A crise de extinções antropogênicas é um problema planetário que erode a biodiversidade a taxas muito superiores àquelas registradas pelos eventos geológicos de extinção. Essa grande perda de espécies pode desencadear a sexta onda de extinções em massa, ocasionando um empobrecimento na evolução mundial e comprometer os processos de especiação. Nas últimas décadas surgiram muitas iniciativas de conservação que atuam em diferentes esferas para proteger a biodiversidade mundial. No entanto, locais insubstituíveis onde ocorrem espécies microendêmicas ameaçadas de extinção deve ser a prioridade em medidas de conservação, pois representam a \"ponta do iceberg\" na crise das extinções. Fatores de ameaça contribuem na vulnerabilidade das espécies microendêmicas, intensificando seu risco de extinção. A Cadeia do Espinhaço em Minas Gerais, inserida no bioma Cerrado, é reconhecidamente uma região de microendemismos da flora e está sujeita a muitos fatores de ameaça como a mineração, a agropecuária e o extrativismo. A identificação das áreas mais vulneráveis às ameaças, bem como, a identificação dos sítios prioritários, onde ocorrem espécies de único refúgio, pode evidenciar a necessidade de conservação de uma região única com biodiversidade exclusiva. Portanto, os objetivos gerais deste estudo são: identificar as espécies-alvo da flora e mapear seus sítios prioritários, avaliar o estado de conservação da Cadeia do Espinhaço em Minas Gerais, identificar as principais ameaças e sua vulnerabilidade e testar a eficiência dos sítios prioritários das espécies microendêmicas típicas como indicadores de espécies ameaçadas. Para isto, foram utilizadas bases cartográficas e imagens de satélite processadas em Sistema de Informação Geográfica, informações de herbários e coordenadas para caracterizar a distribuição das espécies e a aplicabilidade da metodologia da Aliança para Extinção Zero (AZE), identificando os sítios prioritários para conservação. Foram identificadas as principais ameaças que ocorrem nos sítios por meio da análise de uso e ocupação das terras, revisão sistemática da literatura e levantamento das ameaças que afetam diretamente as espécies para calcular os índices de vulnerabilidade dos sítios mapeados. Com isto, foram identificadas 22 espécies-alvo distribuídas em sete sítios prioritários no Espinhaço mineiro, cujas principais ameaças são mineração, agropecuária, queimadas, extrativismo, visitação predatória e expansão urbana. Os resultados monstraram ainda que as ameaças secundárias são muito importantes na região, tornando os sítios de Serra do Cipó, Diamantina e Águas Vertentes os mais vulneráveis a essas perturbações. Os sítios prioritários representam cerca de 83% das espécies ameaçadas no Espinhaço mineiro possibilitando, ações em conservação eficazes nestas áreas. O Brasil é o primeiro País a mapear sítios prioritários para espécies-alvo típicas da flora e testar o estado de conservação destas áreas, revelando quais locais são mais vulneráveis e que necessitam de ações de conservação urgentes / The crisis of anthropogenic extinctions is a planetary problem that erodes biodiversity at rates much higher than those recorded by geological extinction events. This great loss of species can trigger the sixth wave of mass extinctions, causing an impoverishment in world evolution and compromising the processes of speciation. In the last decades many conservation initiatives have emerged that act in different spheres to protect the world\'s biodiversity. However, irreplaceable sites where microendemic species are threatened with extinction should be the priority in conservation measures, as they represent the \"top of the iceberg\" in the crisis of extinctions. Threat factors contribute to the vulnerability of microendemic species, intensifying their risk of extinction. The Espinhaço Mountain Range in Minas Gerais, is part of the Cerrado biome, recognized as a microendemism region of flora and is subject to many threat factors such as mining, farming and extractivism. Identification of areas most vulnerable to threats, as well as identification of priority sites where trigger species occur, may highlight the need for conservation of a unique region with exclusive biodiversity. Therefore, the general objectives of this study are: to identify the target species of the flora and to map their priority sites, to evaluate the conservation status of the Espinhaço Mountain Range in Minas Gerais, to identify the main threats, their vulnerability and to test the efficiency of the priority sites of the typical microendemic species as indicators of endangered species. For this, cartographic bases and satellite images processed in Geographic Information System, herbarium and coordinate information were used to characterize the distribution of species and the applicability of the Alliance for Zero Extinction (AZE) methodology, to identify the priority conservation sites. The main threats that occurred in the sites were identified through analysis of land use and occupation, systematic review of the literature and identification of the threats that directly affect the species to calculate the vulnerability indexes of the mapped sites. Were identifyed 22 trigger species distributed in seven priority sites in the Espinhaço of Minas Gerais, whose main threats are mining, farming, burning, extractivism, predatory visitation and urban expansion. The results also showed that secondary threats are very important in the region, making the Serra do Cipó, Diamantina and Aguas Vertentes sites the most vulnerable to these disturbances. The priority sites represent about 83% of the threatened species in the Espinhaço Mountain Range of Minas Gerais, enabling effective conservation actions in these areas. Brazil is the first country to map priority sites for typical target species of the flora and to test the conservation status of these areas, revealing which sites are most vulnerable and requiring urgent conservation actions

