperformed all the crocodiles (on all measurement criteria) on the lower protein diets. The poor performance of crocodiles on the lowest protein diet correlates with previous research indicating that crocodilians are unable to perform optimally when the majority of the diet’s protein is made up of vegetable protein sources. It was determined that juvenile American alligators would grow at optimal levels when the diet contained a DP content of 450 g/kg. As the Nile crocodiles in this study performed the best when the diet contained a DP value of 468.65 g/kg, it was concluded that juvenile Nile crocodiles have the same range of protein requirements as that determined for juvenile American alligators.
Dissertation (MSc(Agric))--University of Pretoria, 2011.
Animal and Wildlife Sciences
unrestricted

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12

Harris, William Henry. "Ontogenesis in the Cranium of Alligator mississippiensis Based on Disarticulated Cranial Elements". Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etd/2492.

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The American alligator, Alligator mississippiensis, is a large extant archosaur and member of the Order Crocodilia. Crocodilian ontogeny has been studied in great detail, the skull being of particular interest. One aspect of the skull left unstudied is how individual cranial elements change through ontogeny independent of one another. This study observed morphological change in a growth series of 34 specimens of A. mississippiensis from ETSU Vertebrate Paleontology Lab collections. The premaxilla, maxilla, nasal, jugal, frontal, and parietal were analyzed using landmark morphometrics. The frontal, jugal, and parietal showed more allometric growth with the orbits reducing in size posteriorly. The premaxilla, maxilla, and nasal showed more isometric growth. This suggests the common observation that the snout elongates with age is mistaken. The cranium showed allometric growth in very early in life but more isometric growth after that. Unique to this study, the premaxilla showed almost no shape change throughout ontogeny.

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Monck, Eileen K. "Developing a noninvasive method for assessing reproductive status and characterizing gender-specific plasma proteins in the American alligator (Alligator mississippiensis)". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002851.

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14

Milnes, Matthew R. "Effects of environmental contaminants on development, sexual differentiation, and steroidogenesis in Alligator mississippiensis". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010805.

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15

Parrila, Leah. "Myocardinal contractility and oxygen regulation as a determinant of myocardinal plasticity in the hypoxia and hyperoxia reared American alligator, Alligator mississippiensis". Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527405.

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16

Tate, Kevin B. "The Impact of Developmental Stress on Cardiovascular Physiology of Two Archosaur Species: American Alligator (Alligator mississippiensis) and Domestic Chicken (Gallus gallus)". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699922/.

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Crocodilians and birds comprise sister taxa of archosaurs, the development of these vertebrates occurs within an egg case that leaves developing embryos susceptible to fluctuations in the nesting environment. Studies suggest that sub-optimal conditions alter morphological growth and cardiovascular physiology. Regulation of the cardiovascular system is immature in the subjects studied, and embryos may rely on humoral rather than neural control of the cardiovascular system. The primary focus of this dissertation was to assess regulatory mechanisms responsible for maintenance of arterial pressure and heart rate. Dehydration stress had marked effects on embryo growth, and altered baseline cardiovascular parameters, while leaving the response to humoral regulator, angiotensin II (Ang II), unaffected. However, dehydrated alligator embryos developed cholinergic tone on heart rate. Hypoxic incubated chicken embryos were reduced in embryo mass, and altered response to humoral regulatory components Ang I and adenosine in addition identifying a novel regulatory component of the cardiovascular response to acute hypoxia. Collectively, these studies add to the existing knowledge of cardiovascular physiology in embryonic archosaurs and suggest that some components of cardiovascular regulation are plastic following developmental stress.

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Gunderson, Mark Paul. "Alterations in the hepatic biotransformation of steroids as a potential mechanism for contaminant induced changes in plasma testosterone concentrations in juvenile alligators (Alligator mississippiensis)". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010084.

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Ostlin, Janice Christine. "Cardiac shunting and blood flow distribution in the American alligator (ALLIGATOR MISSISSIPPIENSIS)". Thesis, 1997. http://hdl.handle.net/2429/6562.

