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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The new invasive Odontites serotina: impacts, responses and predictive model

Kennedy, Bradley 05 January 2012 (has links)
Invasive alien species (IAS) pose a serious threat to ecosystems and societies worldwide. Local ecological knowledge (LEK) is increasingly valued as a means of understanding environmental issues; however, its application in the context of IAS research has been limited. The overall objective of this study was to document the LEK of farmers and Weed Supervisors to gain insight into a recent IAS, Odontites serotina. I conducted semi-structured interviews with farmers and Weed Supervisors with O. serotina management experience. Results indicated that the socio-economic impacts for farmers were severe in affected rural communities. However, participants had developed promising control techniques, including the application of compost mulch. I used this LEK as well as data on species occurrence, environmental variables, and measures of propagule pressure to forecast the potential distribution of O. serotina across Manitoba. The risk map generated will be useful for guiding future monitoring and public outreach efforts.
12

The new invasive Odontites serotina: impacts, responses and predictive model

Kennedy, Bradley 05 January 2012 (has links)
Invasive alien species (IAS) pose a serious threat to ecosystems and societies worldwide. Local ecological knowledge (LEK) is increasingly valued as a means of understanding environmental issues; however, its application in the context of IAS research has been limited. The overall objective of this study was to document the LEK of farmers and Weed Supervisors to gain insight into a recent IAS, Odontites serotina. I conducted semi-structured interviews with farmers and Weed Supervisors with O. serotina management experience. Results indicated that the socio-economic impacts for farmers were severe in affected rural communities. However, participants had developed promising control techniques, including the application of compost mulch. I used this LEK as well as data on species occurrence, environmental variables, and measures of propagule pressure to forecast the potential distribution of O. serotina across Manitoba. The risk map generated will be useful for guiding future monitoring and public outreach efforts.
13

Ecologia do movimento da rã-manteiga (Leptodactylus latrans) e da rã-touro (Lithobates catesbeianus) / Movement ecology of the Butter Frog (Leptodactylus latrans) and the Bullfrog (Lithobates catesbeianus)

Rafael dos Santos Henrique 10 March 2017 (has links)
O movimento dos animais desempenha papel importante na aptidão dos indivíduos, no fluxo gênico, na dinâmica de metapopulações e na persistência, a longo prazo, de espécies em um ambiente. Dessa forma, o objetivo deste estudo foi compreender aspectos relacionados à ecologia do movimento da rã-manteiga (Leptodactylus latrans) e da rã-touro (Lithobates catesbeianus). Para isso, indivíduos de ambas as espécies foram marcados com radiotransmissores e rastreados com o objetivo de coletar informações sobre seus movimentos. Ressaltamos os seguintes resultados deste trabalho: (1) a área de vida média de L. latrans é de 2034,2 m2; (2) com o aumento do tamanho corpóreo de anuros há o aumento do tamanho da área de vida; (3) indivíduos de L. latrans se locomovem mais em noites escuras, chuvosas e quentes; e (4) o aumento da pressão de propágulos não reflete uma maior probabilidade no aumento da distribuição geográfica de uma dada população de L. catesbeianus. Entender os padrões de locomoção dos anfíbios e como utilizam o espaço na natureza é fundamental para o entendimento de processos ecológicos e evolutivos relacionados às histórias de vida das espécies desse grupo. Além disso, esse conhecimento serve como uma ferramenta importante no estabelecimento de limites de áreas de conservação com significado biológico para espécies ameaçadas. Ainda, saber como espécies invasoras se locomovem é um dos primeiros passos para que se tomem medidas de controle populacional e para o bloqueio do avanço da distribuição de espécies exóticas / The ability of animals to move plays an important role in individual fitness, gene flow, population regulation, metapopulation dynamics and long-term persistence of species. The aim of this study was to understand aspects related to the movement ecology of the Butter Frog (Leptadactylus latrans) and the Bullfrog (Lithobates catesbeianus). We collected movement data by radio tracking individuals of both species. Some of the most important results obtained were: (1) the mean home range of L. latrans is 2034.2 m2; (2) increasing body size increases home range size in anurans; (3) individuals of L. latrans are more likely to move larger distances in dark, rainy and warm nights; (4) the increase in propagule pressure does not reflect an increase in the probability of geographical spread of a given population of L. catesbeianus. Understanding how amphibians move and use the space in nature is fundamental for the understanding of basic ecological and evolutionary processes related to life history of the species. Moreover, this knowledge is a useful tool to establish biologically meaningful conservation boundary areas to threatened species. Yet, understanding how invasive species move in nature is one of the first steps to population control and to block the spread of geographical distribution of exotic species
14

