This thesis evaluates the policy of mandatory detention for asylum seekers maintained by successive Australian governments against several core liberal principles. These principles are derived from various accounts of liberal political thought and the major themes and criticisms inherent in the public debate over the policy. The justifications of the policy given by the Australian government and the criticisms enunciated by scholars, refugee advocates and non-government organisations with respect to the policy strongly correspond with the core liberal principles of fairness, protecting the rights of the individual, accountability and proportionality. The claims of the critics converge on a central point of contention: that the mandatory detention of asylum seekers violates core liberal principles. To ascertain the extent to which the claims of the critics can be supported, the thesis selectively draws on liberal political theory to provide a framework for the analysis of the policy against these liberal principles, a basis for inquiry largely neglected by contributors to the literature. This thesis argues that, on balance, the mandatory detention policy employed by successive Australian governments violates core liberal principles. The claims of the critics are weakened, but by no means discredited, by the importance of the government's maintenance of strong border control. In the main, however, criticisms made by opponents of the policy can be supported. This thesis contributes to the substantial body of literature on the mandatory detention policy by shedding light on how liberal principles may be applicable to the mandatory detention policy. Further, it aims to contribute to an enriched understanding of the Australian government's competence to detain asylum seekers.

Models that are used for predicting species' potential distributions are important tools that have found applications in a number of areas of applied ecology. The majority of these models can be classified as correlative, as they rely on strong, often indirect, links between species distribution records and environmental predictor variables to make predictions. Correlative models are an alternative to more complex mechanistic models that attempt to simulate the mechanisms considered to underlie the observed correlations with environmental attributes. This study explores the influence of the type and quality of the data used to calibrate correlative models. In terms of data type, the most popular techniques in use are group discrimination techniques, those that use both presence and absence locality data to make predictions. However, for many organisms absence data are either not available or are considered to be unreliable. As the available range of profile techniques (those using presence only data) appeared to be limited, new profile techniques were investigated and evaluated. A new profile modelling technique based on fuzzy classification (the Fuzzy Envelope Model) was developed and implemented. A second profile technique based on Principal Components Analysis was implemented and evaluated. Based on quantitative model evaluation tests, both of these techniques performed well and show considerable promise. In terms of data quality, the effects on model performance of false absence records, the number of locality records (sample size) and the proportion of localities representing species presence (prevalence) in samples were investigated for logistic regression distribution models. Sample size and prevalence both had a significant effect on model performance. False absence records had a significant influence on model performance, which was affected by sample size. A quantitative comparison of the performance of selected profile models and group discrimination modelling techniques suggests that different techniques may be more successful for predicting distributions for particular species or types of organism than others. The results also suggest that several different model design! sample size combinations are capable of making predictions that will on average not differ significantly in performance for a particular species. A further quantitative comparison among modelling techniques suggests that correlative techniques can perform as well as simple mechanistic techniques for predicting potential distributions.

Globalization has seen an unprecedented dispersal of exotic and alien species worldwide resulting in worldwide homogenization and sometimes extinction of indigenous or endemic taxa. When an exotic species becomes established in a new habitat the invasive organisms are capable of having an impact on indigenous community dynamics and the overall structure and function of ecosystems. Furthermore, the impact of invasion is determined by the geographical range, abundance and the per-capita or per-biomass effect of the invader. However, the success of the introduced organisms is reliant on their ability to acclimate to the physiochemical conditions of the newly invaded environment.Freshwater ecosystems are especially vulnerable to invasions because there are numerous potential routes of introduction including intentional pathways such as stocking, and unintentional pathways such as the release of ballast water and aquarium releases. Efforts to limit the introduction of invasive species or to manage established exotic populations are often hindered by insufficient understanding of the natural history of problematic species. Relatively little is known regarding the physiological tolerances of many taxa. Knowledge about specific species ecophysiological constraints allows for the prediction of future patterns of invasion more accurately, including where an introduced organism would probably survive, thrive