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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.
11

Occurrence and diversity of bovine coccidia at three localities in South Africa

Matjila, P.T. (Paul Tshepo) 04 January 2007 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2000. / Veterinary Tropical Diseases / unrestricted
12

Phylogeny and Biogeography of the Genus Capricornis (Artiodactyla: Bovidae) Based on Mitochondrial DNA Sequences and Cranial Morphometrics

Chang, Hsun-Cheng 27 June 2002 (has links)
The genus Capricornis Ogilby, 1837, is divided into three species and widely distributed in sourthern China, Tibet, Myanmar, IndoChinese peninsula, Malaysia peninsula, Sumatra, Japanese archipelagos and Taiwan. Using complete cytochrome b sequences (1140 bp) analyzes the genetic variation and phylogeny of genus Capricornis from Taiwan, Japan and Mainland China. Constructed by both distance and maximum parsimony methods, the phyloenetic tree distinguish the Capricornis to three clades: Formosan serow, Japanese serow, and Sumatran serow from mainland China. Formosan serow is more familiar with Sumatran serow than Japanese serow. Local populations of Formosan serow of Taiwan island and Japanese serow of the Japanese archipelagos are already differentiated. Serow and goral are apparently distinguishable. The results of Principal Component Analysis and Discriminant Analysis show that serows from Taiwan, Japan and mainland China and goral are apparently distinguishable at morphological characters. The variation of morphological analysis may be a good tool to identify serow and goral. From the paleogeology and fossil records of serow of Quaternary, we could infer that ancestors of serow from southwestern mountain of mainland China migrated to Taiwan island and Japanese archipelagos through the land bridge of east Asian islands to mainland China in the early Pleistocene caused by the glaciation of Quaternary, then separated from mainland of east Asia and speciation of serow occured in Taiwan island and Japanese archipelagos after the end of the glaciation of Quaternary.
13

The paleoenvironments of early hominins in the Omo Shungura Formation (Plio-Pleistocene, Ethiopia) : synthesizing multiple lines of evidence using phylogenetic ecomorphology

Barr, William Andrew, active 21st century 03 July 2014 (has links)
Ever since Darwin claimed that expanding savannas were the driving force behind humanity's divergence from other apes, our understanding of human evolution has been inextricably linked to the environmental context in which our ancestors evolved. This dissertation explores various aspects of the use of one method of paleoenvironmental reconstruction -- bovid ecomorphology -- and provides new data on paleoenvironmental conditions in the Omo Shungura Formation (Plio-Pleistocene, Ethiopia). Chapter 2 uses phylogenetic simulations to explore the performance of Discriminant Function Analysis (DFA) on simulated ecomorphological data containing phylogenetic signal. DFA is shown to "over-perform" in situations in which predicted and predictor variables both contain phylogenetic signal. Phylogenetic Generalized Least Squares (PGLS) is shown to be a very useful technique for explicitly testing functional hypotheses in ecomorphology while controlling for phylogenetic signal and body size. Chapter 3 presents a functional analysis of the bovid astragalus, which is one of the most commonly preserved bones in the fossil record. Several functional hypotheses linking habitat-specific locomotor performance with the morphology of the astragalus are tested using PGLS. Strong support is found for three of these hypotheses. Thus, the astragalus is shown to be a useful ecomorphological predictor element, a point that is confirmed by the DFA analyses in Chapter 4. Chapter 5 provides new paleoenvironmental data on the Omo Shungura Formation based on habitat reconstructions from astragalar ecomorphology in addition to dietary reconstructions based on dental mesowear. Astragalar data point to a major environmental shift beginning ~2.58 Ma, which is later in time compared with some prior habitat reconstructions using different methods. Furthermore, astragalar data show environmental fluctuations of similar magnitude later in the sequence. Mesowear data on the Shungura Tragelaphini do not offer evidence for any significant grazing adaptation, in spite of relatively high carbon isotope signatures reported based on studies of tooth enamel. These data raise questions regarding the diet of fossil Tragalephini. / text
14

Analysis of the faunal remains of Kemp's Caves and an investigation into possible computerized classification of bones

Swanepoel, Elaine 22 September 2005 (has links)
Please read the abstract in the section 00front of this document / Dissertation (MSc (Anatomy))--University of Pretoria, 2005. / Anatomy / unrestricted
15

Causal Explanations for the Evolution of ‘Low Gear’ Locomotion in Insular Ruminants