A wide range of ecological communities ranging from polar terrestrial to tropical marine environments are affectedby global climate change. Over the last century, atmospheric temperature has increased by an average of 0. 60 C andis expected to rise by 1.1- 6.40C over the next 100 years. This rising temperature has increased the intensity andfrequency of weather extremes due to which a large number of species are facing risk of extinction. Studies haveshown that species existing on lower latitude are more sensitive to temperature variability compared to speciesexisting on higher latitude but temperature is increasing rapidly in higher latitude compare to lower latitude. Thisuneven distribution of temperature sensitive species and warming rate has highlighted the need for combined studiesof temperature variability and sensitiveness of species to predict how the ecosystems will respond to increasinglyvariable climate. Using a generalized Rosenzweig-MacArthur model, I explored how temperature variability andsensitivity of species will affect the extinction risks of species and how the connectance and species-richness ofecological communities will govern this response. This study showed that the risk of extinction of species mostlydepends on their sensitivity to temperature deviation from the optimum value and level of temperature variability.Among these two, sensitivity of species to temperature deviation was most prominent factor affecting extinction risk.In this study, connectance did not show any effect on mean extinction risk and time taken by a certain proportion ofspecies to reach pre-defined extinction thresholds. But, species-richness showed some effect on mean extinction riskof species. It was found that risk of extinction of species in species-rich communities was higher compared tospecies-poor communities. Species-rich communities also took shorter time before they lost 1/6 of the species. Thepresent study also suggests a possible tipping point due to increasing temperature variability in near future. In furtherstudies, different sensitivity of species at different trophic levels and the possible evolution of sensitivity of speciesshould also be consider while predicting how ecological communities will respond to changing climate in the longrun.

Depuis quelques dizaines d’années, un intérêt croissant s’est développé pour la protection des espèces et la compréhension des mécanismes qui les conduisent à l’extinction. Actuellement, les causes d’extinction sont pour la grande majorité d’origine anthropique, mais un certain nombre de facteurs intrinsèques, propres à chaque espèce, peuvent interagir avec ces pressions anthropiques, pour aboutir au risque d’extinction. De nombreuses études ont mis en évidence l’impact des traits d’histoires de vie et des caractéristiques écologiques dans la vulnérabilité des espèces à l’extinction, mais très peu se sont penchées sur le rôle du comportement. Or, de par leur nature, tout un ensemble de comportements pourraient constituer des facteurs de vulnérabilité intrinsèques chez les espèces, que ce soit au niveau du risque d’extinction, ou au niveau des principales pressions anthropiques qui existent actuellement. Le but de cette thèse est de déterminer l’impact des caractéristiques du système social et de l’intensité de la sélection sexuelle dans la vulnérabilité des espèces de Primates i) aux principales pressions anthropiques (i.e. chasse, exploitation forestière et agriculture), à un niveau local, en portant une attention spécial au rôle d’infanticide dans la vulnérabilité à la chasse et ii) au risque d’extinction tel que décrit par l’UICN, au niveau global. Ce dernier point nous a amenés à analyser plus spécifiquement l’impact de l’hétérogénéité de l’empreinte humaine dans le risque d’extinction. Toutes nos études reposent sur une approche d’analyses comparatives. Nos différents travaux ont permis de mettre en évidence des effets du comportement à aux différentes échelles spatiales et pour les deux niveaux de vulnérabilité, mais avec des différences dans la nature des variables comportementales impliquées. Nous avons identifié des effets de la taille moyenne des groupes et du système socio-reproducteur dans la vulnérabilité à l’exploitation forestière, mais pas pour les autres menaces testées. De plus, ces effets ont été retrouvés au niveau du risque d’extinction, mais dans des sens différents. Ainsi, les mécanismes impliqués dans la vulnérabilité des espèces diffèrent selon le type de vulnérabilité étudié, faisant intervenir différents effets Allee. / Improving species protection and better understanding the mechanisms leading to population decline and ultime extinction has become a major research area over the last decades. Nowadays, the causes of extinction are mostly anthropogenic, but some intrinsic factors, specific to each species, can interact with these anthropogenic pressures to determine the extinction risk. Many studies have highlighted the impact of life history traits and ecological characteristics on species vulnerability to extinction, but very few have investigated the role of behaviour. Because of the mechanisms they imply, several behaviours could constitute intrinsic factors of vulnerability among species, at the level of extinction risk, or concerning the main anthropogenic pressures threatening species. The aim of this thesis is to determine the impact of the social system and sexual selection on primate vulnerability i) to the main anthropogenic threats (i.e. hunting, logging and agriculture) and, particularly, the role of infanticide on their vulnerability to hunting, and ii) to the extinction risk as described by the IUCN conservation status. This point has lead us to examine also the impact of human footprint heterogeneity on extinction risk. All our studies are based on a comparative analysis approach. Our different works highlighted several impacts of behavioural variables at the two spatial scales and for the two levels of vulnerability, but with differences in the nature of the behavioural variables. We identified significant effects of the average group size and the socio-reproductive system in species vulnerability to logging, but not in species vulnerability to the other threats. Moreover, these effects have also been found at the level of the extinction risk, but in different ways. Thus, the mechanisms implicated in the vulnerability are different according to the type of vulnerability, and rely on several Allee effects.

