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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.

Linear and nonlinear deterministic character-dependent models with time delay in population dynamics

Castillo-Chávez, Carlos. January 1984 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 115-122).

Role of nitrogen in limiting the abundance of animals / by T.C.R. White

White, T. C. R. (Thomas C. R.), White, T. C. R. (Thomas C. R.). Inadequate environment : nitrogen and the abundance of animals. January 1999 (has links)
Copy of his monograph "The inadequate environment : nitrogen and the abundance of animals" in back pocket. / Includes bibliographic references. / 1 v. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis comprises a review of the impact that the author's published work has had over the last thirty years on the discipline of ecology. (abstract) / Thesis (D.Sc.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 1999

Role of nitrogen in limiting the abundance of animals /

White, T. C. R. White, T. C. R. January 1999 (has links) (PDF)
Thesis (D.Sc.) -- University of Adelaide, Dept. of Applied and Molecular Ecology, 1999. / Copy of his monograph "The inadequate environment : nitrogen and the abundance of animals" in back pocket. Includes bibliographic references.

The design and implementation of a multiple resolution modeling framework with applications to population modeling /

Glass, Kevin Anthony, January 2003 (has links)
Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 205-209). Also available for download via the World Wide Web; free to University of Oregon users.

When can genetic information be used to measure inter-population movement? /

Brennan, Julie M. January 1900 (has links)
Thesis (Ph.D.) - Carleton University, 2007. / Includes bibliographical references (p. 102-109). Also available in electronic format on the Internet.

The effect of static and dynamic spatially structured disturbances on a locally dispersing population model /

Morin, Benjamin R, January 2006 (has links) (PDF)
Thesis (M.A.) in Mathematics--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 58-59).

The Study of Population Biology of Thais spp.

Liu, Yu-Chih 06 September 2002 (has links)
Oyster drills are common on rocky shores and oyster (Crassostrea gigas) farming areas in Taiwan. Most studies on the oyster drill (Thais clavigera) were on its impact on the oyster industry. However, there are at least three Thais species in the west coast of Taiwan. And the basic biology of T. rufotincta and T. keluo was insufficient. Thus, the present study was undertaken to investigate population biology of the three congeneric drills(Thais spp.), including feeding rate, reproductive characters and population dynamics. T. clavigera was distributed from Tamsui to Tongkong along the west coast of Taiwan. But, it was rare at Tongkong. T. keluo was primarily found at Tamsui and Tongkong. The distribution of T. rufotincta was from Tongkong to Tamsui and mostly occurred between Tongkong and Taishi. Mean feeding rates (¡ÓSE) of T. clavigera, T. keluo and T. rufotincta were 0.054(¡Ó0.010), 0.038(¡Ó0.004) and 0.010(¡Ó0.003) oysters/snail¡Eday, respectively. The feeding rate of T. rufotincta was significantly lower than other species (P<0.05). It is suggested that the major damage on oyster culture is caused by T. clavigera and T. keluo. The spawning seasons of T. clavigera, T. keluo and T. rufotincta were from November to May, from February to September, and from April to October, respectively. The number of eggs per capsule was correlated with the length of the capsule (P<0.001) in T. clavigera, T. keluo and T. rufotincta and the number of eggs (¡Ó 95% C.I.) among them was 203(¡Ó14), 168(¡Ó15) and 43(¡Ó3) per capsule, respectively. The mean egg diameter (¡Ó 95% C.I.) of the three drills was 185(¡Ó3), 175(¡Ó4) and 240(¡Ó6) £gm, respectively. Positive curve relationships between size and weight were found among Thais spp. (P<0.001). Using the length-frequency data, analyzed by the ELEFAN (Electronic Length Frequency Analysis) program, the seasonalized von Bertalanffy growth parameters for Thais spp. were estimated. The growth performance index (&#x00F8;') and growth parameter (K) showed a similar trend, i.e. Chiku>Tamsui>Shiangsan for T. clavigera, Tamsui > Tongkong for T. keluo, and Chiku > Tongkong for T. rufotincta. It is suggested that water temperature and food abundance are important factors affecting drills¡¦ growth in the west coast of Taiwan. The recruitment of T. rufotincta at Chiku and Tongkong had two peaks. It was different from T. clavigera and T. keluo with only one peak. Futher studies are necessary to elucidate the relationship between recruitment with different peak periods among sites and environment variables such as primary production, salinity, current and so on.

