Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Melanoides tuberculatus (Müller, 1774) é um gastrópode dulceaquícola de origem afroasiática, atualmente com uma distribuição cosmopolita, devido a seu comportamento invasivo. Utilizamos em nosso trabalho o nome Melanoides tuberculatus por acreditar ser o mais correto para a espécie, pois também é encontrado na literatura o nome Melanoides tuberculata (Müller, 1774), combinação que não atende os preceitos do ICZN. Recuperamos registros em 52 países, sendo 25 na área nativa e 27 na área exótica de distribuição da espécie. Esta espécie foi recentemente introduzida em um riacho na Vila do Abraão (Ilha Grande), possivelmente através do despejo de água de aquário. O objetivo do trabalho foi avaliar a dinâmica populacional deste caramujo neste novo ambiente, assim como seus efeitos sobre a fauna acompanhante, durante dois anos, de julho/2006 até maio/2008, com coletas bimensais. O riacho foi dividido em oito pontos de coleta (P1, o mais a montante até P8, mais a jusante). As coletas foram realizadas através de duas metodologias, coleta direta e Surber. Os animais coletados foram triados, contados e identificados na menor categoria taxonômica possível.Fatores ambientais foram mensurados em cada ponto de coleta. Os testes parasitológicos e identificação do sexo foram realizados com os animais provenientes da coleta direta. Os exemplares de M. tuberculatus foram divididos em quatro classes de tamanho (CL) de acordo com a largura do animal (CL1 0,01 até 2,99 mm; CL2 3,00 até 5,99 mm; CL3 6,00 até 8,99 mm e CL4 >9,00 mm). Os dados foram analisados usando planilha Excel e o pacote estatístico SYSTAT 12. A população de M. tuberculatus apresentou um crescimento em quatro fases: lag, crescimento exponencial, queda e estabilização, diferindo do encontrado nos demais moluscos deste riacho, que apresentaram flutuações populacionais irregulares. O pico populacional foi em novembro/2007 com 3156 exemplares. A espécie se reproduz o ano todo, porém com um pico entre maio/2007 e novembro/2007, quando os indivíduos da CL1 representaram mais de 50% do total. A mortalidade se concentra nos indivíduos maiores (CL3 e CL4), a CL4 sempre representando menos de 5% dos animais coletados. Os testes parasitológicos foram todos negativos, não sendo encontradas interações com a helmintofauna. Observamos apenas fêmeas na população, tratando-se possivelmente de uma população inteiramente partenogenética. A espécie formou grandes agregados populacionais, com uma densidade máxima estimada de 47555 ind./m2, sendo o trecho onde a espécie foi primariamente detectada (P6-P8) o que apresentou as maiores densidades. A biomassa retirada foi de 4,578 kg e foram observados dois picos de biomassa, em março/2007 e novembro/2007. A dispersão de M. tuberculatus neste riacho foi predominantemente ativa, em um processo contra a corrente: em julho/2006 a espécie só ocorria entre o P6 e o P8, em setembro/2006 a identificamos no P5 e em maio/2007 no P4. As médias de tamanho nos pontos de coleta recém colonizados eram sempre maiores que nos pontos colonizados há mais tempo. O agrupamento obtido na Análise Discriminante com os dados da comunidade de macroinvertebrados reflete a alteração da comunidade provocada por M. tuberculatus, juntando os pontos de coleta onde não há a presença da espécie exótica e em outro grupo os pontos onde a espécie já ocorre, entre estes dois extremos ficaram os pontos colonizados durante o estudo. Foi observado o efeito negativo de M. tuberculatus sobre Chironomidae, Odonata e Pisidium punctiferum (Guppy, 1867) (regressões com tendência negativa e p<0,05). Estas espécies também foram menos abundantes nos pontos de coleta nos quais a espécie exótica ocorria. Efeitos não conclusivos foram observados sobre outros grupos. Concluímos que M. tuberculatus apresentou um crescimento populacional em quatro fases, como o demonstrado para outras espécies exóticas invasoras; sua dispersão ao longo do riacho ocorre de forma ativa e, alterou a estrutura da comunidade afetando negativamente outras espécies. / Melanoides tuberculatus (Müller, 1774) is an afro-asiatic freshwater gastropod but nowadays with a cosmopolitan distribution, due his invasive behavior. In this study are used the name Melanoides tuberculatus, it is also found in literature the name Melanoides tuberculata (Müller, 1774), this last name is not in accordance with ICZN rules. We found reports of this species in 52 countries, 25 in native area of distribution and 27 in exotic area. This species was recently introduced in a stream in Vila do Abraão (Ilha Grande), possibly by an aquarist. The aim of this work was to evaluate M. tuberculatus population dynamics in the new habitat, as also the effects of this snail over the fauna. The study was conducted between July/2006 and