• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 294
  • 80
  • 17
  • 17
  • 17
  • 17
  • 17
  • 16
  • 14
  • 1
  • 1
  • Tagged with
  • 472
  • 472
  • 120
  • 117
  • 117
  • 109
  • 49
  • 35
  • 35
  • 33
  • 29
  • 28
  • 26
  • 25
  • 25
  • 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.
141

The anterior-most vertebrae and occiput of Eusthenopteron : implications in the origin of the tetrapod atlas-axis complex

Hitchcock, Edward C. (Edward Curtice) January 1992 (has links)
The anterior-most elements of the vertebral column of Eusthenopteron foordi are examined by direct observation of articulated material. Large blade-like supraneural spines are present above neural arches 1, 3, and 5, but not 2 or 4. The supraneural spines support a muscular complex involved in feeding, not only through raising the snout, but also in depressing the lower jaws by the forward swing of the quadrate. The similarity in skulls of osteolepiforms, and between osteolepiforms and Paleozoic tetrapods implies that a cranio-vertebral joint of similar function existed in the ancestor of tetrapods, forming the precursor of the tetrapod atlas-axis complex. / The distinct nature of the basioccipital and exocippitals of tetrapods is the result of reduced ossification of the occiput, and no the incorporation of vertebral elements onto the back of the braincase relative to the rhipidistian condition. The similarity between the occiput and succeeding vertebrae of some primitive tetrapods is due to analogous ossification of notochordal tissue. Bony occipital condyles arose separately in many lineages of Paleozoic tetrapods. The atlas-axis complex of tetrapods is constrained by the pattern of occipital articulation. It is an excellent character for diagnosis of particular groups, but a poor character for determining relationships between separate lineages.
142

Indirect genetic effects of social environment influence the expression of antipredator behavior in guppies, Poecilia reticulata

Bleakley, Bronwyn H. January 2007 (has links)
Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5787. Adviser: Edmund D. Brodie, III. Title from dissertation home page (viewed May 9, 2008).
143

Abundance trends and environmental habitat usage patterns of bottlenose dolphins (Tursiops truncatus) in lower Barataria and Caminada bays, Louisiana

Miller, Cara. Unknown Date (has links)
Thesis (Ph.D.)--Louisiana State University and Agricultural & Mechanical College, 2003. / (UnM)AAI3182902. Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3592. Director: Donald M. Baltz.
144

Blue and fin whale acoustics and ecology off Antarctic Peninsula

Sirovic, Ana. Unknown Date (has links)
Thesis (Ph.D.)--University of California, San Diego, 2006. / (UnM)AAI3214542. Adviser: John A. Hildebrand. Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 1862.
145

A preliminary study of predation in continuous culture

Liu, Shu-Len Huang, January 1970 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
146

Molecular evolution of visual pigments of the Tokay gecko and bluefin killifish

Blow, Nathan S. Belote, John. January 2004 (has links)
Thesis (Ph. D.)--Syracuse University, 2004. / "Publication number AAT 3132680."
147

An investigation of the effects of sexual reproduction on the genetic architecture of the cyclical parthenogen, Daphnia pulicaria

Allen, Desiree Elizabeth, January 2006 (has links)
Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006. / "Title from dissertation home page (viewed July 17, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: B, page: 5603. Adviser: Michael Lynch.
148

Evolutionary, demographic, physiological and behavioral contributors to mortality plateaus /

Reynolds, Rose M. January 2007 (has links)
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0875. Adviser: Kimberly A. Hughes. Includes bibliographical references (leaves 115-125) Available on microfilm from Pro Quest Information and Learning.
149

Dietary Constraints and Strategies in the Red-Bellied Lemur (Eulemur Rubriventer), and Their Implications for Conservation