Genética de populações aplicada à  biologia da invasão: um panorama da invasão da rã-touro (Lithobates catesbeianus) / Population genetics applied to invasion biology: a panorama of the bullfrog invasion (Lithobates catesbeianus)

Cohen, Gabriel Jorgewich 15 March 2018 (has links)
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
15

New Zealand Calanoid Copepod Invasions: Has Artificial Lake Construction Facilitated Invasions, and are our Coastal Waters Uninvaded?

Banks, Christopher Mark January 2007 (has links)
Non-indigenous species have become a global issue of increasing importance in recent years, with many causing significant environmental and economic damage. Identifying locations vulnerable to invasion allows for focus of management efforts towards prevention of invasions at those locations. In order to determine whether constructed water bodies, such as reservoirs, ornamental lakes or retired mines, are more easily invaded environments than natural water bodies, owing to decreased biotic resistance, the distributions of native and non-indigenous freshwater calanoid copepod species in the North Island were examined. Calanoid copepods in ports and other coastal environments were also examined, in order to determine whether ports are more frequently invaded owing to increased propagule supplies from visiting ships and other sources. The distributions of the native freshwater calanoid copepod species Boeckella hamata, B. propinqua, B. delicata and B. tanea are confined in the North Island of New Zealand to specific technostratigraphic terranes when natural waters only are examined, and as such each species can be considered to have a native range. The recently colonised calanoid copepod species Boeckella minuta (6 locations), Skistodiaptomus pallidus (3 locations) and Sinodiaptomus valkanovi (2 locations) are to date confined to constructed water bodies. Boeckella symmetrica (2 locations) may be confined to constructed water bodies, but the status of one location is unclear. Boeckella triarticulata, a species common in the South Island, is known only from a single farm dam in the North Island. The native species Boeckella hamata, B. propinqua and B. delicata were found to occur in constructed waters, but only B. propinqua was found in constructed water bodies outside their natural ranges (9 locations). Calamoecia lucasi is found in lakes throughout most of the North Island, and is not confined to any one terrane. My results indicate that constructed water bodies are more easily invaded by non-indigenous species than natural water bodies, represents a potential pathway for future invaders to establish, and provides locations for species to spread. In order to determine whether recently established freshwater calanoid copepod species have the potential to spread from their present habitats into other water bodies, the prosomal lengths of non-indigenous calanoid copepod species were measured and compared with those for native species. The results suggest that dietary overlap should prevent the non-indigenous species present to date from spreading into any water bodies with established Boeckella populations, although Sinodiaptomus valkanovi and Boeckella triarticulata could potentially spread to lakes containing only Calamoecia lucasi. Data on the co-occurrences of native freshwater calanoid copepod species support the theory of dietary exclusion, as Boeckella species have not been found to coexist. In order to test whether New Zealand marine environments have been invaded by non-indigenous calanoid copepods, and whether ports have been more regularly invaded than non-port areas, calanoid copepods were sampled from various coastal locations around the North Island. With the possible exception of Sulcanus conflictus, no non-indigenous species were found, indicating that non-indigenous marine calanoid copepod species are not establishing in New Zealand despite a history of invasion elsewhere.
16

Padrões e processos de diferenciação taxonômica da fauna de peixes de uma ecoregião da América do Sul / Patterns and process of taxonomic differentiation of fish fauna of South America ecoregion