A dinâmica de populações trata das variações, no tempo e no espaço, das densidades e tamanhos de populações. Estudos sobre a dinâmica de espécies arbóreas tropicais, mais especificamente, só ganharam notoriedade a partir da década de 1970, quando o risco de extinção de espécies de interesse econômico tornou-se premente. Como a destruição dos biomas brasileiros vem sendo progressiva e contínua, uma parcela significativa da diversidade encontra-se sob ameaça de extinção, particularmente na Floresta Ombrófila Densa Atlântica, cujos remanescentes correspondem a menos de 7,5 % de sua cobertura original. Os objetivos deste trabalho são: (1) descrever as dinâmicas populacionais de Schefflera angustissima (Araliaceae) e de Andira anthelmia (Fabaceae), (2) estabelecer suas relações com o clima e a vegetação e (3) investigar se existe risco de extinção local. As populações foram amostradas em 4 áreas de 0,25ha, em um remanescente de Floresta Ombrófila Densa Atlântica na região de São Paulo. Investigaram-se as relações de suas estruturas verticais e espaciais com a estrutura e a dinâmica da cobertura da vegetação. Seus ciclos de vida foram estudados e modelados. Foi investigada a influência de processos regulatórios. Suas dinâmicas foram estudadas com base em projeções de modelos matriciais determinísticos e estocásticos ambientais. Os riscos de extinção foram inferidos dos resultados destas projeções. Áreas com vegetação menos densa e sujeitas a maior influxo de energia luminosa parecem favorecer mais S. angustissima do que A. anthelmia. Ambas as populações estão sujeitas a processos regulatórios, mas estes pouco influenciam suas dinâmicas atuais. Em geral, S. angustissima apresentou desempenho superior ao de A. anthelmia. As duas populações mostraram-se sob risco de extinção segundo os modelos determinísticos, mas apenas A. anthelmia segundo os modelos estocásticos. Nos dois casos, sobrevivência e crescimento mostraram-se mais importantes do que a fecundidade, e os principais fatores responsáveis por mortes e retardo no crescimento das plantas foram o ataque de lianas lenhosas e a queda de galhos e de árvores mortas. Foram ainda encontradas evidências da presença de um “gargalo" no ciclo de vida de A. anthelmia, onde o crescimento de infantes está sendo tão restringido que estas plantas não estão conseguindo avançar em sua ontogenia. Aparentemente, esse gargalo resulta do ataque de insetos formadores de galhas. Incrementos plausíveis nas taxas de sobrevivência e de crescimento das plantas mostraram–se suficientes para reverter os riscos de extinção. / Population dynamics deals with variation in time and space in the density and abundance of populations. The studies about the dynamics of tropical rain forest tree species, in particular, have become popular only about 1970, when the extinction risks for species of economic interest became pressing. Because the Brazilian biomes are being destroyed progressive and continuously, a significant portion of their diversity is threatened, specially in the Atlantic Rain Forest; whose remnants enclose less than 7,5 % of its original cover. The objectives of this thesis are: (1) to describe the population dynamics of Schefflera angustissima (Araliaceae) and Andira anthelmia (Fabaceae), (2) to expose their relation to the climate and the vegetation and (3) to investigate whether they are under local extinction risks. The populations were sampled in four 0,25ha areas, within an Atlantic Rain Forest remnant in São Paulo region. The relations between the populations’ vertical and spatial structures and the vegetation structure and cover dynamics were investigated. Their life cycles were studied and modeled. The influences of regulatory processes were also