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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.
71

Determinants of population structure in the world's smallest primate, <i>Microcebus berthae</i>, across its global range in Menabe Central, Western Madagascar / Determinanten der räumlichen Populationsstruktur des kleinsten bekannten Primaten, <i>Microcebus berthae</i>, in dessen globalem Verbreitungsgebiet Menabe Central, West-Madagaskar

Schäffler, Livia 16 December 2011 (has links)
No description available.
72

Rhythms and Evolution: Effects of Timing on Survival

Pace, Bruno 14 November 2016 (has links) (PDF)
The evolution of metabolism regulation is an intertwined process, where different strategies are constantly being developed towards a cognitive ability to perceive and respond to an environment. Organisms depend on an orchestration of a complex set of chemical reactions: maintaining homeostasis with a changing environment, while simultaneously sending material and energetic resources to where they are needed. The success of an organism requires efficient metabolic regulation, highlighting the connection between evolution, population dynamics and the underlying biochemistry. In this work, I represent organisms as coupled information-processing networks, that is, gene-regulatory networks receiving signals from the environment and acting on chemical reactions, eventually affecting material flows. I discuss the mechanisms through which metabolism control is improved during evolution and how the nonlinearities of competition influence this solution-searching process. The propagation of the populations through the resulting landscapes generally point to the role of the rhythm of cell division as an essential phenotypic feature driving evolution. Subsequently, as it naturally follows, different representations of organisms as oscillators are constructed to indicate more precisely how the interplay between competition, maturation timing and cell-division synchronisation affects the expected evolutionary outcomes, not always leading to the \"survival of the fastest\".
73

Evolution isolierter Teilpopulationen der Laubholz-Säbelschrecke Barbitistes serricauda (FABRICIUS 1798) / Evolution of Isolated Subpopulations of the Bushcricket Barbitistes serricauda (FABRICIUS 1798)

Richter, Christian 22 January 2008 (has links)
No description available.
74

Studies on genetic properties of porcine parvoviruses

Streck, André Felipe 02 April 2013 (has links)
Porcine parvovirus (PPV) is considered to be one of the most important causes of reproductive failure in swine. Fetal death, mummification, stillbirths and delayed return to estrus are some of the clinical signs commonly associated with PPV infection in a herd. The virus genome is considered to be conservative, with substitution rates near to that of their host. However, it has been shown that some parvoviruses exhibit a substitution rate close to that commonly determined for RNA viruses. In this scenario, new PPV phenotypes may reduce the effectiveness of the currently used vaccines, recommending the continuous monitoring of the currently prevalent PPV strains. In addition, a number of novel porcine parvoviruses have been described during the last decade, but the importance and characteristics of these viruses remain unknown. In the present dissertation, three studies were performed to address the PPV genetic variability, to monitor the emergence of new PPV strains and the prevalence of novel parvoviruses. In the first study, recent PPV field isolates from Austria, Brazil, Germany and Switzerland were sequenced and analyzed. These samples, together with sequences retrieved from GenBank, were included in three datasets (viral protein complete gene, viral protein partial gene and non-structural protein complete gene). For each dataset, the nucleotide substitution rate was determined and a molecular clock estimated. The analysis revealed that for the new strains, the amino acids substitutions were located mainly in the viral capsid loops. Only the capsid protein datasets present the higher suitability for phylogenetic analysis. In them, a higher divergence was found, with three well defined clusters. By inferring the evolutionary dynamics of the PPV sequences, a nucleotide substitution rate of approximately 10 -4 substitutions per site per year was found for these datasets. An association of the phylogenetic tree with the molecular clock revealed that the main divergence of the PPV strains for the viral protein ocurred in the last 30 years. In the second study, the population dynamic of PPV isolates from swine herds was analyzed using PPV complete protein gene and partial sequences deposited in GenBank. The population dynamic of the virus was calculated using a Bayesian approach with a Bayesian skyline coalescent model. Additionally, an in vitro model was performed by twenty-one consecutives passages of the Challenge strain (a virulent field strain) and NADL2 strain (a vaccine strain) in PK15 cell-line supplemented with polyclonal antibodies raised against the vaccine strain (negative control was not supplemented). The Bayesian analysis indicated a decrease in the population diversity over the years and the predominance of some PPV strains. In agreement, the in vitro study revealed that a lower number of mutations appeared for both viruses in the presence of anti-PPV antibodies in comparison with the control passages without antibodies. In the third study, tonsils and hearts from 100 pigs were collected in a German slaughterhouse in 2010 and tested for PPV, porcine parvovirus 2 (PPV2), porcine parvovirus 3 (PPV3) and porcine parvovirus 4 (PPV4). Positive samples of PPV, PPV2 and PPV3 were sequenced. PPV was observed in 60/100 hearts and 61/100 tonsils and PPV2 in 55/100 hearts and 78/100 tonsils. PPV3 and PPV4 could not be detected in the heart samples but 20/100 and 7/100, respectively, of the tonsils were tested positive. The phylogenetic analysis of the PPV, PPV2 and PPV3 sequences revealed that the German samples could be divided in at least two clusters or clades for each virus. Altogether, it can be concluded that PPV is continuously evolving. Apparently, PPV vaccines largely used in the last 30 years probably have reduced the genetic diversity of the virus and induced the predominance of strains with distinct capsid profile from the original vaccine-based strain. Moreover, the high prevalence of the PPV, PPV2 and PPV3 and their genetic diversity highlight the importance of the continuous monitoring of these viruses.
75