Fernandes, Rogerio Taygra Vasconcelos 19 December 2013 (has links)
Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-05-18T15:15:57Z No. of bitstreams: 1 RogérioTVF_DISSERT.pdf: 779741 bytes, checksum: 9814a6c7549bf62e7bc2094c8b14cdb0 (MD5) / Made available in DSpace on 2017-05-18T15:15:57Z (GMT). No. of bitstreams: 1 RogérioTVF_DISSERT.pdf: 779741 bytes, checksum: 9814a6c7549bf62e7bc2094c8b14cdb0 (MD5) Previous issue date: 2013-12-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Here, we quantified the patterns of change in the similarity of the fish fauna of the Upper Paraná ecoregion, caused by the introduction of non-native species and anthropogenic factors, such as the construction of dams and the elimination of a biogeographic barrier. Additionally, we evaluated the importance of changes in rates of turnover and richness species in homogenization/differentiation dynamics. For the study, we mapped the spatial distribution of fish species through occurrence data georeferenced of Brazilian zoological museums. To evaluate temporal changes in the composition of the fish fauna, the data with the distribution of the species were divided into two periods: historical period composed entirely of native species, and the contemporary period, consisting of historical fauna plus non-native species. Changes in similarity patterns between fish assemblages were quantified using the Jaccard dissimilarity index to the historical and contemporary periods. To evaluate the influence of the non-native richness species, number of dam and distance to the Itaipu Dam on changes of similarity, we performed simple and partial Mantel tests. The results showed that the fish fauna has become more dissimilar over time, due to increases in turnover rates and addition of species. Furthermore, factors related to the heterogeneity of the basins and propagules pressure after removal of a biogeographical barrier has determined the patterns of changes in the similarity of the fish fauna / Nesse estudo foram quantificados os padrões de mudança na similaridade da fauna de peixes da ecoregião do alto Paraná, produzidas pela introdução de espécies não-nativas e de fatores antropogênicos, como a construção de barragens e a eliminação de uma barreira biogeográfica. Adicionalmente, foi avaliada a importância de mudanças nas taxas de turnover e de riqueza nas mudanças de similaridade das assembleias de peixes. Para realizar o estudo, a distribuição espacial de espécies de peixes de dez bacias de drenagem do alto Paraná foi mapeada através de dados de ocorrência geo-espacializados tombados em museus zoológicos de instituições brasileiras. Para avaliar as mudanças temporais na composição da fauna de peixes, os dados com as distribuição das espécies foi divido em dois períodos: período histórico, composto somente por espécies nativas, e período contemporâneo, composto por espécies nativas mais não-nativas. Os padrões de similaridade entre as assembleias de peixes para os períodos histórico e contemporâneo foram quantificados através do índice de dissimilaridade de Jaccard. As mudanças na similaridade entre assembleias foi calculada através da diferença entre as similaridades contemporâneas e históricas. Para avaliar os efeitos da riqueza de espécies não-nativas, número de barragens e área das bacias, e a distância das bacias até a barragem de Itaipu foram utilizados testes de Mantel simples e parciais. Os resultados demostraram que a fauna de peixes tem se tornado mais dissimilar ao longo do tempo, em função de aumentos nas taxas de turnover e de adição de espécies. Além disso, fatores relacionados à heterogeneidade das bacias e da pressão de propágulos após a eliminação de uma barreira biogeográfica tem determinado os padrões de mudanças na similaridade da fauna de peixes / 2017-05-18
17

Genética de populações aplicada à  biologia da invasão: um panorama da invasão da rã-touro (Lithobates catesbeianus) / Population genetics applied to invasion biology: a panorama of the bullfrog invasion (Lithobates catesbeianus)

Gabriel Jorgewich Cohen 15 March 2018 (has links)
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
18