investigated. Their dynamics were studied trough projections of deterministic and environmental stochastic matrix models. The extinction risks were inferred from these projections’ results. Sites where the vegetation is less dense and subject to a higher influx of luminous energy seem to favor more S. angustissima than A. anthelmia. Both populations are subject to regulatory processes, but these processes have little influence on their present dynamics. In general, S. angustissima showed a higher fitness than A. anthelmia. According to the deterministic models, both populations are under extiction risk, though only A. anthelmia is, according to the stochastic models. In both populations, survivorship and growth rates were more important than fecundity rates, and the major factors responsible for death and retardation of plants’ growth were the woody lianas attack and the fall down of dead trees and branches over the plants. There are also evidence of a “bottle neck" effect in the A. anthelmia’s life cycle, where the infants growth is being so restricted that these plants are not succeeding at advancing along their ontogeny. Apparently, this “bottle neck" effect results from the attack of gall forming insects. Reasonable increments in the plants’ survivorship and growth rates are enough to revert the populations’ extiction risks.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-08-28T11:09:57Z No. of bitstreams: 2 Tese - Flávia de Figueiredo Machado - 2018.pdf: 3861358 bytes, checksum: d1d99c2f2391b7000da1d2f269179035 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-08-28T11:16:05Z (GMT) No. of bitstreams: 2 Tese - Flávia de Figueiredo Machado - 2018.pdf: 3861358 bytes, checksum: d1d99c2f2391b7000da1d2f269179035 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-08-28T11:16:05Z (GMT). No. of bitstreams: 2 Tese - Flávia de Figueiredo Machado - 2018.pdf: 3861358 bytes, checksum: d1d99c2f2391b7000da1d2f269179035 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / (Sem resumo em outra língua) / Nesta tese tive o objetivo de investigar os fatores relacionados ao risco de extinção em primatas, assim como as tendências e vieses nos esforços de pesquisas voltadas para a conservação do grupo. No primeiro capítulo, por meio de uma cienciometria, mostrei quais são os temas, abordagens e espécies mais estudadas, bem como as instituições e locais que mais realizam esses estudos. Demonstrei que os esforços de pesquisa com conservação de primatas não têm sido motivados pelo status de conservação das espécies e tamanho da sua distribuição, e sim pelo peso corporal e idade (tempo desde a sua descrição). No segundo capítulo, testei se a dieta de primatas pode predizer o risco de extinção das espécies, mensurando dieta de diferentes maneiras: amplitude de dieta, diversidade de dieta, tipo de dieta e disparidade de itens. Concluí que a dieta prediz o risco de extinção, mas apenas pela métrica de disparidade de itens, sendo que espécies capazes de consumir itens mais diferentes entre si estarão menos propensas à extinção. No terceiro e último capítulo, avaliei os padrões de risco de extinção em primatas. Incluí variáveis intrínsecas e extrínsecas em modelos que particionam a variância em componentes espaciais, filogenéticas e independentes. Mostrei que espécies próximas na filogenia e no espaço tendem a apresentar status de ameaça semelhantes. Além disso, encontrei que a região Madagascar é a pior para os primatas e que o tempo de desmame, tamanho da distribuição geográfica e fatores como “human footprint” e pobreza humana influenciam no risco de extinção das espécies. Por fim, demonstrei que o espaço possui grande influência no risco de extinção de primatas, não devendo ser ignorado nesse tipo de análise.