and disperse. Furthermore, data on the physiological tolerances of an introduced exotic organism may provide data necessary for effective management and control. This studyinvestigated three invasive species in the Nseleni River system in a protected area in KwaZulu-Natal. The species studied were, Tarebia granifera (Quilted melania – Lamarck, 1822), Pterygoplichthys disjunctivus (Suckermouth armoured catfish - Weber, 1991) and Eichhornia crassipes (water hyacinth – (Martius) Solms-Laubach,). The Nseleni River flows into Lake Nsezi which is responsible for providing potable water to the surrounding towns and industry, as well as the surrounding rural communities. The Enseleni Nature reserve has become the centre for biodiversity dispersal in the immediate area, due to the change in landscape surrounding the protected area.An important step in developing alien invasive species management strategies in protected areas is determining their extent and invasive traits. Tarebia granifera is a prosobranch gastropod originally from South-East Asia that has become invasive in several countries around the world including South Africa. Snail populations were sampled at nine sites throughout the Nseleni/Mposa river system every six weeks over a twelve month period. The snail was abundant throughout the system, especially in shallow waters of less than 1m in depth.The first positive identification the loricariid catfish Pterygoplichthys disjunctivus for the Nseleni River was in 2006. The original introduction is believed to have been via the aquarium trade. The aim of the study was to assess the usefulness of the unified framework with regard to management of fish invasions by assessing the invasion stage of the loricariid population and identifying appropriate management actions using the Blackburn et al. (2011) framework. The fish were sampled at nine different sites and three different depths over a period of twelve months, as well as when two ichthyological surveys were carried out on the Nseleni River system. This invasive fish has been located throughout the system and both male and female fish were collected. The smallest fish sampled was a fingerling of a day or two old and the smallest pregnant female was a mere 270mm TL. This is a clear indication that this fish is breeding in the river system.Although T. granifera and P. disjunctivus were abundant in the Nseleni/Mposa river system, it was not clear what their role in the system was, and in particular if they were competing with any of the indigenous species. Therefore, isotope samples were collected from numerous taxa over a two week period, with the exception of Pterygoplichthys disjunctivus samples, which were collected over 12 months. The δ13C and δ15N signatures of all samples were determined. The niche overlap between the invasive and indigenous snails was effectively zero (1.02E-13%), indicating no shared food resources. The medium ranges of dNRb (7.14) and dCRb (9.07) for the invasive fish indicate that it utilizes a wider range of food resources and trophic levels than the majority of indigenous fish. A medium CDb value (2.34) for the invasive fish species, P. disjunctivus, describes medium trophic diversity, with three indigenous species possessing higher diversity and three possessing lower diversity. Furtherresults indicated that there was no direct dietary competition between P. disjunctivus and indigenous species. Eichhornia crassipes was first recorded on the Nseleni River in 1978, and has been shown to have a significant negative impact on the biodiversity of the Nseleni/Mposa River system and therefore required a control intervention. Although biological control using the two weevil species Neochetina eichhornia (Warner) and N. bruchi (Hustache) has been credited with affecting a good level of control, the lack of a manipulated post-release evaluation experiments has undermined this statement. Five experimental plots of water hyacinth of 20m2 were sprayed with an insecticide to control weevils. After ten months the plants in the sprayed plots were significantly bigger and heavier than those in the control plots that had natural populations of the biological control agents. This study has shown unequivocally that biological control has contributed significantly to the control of water hyacinth on the Nseleni/Mposa River system.The management plan for the Enseleni Nature Reserve identifies the need to control invasive and/or exotic organisms within the boundary of the protected area. In addition, set guidelines have been implemented on how to control these organisms, so that indigenous organisms are least affected. Lack of control of exotic organisms can have serious consequences for indigenous species. It is therefore of utmost importance that the population dynamics of the invading organism be understood, what the potential impact could be and how to control them. Furthermore, it has also acknowledged the threat of possible exotic species invasions from outside of the protected area that might result in threats to the protected area and that these must be investigated, researched and managed.This thesis has identified Tarebia granifera, Pterygoplichthys disjunctivus and Eichhornia crassipes as being a threat to indigenous biodiversity within the protected area, as well as in adjacent areas to the protected area. The thesis will therefore investigate the hypothesis that both Tarebia granifera and Pterygoplichthys disjunctivus are having a direct negative effect on available food resources for indigenous species of organisms. In addition, this thesis will investigate if theNeochetina species that have previously been introduced onto E. crassipes are having any negative effect on this invasive alien aquatic plant.