Untersuchung des Krankheitsgeschehens und der Haltungsprobleme von Dallschafen (Ovis dalli dalli) in drei zoologischen Gärten

Junghans, Burghard 02 November 2000 (has links)
Aufgabenstellung dieser Arbeit ist es, wichtige Hinweise zur Verbesserung der Betreuung von Ovis d. dalli, einer in menschlicher Obhut noch äußerst krankheitsanfälligen Tierart, zu erarbeiten. Dafür wird die Haltung von Ovis d. dalli in 3 deutschen zoologischen Gärten bezüglich der Häufigkeitsverteilung der klinischen Erkrankungen, der Todesursachen, der annualen Verteilung der Geburten, der Populationsdynamik, der Fütterung und der Gehegegestaltung untersucht. Weiterhin werden Referenzwerte für labordiagnostische Parameter bei klinisch gesunden Tiere gewonnen. Die Erkrankungshäufigkeit – Erk/Jahr – wird als Beurteilungskriterium für das klinische Herdengeschehen empfohlen. Die Gesamterkrankungshäufigkeit liegt bei 1,09 Erk/Jahr, wobei sich eine Zunahme der Erkrankungshäufigkeit während der Haltungsperioden nachweisen läßt. Der Vergleich der Erkrankungshäufigkeiten ergibt, daß die Schwerpunkte des klinischen Geschehens im Bereich des Digestionsapparates, des Bewegungsapparates und bei Weibchen im Abortgeschehen liegen. Als besonders schwerwiegendes Geschehen erweist sich die Paratuberkulose in 2 Beständen. Weitere bedeutungsvolle Krankheiten sind Chorioptesräude, Ostertagiose und systemische Infektionen der Jungtiere. Für eine Beurteilung der Schutzwirkung der Impfstoffe sind die Gruppen zu klein und zu viele ungeklärte epizootiologische Fragen offen, um eine eindeutige Aussagen treffen zu können. Die Besonderheiten der labordiagnostischen Parameter, die in den eigenen Untersuchungen bestimmt werden, bestätigen im wesentlichen die Werte von Untersuchungen aus der Wildbahn. Bei der Auswertung der Todesursachen stehen mit 37 % ebenfalls Störungen des Verdauungsapparates im Vordergrund. Ein weiterer Schwerpunkt sind mit 29 % Störungen des Respirationsapparates, die im klinischen Geschehen eine unbedeutende Rolle spielen. In menschlicher Obhut und in der Wildbahn sind Pasteurella sp. maßgeblich am Pneumoniegeschehen beteiligt. Die meisten Verluste treten während der Aufzuchtphase auf, so daß die Überlebenswahrscheinlichkeit zu Beginn der Geschlechtsreife für Männchen bei 29,5 % und für Weibchen bei 40,3 % liegt. Der Konzentratfutteranteil der Fütterung sollte günstiger über den Tag verteilt und nicht als Erstfutter am Morgen verabreicht werden. Die Fütterung von Rauhfutter sollte in überdachten Raufen erfolgen. Der annuale Zyklus der Nahrungsveränderung in der Wildbahn – mit der Zielstellung der Senkung der Aufzuchtverluste – sollte durch höhere Rohproteinanteile in der Ration ab April wenigstens partiell simuliert werden. Die Verabreichung von Supplementen ist sorgfältig zu kontrollieren, um einen Abusus zu vermeiden. Die Analyse der Populationsdynamik hat die stetige Überalterung der Bestände ausgewiesen, die zu langsamen Generationsfolgen und zum Zusammenbruch von Populationen geführt hat. Für die wildbahnunabhängige Erhaltung von Ovis d. dalli in menschlicher Obhut ist es notwendig, mit dem stattfindenten Inzuchtprozeß gezielt umzugehen. Insbesondere ist zur Vorbeuge von hereditären Störungen eine Anpaarung mit nur einem Bock über einen längeren Zeitraum zu vermeiden. Bei der Gehegegestaltung sind komplizierte Aufbauten zu vermeiden, da sie möglicherweise ein erhöhtes Verletzungsrisiko in sich bergen. Als vorteilhalft werden Stallungen mit mehreren Zugängen, Sichtblenden durch Strukturierung des Geheges und Verhinderung des direkten Besucherkontaktes erkannt. Für