Du Bour, Amanda Marie 20 June 2018 (has links)
<p> Understanding the diet of the vulnerable red-bellied lemur (<i> Eulemur rubriventer</i>) is essential for preventing its extinction. Previous <i>E. rubriventer</i> research focused on populations in Ranomafana National Park, located in the southeast part of the island, making research in other forest locations a priority for the understanding of dietary breadth and constraints in this species. My research questions consider whether protein is the nutritional driver for foraging choices in <i>E. rubriventer, </i> how fiber influences cathemeral activity, and seasonal variability in day and night time dietary items. My research team and I identified the plant and animal species that composed a single female&rsquo;s diet in the Ankadivory region, near Tsinjoarivo. A team of three to four people conducted daytime follows for 30 days during the lean season. For six of these days, three teams worked in shifts to cover the 24-hour cycle. Additionally, there were six 24-hour abundant season data collection days following the same procedure. Dietary food items were sampled for laboratory analysis. Analysis of plant samples for macronutrient content was used to quantify intake of available protein, non-protein energy (carbohydrates and fat), and fiber. The first hypothesis I tested, protein is the limiting macronutrient in <i> E. rubriventer</i> diets and it drives foraging choices, was not supported. The study subject was able to meet her daily requirements of protein in the lean season, and fat was the most constrained macronutrient between seasons. The second hypothesis I examined, fiber intake is a good predictor of cathemerality of <i>E. rubriventer,</i> was also not supported. Fiber was consumed all year at relatively constant amounts (NDF CV: lean season = 12.7 %, abundant season 9.2 %) and fiber consumption did not correlate with increased nighttime feeding. The third hypothesis I tested, nighttime diet composition differs from daytime diet composition, was supported. The <i>E. rubriventer</i> consumed dietary items higher in fiber during nocturnal feeding bouts (leaves in the lean season and flowers in the abundant season). This project provides information crucial for a more comprehensive understanding of food selection by <i>E. rubriventer.</i> The 24-hour diet information revealed that, for cathemeral animals such as <i>E. rubriventer,</i> only looking at daytime diet consumption can lead to an inaccurate diet profile. </p><p>
150

The Effects of Reduced pH on Decorator Crab Morphology, Physiology and Behavior

Rankin, Ashley 13 March 2018 (has links)
<p> Crabs in the family Majoidae camouflage by decorating their exoskeletons with organisms and debris from their environment. This form of camouflage, involving both the act of decorating and carrying of these decorations, is thought to be energetically costly, and may present a trade-off under stressful environmental conditions. The energetic cost of decoration behavior has been evinced by reduced organic content due to elevated metabolism. In the context of previous research demonstrating that many marine calcifiers experience metabolic costs under experimental ocean acidification conditions, we hypothesized that decorator crabs exposed to reduced pH will have insufficient energy to support regulatory processes along with decoration behavior. Thus, we predicted that energy will be allocated towards growth and calcification at the expense of decoration behavior. Dwarf teardrop crabs, <i>Pelia tumida</i>, were exposed to ambient (pH = 8.0, pCO<sub>2</sub> = 613 &micro;atm) and reduced (pH = 7.75, pCO<sub>2</sub> = 894 &micro;atm) pH conditions for five weeks. Half of the animals in each treatment were given two sponge species, <i> Halichondria panacea</i> and <i>Haliclona permollis</i>, to decorate with, whereas the remaining animals were not allowed to decorate. At the end of the experiment, all animals were analyzed for exoskeleton mineral content (Ca and Mg) using EDX and ICP-MS, organic content (a proxy for metabolism) using TGA, and decoration behavior by quantifying sponge mass and percent cover. Overall, decorator crabs showed no signs of energy limitation under reduced pH conditions. Neither growth, exoskeleton mineral content, nor organic content of crabs differed among pH or decoration treatments. In addition, both sponge mass and percent cover remained the same across pH treatments, indicating no effect of reduced pH on decoration behavior, and thus the ability to camouflage. The maintenance of physiological processes without metabolic costs in <i>P. tumida</i> exposed to reduced pH radiates from the emerging trends on the susceptibility of crustaceans to changes in ocean chemistry associated with ocean acidification.</p><p>

Page generated in 0.1412 seconds