May/2008 with collections every two months. The stream was divided in eight collecting stations, being P1 the most upstream and P8 the most upstream. In each collecting station were performed two collecting methodologies, timed search and Surber. Collected animals were screened, counted, measured and identified to the lowest possible taxonomic level. Environmental factors were measured in each collection station. Melanoides tuberculatus specimens were divided in four size classes (CL) according to the animal width(CL1 0.01 to 2,99 mm; CL2 3.00 to 5.99 mm; CL3 6.00 to 8.99 mm e CL4 >9.00 mm). Data analysis was done in Excel and SYSTAT 12. The M. tuberculatus population showed a four stages growth: lag, exponential growth, falling and stabilization, a pattern different from others freshwater snails in this stream. Population maximum size was reached in November/2007, when was collected 3156 snails. This species reproduced along the year but with a reproduction peak from May/2007 to September/2007, when CL1 represented more than 50% of collected snails. Mortality was concentrated in biggest specimens (CL3 e CL4), CL4 represented less than 5% of collected snails. All parasitological tests were negative, so interactions with helminthes in the study period are nonexistent. Males are not observed in this population, being a entire partenogenetic population. Melanoides tuberculatus reached a dense population in this stream; maximum estimated density was 47555 snails/m2 on the place that this snail was first observed (P6-P8). Estimated removed biomass was 4,578 kg and was observed two biomass peaks in March/2007 and November/2007. Melanoides tuberculatus dispersal in this stream was active going upstream, reaching P5 in September/2006 and P4 in May/2007. The average size in recently colonized collection stations was bigger than in the other collection stations at the same time. Community composition groups obtained in Discriminant Analysis was influenced by distribution of M. tuberculatus in the stream, in one group was joined the collection stations without M. tuberculatus, in other group the stations with M. tuberculatus. The negative effect of this species was observed over Chironomidae, Odonata and Pisidium punctiferum (Guppy, 1867) (regression with negative tendencies and p<0,05). This species were less abundant in collect stations where M. tubercuatus occurs. Finally, we conclude that M. tuberculatus had a population growth in four stages, as described for other exotic invasive species; dispersion in this stream was active and changed community structure with negative effects over other species.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os fatores que explicam a distribuição observada em plantas e animais é uma pergunta que intriga naturalistas, biogeógrafos e ecólogos há mais de um século. Ainda nos primórdios da disciplina de ecologia, as tolerâncias ambientais já haviam sido apontadas como as grandes responsáveis pelo padrão observado da distribuição dos seres vivos, o que mais tarde levou à concepção de nicho ecológico das espécies. Nos últimos anos, o estudo das distribuições dos organismos ganhou grande impulso e destaque na literatura. O motivo foi a maior disponibilidade de catálogos de presença de espécies, o desenvolvimento de bancos de variáveis ambientais de todo o planeta e de ferramentas computacionais capazes de projetar mapas de distribuição potencial de um dado organismo. Estes instrumentos, coletivamente chamados de Modelos de Distribuição de Espécies (MDEs) têm sido desde então amplamente utilizados em estudos de diferentes escopos. Um deles é a avaliação de potenciais áreas suscetíveis à invasão de organismos exóticos. Este estudo tem, portanto, o objetivo de compreender, através de MDEs, os fatores subjacentes à distribuição de duas espécies de corais escleractíneos invasores nativos do Oceano Pacífico e ambas invasoras bem sucedidas de diversas partes do Oceano Atlântico, destacadamente o litoral fluminense. Os resultados mostraram que os modelos preditivos da espécie Tubastraea coccinea (LESSON, 1829), cosmopolita amplamente difundida na sua região nativa pelo Indo- Pacífico demonstraram de maneira satisfatória suas áreas de distribuição nas áreas invadidas do Atlântico. Sua distribuição está basicamente associada a regiões com alta disponibilidade de calcita e baixa produtividade fitoplanctônica. Por outro lado, a aplicação de MDEs foi incapaz de predizer a distribuição de T. tagusensis (WELLS,1982) no Atlântico. Essta espécie, ao contrário de sua congênere, tem distribuição bastante restrita em sua região nativa, o arquipélago de Galápagos. Através de análises posteriores foi possível constatar a mudança no nicho observado durante o processo de invasão. Finalmente, o sucesso preditivo para T. coccinea e o fracasso dos