Visando melhor apresentação do texto, a dissertação foi divida em três capítulos: Capítulo 1: Regeneração natural lenhosa e cobertura do solo em duas veredas de uma fazenda produtora de Eucalyptus sp. no Triângulo Mineiro. Esse capítulo teve como objetivo analisar a regeneração lenhosa e a representatividade de grupos vegetais na cobertura do solo em duas veredas sob pressões ambientais semelhantes na presença e ausência de vegetação nativa adjacente à borda, de modo a identificar possíveis diferenças relacionadas a impactos ambientais indiretos nas veredas. Capítulo 2: Variáveis ambientais e caracterização do solo e sua relação com a distribuição da vegetação nativa e exótica em duas veredas. Objetivou-se, nesse capítulo, descrever as condições ambientais e as características do solo em duas veredas e relacionar estas características com a regeneração natural lenhosa, cobertura relativa do solo e invasão biológica por Pinus caribaea, Trembleya parviflora e gramíneas exóticas. Capítulo 3: Natural regeneration and biological invasion by Pinus caribaea Morelet in two vereda sites: woody vegetation response. Teve como objetivo analisar a regeneração natural, cobertura da vegetação lenhosa e as espécies exóticas potencialmente invasoras em duas veredas em estádio de sucessão secundária na porção central do bioma Cerrado. / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As veredas são ecossistemas heterogêneos quanto às condições ambientais e composição florística. Apesar de considerados como Áreas de Preservação Permanente, são altamente sensíveis a impactos ambientais que podem refletir na composição das comunidades vegetais. Nesse sentido, este trabalho teve como objetivo analisar a regeneração lenhosa e a representatividade de grupos vegetais na cobertura do solo em duas veredas sob pressões ambientais semelhantes na presença (vereda 1) e na ausência (vereda 2) de vegetação nativa adjacente à borda. Para isso, regenerantes lenhosos foram amostrados em 15 parcelas ao longo de transectos perpendiculares à linha de drenagem em cada vereda. A cobertura do solo foi medida pelo método do intercepto linear nas parcelas. Foram amostrados 369 indivíduos regenerantes lenhosos na vereda 1 e 1.053 na vereda 2. Apesar da diferença significativa na densidade, a diversidade de regenerantes foi semelhante nas duas áreas (30 espécies na vereda 1 e 35 espécies na vereda 2). As famílias mais representativas foram: Melastomataceae, Asteraceae e Myrtaceae na vereda 1 e Melastomataceae, Myrtaceae e Fabaceae na vereda 2. Além da baixa riqueza, a regeneração lenhosa das veredas foi dominada por um número reduzido de espécies, sendo Leandra erostrata a espécie com maior densidade. Foram observadas espécies de fitofisionomias de formações florestais na composição florística da regeneração, especialmente na vereda 2. A espécie exótica Pinus caribaea foi amostrada nas duas veredas, mas apresentou maior índice de Regeneração Natural Total na vereda 1. Esta vereda também apresentou tendências características de zonação na cobertura do solo e na composição da regeneração e, embora tenha apresentado menor densidade da invasora nativa Trembleya parviflora, houve formação de “zona trembleyal” na borda esquerda. Com a presença de espécies mais sensíveis a condições de perturbação como Miconia theizans e mais resistentes como T. parviflora, as veredas parecem abrigar diferentes condições de degradação ambiental. Apesar da presença de vegetação nativa adjacente à borda da vereda 2, essa área apresenta indícios de impactos na vegetação ligados ao rebaixamento de lençol freático, enquanto a vereda 1, apresenta indícios de maiores perturbações na borda, além de invasão biológica por Pinus caribaea. / Veredas are heterogeneous ecosystems when it comes to environmental conditions and floristic composition. Although regarded as Permanent Protection Areas – according to Brazilian environmental law, they are highly sensitive to indirect environmental impacts which might affect the plant community composition. In this sense, our research aimed to analyze the woody regeneration and the representativeness of plant groups on soil coverage at two vereda areas under similar environmental pressures in presence (vereda 1) and absence (vereda 2) of native vegetation adjacent to the edge. For this purpose we sampled 15 woody regenerating individuals throughout transects perpendicular to the drain line in which vereda area. We measured the soil coverage using the Line - Intercept method in the plots. We found 369 woody regenerating individuals in vereda 1 and 1.053 individuals in vereda 2. In despite of the significant difference in density, the woody regeneratings diversity was similar in both areas (30 species in vereda 1 and 35 species in vereda 2). The most representative families were as follow: Melastomataceae, Asteraceae and Myrtaceae in vereda 1 and Melastomataceae, Myrtaceae and Fabaceae in vereda 2. Besides the low observed diversity, a reduced number of species were dominant in woody regeneration at both vereda sites, being Leandra erostrata the species bearing the highest density value. We found species related to forest formations in the regenerating floristic composition, especially in vereda 2. We observed the alien species Pinus caribaea in both vereda areas, the vereda 1 showed the highest natural regeneration índex though. We also observed typical zonation tendencies on soil coverage and woody regeneration composition, although we recorded a “trembleyal zone” on the left edge. Regarding the presence of species more sensitive to environmental disturbances such as Miconia theizans and more resistant ones such as T. parviflora, the veredas seem to foster distinct degradation conditions. In despite of the presence of native regeneration adjacent to vereda 2, this are shows signs of impact on vegetation, linked to water table lowering whilst vereda 1 shows signs of higher disturbances in the edge, besides a remarkable biological invasion by Pinus caribaea. / Dissertação (Mestrado)