die Reduzierung von Stressoren in der Herde – insbesondere während der Lammsaison – sind Muttergruppen nur während der Brunft gemeinsam mit geschlechtsreifen Böcken zu halten. / It is the goal of this study to research the important factors that would contribute to a better care of Ovis d. dalli – a species which is still rather prone to disease in human care. Therefore the keeping of Ovis d. dalli was studied in three German zoological gardens with respect to incidence rates, causes of death, annual distribution of births, population dynamics, feeding, and enclosure design. Furthermore, reference values for laboratory parameters in healthy animals could be gained. The incidence rate (cases of disease per annum) is recommended as criterion for the evaluation of the current health state of a flock. In this study the total incidence rate is 1.09 cases/annum, whereby an increase in the incidence rate could be documented for the periods of keeping. The comparison of incidence rates shows that the main areas of healthconcerns are located in the digestive system, the skeletal and muscular system, and in females abortions. As a particularly serious event paratuberculosis in two stocks needs to be mentioned. Further important disorders include Chorioptes mange, Ostertagia infection and systemic infection in young animals. Due to many unsolved epizootiological issues and too small groups, the evaluation of the effectiveness of vaccines defies definite and conclusive interpretation. The specific pattern of laboratory values, which were determined in the investigations of this study, confirm basically the values drawn from investigations in the wild. The analysis of deaths also shows that with 37 %disorders of the digestive system are a main area of concern. Another area of concern are disorders of the respiratory system with 29 %, which play a less important role in clinical cases. In human care as well as in the wild primarily Pasterurella sp. are involved in pneumonia cases. The highest losses occur during the rearing stage so that the probability of survival at the beginning of maturity is 29.5 % in males and 40.3 % in females. The portion of concentrated food in the feed should be better spread out throughout the whole day and not be given all at once with the first morning feed. The feeding of roughage should be offered in troughs with coverd shelters. In order to lower the number of lossses during rearing, the annual cycle of food changes in the wild should be at least partially copied by feeding higher portions of crude protein starting in April. The adding of supplements needs to be carefully controlled to prevent abuse. The analysis of population dynamics reveals a continuous increase in the percentage of old animals resulting in slower alternation rates of generations and the breakdown of populations. In order to keep Ovis d. dalli successfully in human care – independent from the wild, it is imperative to pay the current inbreeding the required attention. To prevent hereditary disorders it is particularly important to avoid breeding with only one ram over longer periods of time. Enclosure design should abstain from sophisticated structures because they seem to increase the risk of injury. As advantageous the following features could be identified: shelters with several entrances, structuring of the enclosure in such a way that visibility is limited and direct contact with visitores is prevented. To reduce stress in the flock, especially during lambing season, groups of ewes are to be kept with mature rams only during rutting season.
76