modelos para T. tagusensis levantam importantes questões sobre quais os aspectos ecológicos das espécies são mais favoráveis à aplicação de MDEs. Adicionalmente, lança importantes ressalvas na utilização recentemente tão difundida destas ferramentas como forma de previsão de invasões biológicas e em estudos de efeitos de alterações climáticas sobre a distribuição das espécies. / The factors underpinning the observed distribution of plants and animals across time and space are a central question in ecology and has intrigued scientists for over a century. But even back on those early times, the role of climatic tolerances of the species were recognized as one of the main explanations for such distributional patterns. Later, these assumptions gave rise to the concept of niche which triggered several advances in the study of natural history. Recently, these studies were addressed in the light of novel computational techniques capable of providing potential distributional maps for a given species, generically called Species Distribution Models (SDMs). This coupled with the broader availability of species occurrence records and of environmental data from international databases made studies with SDMs very popular and ubiquitous in the literature. One of the main uses of the SDMs approach is the assessment of potentially susceptible areas of invasion by non- indigenous species. Therefore, here we used SDMs to better understand the major factors related to the current distribution of two well established invasive scleractinian coral species in the Atlantic, both from the Pacific Ocean. The results showed that the models were successful in predicting the potentially invaded sites by the cosmopolitan Tubastraea coccinea (LESSON, 1829), broadly distributed throughout the Pacific. This species distribution was basically associated with increasing concentrations of calcite and lower levels of phytoplankton activity. However, the models were incapable of predicting the survival and establishment of T. tagusensis (WELLS, 1982) in the Atlantic. This species, unlike its congener, has a very restricted distribution in its native regions, the Galapagos Islands. A posterior analyzes indeed showed a niche shift during the invasion event of T. tagusensis in the Atlantic. Finally, the good modelling results for T. coccinea contrasted with the failure of modelling T. tagusensis invasion highlight important explanations on methodological procedures in SDMs. It also helps to better understand which ecological aspects of the species are favourable toward good modelling performance. In addition to that, these results calls for precaution when analyzing SDMs results, particularly in invasion and climate change scenarios studies.

As invasões por espécies exóticas vêm acarretando a homogeneização das comunidades naturais tornando-se; atualmente, a segunda principal causa da perda da biodiversidade. Entre os domínios brasileiros mais afetados está o Cerrado, que possui mais de 11 fitofisionomias e 33% de toda biodiversidade vegetal do país. As alterações pela atividade humana foram facilitadas em decorrência das áreas de Cerrado estarem dispostas em quase todo o território nacional e, na fisionomia de campo sujo, em particular, pela facilidade de mecanização e consequentemente pelo emprego da agricultura em larga escala. Dessa forma, foram inseridas gramíneas exóticas africanas para a melhoria da qualidade e produtividade do forrageio. Essas gramíneas se ajustaram tão bem em áreas de campo sujo que se expandiram desordenadamente e conduziram a um desequilíbrio estrutural e funcional destas áreas. O objetivo deste estudo foi investigar os padrões de utilização de recursos em gramíneas nativas e invasoras em um campo sujo levando em conta os períodos de maior e menor disponibilidade hídrica e os possíveis efeitos das variáveis microclimáticas sobre as respostas fisiológicas de gramíneas nativas e invasoras. A área de estudo localiza-se no Parque Estadual do Juquery, município de Franco da Rocha, Estado de São Paulo. As espécies utilizadas para o estudo foram as nativas: Tristachya leiostachya, Imperata brasiliensis, Axonopus pressus e Axonopus siccus. E as invasoras: Urochloa brizantha e Melinis minutiflora. As respostas fisiológicas frente às flutuações entre os períodos chuvoso e seco foram obtidas através de análises de trocas gasosas, análise de fluorescência e de medições das variáveis microclimáticas ao longo de 23 meses entre 8:00 e 12:00. Os resultados indicaram que gramíneas nativas investem 16% menos em fotoproteção do que gramíneas invasoras, sendo estas mais sensíveis aos fotodanos. No entanto, gramíneas nativas investem 13% a mais na síntese de clorofila total e se equivalem na capacidade de assimilação de carbono (A) e quanto as taxas de transporte de elétrons (ETR) indicando uma aprovável equivalência no uso da luz que pode estar associada a maiores taxas de eficiência no uso do nitrogênio em nativas tanto no período chuvoso (70%) quanto no seco (70%), além da ausência de diferença estatística no conteúdo de fósforo foliar por massa seca (Pmg/ms) e na eficiência no uso deste recurso (EUP). A condutância estomática (gs) e transpiração (E) foram respectivamente 22 e 60% maiores nas gramíneas nativas, por isso, a eficiência no uso da água foi 60% menor nestas em comparação às invasoras, tanto no período chuvoso quanto no seco. Tal regulação da condutância provavelmente esteve relacionada ao conteúdo de nitrogênio foliar que foi 100% maior nas invasoras no período chuvoso e 85% maior no período seco. Como esperado, gramíneas nativas apresentaram respostas de menor sensibilidade à seca em comparação às invasoras. Gramíneas invasoras, por sua vez, não corroboraram a expectativa de maior oportunismo em relação às nativas no período chuvoso quanto a captação de recursos, assim como, diferentemente do esperado, não se mostraram tão sensíveis à seca devido a um comportamento conservador no uso da água / Invasions by alien species are causing the homogenization of natural communities, becoming; currently the second leading cause of biodiversity loss. And among the most affected areas are the Brazilian Cerrado, which has more than 11 vegetation types and 33 % of all the country\'s biodiversity. The changes were facilitated by human activity due to the Cerrado areas are arranged in almost all the national territory. And in the face of dirty field, in particular, the ease of mechanization and consequently the employment of agriculture. Thus, African exotic grasses to improve the quality and productivity of foraging were inserted. These grasses have adjusted so well in areas of Cerrado dirty field that expanded wildly and led to a structural and functional imbalance of these areas. The aim of this study was to investigate the patterns of resource use of native grasses and weeds in a field Cerrado dirty taking into account periods of high and low water availability and the possible effects of microclimatic variables on the physiological responses of native and invasive grasses . The study area is located in the Juquery State Park, city of Franco da Rocha, State of Sao Paulo. The species used for the study were native: Tristachya leiostachya , Imperata brasiliensis , Axonopus pressus and Axonopus siccus. And the invaders: Urochloa brizantha and Melinis minutiflora. The physiological responses to fluctuations between wet and dry periods were obtained from analyzes of gas exchange, fluorescence analysis and measurements of microclimate variables over 23 months between 8:00 am and 12:00 am. The results indicate that native grasses Invest 16 % less than photoprotection grass weeds, which are more sensitive to photodamage. However, native grasses invest 13 % more in the synthesis of chlorophyll and are equivalent in capacity to carbon assimilation (A) and on the rate of electron transport (ETR) indicating an approvable equivalence in the use of light that can be associated with higher rates of nitrogen use efficiency in native both in the rainy season (70%) and the dry (70 %). Besides the lack of statistical difference in the content of phosphorus of leaf dry mass (Pmg/ms) and efficient use of this resource (EUP). The stomatal conductance (gs ) and transpiration ( E) were respectively 22 and 60 % higher in native grasses , so ; efficiency in water use was 60 % lower compared to these invasive both in the rainy season as in the dry. Such regulation conductance probably was related to leaf N content that was 100 % higher in invasive in the rainy season and 85 % higher in the dry season. As expected, responses of native grasses showed lower sensitivity to drought compared to invasive. Invasive grasses in tur ; does not support the expectation of greater opportunism in relation to native in the rainy season as fundraising , as well as , unlike expected, were not as sensitive to drought due to a more conservative behavior in water use