A dinâmica de populações trata das variações, no tempo e no espaço, das densidades e tamanhos de populações. Estudos sobre a dinâmica de espécies arbóreas tropicais, mais especificamente, só ganharam notoriedade a partir da década de 1970, quando o risco de extinção de espécies de interesse econômico tornou-se premente. Como a destruição dos biomas brasileiros vem sendo progressiva e contínua, uma parcela significativa da diversidade encontra-se sob ameaça de extinção, particularmente na Floresta Ombrófila Densa Atlântica, cujos remanescentes correspondem a menos de 7,5 % de sua cobertura original. Os objetivos deste trabalho são: (1) descrever as dinâmicas populacionais de Schefflera angustissima (Araliaceae) e de Andira anthelmia (Fabaceae), (2) estabelecer suas relações com o clima e a vegetação e (3) investigar se existe risco de extinção local. As populações foram amostradas em 4 áreas de 0,25ha, em um remanescente de Floresta Ombrófila Densa Atlântica na região de São Paulo. Investigaram-se as relações de suas estruturas verticais e espaciais com a estrutura e a dinâmica da cobertura da vegetação. Seus ciclos de vida foram estudados e modelados. Foi investigada a influência de processos regulatórios. Suas dinâmicas foram estudadas com base em projeções de modelos matriciais determinísticos e estocásticos ambientais. Os riscos de extinção foram inferidos dos resultados destas projeções. Áreas com vegetação menos densa e sujeitas a maior influxo de energia luminosa parecem favorecer mais S. angustissima do que A. anthelmia. Ambas as populações estão sujeitas a processos regulatórios, mas estes pouco influenciam suas dinâmicas atuais. Em geral, S. angustissima apresentou desempenho superior ao de A. anthelmia. As duas populações mostraram-se sob risco de extinção segundo os modelos determinísticos, mas apenas A. anthelmia segundo os modelos estocásticos. Nos dois casos, sobrevivência e crescimento mostraram-se mais importantes do que a fecundidade, e os principais fatores responsáveis por mortes e retardo no crescimento das plantas foram o ataque de lianas lenhosas e a queda de galhos e de árvores mortas. Foram ainda encontradas evidências da presença de um “gargalo” no ciclo de vida de A. anthelmia, onde o crescimento de infantes está sendo tão restringido que estas plantas não estão conseguindo avançar em sua ontogenia. Aparentemente, esse gargalo resulta do ataque de insetos formadores de galhas. Incrementos plausíveis nas taxas de sobrevivência e de crescimento das plantas mostraram–se suficientes para reverter os riscos de extinção. / Population dynamics deals with variation in time and space in the density and abundance of populations. The studies about the dynamics of tropical rain forest tree species, in particular, have become popular only about 1970, when the extinction risks for species of economic interest became pressing. Because the Brazilian biomes are being destroyed progressive and continuously, a significant portion of their diversity is threatened, specially in the Atlantic Rain Forest; whose remnants enclose less than 7,5 % of its original cover. The objectives of this thesis are: (1) to describe the population dynamics of Schefflera angustissima (Araliaceae) and Andira anthelmia (Fabaceae), (2) to expose their relation to the climate and the vegetation and (3) to investigate whether they are under local extinction risks. The populations were sampled in four 0,25ha areas, within an Atlantic Rain Forest remnant in São Paulo region. The relations between the populations’ vertical and spatial structures and the vegetation structure and cover dynamics were investigated. Their life cycles were studied and modeled. The influences of regulatory processes were also investigated. Their dynamics were studied trough projections of deterministic and environmental stochastic matrix models. The extinction risks were inferred from these projections’ results. Sites where the vegetation is less dense and subject to a higher influx of luminous energy seem to favor more S. angustissima than A. anthelmia. Both populations are subject to regulatory processes, but these processes have little influence on their present dynamics. In general, S. angustissima showed a higher fitness than A. anthelmia. According to the deterministic models, both populations are under extiction risk, though only A. anthelmia is, according to the stochastic models. In both populations, survivorship and growth rates were more important than fecundity rates, and the major factors responsible for death and retardation of plants’ growth were the woody lianas attack and the fall down of dead trees and branches over the plants. There are also evidence of a “bottle neck” effect in the A. anthelmia’s life cycle, where the infants growth is being so restricted that these plants are not succeeding at advancing along their ontogeny. Apparently, this “bottle neck” effect results from the attack of gall forming insects. Reasonable increments in the plants’ survivorship and growth rates are enough to revert the populations’ extiction risks.

Societal Impact Statement Plants play fundamental roles in ecosystems, yet merely 10% of species have an assessment of their global extinction risk. Through the integration of national Red Lists and comprehensive global plant distribution data, we identify previously unassessed plant species in Europe that are threatened throughout their geographic range and thus at risk of global extinction. Our workflow can be replicated to facilitate the integration of disparate national monitoring efforts around the world and help accelerate global plant risk assessments. Summary • A comprehensive extinction risk assessment for plant species is a global biodiversity target. However, currently, only 10% of plant diversity is assessed in the global Red List of Threatened Species. To guide conservation and restoration actions in times of accelerated species extinction, plant risk assessments must be expedited. • Here, we examine the extinction risk of vascular plant species in Europe through the integration of two data streams: (1) national Red Lists and (2) global plant distribution data from Kew's Plants of the World Online database. For each species listed on a national Red List, we create a list of countries that form part of its range and indicate the threat status in these countries, allowing us to calculate the percentage of the range in which a given species is listed as threatened. • We find that 7% to 9% of European vascular plant diversity is threatened in its entire range, the majority of which are single-country endemics. Of these globally threatened species, 84% currently have no assessment in the global Red List. • With increasing national biodiversity monitoring commitments shaping the post- 2020 policy environment, we anticipate that integrating national Red Lists with global plant distribution data is a scalable workflow that can help accelerate global risk assessments of plants.