Zur Populations- und Aktivitätsdynamik des nützlichen Rhizobakteriums Bacillus subtilis (Ehrenberg) Cohn nach Introduktion in natürliche Systeme von Pflanze und Boden

Zimmer, Jens 25 May 2004 (has links)
Die Besiedlung der Pflanzenwurzel und das Vorhandensein aktiver Zellen sind grundlegende Voraussetzungen für das Zustandekommen phytoeffektiver und Pathogen unterdrückender Effekte durch Applikation des Nutzbakteriums Bacillus subtilis. Der Einfluss ökologischer und edaphischer Faktoren auf das Besiedlungsverhalten der introduzierten Bakterien wurde im Rahmen umfangreicher populations- und aktivitätsdynamischer Untersuchungen ergründet. Die Versuche wurden in drei verschiedenen Substrattypen an der Modellpflanze Erbse (Pisum sativum L. cv. ''Bördi'') unter kontrollierten Bedingungen in der Klimakammer durchgeführt. Die Populationsdichte von Bacillus subtilis war in starkem Maße abhängig von der angewendeten Dosis. Die Verwendung von Kaliumnitrat, Sand oder Maisstärke als Trägerstoff für die Bacillus subtilis-Formulierung war für das Besiedlungsverhalten des Nutzbakteriums unerheblich. Die Entwicklung von Bacillus subtilis-Populationen an Pflanzenwurzel und im Substrat war temperaturabhängig. Höhere Versuchstemperaturen hatten größere Populationsdichten zur Folge. Der Temperatureinfluss war in Quarzsand wesentlich stärker als in Feldboden. Die peripheren Wurzelteile wiesen in Quarzsand zumeist größere Populationsdichten auf als die in Samennähe befindlichen Wurzelteile. Der Zusatz des Neem-Präparates Rhakshak Gold führte in vivo weder zu einer signifikanten Erhöhung der Populationsdichte von Bacillus subtilis noch zu einer Aktivitätserhöhung. Die Gesamtkeimzahlen in Rhizosphäre und Substrat wurden durch die Anwendung von Bacillus subtilis nicht beeinflusst. Die Aktivität von Bacillus subtilis in Rhizosphäre, Rhizoplane und Substrat war gering, der größte Teil der Keime lag versport vor. Die geringsten Versporungsgrade wurden in Quarzsand in der Rhizoplane sowie in Feldboden im Substrat festgestellt. Die Applikation des Nutzbakteriums führte zu einem reduzierten Krankheitsbefall der Erbsenpflanzen mit Phoma pinodella und Rhizoctonia solani. Die antifungale Wirkung kam in Feldboden und Aussaaterde wesentlich stärker zum Tragen als in Quarzsand. Es war kein direkter Zusammenhang zwischen Populationsdichte der introduzierten Bakterien in Rhizosphäre und Substrat und deren phytoeffektiver sowie antifungaler Leistung erkennbar. Als Ursache dafür wird der hohe Anteil versporter Zellen in der Bacillus subtilis-Population angesehen. Die Ergebnisse werden hinsichtlich der Bedeutung des Besiedlungsverhaltens und der Aktivität von Bacillus subtilis für dessen phytoeffektive und antifungale Wirkung diskutiert. / The colonization of the plant root and the presence of physiologically active bacterial cells are basic conditions to obtain plant growth promotion and disease suppression by application of Bacillus subtilis. Studies of the population- and activity dynamics of the introduced bacteria were carried out to determine the influence of different soil types and ecological factors on colonization of plant roots by Bacillus subtilis. Pea plants (Pisum sativum L. cv. ''Boerdi'') which were treated with these bacteria have been grown in three different types of substrate under controlled conditions in the climate chamber. The population density of Bacillus subtilis was strongly dependend on the applied number of cfu (colony forming units). The use of potassium nitrate, sand or maize starche as carrier for the bacterial formulation did not affect the colonization behaviour. The development of Bacillus subtilis-populations at the plant roots and in the substrate was significantly influenced by temperature. Higher temperatures during the trials resulted in larger population sizes of the introduced bacteria. The influence of temperature was much stronger in quartz sand compared with field soil. In most cases the colonization of the outer parts of the root near the root tip was better than the colonization of the root parts near the seed. The addition of the neem-extract Rakshak Gold did not have a significant influence on population density and activity of Bacillus subtilis in vivo. Nearly no effects of the bacterial treatments on the indigenous microflora could be found. The physiological activity of Bacillus subtilis in the rhizosphere, on the root surface and in the substrate was low. The bacterial population consisted largely of spores. The lowest percentage of spores was determined directly on the root surface (in quartz sand) and in the substrate (in field soil) respectively. The bacterial treatments led to a reduced disease severity on pea plants caused by Phoma pinodella and Rhizoctonia solani. The antifungal activity was higher in field soil and horticultural substrate compared with quartz sand. There was no correlation between the population density of the introduced bacteria in rhizosphere and substrate and their plant growth promoting or antifungal effects. A possible reason for that is the high percentage of non-active cells within the population of Bacillus subtilis. The results would be discussed towards the importance of population dynamics and activity of the rhizobacterium Bacillus subtilis for its plant growth and health promoting effects.
77

