No description available.

To make reference to Trakai district`s variety of predators mammals and the spread of the researches, literature, hunters, foresters, and environment agency workers data, there are existing 13 of predator mammals.

The study was initially a long term study of the ecology of small mammals at Mlawula Nature Reserve in the eastern part of Swaziland. Due to the drought and dwindling numbers of rodents in the reserve the study was redirected to determining the factors resulting in the low numbers. The impacts of food and cover and grazing by the larger ungulates were studied. In addition, the age class distribution and gastro-intestinal parasites of small mammals were studied. A study of the small mammals in the Siphiso Valley of Mlawula Nature Reserve was conducted over four years from August 2000. The population density, biomass and composition of the small mammal community in the area were studied. The community comprised of Mus minutoides A. Smith, 1834, Mastomys natalensis (A. Smith, 1834), Lemniscomys rosalia (Thomas, 1904), Crocidura hirta Peters, 1952, Steatomys pratensis Peters, 1846 and Graphiurus murinus (Desmarest, 1822). Mus minutoides was the dominant species with pregnant females caught from November to May. Species richness varied significantly with the time of the year. The biomass, density and numbers of small mammals were low and by the end of the second year of the study, small mammal density was close to zero. Mastomys natalensis from a Middleveld study site, Luyengo, Swaziland were used to study the age structure of the population by means of eye lenses. The eye lens to age (in days) curve determined by Leirs (1994) was applied. A large percentage of M. natalensis in winter (June) were 2 months old while in spring/summer (October to March) the population consisted mainly of 3 month old specimens. A very low number of specimens were older than 4 months. This suggests a high mortality/removal rate of the young especially in the winter months. The impact of grazing pressure and rainfall on small mammal densities were investigated. High grazing pressure by ungulates rendered the habitat unsuitable for small mammals as it removed cover and encouraged colonization by alien invasive plant species. This effect was exacerbated by diminishing and unpredictable rains, such that mild grazing pressure negatively impacted on small mammal communities and on individual species. When the small mammals disappeared from the study site, M. natalensis was reintroduced to determine the factors that led to the disappearance. Supplementary food resulted in the longest persistence of the reintroduced mice while the impact of additional cover was small. Predation was likely responsible for the rapid decline of the reintroduced mice. Small mammals were examined for ectoparasites and gut parasites as these were thought to negatively impact on their physiology and reproduction. Ectoparasites collected included the ticks Ixodes sp. and Boophilus sp., the mite Allodermanyssus sp. and another species of mite. The gastrointestinal tracts contained the helminths Syphacia sp., Heligmonina sp., Trichuris sp., Protospirura sp., two unidentified nematode species and different cestode species. A new species of heligmosomoid nematode is described and named. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 72-80). Also available on the World Wide Web.

Thesis (M. Sc.), Memorial University of Newfoundland, 1999. / Bibliography: p. 109-117.

Thesis (Ph. D.)--University of British Columbia, 1977. / Title from PDF t.p. (viewed on May 28, 2010). Includes bibliographical references (leaves 566-585).

Thesis (M.Phil)--Aberdeen University, 2009. / Title from web page (viewed on July 28, 2009). Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 75-83). Also available on the World Wide Web.

In this study I examine the effect of seasonal resource limitation on the behaviour and population dynamics of white-eared kob, Kobus kob leucotis, in the Boma region of the southern Sudan. This population, numbering over 800,000, migrates seasonally between savannah grasslands in areas with low rainfall and ephemerally swamped grasslands in areas with high rainfall. The aims of the study were: (1) to examine whether kob migration tracks ephemeral distributions of food or water resources, (2) to test the hypothesis that the Boma kob population is limited by food availability, (3) to determine if calf production is cued to seasonal peaks in food abundance, and (4) to evaluate the effect of breeding synchrony on lekking behavior and male competition. Seasonal climatic changes produced pronounced changes in the distribution and abundance of both green forage and water supplies. Dry season migration primarily tracked limited supplies of water. Within the dry season range, kob aggregated at high densities (over 1,000 per km²) in low-lying meadows that supported grass re-growth when little green grass was available elsewhere in the ecosystem. However, southerly movements in the wet season were not explainable by the resource hypothesis, since both food and water were widely distributed during the wet season. I suggest that kob may move southward in order to avoid surface flooding during the wet season. Kob mortality during the dry seasons of 1982 and 1983 was considerably higher than estimated mortality during the wet season. Unusual rainfall during the dry season of 1982 provided a "natural experiment" to test the food limitation hypothesis. Adult mortality was significantly lower during the dry season of 1982 than during the more typical dry season of 1983. Calf mortality did not vary significantly between years. Adult mortality rates were related to dry season duration. Dry season mortality was related to sub-maintenance food intake and declining fat reserves. The age structure of the kob population in 1983 suggests that large-scale mortality (ca. 40%) occurred in the 1980 drought that immediately preceded this study. These findings support the food limitation hypothesis. Kob exhibited a 4 month period of calf production during the late wet season, when food availability was highest. As a consequence, females continued lactation through the dry season period of food scarcity. I suggest that kob reproductive phenology may result from an obligatory delay during which females restore their fat reserves prior to calving or selection pressures imposed by predation during the vulnerable post-partum period. Synchronous breeding in the Boma kob was related to increased rates of aggression between males and increased color dimorphism, in comparison to the asynchronous breeding Uganda kob, Kobus kob thomasi. Male aggression served not only to establish dominance relations between males on leks, but also disrupted the mating activities of neighboring males. Young adult males suffered higher age-specific mortality than females, possibly resulting from injuries incurred during strenuous fighting on leks. In order to analyze the age structure of the kob population, I devised a new method for estimating age-specific mortality rates that is free of the restrictive assumptions that underlie most conventional techniques. The proposed method has somewhat greater sampling variation, but is considerably more robust, than two current methods. Moreover, the proposed method permits calculation of age-specific mortality at frequent intervals during periods of population fluctuation and, under some circumstances, population numerical trends may be directly determined from age structure. / Science, Faculty of / Zoology, Department of / Graduate

Long undecoded transcript isoforms (LUTIs) are a class of non-canonical mRNAs that repress gene expression by a combined mechanism of transcriptional and translational interference. Although this mechanism has been shown to be widespread in yeast, its prevalence in mammals has not been established. Using human embryonic stem cells (hESCs) differentiated into endoderm, mesoderm, and ectoderm lineages and further differentiation into polyhormonal cells, cardiomyocytes, and motor neurons, respectively, we obtained a comprehensive dataset through mRNA-seq, ribosome profiling, and quantitative mass spectrometry measurements. Our analysis revealed that LUTI-based regulation is context-dependent, with a total of 271 genes identified in ectoderm to motor neuron differentiation, 69 genes in mesoderm to cardiomyocyte differentiation, and 99 genes in endoderm to polyhormonal cell differentiation. Translational repression of LUTI candidates was found to be primarily dependent on upstream open reading frames (uORFs), while LUTI-based transcriptional repression displayed variability. This study enhances our understanding of gene expression and regulation during mammalian development and highlights the potential significance of LUTI-based regulation in the development of specific cell types or tissues. The findings lay the groundwork for further exploration into the role of LUTI- based regulation in other mammalian developmental programs and its potential implications for therapeutic targets in developmental disorders and diseases.