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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.

Reproductive strategies of males in the egg parasitoid Trichogramma turkestanica Meyer (Hymenoptera:Trichogrammatidae)

Martel, Véronique. January 2007 (has links)
In most animals, males are assumed to have access to an unlimited supply of sperm, while females produce few eggs that are large and costly to produce. In parasitoids, there is a paradigm to the effect that males are polyandrous, inseminate as many females as possible and express no optimization in their behaviours. In reality, sperm production incurs non-trivial costs. Because sperm are transferred in ejaculates and that their cost is greater than that of individual sperm, males can gain by carefully allocating their ejaculates. In this thesis I have investigated different aspects of males' reproductive strategies, mainly sperm and time allocation, in the egg parasitoid Trichogramma turkestanica Meyer (Hymenoptera: Trichogrammatidae). / In T. turkestanica, mating mainly occur on the emergence patch. However, results show that mating opportunities are not distributed equally among males and 2.9% of successful males are sperm-depleted when they disperse from the emergence patch. Nevertheless, 97.1% of males disperse non sperm-depleted, suggesting off-patch mating potential. Male T. turkestanica have thus an insemination capacity higher than necessary to inseminate the females present on the emergence patch, a pattern that seems to be common among parasitic wasps. / On the emergence patch, both virgin and mated females can be encountered. Males are able to discriminate between those mates and prefer virgin ones. This preference is stronger for energy- and time-limited males. / Sperm competition risks and/or intensity are important for males that decrease their sperm investment when the number of rivals increases. Such response is optimal when the benefits from investing more sperm become lower than the costs of a low paternity assurance under intense sperm competition. / Finally, male T. turkestanica express behaviours enabling them to optimize their patch time exploitation. Depending on their evaluation of the patch quality, males modify their patch residence time. / This thesis shows that time- and sperm-limited male T. turkestanica are not simply maximizing the number of females inseminated, but rather maximize their lifetime fitness by optimizing sperm and patch time allocation.

Induction and maintenance of corpora lutea in prepuberal gilts.

Segal, Donald Howard. January 1970 (has links)
No description available.

Aspects of prolificacy in Cambridge sheep

Nassiri, Mohammad Taghi Beigi January 1996 (has links)
No description available.

Consequences of competitive asymmetry in broods of the black guillemot Cepphus grylle

Cook, Mark I. January 1999 (has links)
No description available.

Functional long-term storage of spermatozoa in oviducts of the common house gecko, Hemidactylus frenatus

Murphy-Walker, Susan Gene January 1994 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 90-99). / Microfiche. / x, 99 leaves, bound ill. 29 cm

A child at any cost : A study on how the issue about assisted reproduction for single people is being interpreted by the Swedish media

Nyame, Hallex Berry January 2012 (has links)
March 13th 2012 the Swedish social Committee brings up a proposal that assisted reproduction should be legalize for single women in Sweden. The suggestion was quickly forwarded to the parliament for a decision making. Although majority of the Swedish parties (the alliances) are positive about this proposal, there are also a few who are strongly against the proposal, for example the Christian Democratic Party. The purpose of this study has been to investigate how the two Swedish newspapers Dagens Nyheter and Svenska Dagbladet has written about the issue on legalizing assisted reproduction for single women in Sweden. To help me come to my results and conclusion on this study I decided to use the quantitative content analysis and the qualitative text analysis method. I have specifically chosen to concentrate on how these two newspapers have chosen to present this issue and what angles do Dagens Nyheter and Svenska Dagbladet uses to present this issue to their readers. After my qualitative text analysis, I came to the conclusion that this issue didn’t get the attention that it deserves from both of the newspapers. Since the issue is about babies, women and their bodies, I expected the newspapers to write about this issue as a gender issue, but that was not the case. Instead it was twisted around by the press and made into a political fight between the Christian Democrat party that is against the proposal and the alliances that is positive to the proposal. In all the articles I had chosen to analyze, I as a reader was met by the voices of different politicians that had strong opinions about legalizing assisted reproduction for single women. The opinion of ordinary people didn’t seem to matter to any of the journalist and neither was the opinion of women, because I realized that neither of these groups were found in the articles. Even more interesting was the fact that the voices of the politicians were all dominated by men. In conclusion looking at the issue on legalizing assisted reproduction for single women, one would supposed that the issue is going to be based on subjects about babies, hospitals, women and their bodies. Instead the issue was made into a political fight and dominated by male voices and opinions.

On the perseverative tendency

Foster, William S. January 1900 (has links)
Thesis (Ph. D.)--Cornell University, 1913. / "Reprinted from the American journal of psychology July, 1914, vol. XXV." "From the Psychological laboratory, Cornell university."

Interrelationships of certain thermal and endocrine phenomena and reproductive function in the female bovine

Gwazdauskas, Francis Charles, January 1974 (has links)
Thesis (Ph. D.)--University of Florida, 1974. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 108-117).

Untersuchungen über den Zyklus der Stute 1. Beitrag: Kussere Rosse und Scheidenbild ...

Boden, Gerhard. January 1939 (has links)
Inaug.-Diss.--Tierärztliche Hochschule zu Hannover. / At head of title: Aus der Klinik für Geburtshilfe und Rinderkrankheiten der Tierärztlichen Hochschule zu Hannover ... "Literatur": p. 9-16. "Literaturverzeichnis": p. 44.

Reproductive and digestibility studies with gestating gilts and sows as affected by energy level

Arbabian, Morteza, January 1971 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography (leaves 178-189).

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