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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.
1

Rodent ecology and seed predation in logged and unlogged forest, Uganda

Stanford, Angela January 2000 (has links)
No description available.
2

Habitat refuges and the management of predators for conservation

Carter, Stephen Paul January 2002 (has links)
No description available.
3

Effects of risk on foragers a simulation /

Niemeyer, Nancy Marie. January 1984 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-75).
4

Population models with harvesting and delay stability of equilibria /

Astaburuaga, Maria Angelica. January 1978 (has links)
Thesis--Wisconsin. / Vita. Includes bibliographical references.
5

Resource recovery delays in harvested predator-prey models

Griesmer, Stephen Joseph 11 1900 (has links)
This thesis investigates the effect of resource recovery delays, both continuous and discrete, on the behaviour and population dynamics of harvested predator-prey systems. Three models were tested with respect to local stability, global stability, and state-space trajectories. The method of D-partitions was used to determine local stability properties while simulations were performed to discover global properties. Generally, delays were found to induce multiple transitions between locally stable and unstable equilibria as harvest rates are changed. This phenomenon occurred under the management strategies of constant-effort harvesting and constant-quota stocking and harvesting. In addition, in the predator-prey models with delay, a high conversion efficiency and a high satiation limit for the predators can effect instability; this is not possible without delays. Global investigations confirmed the local results and extended them to the simultaneous harvesting of the predator and prey for constant-quota harvesting and stocking. The simulations also showed bifurcations in limit cycles as the carrying capacity was altered and as the stocking rates were varied. Nutrient-limited phytoplankton cultures in chemostats were analyzed with the mathematical techniques. It is shown that multiple stability transitions with changes in dilution rates are theoretically possible but observed delays are not large enough to produce this behaviour. / Graduate and Postdoctoral Studies / Graduate
6

Seed predation and potential dispersal of Ceratocaryum argenteum (Restionaceae) nuts by the striped mouse (Rhabdomys pumilio) / Joseph Douglas Mandla White

White, Joseph Douglas Mandla January 2013 (has links)
This study aimed to better understand the role of rodents as seed predators and dispersers in the fynbos biome at De Hoop Nature Reserve, South Africa in May and June, 2013. Based on previous studies I hypothesised that the large, nut-like seeds of Ceratocaryum argenteum (Restionaceae) are scatter-hoarded by rodents and that rodent seed choices and seed fates are affected by seed size and hull thickness. Field trials using three seed types showed that smaller seeds with a high reward and low processing cost were consumed significantly(p<0.01) more than large, thick hulled seeds. Application of wire tags to facilitate discovery of relocated seeds had no significant influence on seed choice (p>0.05), but further research should be conducted to determine if spooling of C. argenteum seeds influences rodent seed choice. Smaller seeds with a high-reward and low processing cost showed a significantly greater percentage of usage (p<0.01) where seed stations were encountered and exploited. Rhabdomys pumilio was confirmed as being the most common murid at the study site, however, it seems unlikely that it scatter-hoards C. argenteum seeds, as no consumption or burial of seeds was observed. However, R. pumilio did show an interest in C. argenteum seeds and attempted to consume some seeds or carried seeds over distances not significantly different (p>0.05) from the observed distances between nearest neighbour C.argenteum plants before discarding them on the soil. Additionally, the maximum distance R. pumilio moved C. argenteum seeds was commensurate with the maximum distance between nearest neighbour C. argenteum stands, so the end fate of the seeds remains unknown. Further research should account for seasonal variability in scatter-hoarding behaviour.
7

A STUDY OF THE ROLE OF INTRAGUILD PREDATION IN THE POPULATION DYNAMICS OF THREE SPECIES OF RHYACOPHILA

Wright, Charles Stewart IV 05 July 2011 (has links)
Intraguild (IG) predation, where species within the same guild prey on each other, is common in aquatic communities. I used the abundance and distributional patterns of three species of Rhyacophila (Trichoptera), derived from a survey of 25 streams in Nova Scotia, Canada, to test several predictions of IG theory. I first sampled microhabitats and conducted behavioural observations to establish that the species do co-occur and prey on each other. Abundance patterns did not conform to two key model predictions: (1) Neither of the IG prey (R. minor, R. vibox) was excluded from the most productive streams, and (2) IG prey densities were not inversely related to productivity in streams with the IG predator (R. fuscula). It remains possible that intraguild predation occurs between these species of Rhyacophilia, the measured abundances do not indicate any measurable effects from IGP, the abundance being determined instead by the availability of prey.
8

Body mass regulation in birds

Lee, Sonia Jean January 1996 (has links)
No description available.
9

A study of the mortality factors in the Apanteles glomeratus-Pieris spp. system

Bradley, J. January 1987 (has links)
No description available.
10

The role of native and invasive amphipods (Crustacea) in freshwater communities

Kelly, D. W. January 2001 (has links)
No description available.

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