Das Aussterberisiko einer Art ist nicht zufällig, sondern wird von mehreren Faktoren bestimmt, die geografische, ökologische und morphologische Merkmale umfassen. Einige dieser Merkmale sind Teil der Kriterien zur Einschätzung der Gefährdung einer Art, wie zum Beispiel in der Roten Liste der IUCN. Diese Beurteilungen sind ein wichtiges Werkzeug für den Artenschutz, da sie eine Verteilung der Maßnahmen auf die am stärksten gefährdeten Arten ermöglichen. Dies ist besonders wichtig für Amphibien, die Wirbeltiergruppe mit dem derzeit höchsten Anteil an bedrohten Arten. Bei einem großen Teil der Arten fehlt jedoch eine Einschätzung des Aussterberisikos. Weiter mangelt es auch an einer endgültigen Verifizierung des Einflusses der genutzten Merkmale auf das Aussterberisiko, da Aussterbeereignisse auf neontologischen Zeitskalen schwer zu erkennen sind. Der Fossilbericht stellt ein enormes Archiv an bereits geschehenen Aussterbeereignissen dar und bietet die Möglichkeit den Einfluss bestimmter Merkmale auf die Gefährdung zu testen. In der vorliegenden Arbeit untersuche ich Merkmale von Amphibienarten, die zum Aussterberisiko dieser zunehmend gefährdeten Gruppe beitragen und bestätige die Bedeutung der geographischen Reichweite für das Aussterberisiko. Die in dem sich aktuell entwickelnden Gebiet Conservation Paleobiology angesiedelte Arbeit konzentriert sich auf die Verbindung von paläontologischen und neontologischen Daten, und wie diese Kombination dazu beitragen kann das Wissen über Aussterberisiko-beeinflussende Faktoren zu erweitern. Dies wird durch die Analyse verschiedener im Fossilbericht überlieferter Artmerkmale und der Kombination der Erkenntnisse mit Ergebnissen der Roten Liste und Klimadaten erreicht. In meiner Arbeit zeige ich mögliche Anwendungen des Fossilberichts auf aktuellen Themen des Artenschutzes und wie eine Kombination beider Bereiche zum tieferen Verständnis von Gefährdungsfaktoren beitragen kann. / The extinction risk of a species is not random, but rather shaped by several factors comprising geographical, environmental and morphological traits. Some of these traits have been incorporated in assessment procedures for the classification of extant species' extinction risk, such as the International Union for Conservation of Nature (IUCN) Red List. These assessments are an important tool for conservation purposes, as they direct the available resources to species that are most reliant on support. This is especially important for amphibians, which are the the most endangered terrestrial vertebrate taxon today. However, a large number of species lack an assessment for extinction risk. Also, additional verification of the general influence of incorporated traits on extinction risk is needed, as real extinction events are difficult to detect on neontological time scales. The fossil record offers the opportunity to test the influence of certain traits on extinction risk as it provides an enormous archive of extinction events that already happened. In this thesis, I examine traits in amphibian species that contribute to the extinction risk of this increasingly endangered group and provide support for the importance of geographic range size on the extinction risk of species. Placed in the developing field of Conservation Paleobiology, the study concentrates on the connection between paleontological and neontological data and how this unique combination can add to the knowledge about traits that shaped the extinction risk of amphibian species. This is achieved by investigating species traits, conserved in the amphibian fossil record, and combining these findings with results from the IUCN Red List and climate data. The present dissertation shows possible applications of the fossil record to current questions in conservation biology and shows how a combination of both fields contributes to the understanding of factors that influence the extinction risk of species.

