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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

THE ADAPTATION OF NEW WORLD MONKEYS TO NEW ENVIRONMENTAL SITUATIONS: FOOD ACQUISITION AND FOOD PROCESSING BEHAVIORS.

LANDAU, VIRGINIA ILENE. January 1987 (has links)
Food cleaning behavior has been observed among laboratory squirrel monkeys. A Wilcoxon signed-ranks test showed that significantly more cleaning behavior occurred when hard monkey chow pellets and soft fruit were coated with edible debris. Monkeys removed fewer pieces of fruit from a food crock containing fruit coated with edible debris in a timed test. A principal component analysis of the food cleaning behaviors showed two underlying correlated factors. The first factor was the use of the body to clean food. The second factor was the use of the environment to clean food. Two groups of squirrel monkeys, one without previous learners and one with previous learners, were subjects in a fishing study. The presence of previous learners in the social group was not significant for monkeys fishing in water filled crocks. But there was a significant difference in the number of fishing attempts made by the No Previous Learners Group when fishing in wading pools. The Previous Learners group did not make significantly more fishing attempts fishing in wading pools than in crocks. A significant difference was observed in fishing attempts during Phase 1 and Phase 2 of the wading pool experiment for both groups. All monkeys in the group fishing experiments ate fish when it could be obtained. Monkeys who did not learn to fish successfully learned alternative behaviors to obtain fish. The Previous Learners group in the wading pool experiment were subjects in a more difficult fishing test. Significantly fewer fishing attempts were made but the number of monkeys that caught fish was larger. Caged squirrel monkeys scored a lower percentage of fishing attempts than squirrel monkeys living in a social group. While Cebus monkeys caught fish, unlike squirrel monkeys, they did not attempt to eat them.
52

Visual adaptations in sharks, skates and rays

Unknown Date (has links)
The central importance of vision to an organism is evident in the anatomical and physiological adaptations within the eye that can be correlated to the organism's behavior and ecology. The goal of this study was to perform a functional analysis of adaptations within the elasmobranch visual system. An integrative approach was used to examine morphological and physiological adaptations in several species and link these adaptations to phylogeny, locomotion, habitat, behavior and ecology. Functional aspects investigated were eye position, pupil shape, spectral sensitivity, temporal resolution, the extent of the visual field and ultimately the integration of the visual and electrosensory systems. The elasmobranch eye adapts to the light environment of its habitat. Sharks from similar habitats had similar spectral sensitivities such as the bonnethead and blacknose sharks, both maximally sensitive to blue light of 480 nm. The spectral sensitivity of the scalloped hammerhead, which lives in a different environment, was maximally sensitive to green light (530 nm). The temporal characteristics of the eye also matched habitat and lifestyle. Species experiencing variable light conditions exhibited increased critical flicker-fusion frequencies, such as the bonnethead (31 Hz) and scalloped hammerhead (27 Hz), in contrast to deeper or more nocturnal species such as the blacknose shark (18 Hz). Elasmobranch visual fields correlated to each species' lifestyle, habitat and foraging strategy. Expansive monocular views, including a 360° panoramic view in the yellow stingray, were measured in species that rely on vision for vigilance against predators. / The Atlantic stingray possessed large binocular overlaps (72°), which provided depth perception useful for tracking prey. By comparison, the frontal binocular overlaps of hammerhead species were larger than sharks with a more conventional head shape.This study quantified the range of the electrosensory system and the exte the visual field of several shark species, confirming both systems overlap around the head facilitating near seamless visual and electrosensory sensory function relevant to prey detection. The findings of this study indicate that ambient environmental light strongly influenced the function of the elasmobranch eye and that the extent of species' visual fields correlated with aspects of their morphology, locomotion and ecology. / by Dawn Michelle McComb. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
53

Effects of stressors on differential gene expression and secondary metabolites by Axinella corrugata

Unknown Date (has links)
Sponges are an important source of bioactive marine natural products, or secondary metabolites. The common Caribbean reef sponge, Axinella corrugata, produces an antitumor and antibacterial chemical, stevensine. This study determined whether environmental stressors, such as elevated temperature and exposure to Amphibalanus amphitrite larvae, affect the production of stevensine by A.corrugata and if the stressors caused A.corrugata to exhibit differential gene expression. Temperature stress resulted in no significant change in the production of stevensine; only two genes were significantly differentially expressed, including hsp70. Larval stressed resulted in increased production of stevensine and significant differential gene expression (more than seventy genes). This study suggests that A.corrugata may be resilient to elevations in temperature and that one of stevensine's roles in nature is as an antifoulant. / by Jennifer Grima. / Thesis (M.S.)--Florida Atlantic University, 2013 / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
54

Cognitive and magnetosensory ecology of the yellow stingray, Urobatis jamaicensis