La mondialisation et les changements globaux actuels ont un impact considérable sur la distribution des espèces et la composition des communautés. Lorsque ces espèces sont impliquées dans une interaction hôte-parasite les changements dans leur répartition peuvent entraîner la (ré)émergence de maladies infectieuses. La fasciolose, maladie causée par les grandes douves du foie (Fasciola hepatica et Fasciola gigantica) est réémergente dans de nombreux points du globe. Il est difficile de mettre en place des programmes de contrôle parce que (1) les hôtes intermédiaires, des mollusques d’eau douce de la famille des Lymnaeidae, sont composés d’un groupe d’espèces cryptiques difficilement identifiables et (2) plusieurs espèces impliquées dans cette maladie sont invasives. L’objectif de cette thèse était d’étudier les facteurs écologiques et évolutifs à large échelle de l’interaction entre la grande douve du foie et ses hôtes intermédiaires susceptibles de favoriser une (ré)émergence de la fasciolose. J’ai, dans un premier temps, développé des approches moléculaires pour reconnaître les espèces cryptiques tant du côté de la grande douve du foie que du côté des Lymnaeidae. L’utilisation d’une des techniques développées sur Galba schirazensis, Galba cubensis et Galba truncatula, trois espèces de limnées, m’a permis d’identifier leur distribution respective et de modéliser leur niches bioclimatiques grâce à l’utilisation de modèles de niches écologiques. Cette approche de modélisation de niches permet d’inférer la distribution potentielle des trois espèces et nous amène à discuter des avantages potentiels de ces modèles dans la gestion de la fasciolose. Dans un second temps, je me suis intéressée à la structuration de la diversité génétique chez des espèces invasives du système grande douve du foie-limnée, par des approches de génétique des populations et de phylogénie. J’ai pu retracer l’histoire de colonisation, les dynamiques démographiques et le système de reproduction chez P. columella, G. schirazensis et G. cubensis. J’ai montré que ces trois espèces font préférentiellement de l’autofécondation entrainant des pertes drastiques de diversité génétiques sur le front d’invasion. G. cubensis présente cependant une coexistence de plusieurs génotypes dans les aires anciennement colonisées. Les différences génétiques entre ces trois espèces sont discutées à la lumière de ce qu’on sait de leur écologie. Enfin ces résultats m’ont permis de discuter de l’avantage d'être autofécondant en cas d’invasion biologique. Pour conclure l’invasion par ces populations d’hôtes intermédiaires dépourvus de diversité génétique pourrait représenter un risque épidémiologique. En effet un parasite a plus de probabilité de circuler dans une population hôte clonale que dans une population polymorphe. Cette thèse fait le lien entre écologie, interactions hôtes-parasites et génétique de l’invasion afin de mieux comprendre les facteurs d’expansion de la fasciolose à échelle globale. / Globalization and the current global change have significant impacts on species distribution and community composition. When these species are involved in a host-parasite interaction, changes in species range distribution can result in the (re)emergence of infectious diseases. Fasciolosis, a disease caused by the liver flukes (Fasciola hepatica and Fasciola gigantica) is reemerging in many parts of the world. It is difficult to implement control programs because (1) the intermediate hosts, freshwater molluscs of the Lymnaeidae family, are composed by a group of cryptic species (2) several species involved in this system are invasive. The objective of this thesis was to study the ecological and evolutionary factors at a large scale in the interaction between the liver fluke and its intermediate hosts that might drive to fasciolosis (re)emergence. First, I developed molecular approaches to quickly identify cryptic species on the two liver flukes and on three Lymnaeidae species. Using one of these techniques, I identify the respective distribution of Galba schirazensis, Galba cubensis and Galba truncatula and infer their respective climatic envelope by ecological niche modelling. We then modelled and projected the potential species distribution ranges. We discussed the contribution of models to predict the species distribution in space and time giving a considerable advantage to control fasciolosis. I then study the genetic diversity structuration in invasive snails involved in the transmission of F. hepatica, using population genetics and phylogeny. I could infer colonization history, population dynamics and reproductive system of Pseudosuccinea columella, G. schirazensis and G. cubensis. I showed that these three species preferentially make inbreeding causing drastic losses of genetic diversity in the invasion front. However G. cubensis presents a coexistence of several genotypes in formerly colonized areas. Genetic differences between these three species are discussed in the light of what we know about their ecology. Overall, these results illustrate how dramatic the reduction in genetic diversity can be for hermaphrodite animals. Finally, we discuss the epidemiological risk related to the invasion by intermediate hosts depleted in genetic diversity. Indeed, a parasite might circulate easily in a clonal host population than in a polymorphic population. In my thesis I linked ecology, host-parasite interactions with genetics of the invasion to better understand the expansion of fasciolosis at a global scale.