Rozzi, Roberto, Varela, Sara, Bover, Pere, Martin, Jeff M. 01 October 2020 (has links)
Aim: Mammals on islands often undergo remarkable evolutionary changes. The acquisition of ‘low gear’ locomotion, namely short and robust limb elements, has been typically associated with the island syndrome in large mammals and, especially, ruminants. Here we provide an investigative framework to examine biotic and abiotic selective factors hypothesized to influence evolution of this peculiar type of gait. Location: Islands worldwide. Taxon: Bovidae. Methods: We calculated response variables associated with ‘low gear’ locomotion in 21 extinct and extant insular bovids. We assembled data on the physiography of 11 islands and on life history and ecological traits of the focal taxa. We estimated 10 predictors (island area and four topographic indices, body mass, body size divergence, number of predators and competitors, large mammal richness) and used multiple regressions, regression trees, and random forests to assess their contextual importance. Results: The acquisition of ‘low gear’ locomotion generally happens on islands with a small number of competitors. However, the roughness of the island terrain appears to be also important, without being a main driver. Finally, although the most extreme cases of ‘low gear’ locomotion occurred on islands with no mammalian predators, our models show a non-significant relationship with this factor. Main conclusions: The evolution of ‘low gear’ locomotion in insular ruminants does not simply result from phyletic dwarfing and predatory release. Variation in morphological responses within Bovidae to ecological and topographic traits suggests, instead, a complex interplay of biotic and abiotic factors. Current understanding on the main drivers of species evolutionary pathways and biogeographic patterns are disproportionally based on few taxa, mainly vertebrates, and in some extreme cases (like this one) even on few species. Here we show how adding more data, even within the same taxonomic group, can challenge historically accepted macroevolutionary and macroecological concepts.
16

The comparative paleoecology of late Miocene Eurasian hominoids

Scott, Robert Smith 28 August 2008 (has links)
Not available / text
17

Écomorphologie et évolution phénotypique : méthodes et applications aux ruminants actuels et aux « ongulés » fossiles lors de la Crise de Salinité Messinienne à la limite Mio-Pliocène / Pas de titre anglais

Clavel, Julien 06 October 2014 (has links)
Comprendre comment évoluent les écosystèmes lors de perturbations majeures de l'environnement nécessite de prendre en compte l'histoire évolutive des espèces, c'est-à-dire leur phylogénie. Dans ce Mémoire de thèse, j'utilise une approche modélisatrice afin d'étudier l'évolution phénotypique en lien avec l'environnement (écomorphologie), approche incluant des données actuelles et fossiles et visant in fine à comprendre comment les écosystèmes se diversifient et s'organisent structurellement et fonctionnellement à l'échelle des temps géologiques. Le cadre historique, fourni par la phylogénie, définit une trame analytique commune à l'étude de taxons actuels et fossiles. Différents outils dédiés, d'une part au traitement de données morphométriques souvent incomplètes, et d'autre part aux études écomorphologiques évolutives dans un contexte phylogénétique, sont développés et discutés. Cette thèse s'articule autour de deux ateliers consacrés à l'étude macroévolutive et macroécologique de grands mammifères « ongulés » : Bovidae, Cervidae, et Equidae. Le premier atelier concerne les ruminants actuels, clade très diversifié et à l'écologie des espèces constitutives connue. Les analyses révèlent des modes évolutifs contrastés entre Cervidae et Bovidae actuels, en fonction des niches écologiques et des caractères écomorphologiques considérés. La diversification moi pliocène des Bovidae africains apparaît corrélée à des évènements globaux, tandis que leur évolution phénotypique révèle des modes de diversification différents selon les habitats. Le second atelier est focalisé sur l'impact d'un événement majeur ayant affecté l'ensemble du pourtour méditerranéen à la limite Miocène- Pliocène, il y a 5,3 millions d'années : la Crise de Salinité Messinienne. Il repose sur l'étude d' « ongulés » fossiles et apporte des précisions sur l'aspect temporel de l'évolution de ces mammifères avant et après cet événement. Les principaux résultats illustrent des variations rapides de la structure phylogénétique des assemblages d'ongulés qu'il est possible de relier au contexte biogéographique et aux variations climatiques locales et régionales. Les renouvellements fauniques (acteurs) et fonctionnels (rôles), initiés dès la fin du Miocène moyen, apparaissent progressifs et non soudains. Les résultats obtenus offrent une meilleure caractérisation et compréhension des réponses évolutives de ces mammifères, grands consommateurs primaires souvent parmi les premiers menacés lors de perturbations climatiques et environnementales majeures / Understanding how ecosystems evolve when facing severe climatic perturbations of the environment requires an historic perspective provided by species phylogenies. In this thesis, I use a modelling framework to investigate the question of the phenotypic evolution of species as an adaptation to the environment (ecomorphology). I combine extant and fossil data to study how ecosystems are diversifying and organizing structurally and functionally on a geological time scale. The historical context provided by the phylogeny defines a unified analytical framework for the study of extant and fossil taxa. Several analytical tools dedicated, on the one hand to deal with missing cases in morphometric studies, and on the other hand to ecomorphological studies in a phylogenetic context, are developed and discussed. This PhD thesis is organized along two main research axes dedicated to the macroevolutionary and macroecological study of three large mammals “ungulate” families: Bovidae, Cervidae, and Equidae. First I focus on extant ruminants, a well diversified clade for which species ecological preferences are well known. The analyses show contrasted evolutionary modes between extant cervids and bovids, depending on the ecological niche and ecomorphological traits under scrutiny. The Mio-Pliocene diversification of African bovids appears to be correlated with global climatic events while their phenotypic evolution shows contrasted evolutionary patterns depending on the habitat. The second axis focuses on the circum Méditerranean impact of a major event that took place at the Miocene-Pliocene boundary, 5.3 million years ago: the Messinian Salinity Crisis. The comparative study of extinct “ungulates” living before and after this event provides some clues about the evolutionary rates and spatial patterns of phylogenetic diversity of these large mammals. The phylogenetic structure of the ungulate communities shows abrupt changes related to the local and regional biogeographic context as well as variations in climate conditions. Meanwhile, progressive faunal (actors) and functional (roles) turnovers are depicted from the beginning of the Late Miocene onward. These results provide a better characterization and understanding of the evolutionary responses to broad climatic and environmental perturbations of these often-threatened, large primary consumer “ungulate” mammals
18