Unknown Date (has links)
Elasmobranchs (sharks, skates, and rays) migrate across a wide range of spatiotemporal scales, display philopatry, seasonal residency, and maintain home ranges. Many animals use the Earth’s magnetic field to orient and navigate between habitats. The geomagnetic field provides a variety of sensory cues to magnetically sensitive species, which could potentially use the polarity, or intensity and inclination angle of the field, to derive a sense of direction, or location, during migration. Magnetoreception has never been unequivocally demonstrated in any elasmobranch species and the cognitive abilities of these fishes are poorly studied. This project used behavioral conditioning assays that paired magnetic and reinforcement stimuli in order to elicit behavioral responses. The specific goals were to determine if the yellow stingray, Urobatis jamaicensis, could detect magnetic fields, to quantify the nature of the magnetic stimuli it could detect, and to quantify the learning and memory capabilities of this species. The results supported the original hypotheses and demonstrated that the yellow stingray could: discriminate between magnetic and non-magnetic objects; detect and discriminate between changes in geomagnetic field strength and inclination angle; and use geomagnetic field polarity to solve a navigational task. The yellow stingray learned behavioral tasks faster and retained the memories of learned associations longer than any batoid (skate or ray) to date. The data also suggest that this species can classify magnetic field stimuli into categories and learn similar behavioral tasks with increased efficiency, which indicate behavioral flexibility. These data support the idea that cartilaginous fishes use the geomagnetic field as an environmental cue to derive a sense of location and direction during migrations. Future studies should investigate the mechanism, physiological threshold, and sensitivity range of the elasmobranch magnetic sense in order to understand the effects of anthropogenic activities and environmental change on the migratory ability of these fishes. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
55

Diet of the Purple Swamphen in south Florida and invasion pathways of nonnative avian species in Florida

Unknown Date (has links)
The spread of nonnative invasive species has become the second greatest threat to global biodiversity, making management of invasive species a critical component of the conservation of biodiversity worldwide. Managers and conservation biologists often lack basic life history data, as well as quantitative and theoretical models to predict risk of invasion or other negative effects. I contribute information to both categories by providing life history information (diet and morphology) of the Purple Swamphen (Porphyrio porphyrio) and by characterizing the invasion pathways that nonnative avian species in Florida follow. I found Purple Swamphens are predominantly eating and selecting for Eleocharis cellulosa. Additionally, there is a large amount of variation in nonnative avian species’ propensity to colonize natural habitat and the time it takes to do so. Nine out of 15 species investigated colonized natural habitat and the time it took them to do so ranged from 8 to 41 years. It is through a combination of various techniques that ecologists will begin to fully understand the importance of studying nonnative species as well as reducing the impact that nonnatives have on native ecosystems. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection
56

Anatomy and physiology of the elasmobranch olfactory system

Unknown Date (has links)
The olfactory system is the most highly developed system for molecular sensing in vertebrates. Despite their reputation for being particularly olfactory driven, little is known about how this sense functions in elasmobranch fishes. The goal of this dissertation was to examine the morphology and physiology of elasmobranchs to compare their olfactory system with teleost fishes and more derived vertebrates. To test the hypotheses that elasmobranchs possess greater olfactory sensitivities than teleosts and that lamellar surface area is correlated to sensitivity, I compared the surface area of the olfactory lamellae and the olfactory sensitivities of five phylogenetically diverse elasmobranch species. The olfactory thresholds reported here (10-9 to 10-6 M) were comparable to those previously reported for teleosts and did not correlate with lamellar surface area. Since aquatic species are subject to similar environmental amino acid levels, they appear to have converged upon similar amino acid sensitivities. To test the hypothesis that elasmobranchs are able to detect bile salt odorants despite lacking ciliated olfactory receptor neurons (ORNs), the type of ORN that mediates bile salt detection in the teleosts, I quantified the olfactory specificity and sensitivity of two elasmobranch species to four, teleost-produced C24 bile salts. Both species responded to all four bile salts, but demonstrated smaller relative responses and less sensitivity compared to teleosts and agnathans. This may indicate that elasmobranchs don't rely on bile salts to detect teleost prey. Also, the olfactory system of elasmobranchs contains molecular olfactory receptors for bile salts independent of those that detect amino acids, similar to teleosts. / In some elasmobranch species, each olfactory bulb (OB) is physically partitioned into two hemi-bulbs; however, the functional significance of this morphology is not fully understood. The organization of the OBs in three species with varying OB morphologies was examined to test the hypothesis that the elasmobranch OB is somatotopically arranged. Glomeruli in the OB received projections from ORNs in 3-4 olfactory lamellae situated immediately anterior. These results indicate a somatotopic arrangement of the elasmobranch OB, which may be unique among vertebrate olfactory systems and potentially led to the hemi-OB morphology. / by Tricia L. Meredith. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
57