Fallopiajaponica (Houtt.) Ronse Decraene (Japanese knotweed), an introduced, invasive, rhizomatous perennial plant, has become an increasing problem for nature conservation and land management in both rural and urban areas in the British Isles. In the native range of the plant, Japan, Taiwan and northern China, a number of varieties are recorded. Three congeners of F. japonica are present in the British Isles, F. sachalinensis, F. japonica var. conipacta and F. baldschuanica in addition to a hybrid F. x bohemica. An investigation by postal survey of the distribution of the hybrid F. x bohemica has identified 131 records for the British Isles. Both male and female plants of F. x bohemica have been recorded. Current understanding suggests that only female plants of F. japonica are present in the British Isles, inferring that the only means of reproduction is through vegetative regeneration. High rates of regeneration were recorded in this study for stem and rhizome material for both F. japonica and F. x bohemica in an aquatic and terrestrial environment. Implications of vegetative regeneration are discussed in terms of current management practices and future methods of control. A combination of digging with a mechanical excavator followed by spraying with the herbicide glyphosate decreased the time required to achieve an effective level of control of F. japonica compared to spraying alone. Fragmentation of the rhizome system through digging resulted in an increase in stem density allowing a more effective delivery of herbicide. Implications in terms of costs for F. japonica treatment on sites awaiting re-development are discussed. Analysis of data collated from surveys of F. japonica in Swansea using a Geographical Information System suggest that the primary habitats infested are waste ground and stream and river banks. Results suggest that disturbance, both by natural means and by human intervention has been the primary cause of spread of F. japonica in the British Isles. Management strategies are proposed which take account of these results and measures are put forward to help prevent future infestations.

Abstract My main objectives in this thesis were to explore general patterns and mechanisms driving salmonid invasions globally and, more specifically, to examine the invasion dynamics and impacts of the North American brook trout in North European stream systems. Non-native salmonids have often spread extensively and caused many harmful impacts on their native counterparts. Among the three globally introduced salmonids, the European brown trout appeared as the 'worst' alien species (strongest impact on native fish), followed by the North American rainbow trout and brook trout. Brook trout, which is widely established in European streams, was found to be a non-aggressive species. Moreover, the growth of brown trout was unaffected by brook trout, indicating negligible interspecific interactions between the two species. Habitat niche segregation between brook trout and brown trout was evident, with brook trout occupying mainly low-velocity pool habitats, whereas brown trout resided in fast-flowing riffles. At the river-wide scale, brook trout occurred mainly in small, slightly acid headwater streams, whereas brown trout was found primarily in larger downstream river sections. Evidently, North European streams with a very low number of native fish species offer underutilized niche space for tolerant headwater specialists such as brook trout. However, the habitat niche filled by brook trout was not completely vacant, as brown trout co-occurred with brook trout in numerous small and mid-sized (3–16 m wide) streams. In these streams, brown trout reproduction was negligible presumably related to the presence of brook trout. Brook trout had also increased in density relative to brown trout during the 10-yr study period (1994 vs. 2004). Moreover, the growth rate and population densities of brook trout were high and the species had spread extensively towards the upmost headwater streams during the 10-yr study period. Thus, harmful effects on the native brown trout by brook trout are likely to occur in the core habitat of the invader, i.e. headwater streams, leaving populations of the native species unaffected elsewhere. Due to the high conservation value of the potentially impacted populations of brown trout, I strongly caution against further stocking of brook trout in European watersheds.