The population dynamics of impala (Aepyceros melampus Lichtenstein) in Mkuzi Game Reserve.

Vincent, John. 18 September 2014 (has links)
The need to understand the dynamics of the impala population in Mkuzi Game Reserve arose during the early 1960's when it became clear that various factors were contributing to an overpopulation of the species in the reserve. Population management was recognized as being necessary and was carried out, but it was based on inadequate information. This study set out to establish a rational basis for future management. The social organization and behaviour of impala in Mkuzi were analysed and placed in perspective relative to the population dynamics. Two methods of counting the animals were used and a relationship obtained between the respective results. The distribution of impala within the reserve, both on a gross population basis and with respect to the various sex and age categories, was determined from sampling. In order to establish the age structure of the population, samples obtained from the control programme were used, and these were aged on the basis of molar wear. At the same time the proportions of young animals and the population sex ratios were obtained by field sampling. Using these data, life tables were constructed, from . which it was possible to interpret the behaviour of the population at the time of the study. However, caution should be exercised in extrapolating these results literally to the same population under different conditions. The study only provides guidelines for regular monitoring to be carried out. At the same time a more detailed study of the vegetation dynamics of Mkuzi Game Reserve is a priority so that the relationship between the animal and plant elements of the reserve can be properly analysed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1979.
19

Reconstructing the Habitat Mosaic of Australopithecus robustus: Evidence from Quantitative Morphological Analysis of Bovid Teeth

Brophy, Juliet 2011 December 1900 (has links)
This research better resolves the environmental mosaic that is typically reconstructed for the A. robustus-bearing faunal assemblages of South Africa and evaluates whether A. robustus were habitat specialists or habitat generalists by testing whether they are associated with numerous, different reconstructed habitats, or if they can be associated with a single, more homogeneous habitat type. Determining the habitat preferences of A. robustus holds important implications for understanding the behavior of these hominins and, potentially, for understanding whether their ultimate extinction might have been climatically influenced, as fluctuations in the environments associated with the robust australopiths provide direct evidence about the responses of hominins to environmental change. To achieve this, a 2-dimensionsal morphometric tool was developed for accurately identifying the abundant bovid teeth that are found in direct association with the hominins using Elliptical Fourier Function Analysis. More accurate taxonomic identifications facilitate more precise estimates of the relative abundance of ecologically sensitive bovids, allowing for finer resolution when segmenting the various components of the reconstructed habitat mosaics. The fossil bovids abundances were compared across the assemblages over time in order to define the environmental mosaic in each assemblage and to determine if environmental heterogeneity existed across the assemblages. The relative abundances of the bovid fossil assemblages and A. robustus were compared to assess the habitat preferences of these hominins. A. robustus were not consistently associated with a particular habitat type suggesting that perhaps they were habitat generalists, capable of surviving in multiple types of habitats.
20

Jak, čím a proč cvakají při chůzi někteří zástupci turovitých (Bovidae)? / Clicking in bovids - basic parameters, origin and function?

ROCHOVÁ, Markéta January 2014 (has links)
Some species of hoofed animals produce clicking sound. This work analysed clicking parameters (dominant frequency, 25% quartile, 50% quartile, 75% quartile) of this species: Kuban Tur (Capra caucasica), Daghestan Tur (Capra cylindricornis) and Aoudad (Ammotragus lervia), which are clicking significantly. Clicks of each individual were recorded using solid state recorder Marantz PMD 620 with microphone. All clicks were analysed using program Avisoft-SAS Lab Pro Software, verze 5.0.01 (2010). Data were analysed using program STATISTICA, version 9 (ANONYMUS 2009). Individuals were compared using one-way ANOVA and discriminant analysis. Species and sexes were compared using discriminant analysis and nested ANOVA. Clicking parameters were correlated with age. A phylogenetic distribution of clicking was determined in Bovidae. Results suggest differences between individuals and species. Differences between sexes wasn't significant. Correlation with age was significant.

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