Pelvic fin locomotion in batoids

Unknown Date (has links)
Although most batoids (skates and rays) are benthic, only the skates (Rajidae) have been described as performing benthic locomotion, termed 'punting'. While keeping the rest of the body motionless, the skate's specialized pelvic fins are planted into the substrate and then retracted caudally, which thrusts the body forward. This may be advantageous for locating and feeding on prey, avoiding predators, and reducing energetic costs. By integrating kinematic, musculoskeletal, material properties, and compositional analyses across a range of morphologically and phylogenetically diverse batoids, this dissertation (i) demonstrates that punting is not confined to the skates, and (ii) provides reliable anatomical and mechanical predictors of punting ability. Batoids in this study performed true punting (employing only pelvic fins), or augmented punting (employing pectoral and pelvic fins). Despite the additional thrust from the pectoral fins, augmented punters failed to exceed the punting c apabilities of the true punters. True punters' pelvic fins had greater surface area and more specialized and robust musculature compared to the augmented punters' fins. The flexural stiffness of the main skeletal element used in punting, the propterygium, correlated with punting ability (3.37 x 10-5 - 1.80 x 10-4 Nm2). Variation was due to differences in mineral content (24.4-48-9% dry mass), and thus, material stiffness (140-2533 MPa), and second moment of area. The propterygium's radius-to-thickness ratio (mean = 5.52 +-0.441 SE) indicated that the propterygium would support true and augmented punters, but not non-punters, in an aquatic environment. All propterygia would fail on land. Geometric and linear morphometric analyses of 61 batoid pelvic girdles demonstrated that pelvic girdle shape can predict punting and swimming ability and taxonomic attribution to Order. / Characteristics of true punters' pelvic girdles, such as laterally facing fin articulations, large surface area formuscle attachment, and tall lateral pelvic processes are similar to characteristics of early sprawled-gait tetrapods' pelvic girdles. This dissertation demonstrates that punting is common in batoids, illustrates the convergent evolution of true punter and early tetrapod pelvic anatomy, and gives possible explanations for the restriction of elasmobranchs to aquatic habitats. / by Laura Jane Macesic. / Thesis ({Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
58

Characterisation of selected soil properties using remote sensing techniques

Fisha, Phuti Cedric January 2019 (has links)
Thesis (M. Sc. (Soil Science)) --University of Limpopo, 2019 / Many conventional laboratory methods are used to characterise spatial and temporal variation of soil properties in order to understand soil quality for different purposes. Currently there is a high demand for accurate soil information by land users. Therefore there is a need to develop a rapid, inexpensive, non-destructive and accurate technique that could compensate or replace conventional laboratory methodologies. Remote sensing has the potential to serve as an alternative approach to characterise soil properties due to its advantages over conventional laboratory methods such as it is rapid, non-destructive and it has low cost. The objectives of this study were to: (i) evaluate the ability of proximal soil sensing to characterise soil properties namely organic matter, soil moisture content, macronutrients, soil texture, cation exchange capacity (CEC), and pH. (ii) Identify bands of relevance from proximal soil sensing (300-2400 nm) that can provide acceptable reflectance variation for different levels of selected soil properties. (iii) Evaluate the performance of models developed from multispectral space-borne image in characterising selected soil properties. In this study spectroradiometer (proximal sensor) and worldview 2 satellite images (space-borne) were the two remote sensing techniques used to collect information about soil at Syferkuil experimental farm of the University of Limpopo. Visible and near infrared spectral data of 98 soil samples were collected at the study site using Analytical spectral device (ASD) field spectroradiometer. Spectral reflectance from spectroradiometer and those extracted from worldview 2 satellite image were used to develop prediction models of selected soil properties using Partial least square regression (PLSR). Bands of relevance were also identified from PLSR models developed from spectral data acquired by spectroradiometer. The results showed that estimation accuracy of PLSR models developed using spectral data from proximal soil sensing were excellent (Category A) for clay, sand, soil organic matter (SOM), and soil moisture content, while good prediction accuracy (Category B) was observed for other soil properties such as silt, ammonium, nitrate, active acidity (pHw), calcium, magnesium, phosphorus, potassium, sulphur, CEC, and reserve acidity (pHKCl). Then, relevant bands which contributed greatly in the prediction of these soil attributes were selected from the electromagnetic spectrum, the range was from 451 nm to 2400 nm. These bands fall within visible, shortwave infrared and near-infrared x regions of electromagnetic spectrum. In addition all selected soil properties were approximately quantitatively estimated using spectral data from satellite image. Based on the results obtained it can be concluded that proximal soil sensing has the ability to predict selected soil properties with various accuracies and it can be used as an alternative technique to characterise soil properties of South African soils. Soil predicting models developed from proximal soil sensing data also showed that there are bands of relevance within spectral range of 451 nm to 2400 nm. However more work is required for space-borne sensing before it can be used as one of the soil characterisation methods since its prediction accuracy was low as compared to that of hyperspectral proximal soil sensing. Keywords: Space-borne sensing; proximal soil sensing; soil characterisation.
59

Studies in the adaptation and evolution of the Australasian fauna : a collection / by P.R. Baverstock

Baverstock, P. R. (Peter Raymond), 1948- January 1987 (has links)
Collection of previously published articles / Includes Allozyme electrophoresis / B.J. Richardson, P.R. Baverstock and M. Adams (1986) / Includes bibliographies / 2 v. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D. Sc.)--University of Adelaide, 1988
60

Molecular and phenotypic adaptation of HSP70 and thermotolerance in drosophila /

Bettencourt, Brian Richard. January 2001 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Organismal Biology and Anatomy, June 2001. / Includes bibliographical references. Also available on the Internet.

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