A atual e a próxima década serão identificadas no tempo como fórum das mais relevantes preocupações com a qualidade ambiental do planeta. Temas como aquecimento global e a eminente perda da quantidade e qualidade da água são discutidos constantemente. Um outro problema ambiental mais específico tem preocupado especialistas no mundo todo, incluindo o Brasil. Trata-se da disseminação em grande escala de espécies exóticas. O tema tem sido tratado no meio científico e acadêmico como invasões biológicas e não se restringe somente às plantas.O estudo aqui apresentado trata de uma espécie arbórea com grande disseminação no país e utilizada em áreas urbanas e faixas de praia devido à sombra proporcionada na época do verão. A ocorrência do chapéu-de-sol em unidades de conservação de proteção integral pode representar uma ameaça às espécies autóctones pela ocupação do espaço. A identificação com metodologia científica das características germinativas e sucesso reprodutivo foram a forma de avaliar o grau de ameaça que a espécie representa para o ambiente de restinga.Assim, esse estudo teve o objetivo de determinar o potencial de contaminação biológica do chapéu-de-sol (Terminalia catappa L.) através da análise do índice de velocidade de germinação (IVG), tempo médio de germinação, velocidade média de germinação, freqüência germinativa, germinabilidade (G%) e análise da taxa de sobrevivência e de transição de plântulas, jovens e adultos. Os resultados indicam que as sementes da espécie podem germinar em ampla faixa de temperatura, principalmente, se estiver a pleno sol. Frutos despolpados apresentaram maior velocidade e taxa de germinação.Plântulas apresentaram elevada taxa de mortalidade comparada aos indivíduos jovens e adultos. Concluiu-se que a espécie precisa ser retirada da área de restinga, pois, apesar de ser considerada estabelecida, em condições favoráveis ela se desenvolverá ocupando o nicho de outras espécies locais. / Current and the next decade they will be identified in the time as group of the most excellent concerns with the ambient quality of the planet. Subjects as global heating and the eminent loss of the amount and quality of the water are argued constantly. A more specific ambient problem has worried specialists in the world all, including Brazil. One is about the large-scale dissemination of exotic species. The subject has been treated in the half academic as biological invasions and it is not only restricted to the plants. The study presented here it at the time deals with a trees species with great dissemination in the country and used in urban areas and beach bands due to proportionate shade of the summer. The occurrence of the singapure almond in protect areas of integral protection can represent a threat to the species for the occupation of the space. The identification with scientific methodology of the germination characteristics and reproductive success had been the form to evaluate the threat degree that the species represents for the environment of restinga. Thus, this study it had the objective to determine the potential of biological contamination of the singapure almond (Terminalia catappa L.) through the analysis of the index of germination speed (IVG), average time of germination, average speed of germination, frequency of germination, germinability (G%) and analysis of the tax of survival and transistion of seedly, young and adults. The results indicate that the seeds of the species can germinate in ample band of temperature, mainly, will be the full sun. Pulped fruits had presented greater speed and tax of germination. Seedly had presented high tax of comparative mortality to adult and youngs. The necessary species was concluded that to be removed of the area of restinga, therefore, although to be considered established, in favorable conditions it will develop itself occupying the niche of other local species.

Invasões biológicas tem um papel cada vez mais importante nas políticas ambientais, visto que espécies invasoras desempenham uma crescente influência sobre novos ambientes onde são introduzidas, podendo gerar grandes impactos naturais e financeiros. Estudos na área da biologia da invasão se fazem extremamente necessários para remediar e evitar novas introduções. Dentre as metodologias aplicadas ao estudo das invasões biológicas, a genética de populações apresenta diversas ferramentas uteis para responder perguntas relevantes nos esforços de controle de espécies invasoras. No presente trabalho usamos recursos moleculares aplicados à genética de populações da rã-touro (Lithobates catesbeianus), o anfíbio invasor mais disseminado no planeta. Através deste estudo foi possível compreender mais sobre a estrutura genética das populações invasoras do Brasil e do mundo, além de seu histórico de invasão e sua população nativa de origem. Entender e contextualizar as características e motivos que levam ao sucesso de uma invasão biológica é importante para esforços de combate a pragas e para evitar que outros invasores se fixem em novos ambientes. Este trabalho levantou novos conhecimentos que podem e devem ser usados em políticas de combates à invasão da rã-touro / Biological invasions play an increasingly important role in environmental policies as invasive species represent a growing impact in new environments where they are introduced, potentially causing large natural and financial problems. Studies in the field of invasion biology are extremely necessary to remedy and prevent new introductions. Among the methodologies applied to the study of biological invasions, population genetics presents several useful tools to answer relevant questions in efforts to control invasive species. In the present work we used molecular resources applied to the genetics of populations of the American Bullfrog (Lithobates catesbeianus), the most widespread invasive amphibian on the planet. Through this study it was possible to understand more about the genetic structure of the invasive populations in Brazil and in the world, and its history of invasion and its native population of origin. Understanding and contextualizing the characteristics and motives that lead to the success of a biological invasion is important for pest control efforts and to prevent other invaders from focusing on new environments. This work has raised new knowledge that can and should be used in policies to combat Bullfrog invasion

Analysis of the flora of the Pondoland Centre of Endemism (PCE) recorded 2253 species in the combined checklist of four sites (Port St. Johns, Mkambati, Umtamvuna and Oribi Gorge). Of these 1 % species are endemic to Pondoland, representing 8.7% of the Species, 15% of the genera and 26% of the families of the combined flora. Forty-four percent ofthe combined flora was only recorded from one locality (between 17% and 26% of each flora) and only 12% of the flora was present in all four localities. Of the endemics only sixteen (8%) occurred in all four sites thus each site had its own complement of unique endemics and 21 % endemics were not recorded from any of the four sites. At species level the floras of Mkambati and Umtamvuna were the most similar, followed by that of Umtamvuna and Oribi Gorge. Port St Johns had the least in common with any of the othersites, but more in common with non-neighbours Umtamvuna and Oribi Gorge than with its nearest neighbour Mkambati. Mkambati and Umtamvuna had the largest proportion of PCE endemics and Port St Johns had the lowest. The four sites are quite similar at family level, sharing thirteen families in the top ten family list between them, but much less similar at generic level.

Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.

Alongside the destruction of habitat, the impact of invasive alien species (IAS) is considered as one of the most important threats to global biodiversity. Therefore, international directives as well as national legislation call for measures to prevent the further spread of already established IAS as well as to limit their negative effects on native flora and fauna. This study deals with one of these non-native species – the American mink (Neovison vison). In order to get information about ecology and behaviour of this semiaquatic carnivore, a small population in a north German fishpond area, where mink has been spreading since the 1970s, was investigated. During the years 2003 to 2006 data about annual and circadian activity patterns, space use, territorial system as well as feeding habits and their variations during different seasons were collected. For this purpose, altogether 14 individuals (nine males, five females) were monitored using radio-telemetry. Based on the results, the potential impact of American mink on indigenous species was discussed and implications for mink control and management were deduced. American mink are difficult to radio tag. The small difference between their head and neck circumferences mean that the radio collars must be worn tightly to prevent loss. A methodological evaluation of conventional collar transmitters revealed that in six out of eight cases serious skin injuries on the necks were the consequences. Therefore, all radio collars were removed and radio transmitters were surgically implanted in the peritoneal cavity of mink by veterinarians. One male bit open the sutures and died after emergency surgery, but in 13 cases implantation did not affect survival or reproduction of the mink. With reference to animal welfare, intraperitoneal implantation of radio transmitters (in combination with observation and quarantine for several days after operation) instead of external radio collars were recommended for long term telemetry studies of American mink. Analyses of annual activity patterns revealed significant differences in seasonal activity rates. Both sexes reduced their average activity rates in cold winter months (October to February) to about 23 %. This energy-saving strategy is possible because of sufficient food availability, especially of fish, at this time. In March, male as well as female mink considerably increased their activity to almost 40 % due to the mating season. In summer months, during the pup-raising period (May to August), female activity continued to be high (between 40 and 50 %). However, male mink which are not involved in rearing the young, were less active (about 30 %) until July. But in August and September, the time of juvenile dispersal followed by changes in the territorial system and intraspecific aggression, activity rates of males increased again up to 43 %. Circadian activity rhythms differed markedly between sexes. All investigated females exhibited a perennial diurnal pattern. Three of five investigated male mink showed typical nocturnal activity throughout the year. Two males displayed arrhythmic behaviour; they did not prefer any time of the day for activity. On the one hand, gender differences in annual as well as circadian activity patterns of American mink reflect the diversity in ecological constraints, primarily the investment into reproduction. On the other hand, the different temporal strategies of sexes may have the potential to reduce intraspecific, especially intersexual competition. Investigating territorial systems and space use of mink, in comparison to other European studies, relatively large home ranges combined with a quite low population density were observed. In summer months male mink used on average 15.4 km length of waterway and female mink used on average 9.3 km length of waterway. In accordance with the trend of activity rates, male and female mink reduced their large summer home ranges by more than half during the cold winter period. But all-season male mink used significantly larger areas than female mink. High intersexual overlapping rates of home ranges and low levels of intrasexual overlapping of neighbouring home ranges confirm intrasexual territoriality of American mink. Probably, the low population density (0.6-0.7 individuals/km2) allows such high variations in seasonal and sexual home range size. During the mating season males considerably enlarged their home ranges and roamed nearly through the entire study area in search of receptive females. The shifting of stable temporary home ranges observed within one season or between the same seasons of consecutive