Bien moins médiatisées que la déforestation ou le changement climatique, les invasions biologiques n’en demeurent pas moins problématiques pour la conservation de nombreux écosystèmes ou le bon déroulement de nombreuses activités socio-économiques.Comprendre la façon dont les espèces exotiques envahissantes s’étendent dans les différents milieux qu’elles colonisent c’est permettre à la fois de mieux appréhender leurs impacts, de pouvoir de prédire leur expansion, et de trouver les endroits stratégiques où agir pour contrer ou atténuer les effets indésirables de ces espèces. Le problème est que dynamiques d’invasions d’une espèce regroupent en fait une hiérarchie de processus se produisant simultanément à différentes échelles spatiotemporelles et qui sont contrôlés par des facteurs qui changent en fonction du temps et du contexte d’invasion. Pour acquérir une compréhension profonde de ces dynamiques, il faut donc étudier leurs manifestations et leurs causes aux diverses échelles spatiales et temporelles auxquelles elles se produisent.Présentes sur les cinq continents et très envahissante sur au moins deux, les renouées asiatiques (Reynoutria spp.) sont reconnues comme faisant partie des espèces les plus invasives de la planète. Dotées d’une grande tolérance environnementale et d’importantes capacités de multiplication végétatives, ces plantes herbacées géantes peuvent former rapidement de grandes monocultures clonales qui excluent les autres espèces végétales, modifient les cycles biogéochimiques des zones envahies et perturbent diverses activités anthropiques. Cibles de campagnes de gestion depuis des décennies, elles affichent cependant une résilience insolente qui désespère de nombreux gestionnaires. Bien que très étudiées, de nombreux détails concernant leurs dynamiques nous échappent toujours. Dans ce travail de thèse, nous avons donc cherché à identifier quels sont les facteurs qui contrôlent les dynamiques spatiotemporelles des renouées à différentes échelles, et comment une meilleure compréhension de ces dynamiques clés pourrait profiter à leur gestion ?Pour ce faire, nous nous sommes donc d’abord intéressés à leur dynamiques clonales et à leurs variations en fonction de différentes conditions de stress (ombrage) ou de perturbation (fauchage répétée). Nous avons montré que si les renouées sont bien affectées par des conditions stressantes ou perturbées, cela ne les empêche ni de s’établir, ni de croître. En fait, les renouées semblent pouvoir adopter différentes stratégies de croissance pour pallier ces contraintes, soulevant différentes questions liées à la gestion. Dans une deuxième étude, nous avons cherché quels étaient les variables qui expliquaient l’expansion des taches de renouées le long d’un gradient altitudinal. Si nous avons montré que les dynamiques d’expansion des taches étaient principalement contrôlées par leur taille (et donc potentiellement leur âge) ainsi que par la proximité de routes et de rivières, nous avons également apporté des indices qui suggèrent que les renouées pourraient être potentiellement capables d’envahir les montagnes. Ensuite, pour tenter d’aider à résoudre le problème de l’acquisition des données de distribution des renouées à large échelle, nous avons développé une méthode pour détecter et cartographier les populations de renouées à partir d’images satellites et issues de drones. Notre méthode a montré des résultats encourageants et celle-ci pourrait être utile à l’étude des invasions ainsi qu’à la détection des nouveaux foyers d’invasion pour une gestion plus précoce et efficace des renouées.Enfin, nous avons tenté de dresser un portrait global de la compréhension actuelle des dynamiques d’invasion des renouées en réalisant, en guise de discussion, une grande revue de littérature sur les mouvements de ces plantes à travers les échelles spatiales et temporelles et en y intégrant les apports des autres travaux de cette thèse. / Although less mediatized than deforestation or climate change, biological invasions remain problematic for the conservation of many ecosystems and the maintenance of various socio-economical activities.Understanding the way invasive non-native species spread in their introduced range is enabling a better apprehension of their impacts, the possibility to predict their expansion, and the development of better management strategies. A problem is that a species invasion dynamics are actually composed of a hierarchy of processes occurring simultaneously at various spatiotemporal scales and which are controlled by drivers that are time- or context-dependent. To gain more profound insights into these dynamics, one has to study the patterns they create and their underlying processes at all relevant scales.Occurring on the five continents and highly invasive on at least two of them, Asian knotweeds (Reynoutria spp.) are acknowledged as being among the most invasive species in the world. Gifted with a large environmental tolerance and high abilities for vegetative multiplication, these giant herbaceous plants can quickly form large clonal monocultures that exclude the other plant species, modify biogeochemical cycles, and affect various anthropic activities. Target of management campaigns for decades, knotweeds display an insolent resilience to the great despair of many stakeholders. Despite having been extensively studied, many aspects of their dynamics are still elusive. Consequently, in this thesis, we have tried to highlight what the drivers of the spatiotemporal dynamics of knotweeds across scales are, and how their management could benefit from a better understanding of these dynamics?To answer these questions, we first focused our attention on the clonal dynamics of knotweeds and on their variations when they experience differing conditions in terms of light availability and disturbance (repeated mowing). We have shown that although shade or mowing affects the vigour and the development of clones, it does not prevent their establishment or their growth. In fact, knotweeds seem able to adopt different growth strategies to cope with environmental heterogeneity, suggesting some management avenues. In a second study, we tried to identify the drivers that controlled the expansion of knotweed stands along an elevational gradient. If we showed that the lateral expansion of stands is mostly constrained by their size (and thus, possibly their age) and the vicinity of roads and rivers, we also brought evidences that knotweeds could have the potential to invade mountain regions. Then, to help for the acquisition of large-scale datasets on knotweeds’ distribution, we developed a procedure to accurately detect and map knotweeds using satellite or drone imagery. Our results were quite encouraging and could be useful to both the basic research and to the detection of newly invaded areas, enabling earlier control operations and more efficient management.Finally, we tried to draw a full picture of the current knowledge on the invasion dynamics of knotweeds by reviewing the literature on the movement of these plants across spatial and temporal scales, to discuss and expand the reach of the insights gained in the various chapters of this thesis.