<p>Ecological models have problems showing the positive relationship between diversity and stability found in nature. Theory states that complex food webs have high extinction risks and low stability. However, persistent food webs found in nature are large and complex containing many interconnections between species. There are many possible mechanisms enabling persistent food webs such as; complex interaction patterns, asynchronous fluctuations of species densities, environmental fluctuations and spatial distribution. These factors have not been used in classical models. In this study, coloured environmental 1/f noise and dispersal between subpopulations were incorporated into a diamond shaped food web based on a model by Vasseur and Fox 2007. Contradictions between theoretical and empirical results regarding food webs can be resolved by detailed analyses of models, withholding stabilizing mechanisms. Weak environmental 1/f noise generated an increased coefficient of stability but the stabilizing effect of noise can be questioned because of a decreased mean food web biomass and reduced stabilizing effect when reddened. However, detailed studies of the food web revealed that noise can redistribute density proportions between species, evading lowest species density and thereby increase food web resistance to demographic stochasticity and catastrophes. Noise induced density proportion shifts imply that large population sizes are no insurance towards future increase in environmental variance. Synchrony of species environmental responses and dispersal between subpopulations can both have major influences on stability and extinction risk of smaller food webs indicating that spatial structure could be one of the dominating factors stabilizing complex food webs found in nature.</p>

Natural and human induced environmental changes affect populations at different time scales. If they occur in a spatial heterogeneous way, they cause spatial variation in abundance. In this thesis I addressed three topics, all related to the question, how environmental changes influence population dynamics.<br><br> In the first part, I analysed the effect of positive temporal autocorrelation in environmental noise on the extinction risk of a population, using a simple population model. The effect of autocorrelation depended on the magnitude of the effect of single catastrophic events of bad environmental conditions on a population. If a population was threatened by extinction only, when bad conditions occurred repeatedly, positive autocorrelation increased extinction risk. If a population could become extinct, even if bad conditions occurred only once, positive autocorrelation decreased extinction risk. These opposing effects could be explained by two features of an autocorrelated time series. On the one hand, positive autocorrelation increased the probability of series of bad environmental conditions, implying a negative effect on populations. On the other hand, aggregation of bad years also implied longer periods with relatively good conditions. Therefore, for a given time period, the overall probability of occurrence of at least one extremely bad year was reduced in autocorrelated noise. This can imply a positive effect on populations. The results could solve a contradiction in the literature, where opposing effects of autocorrelated noise were found in very similar population models.<br><br> In the second part, I compared two approaches, which are commonly used for predicting effects of climate change on future abundance and distribution of species: a "space for time approach", where predictions are based on the geographic pattern of current abundance in relation to climate, and a "population modelling approach" which is based on correlations between demographic parameters and the inter-annual variation of climate. In this case study, I compared the two approaches for predicting the effect of a shift in mean precipitation on a population of the sociable weaver <i>Philetairus socius</i>, a common colonially living passerine bird of semiarid savannahs of southern Africa. In the space for time approach, I compared abundance and population structure of the sociable weaver in two areas with highly different mean annual precipitation. The analysis showed no difference between the two populations. This result, as well as the wide distribution range of the species, would lead to the prediction of no sensitive response of the species to a slight shift in mean precipitation. In contrast, the population modelling approach, based on a correlation between reproductive success and rainfall, predicted a sensitive response in most model types. The inconsistency of predictions was confirmed in a cross-validation between the two approaches. I concluded that the inconsistency was caused, because the two approaches reflect different time scales. On a short time scale, the population may respond sensitively to rainfall. However, on a long time scale, or in a regional comparison, the response may be compensated or buffered by a variety of mechanisms. These may include behavioural or life history adaptations, shifts in the interactions with other species, or differences in the physical environment. The study implies that understanding, how such mechanisms work, and at what time scale they would follow climate change, is a crucial precondition for predicting ecological consequences of climate change.