years demonstrates the highly dynamic nature of spatial behaviour among American mink. The recorded characteristic features of spatial and temporal behaviour should be considered when planning monitoring- and management measures of this invasive carnivore. For instance, the reduced home ranges and activity rates during winter months should be taken into account in mink trapping projects. Analyses of more than 2500 scatsamples of radio tracked mink show that investigated animals principally prey on fish, small mammals and birds (eggs inclusive). There were significant seasonal variations of diet composition. In spring, the three categories of prey - fish, mammals and birds (eggs inclusive) - were hunted in similar amounts. During summer, birds and their eggs made up the main part of the diet followed by mammals. In autumn, the proportion of birds in the mink diet decreased, whereas fish gained in importance. This trend continued during the winter period, when mink preyed almost exclusively on fish. Throughout the entire year amphibians, crustaceans, insects, molluscs and reptiles were found only occasionally in scatsamples. Among birds, the mink preyed mainly on the Eurasian Coot (Fulica atra) followed by the Mallard (Anas platyrhynchos). Mammalian prey was clearly dominated by the water vole (Arvicola terrestris) and among fish, mink hunted especially perch (Perca fluviatilis), roach (Rutilus rutilus) and carp (Cyprinus carpio). Results clearly demonstrate that mink is an opportunistic predator, which hunts its prey according to availability and vulnerability, respectively. Despite the high portions of fish in the autumn and winter diet, the economic damage to fishery caused by mink seems to be low. Perch and roach were preyed on in higher frequencies than the carp which is economically relevant. However, high predation on birds and their eggs during the breeding season indicates a potential negative impact of mink on waterfowl. To summarise, it can be noted that characteristic features of the anthropogenically influenced study area affect feeding habits, activity patterns, space use and density of local mink population. In this regard the management of fishponds, which influences seasonal availability of habitat- and food resources for mink, plays an important role. American mink is regarded as “invasive”, because a negative impact on native species has been proved by several European studies. Consequently, this study recommends management with a focus on effective monitoring and, if necessary, control or exclusion measures adapted to the specific local requirements. Furthermore, to prevent additional introductions into the wild, the still existing farms have to be protected against outbreaks and liberations. In the long term, a general ban on the trade and keeping of American mink would be desirable. / Der Einfluss invasiver, gebietsfremder Arten wird neben der Habitatzerstörung als eine der größten Gefährdungen der Biodiversität weltweit angesehen. Sowohl internationale Umweltvereinbarungen als auch die nationale Gesetzgebung fordern daher Maßnahmen, die eine weitere Ausbreitung bereits etablierter invasiver Neozoen verhindern und deren negative Einflüsse minimieren. Die vorliegende Studie befasst sich mit einer dieser Neozoen - dem Amerikanischen Nerz bzw. Mink (Neovison vison). Um Erkenntnisse zu Ökologie und Verhalten des semiaquatischen Musteliden in Deutschland zu gewinnen, wurden Daten zu tages- und jahreszeitlichen Aktivitätsmustern, zu Raumnutzung und Territorialsystem sowie zur Nahrungswahl und den jahreszeitlichen Unterschieden im Beutespektrum der Art erhoben. Dafür konnten in den Jahren 2003 bis 2006 in einem Fischteich-Gebiet in Mecklenburg-Vorpommern, wo sich Minke bereits seit den 1970er Jahren etabliert haben, insgesamt 14 Individuen (neun Männchen, fünf Weibchen) radiotelemetrisch überwacht werden. Anhand der Ergebnisse wird einerseits der potentielle Einfluss des gebietsfremden Raubsäugers auf einheimische Arten abgeschätzt und diskutiert. Andererseits werden die Ergebnisse herangezogen, um effektive Monitoring- und Managementmaßnahmen abzuleiten. Eine methodische Evaluation von Halsbandsendern zeigte, dass in sechs von acht Fällen die getesteten Halsbänder, die aufgrund des sehr ähnlichen Hals-Kopf-Umfanges der Individuen relativ eng angelegt werden müssen, Hautverletzungen verursachten. Infolgedessen wurden die Halsbandsender gegen durch Tierärzte operativ in die Bauchhöhle eingesetzte Implantationssender ausgetauscht. Auch bei allen nachfolgend gefangenen Tieren wurden die Sender implantiert. Bei insgesamt 14 durchgeführten Erstimplantationen beeinflussten mit Ausnahme eines Falles (Tod durch