Diversity and Ecological patterns of Bolivian deciduous forests / Diversität und ökologische Muster in saisonalen Wäldern Boliviens

Linares-Palomino, Reynaldo 30 January 2009 (has links)
No description available.
78

Late Quaternary landscape dynamics in the Podocarpus National Park region in the southeastern Andes of Ecuador / Spätquartäre Landschaftsdynamik in der Region des Podocarpus National Parks in den südlichen Ostanden Ecuadors

Brunschön, Corinna 09 August 2010 (has links)
No description available.
79

Säugetierkundliche Freilandforschung zur Populationsbiologie des Waschbären (Procyon lotor Linnaeus, 1758) in einem naturnahen Tieflandbuchenwald im Müritz-Nationalpark (Mecklenburg-Vorpommern) / Population biology of the North American raccoon (Procyon lotor Linnaeus, 1758) in a Northern German lowland beech forest (Müritz National Park)

Michler, Frank-Uwe Fritz 12 March 2018 (has links) (PDF)
In der Dissertation werden Fragen zur Populationsbiologie des neozonalen Nordamerikanischen Waschbären (Procyon lotor) behandelt. Die knapp sechsjährigen Freilanduntersuchungen fanden im Rahmen eines umfangreichen Waschbärenforschungsprojektes (www.projekt-waschbaer.de) in einem naturnahen Tieflandbuchenwald im Müritz-Nationalpark (Mecklenburg-Vorpommern) statt. Das Nationalparkgebiet wird nachweislich seit Ende der 1970er Jahre vom Waschbären besiedelt und stellt aufgrund seines Gewässerreichtums und seiner alten Laubbaumbestände einen idealen Lebensraum für Waschbären dar. Die Dissertation schließt die populationsbiologischen Arbeiten des Gesamtprojektes ab und stellt die Ergebnisse in fünf separaten Themenschwerpunkten vor (I. Raumverhalten, II. Sozialverhalten, III. Reproduktionsbiologie, IV. Populationsstruktur, V. Populationsdynamik). Übergeordnetes Ziel der Arbeit war die Erhebung valider populationsbiologischer Daten, um eine grundlegende ökologische Charakterisierung des Waschbären unter dem Aspekt des Natur- und Artenschutzes vornehmen zu können. Dazu wurden zwischen 2006 und 2011 in einem 1.114 ha großen Fallennetz im Serrahner Teilgebiet des Nationalparks an 53 verschiedenen Fallenstandorten 145 verschiedene Waschbären (62 ♀♀, 83 ♂♂) insgesamt 489 Mal gefangen, genetisch beprobt, vermessen und individuell markiert. 51 adulte Waschbären (23 ♀♀, 28 ♂♂) und 18 Jungtiere (10 ♀♀, 8 ♂♂) wurden darüber hinaus mit einem UKW-Halsbandsender ausgestattet und im Rahmen der telemetrischen Arbeiten insgesamt 31.202 Mal geortet (≙ im Mittel 452 Lokalisationen pro Tier). Im Kernuntersuchungsgebiet wurde an 36 beköderten Standorten ein Fotofallenmonitoring durchgeführt. Bei einer Überwachungsdauer von 5.365 Fotofallennächten entstanden dabei 18.721 Aufnahmen von 183 verschiedenen Waschbären. 82 % aller Waschbärenbilder zeigten individuell markierte Individuen. Alle 145 gefangenen Waschbären wurden im Rahmen eines separaten Teilprojektes mit hochvariablen Mikrosatelliten erfolgreich genotypisiert, so dass die Verwandtschaftsverhältnisse sowie der individuelle Reproduktionserfolg der Untersuchungstiere bekannt sind. Für die Analysen zur Populationsstruktur wurden unter anderem von 120 verendet aufgefunden Waschbären (Totfunden) aus dem unmittelbaren Umfeld des Nationalparks klassische morphometrische und phänotypische Merkmale sowie die Mortalitätsursachen erfasst. / This study considers questions concerning the spatial and social behaviour, reproduction, population