An application of the Tracking-Trapping technique in estimating population density.

O'Neil, J. Kevin January 1976 (has links)
No description available.

Remotely Administered Immunocontraception as an Effective and Humane Management Tool for Feral Horses (Equus caballus) in Overpopulated Rangelands

Bruegl, Hilary A 01 January 2014 (has links)
Since the advent of world travel and exploration, humans have been introducing animals to new countries and environments to which they were not native. Wild horses in North America are protected by the Wild Free-Roaming Horses & Burros Act, and their growing populations can damage native species and ecosystems. These feral horses organize themselves into harems consisting of several mares, a dominant stallion, and occasionally subordinate stallions. In the breeding season, a peak in stallion libido and mare ovulation elicit distinct reproductive behaviors. Population numbers of feral horses (Equus caballus) need to be humanely controlled without the disruption of these key behaviors. The Adopt-A-Horse program, a current program consisting of roundup and public adoption for a fee, is not effective on its own. The proposed study examines two minimally-invasive immunocontraceptive methods that may be effective in reducing population growth: Gonadotropin releasing hormone (GnRH) agonists, antibodies that prevent mares from entering estrous, and porcine zona pellucida (PZP), an antibody that changes the conformation of ova sperm receptors to prevent fertilization. This potential study proposes that 8 independent populations of feral horses will be tracked for 4 years to assess normal behavior. After 4 years, populations will undergo one of four treatments: control (n=1), roundup and adoption (n=1), mares treated with 2-year remotely administered PZP vaccine (n=3), and mares treated with 2-year remotely administered GnRH agonist (n=3). Urinalysis will be used to test for pregnancy, and behavior of mares will be monitored over the course of 4 years after administration. Combined observations of behavioral effects and growth rates will be used to determine the most efficient and humane method of population control. Both chemical methods of fertility control should greatly reduce the overall number of foals produced. Where PZP will potentially be the better choice for immunocontraception due to its minimal interference with the endocrine system of feral horses, GnRH agonists are likely to affect normal behavior and may not be suitable for implementation in wild rangelands. Efforts to control populations will be most effective when the current Adopt-A-Horse program is combined with administration of PZP every second year. Success of an immunocontraception program for feral horses in overpopulated rangelands may pave the way for more invasive populations to be controlled in this manner.

The factors affecting reproductive success and breeding density in a rural population of blackbirds, Turdus merula L

Chamberlain, Daniel January 1994 (has links)
The aim of this thesis was to identify the factors determining reproductive success and breeding density in a rural population of blackbirds occupying contiguous woodland and farmland habitats. Once these factors were identified, an attempt was made to assess the quality of the two habitats in terms of reproductive success. Predation was the major factor affecting reproductive success. There were no significant effects of habitat on predation when habitat was defined as farmland, woodland and woodland edge. When defined in terms of nesting density, high density 'hot-spot' areas had significantly greater nesting cover and lower predation rates than territories in farmland or in the rest of the wood. Parents could adjust their provisioning rates according to chick demand. Consequently chicks in larger broods were not significantly different in weight to chicks in smaller broods. The seasonal change in clutch size is therefore well adapted to conditions for raising nestlings, although there was indirect evidence that female condition may limit clutch size early in the season. The nestlings were fed two main diet types, earthworms and caterpillars, the availability of the former being related to rainfall and temperature and the latter occurring in a seasonal peak. Nestlings fed on predominantly earthworm diets were significantly heavier, thus caterpillars are probably a lower quality prey. Starvation was a minor cause of nestling mortality. There was some evidence that farmland birds were more dependent on earthworms than woodland birds, and consequently only farmland broods showed a significant relationship between weight and rainfall. This conferred no disadvantage to farmland broods, although this may have implications for reproductive success in very dry years. Farmland breeders showed some characteristics of a population in a suboptimal habitat. Breeding density was low on farmland compared with woodland. This in part may have been due to lack of suitable nesting cover. An experiment with artificial nests indicated that predation would be proportionately higher on farmland if nesting density was increased. Year-to-year variations in density across the whole study site paralleled the relative harshness of the preceding winter. Food supplementation prior to the breeding season had no effect on subsequent breeding density or clutch size. It is concluded that farmland is potentially a sub-optimal habitat if subject to different conditions of weather or breeding density than those observed during the three years of this study.

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