Aufbeißen der Naht) die Implantate weder das Überleben, noch die Reproduktion der Minke. Daher ist v.a. in Hinblick auf Tierschutzaspekte die Senderimplantation (in Kombination mit einer Mehrtages-Quarantäne) anstatt der Verwendung von externen Halsbandsendern zu empfehlen. Die Analyse der circannuellen Aktivitätsmuster ergab signifikante Unterschiede der saisonalen Aktivitätsraten. Während der kalten Wintermonate (Oktober bis Februar) zeigten beide Geschlechter mit durchschnittlich etwa 23 % eine vergleichsweise geringe Aktivität. Diese energiesparende Verhaltensweise war möglich, da auch im Winter ein ausreichend hohes Nahrungsangebot, vor allem an Fisch, vorhanden war. Im März kam es sowohl bei den Männchen als auch bei den Weibchen zu einem durch die Paarungszeit verursachten, beträchtlichen Anstieg der mittleren Aktivitätsraten auf fast 40 %. In den Sommermonaten (Mai bis August) waren die weiblichen Tiere, durch die Anforderungen der Jungenaufzucht bedingt, anhaltend häufig aktiv (zwischen 40 und 50 %). Die Aktivitätsraten der nicht an der Jungenaufzucht beteiligten Männchen dagegen nahmen im April wieder ab, um bis zum Juli auf einem vergleichsweise geringen Niveau von etwa 30 % zu bleiben. Sie stiegen jedoch während der Monate August und September erneut auf etwa 43 % an. Zu dieser Zeit wandern gewöhnlich die Jungtiere ab und suchen sich ein eigenes Streifgebiet (= Aktionsraum), dadurch kommt es zu Änderungen im Territorialsystem und damit einhergehenden innerartlichen Auseinandersetzungen. Beide Geschlechter unterscheiden sich stark in ihren tageszeitlichen Aktivitätsrhythmen. Alle Weibchen waren ganzjährig tagaktiv. Von den fünf untersuchten Männchen zeigten drei typische Nachtaktivität im gesamten Jahresverlauf. Die beiden anderen männlichen Tiere verhielten sich in ihren Aktivitätsrhythmen indifferent, sie zeigten das ganze Jahr über keine Präferenzen für eine bestimmte Tageszeit. Die geschlechtsspezifischen Unterschiede sowohl in den circannuellen als auch in den circadianen Aktivitätsmustern spiegeln zum einen die verschiedenen Anforderungen an die Geschlechter wieder, vor allem die Investitionen in die Fortpflanzung. Zum anderen können die geschlechtsspezifisch unterschiedlichen Zeitnutzungs-Strategien zu einer Minimierung der innerartlichen, vorzugsweise der intersexuellen Konkurrenz führen. Die Analyse der Telemetriedaten hinsichtlich Raumnutzung und Territorialsystem ergab im Vergleich zu anderen europäischen Studien relativ große individuelle Aktionsräume verbunden mit einer geringen Populationsdichte im Untersuchungsgebiet. So erstreckten sich die durchschnittlich genutzten Sommerstreifgebiete der Männchen auf 15,4 km und die der Weibchen auf 9,3 km Flusslauf bzw. Teichufer. Entsprechend dem Trend der saisonalen Aktivitätsmuster, reduzierten beide Geschlechter ihre großen Sommerstreifgebiete während der Winterhalbjahre um mehr als die Hälfte der Fläche. Allerdings nutzten die Männchen zu allen Jahreszeiten wesentlich größere Aktionsräume als die weiblichen Minke. Große Streifgebietsüberlappungen zwischen den Geschlechtern sowie verhältnismäßig niedrige Überlappungsraten der benachbarten Streifgebiete von Tieren des gleichen Geschlechts bestätigen die intrasexuelle Territorialität der Art. Die erheblichen Unterschiede der saisonalen und geschlechtsspezifischen Aktionsraumgrößen werden vermutlich durch die ermittelte, vergleichsweise geringe Populationsdichte (0,6-0,7 Individuen/km2) ermöglicht. Die ausgedehnte und sich fast über das gesamte Untersuchungsgebiet erstreckende Raumnutzung der Männchen während der Paarungszeit ist durch die Suche nach fortpflanzungsbereiten Weibchen bedingt. Die Raumnutzung der untersuchten Minke unterliegt einer hohen Dynamik, dies wird durch die häufige räumliche Verschiebung temporär stabiler Streifgebiete innerhalb einer Jahreszeit oder auch zwischen den gleichen Jahreszeiten aufeinanderfolgender Jahre verdeutlicht. All diese ermittelten charakteristischen Besonderheiten im Raum-Zeit-Verhalten der Art sollten bei der Entwicklung von Monitoring- und Managementkonzepten berücksichtigt werden. So müssen beispielsweise bei der Fallenjagd im Winter die zu dieser Zeit stark verkleinerten Streifgebiete und die reduzierten Aktivitätsraten Beachtung finden. Die Analyse der über 2500 Losungsproben telemetrierter Minke zeigte, dass sich die untersuchten Tiere hauptsächlich von Fisch, Kleinsäugern und Vögeln (inklusive deren Eiern) ernährten. Dabei traten allerdings signifikante saisonale Unterschiede in der Nahrungs-zusammensetzung auf. So wurden im Frühjahr die drei Beutekategorien Fisch, Kleinsäuger sowie Vögel und deren Eier in ähnlichen Anteilen erbeutet. Während des Sommers