structure and dynamics of the alien North American raccoon (Procyon lotor) in Germany. The investigations took place within the framework of a comprehensive raccoon research project (www.projekt-waschbaer.de) over a period of nearly six years in a close-to-nature lowland beech forest in the Müritz National Park (Mecklenburg-West Pomerania). The National Park has been verifiably colonized by raccoons since the end of the 1970s, and due to its abundance of water and its old deciduous tree population it represents an ideal habitat for this mammal. Between 2006 and 2011, 145 individual raccoons (62 ♀♀ and 83 ♂♂) were captured, genetically sampled, measured and individually tagged. Sampling took place within a 1,114 hectare area of the National Park, at 53 trap sites and with 489 trappings. 51 adult raccoons (23 ♀♀, 28 ♂♂) and 18 juveniles (10 ♀♀, 8 ♂♂) were also fitted with radio collars and located a total of 31,202 times as part of the telemetric survey (=452 localisations per individual). Camera trap monitoring was carried out at 36 baited locations of the main investigation area (1,628 ha): 18,721 camera trap pictures were taken of 183 different raccoons over a monitorring period of 5,365 nights. 82 % of all the raccoon pictures showed individually tagged ani-mals. All 145 of the trapped raccoons were successfully genotyped as part of a subproject with highly polymorphic microsatellites. Both the familial relationships and the individual reproductive success of the subject animals could be determined with the genotyping results. For the analyses of the population structure, classic morphometric and phenotypical characteristics, as well as the cause of mortality of 120 raccoon carcasses in the immediate vicinity of the National Park, were recorded.
80

Rhythms and Evolution: Effects of Timing on Survival

Pace, Bruno 11 March 2016 (has links)
The evolution of metabolism regulation is an intertwined process, where different strategies are constantly being developed towards a cognitive ability to perceive and respond to an environment. Organisms depend on an orchestration of a complex set of chemical reactions: maintaining homeostasis with a changing environment, while simultaneously sending material and energetic resources to where they are needed. The success of an organism requires efficient metabolic regulation, highlighting the connection between evolution, population dynamics and the underlying biochemistry. In this work, I represent organisms as coupled information-processing networks, that is, gene-regulatory networks receiving signals from the environment and acting on chemical reactions, eventually affecting material flows. I discuss the mechanisms through which metabolism control is improved during evolution and how the nonlinearities of competition influence this solution-searching process. The propagation of the populations through the resulting landscapes generally point to the role of the rhythm of cell division as an essential phenotypic feature driving evolution. Subsequently, as it naturally follows, different representations of organisms as oscillators are constructed to indicate more precisely how the interplay between competition, maturation timing and cell-division synchronisation affects the expected evolutionary outcomes, not always leading to the \"survival of the fastest\".

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