<br><br> In the third part of the thesis, I tested why colony sizes of the sociable weaver are highly variable. The high variation of colony sizes is surprising, as in studies on coloniality it is often assumed that an optimal colony size exists, in which individual bird fitness is maximized. Following this assumption, the pattern of bird dispersal should keep colony sizes near an optimum. However, I showed by analysing data on reproductive success and survival that for the sociable weaver fitness in relation to colony size did not follow an optimum curve. Instead, positive and negative effects of living in large colonies overlaid each other in a way that fitness was generally close to one, and density dependence was low. I showed in a population model, which included an evolutionary optimisation process of dispersal that this specific shape of the fitness function could lead to a dispersal strategy, where the variation of colony sizes was maintained. / Änderungen in der Umwelt - sowohl natürliche Variabilität als auch anthropogene Änderungen - beeinflussen Populationen auf verschiedenen Zeitskalen. Wenn sie räumlich heterogen wirken, verursachen sie räumliche Variabilität in der Abundanz. In dieser Dissertation habe ich drei Themen bearbeitet, die sich auf den Effekt von Änderungen in der Umwelt auf Populationsdynamiken beziehen.<br><br> Im ersten Teil untersuchte ich an einem einfachen Populationsmodell den Effekt von positiver zeitlicher Autokorrelation im Umweltrauschen auf das Extinktionsrisiko einer Population. Der Effekt der Autokorrelation hing davon ab, wie empfindlich eine Population gegenüber singulären, katastrophenähnlichen Ereignissen schlechter Umweltbedingungen war. War die Population nur dann direkt bedroht, wenn eine Serie von schlechten Umweltbedingungen auftrat, erhöhte positive Autokorrelation das Extinktionsrisiko. Konnte eine Population auch dann aussterben, wenn schlechte Umweltbedingungen einzeln auftraten, verringerte positive Autokorrelation das Extinktionsrisiko. Diese unterschiedlichen Effekte konnten durch zwei Eigenschaften autokorrelierter Zeitreihen erklärt werden. Einerseits erhöht positive Autokorrelation die Wahrscheinlichkeit, daß in einer Zeitreihe Serien von schlechten Bedingungen auftreten. Andererseits führt die Aggregation von schlechten Jahren auch zu langen Zeiträumen mit relativ guten Bedingungen. Deshalb ist die Wahrscheinlichkeit, daß innerhalb eines bestimmten Zeitraums zumindest ein extrem schlechtes Jahr auftritt, geringer unter positiver Autokorrelation. Die Ergebnisse konnten einen Widerspruch in der Literatur aufklären, in dem unterschiedliche Effekte von autokorreliertem Umweltrauschen auf das Extinktionsrisiko gefunden wurden, obwohl sehr ähnliche Modelle verwendet wurden.<br><br> Im zweiten Teil, verglich ich zwei Methoden, die häufig verwendet werden, um den Effekt von Klimawandel auf die zukünftige Verbreitung und Abundanz von Arten vorauszusagen: Ein "Raum-ersetzt-Zeit-Ansatz" ("space for time approach"), in dem Voraussagen aufgrund der aktuellen geographischen Verbreitung und Abundanz einer Art in Relation zum Klima getroffen werden, und ein "Populationsmodell-Ansatz", der auf Korrelationen zwischen demographischen Parametern und der jährlichen Variabilität im Klimas beruht. In einer Fallstudie verglich ich die beiden Methoden, um den Effekt einer Änderung im mittleren Niederschlag auf eine Population des Siedelwebers <i>Philetairus socius</i> vorauszusagen. Der Siedelweber ist eine häufige, koloniale Vogelart in semiariden Savannen im südlichen Afrika. Im "space for time approach" verglich ich zwei Populationen des Siedelwebers in Gebieten mit stark unterschiedlichem mittleren Niederschlag. Die Untersuchung zeigte keinen Unterschied zwischen den beiden Populationen. Sowohl dieses Ergebnis als auch das weite Verbreitungsgebiet des Siedelwebers implizieren keine sensitive Reaktion der Art auf eine geringfügige Änderung im mittleren Niederschlag. Im Unterschied dazu zeigte der "Populationsmodell-Ansatz", der auf einer Korrelation zwischen Niederschlag und dem Reproduktionserfolg des Siedlerwebers beruhte, eine sensitive Reaktion in den meisten der untersuchten Modelltypen. Die Inkonsistenz der Ergebnisse wurde in einer Kreuz-Validierung der beiden Ansätze bestätigt. Aus der Untersuchung folgerte ich, daß die unterschiedlichen Ergebnisse dadurch verursacht wurden, daß die beiden Methoden unterschiedliche Zeitskalen widerspiegeln. Auf einer kurzen Zeitskala reagiert die Population sensitiv auf Änderungen im Niederschlag. Auf einer großen Zeitskala oder im räumlichen Vergleich kann die sensitive Reaktion jedoch durch eine Reihe von Mechanismen gepuffert oder kompensiert werden. Diese Mechanismen können Anpassungen im Verhalten oder in der Lebensgeschichte ("life history"), Änderungen in den Interaktionen mit andern Arten oder Unterschiede in der physikalischen Umgebung beinhalten. Diese Studie zeigt, daß ein Verständnis, wie solche Mechanismen funktionieren, und auf welcher Zeitskala sie wirken, eine wesentliche Voraussetzung ist, um Prognosen über ökologische Effekte des Klimawandels treffen zu können. Im dritten Teil untersuchte ich, warum Kolonien des Siedelwebers so stark in ihrer Größe variieren. Die Variabilität der Koloniegrößen ist erstaunlich, da man in Untersuchungen zur Kolonialität bei Tieren oft davon ausgeht, daß eine optimale Koloniegröße besteht, bei der die individuelle Fitneß maximiert ist. Aufgrund dieser Annahme sollten Vögel sich so im Raum ausbreiten, daß die Koloniegrößen möglicht nahe am Optimum liegen. In dieser Arbeit konnte ich jedoch anhand von Daten zum Reproduktionserfolg und zur Überlebensrate in Relation zur Koloniegröße zeigen, daß die Funktion der Fitneß in Abhängigkeit von der Koloniegröße nicht einer Optimumskurve folgt. Statt dessen überlagern sich positive und negative Effekte der Koloniegröße so, daß die Populationswachstumsrate generell nahe eins ist, und die Dichteabhängigkeit gering ist. Auf diesen Ergebnissen aufbauend zeigte ich in einem Populationsmodell, das einen evolutionären Optimierungsprozeß der Dispersal-Strategie beinhaltet, daß die spezifische Form der Fitneßfunktion zu einer Dispersal-Strategie führen kann, bei der die hohe Variabilität der Koloniegrößen aufrecht erhalten wird.