bildeten Vögel und Vogeleier die Hauptbeute, gefolgt von Kleinsäugern. Im Herbst verringerte sich der Vogel- und Kleinsäugeranteil im Beutespektrum zugunsten von Fisch. Dieser Trend setzte sich bis in den Winter fort; in dieser Jahreszeit ernährten sich die Minke fast ausschließlich von Fisch. Amphibien, Reptilien, Krebstiere, Insekten und Mollusken wurden im gesamten Jahresverlauf nur gelegentlich gefressen. Innerhalb der Gruppe der Vögel prädierten die Minke vor allem Blässhühner (Fulica atra), gefolgt von Stockenten (Anas platyrhynchos). Das Kleinsäuger-Beutespektrum wurde eindeutig von der Schermaus (Arvicola terrestris) dominiert und unter den Fischen erbeuteten die Minke vorzugsweise Flussbarsche (Perca fluviatilis), Plötzen (Rutilus rutilus) und Karpfen (Cyprinus carpio). Die Ergebnisse der Nahrungsanalyse bestätigen den Mink als einen opportunistischen Prädator, der seine Beutetiere je nach Verfügbarkeit bzw. dem erforderlichen Jagdaufwand nutzt. Trotz des hohen Fischanteils in der Herbst- und Winternahrung ist der durch den Mink verursachte ökonomische Schaden schätzungsweise relativ gering. Flussbarsch und Plötze wurden in höheren Frequenzanteilen erbeutet als der wirtschaftlich relevante Karpfen. Die starke Prädation von Wasservögeln und deren Eiern besonders in den Frühjahrs- und Sommermonaten weist allerdings auf einen potentiell negativen Einfluss des invasiven Raubsäugers auf diese Tiergruppe hin. Zusammenfassend lässt sich festhalten, dass die spezifischen Charakteristika des anthropogen geprägten Untersuchungsgebietes sowohl Nahrungsökologie und Aktivitätsmuster als auch Raumnutzung und Populationsdichte der lokalen Minkpopulation beeinflussen. Eine besondere Rolle hierbei spielt die Bewirtschaftung der Fischteiche, denn vor allem daraus resultiert für die Minke eine saisonal unterschiedliche Verfügbarkeit an Lebensraum und Nahrung. Negative Auswirkungen des Amerikanischen Nerzes auf die einheimische Tierwelt wurden in anderen europäischen Ländern belegt und rechtfertigen die Einstufung dieser Art als „invasiv“. Demzufolge wird in der vorliegenden Arbeit ein Management empfohlen, bei dem der Focus auf einem effektiven Monitoring und gegebenenfalls auf zweckmäßigen, an die lokalen Bedingungen angepassten Fang- oder Abwehrmaßnahmen liegt. Zudem sollten, um einer weiteren Ausbringung in das Freiland vorzubeugen, die wenigen noch existierenden Minkfarmen besser gegen Ausbrüche bzw. Freilassungsaktionen gesichert werden. Langfristig ist ein generelles Besitz- und Vermarktungsverbot für die Art wünschenswert.

Philosophiae Doctor - PhD / Moss frogs are restricted to permanently moist terrestrial habitats in the south-western Cape Fold Mountains. There is a very close association between Arthroleptella distribution and Table Mountain Sandstone. Suitable habitats are generally occupied by allopatric populations of moss frogs. Comprehensive spatial sampling of moss frogs (genus Arthroleptella) in the Cape Floristic Region biodiversity hotspot yielded 192 new distribution records; 5 842 advertisement calls from 240 individual male frogs; 31 Rag-1,76 16S, 54 12S sequences and morphological measurements of 90 specimens. There are many differences in male advertisement call and genetic sequences between populations on different mountain ranges, even over small distances. A mitochondrial and nuclear gene phylogeny of the southern African Pyxicephalidae places Natalobatrachus as the sister genus to Arthroleptella. Application of a Bayesian relaxed molecular clock model indicates that Arthroleptella arose between 20 and 39 Ma. Phylogenetic trees return two main clades within Arthroleptella: one consists of species which exhibit chirp-like calls and the second contains species with longer calls composed of a series of clicks. These two clades diverged between 19 and 22 Ma. There is a general pattern of strong phylogeographic structure with many small, isolated populations. Three species are identified within the Chirping clade and seven in the Clicking clade, including three undescribed species. This population structure is a result of the patchy distribution of suitable habitat and low vagility of the moss frogs.The distribution and speciation of moss frogs has been affected by drying and cooling climate change, changing geomorphology over the last 20 Ma and the increasing prevalence of fire over the last 5 Ma. An assessment of the threat status of each species according to IUCN criteria categorised one species as Least Concern, seven as Near Threatened, one as Vulnerable and one as Critically Endangered. The primary threats to Arthroleptella are invasive alien plants and increased fire frequencies and intensities.