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The cardiac and circulatory anatomy of the American alligator (Alligator mississippiensis) is unique in that both the cardiac and systemic circulatory systems display anatomical divisions. This situation may also be of physiological significance to the animal. The purpose of this study was to determine regional blood flow distribution in the alligator, with respect to cardiac blood flow patterns. Animals were instrumented with flow and pressure recorders, and monitored over extended time periods. Fluorescent microspheres capable of being entrapped in tissue capillary beds were introduced into both the right and left aortas under various conditions. Blood flow distribution to tissues during the presence or absence of a pulmonary to systemic (P->S shunt) was of primary interest. Tissue samples depicted a significant separation in the perfusion patterns of the right and left aortas. The right aorta primarily perfused the brain and liver, and to a lesser extent, the digestive system organs. The left aorta perfused the digestive tract organs, including the spleen. Dissection of the circulatory paths of the right and left aortas determined this anatomical division. Possible differences in the left aortic distribution of right ventricular (shunted) blood as compared to left ventricular (not shunted) blood were noted.

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Moore, Liberty Ann. "Distribution of mercury in the American alligator (Alligator mississippiensis), and mercury concentrations in the species across its range". 2004. http://purl.galileo.usg.edu/uga%5Fetd/moore%5Fliberty%5Fa%5F200405%5Fms.

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Thesis (M.S.)--University of Georgia, 2004.
Directed by I. Lehr Brisbin, Jr. and Steven B. Castleberry. Includes articles submitted to Journal of wildlife management, and Archives of environmental contamination and toxicology. Includes bibliographical references.

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(9768401), Nathan J. Poling. "Characterization of a Phylogenetically Convergent Nitrogen-Dependent Antimicrobial Mechanism Against Serratia marcescens Utilizing a D. melanogaster Infection Model". Thesis, 2020.

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Host-pathogen interactions are the result of long term evolutionary processes due to the conflicting goals of the host and the infections pathogens in their quest for survival, creating an interplay of co-evolution as various adaptation are acquired by one and then in turned adapted to by the other. Selection of the host’s antimicrobial strategies and the resultant adaptations of infectious microorganisms leads to the development of complex and dynamic relationships ranging from symbiotic to commensal to pathogenic. In an effort to understand the selective process and identify unique mechanisms of antimicrobial defense, sera from 18 species (7 invertebrate, 11 vertebrate) were tested for antimicrobial potential against 20 Gram-negative and 11 Gram-positive bacteria. Alligator mississippiensis sera exhibited the strongest inhibitory potential. A transposon mutagenesis screen performed on the resistant bacterium Serratia marcescens identified several genes, including glnL, as necessary for defense. The glnL gene encodes for the sensory histidine kinase/phosphatase NtrB, controlling the expression of regulatory genes in response to nitrogen limitation. Attenuated growth of the Tn::glnL mutant in the presence of alligator serum and minimal media was rescued with nitrogen supplementation, suggesting the existence of a mechanism for nitrogen limitation as an antimicrobial strategy in alligator sera. Utilization of a Drosophila melanogaster oral model of infection showed that glnL is required for S. marcescens virulence, and nitrogen supplementation rescued the phenotype, as measured by fly mortality and bacterial cfu recovery. S. marcescens, an environmentally ubiquitous Gram-negative bacterium, is an opportunistic pathogen in several species, including alligators and Drosophila. Subsequent in vitro testing of the antimicrobial potential of invertebrate hemolymph utilizing the Tn::glnL mutant showed a nitrogen-dependent growth inhibition of species in the order Dipteria. Combined, these results support a model of evolutionary convergence of nitrogen limitation as an antimicrobial mechanism. This work not only identifies a novel antimicrobial strategy that could be used in the development of therapeutics, and a novel virulence factor in S. marcescens, but has broad mplications for bacterial management and can provide insight into the evolutionary history of host-pathogen interactions.

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