Biases in invasion science lead to a taxonomic focus on plants, particularly a subset of well-studied plants, and a geographic focus on invasions in Europe and North America. Geographic biases could also cause some branches of invasion science to focus on a subset of environmental conditions in the invaded range, potentially leading to an incomplete understanding of the ecology and management of plant invasions. While broader, country-level geographic biases are well known, it is unclear whether these biases extend to a finer scale and thus affect research within the invaded range. This study assessed whether research sites for ten well-studied invasive plants in the U.S. are geographically biased relative to each species’ invaded range. We compared the distribution, climate, and land uses of research sites for 735 scientific articles to manager records from EDDMapS and iMap Invasives representing the invaded range. We attributed each study to one of five types: impact, invasive trait, mapping, management, and recipient community traits. While the number of research sites was much smaller than the number of manager records, they generally encompassed similar geographies. However, research sites tended to skew towards species’ warm range margins, indicating that researchers have knowledge on how these plants might behave in a warming climate. For all but one species, at least one study type encompassed a significantly different climate space from manager records, suggesting that some level of climatic bias is common. Impact and management studies occurred within the same climate space for all species, suggesting that these studies focus on similar areas – likely those with the greatest impacts and management needs. Manager records were more likely to be found near roads, which are both habitats and vectors for invasive plants, and on public land. Research sites were more likely to be found near a college or university. Studies on these plants largely occur across their invaded range, however, different study types occur within a narrower climate range. This clustering can create gaps in our general understanding of how these plants interact with different environments, which can have important policy and management consequences.

In the Czech Republic, as in other parts of Europe (e.g., British Isles), the native European red deer (Cervus elaphus) has been hybridising with sika deer (C. nippon), which was introduced from East Asia. The hybrids are fertile, and, therefore, can backcross with their parental species and threaten their genetic integrity. Offsprings of such multiple crosses are very difficult to identify according to their morphological traits, while more reliable genetic methods are financially and logistically demanding. This work follows the study of Long et al. from 1998, which showed clear differences in vocalization between red deer, sika deer and the first generation of their hybrids, and thus suggested the third way how to identify hybrids - bioacoustic analysis. We decided to test this method in the Czech Republic in a citizen science project, the aim of which was to map the distribution of parent species and their hybrids using audiorecordings of rut vocalisation. To allow more detailed analysis, we also recorded our own recordings on a professional recording device with a directional microphone. In total, 451 recordings were collected, of which only 263 with a vocalization of 162 individuals were selected for further analysis. Recordings from previous studies from Ireland (Long et al. 1998; Wyman et...

Various interpretations of the Germanic invasions of the early Middle Ages have been advanced. These present to the student of historiography a fertile field for inquiry. In this thesis the interpretations of the Germanic invasions propounded by Jules Michelet (1798-1874) and Gustav Freytag (1816-1875) are examined with a view to establishing the cultural context in which their mutually exclusive versions were formulated, and the extent to which that context lent the interpretations of both writers a perceptible national and aesthetic bias.