Hybridation et goulots d'étranglements induits par l'activité humaine : génétique des populations, morphométrie et parasitologie appliquées au tilapia envahi et envahissant Oreochromis mossambicus (Teleostei, Cichlidae) / Human-induced hybridization and population bottleneck : population genetics, morphometrics and parasitology applied to the invaded and invasive tilapia Oreochromis mossambicus (Teleostei, Cichlidae)

Firmat, Cyril 04 November 2011 (has links)
Les invasions biologiques sont reconnues comme un facteur évolutif important sur une échelle de temps courte. Elles affectent notamment la structure génétique des populations, les patrons d’évolution phénotypique et la richesse des faunes de parasites associées aux populations envahissantes. Cette étude se propose de quantifier les conséquences d’une invasion biologique suivant ces trois niveaux (génétique, phénotypique et parasitologique) en prenant pour exemple le cas du tilapia du Mozambique Oreochromis mossambicus. Ce cichlidé africain présente un statut remarquable en biologie de la conservation puisqu’il est à la fois (i) l’une des espèces les plus envahissantes au monde car dispersée à l’échelle globale au cours du XXème siècle et (ii) une espèce « quasi-menacée » (UICN) sur son aire native (partie du sud-est de l’Afrique) du fait de son hybridation massive avec d’autres Oreochromis sp. introduits. La démarche générale employée ici est de décrire l’histoire récente des populations à l’aide de marqueurs nucléaires (AFLP) et des séquences de l’ADN mitochondrial (ADNmt), puis de mettre en relation ces résultats génétiques avec la diversité morphologique et la parasitologie des populations. Deux systèmes différents ont été étudiés : Au sein de l’aire native, l’étude se focalise sur le Limpopo inférieur et le sous-bassin de la Changane (Mozambique). Des patrons d’introgression incluant trois espèces en présence sont détectés, mais les hybrides sont peu fréquents et leur expansion limitée. Ces résultats sont de plutôt bonne augure pour la conservation d’O. mossambicus et ils permettent d’identifier deux zones de conservation prioritaires. L’étude des parasites indique une plus grande diversité parasitaire mais de faibles prévalences dans les sites de moindre valeur en conservation, ce qui pourrait favoriser le succès des espèces introduites et de leurs hybrides. Parmi les territoires envahis, les AFLP et l’ADNmt soutiennent une homogénéité générale et une diversité génétique faible, qui sont interprétées comme le résultat d’un fort goulot d’étranglement précédant l’expansion à l’échelle mondiale. Une structure des populations en lien avec la géographie à large échelle (Nouvelle-Calédonie, Guadeloupe, Jamaïque) est cependant détectée. La variation de la forme du corps est également structurée à large échelle géographique, ce en dépit des fortes variations environnementales enregistrées à l’échelle locale. Cela suggère un effet des contraintes génétiques sur la diversification morphologique contemporaine. L’absence de parasites monogènes sur les populations introduites en Nouvelle-Calédonie peut être mise en relation avec un évènement fondateur, et est proposé comme l’un des facteurs ayant pu favoriser le succès de l’espèce. En conclusion, une faible diversité génétique ne contraint vraisemblablement pas un potentiel envahissant élevé et une diversification rapide chez les tilapias. / Biological invasions are recognized as a significant evolutionary factor over short time scales. In particular, their effect is well recorded on the genetic structure of populations, the patterns of phenotypic evolution and the richness of parasite fauna associated to invasive populations. This study aims at quantifying the consequences of a biological invasion according to these three levels (genetical, phenotypical and parasitological) taking as example the Mozambique tilapia Oreochromis mossambicus. This African cichlid is characterized by an unusual conservation status since it is both (i) ranked among the world’s worst invasive species due to its global dispersion during the 20th century and (ii) sorted as “near-threatened” (IUCN) over its native range (a part of south-east Africa) because of massive hybridization with alien introduced Oreochromis species. The approach used in this study imply to describe the recent history of populations using nuclear (AFLP) and mitochondrial DNA (mtDNA) markers, and then to compare this genetic background to results describing the morphological and parasitological diversity of populations. Two different biological systems were studied: 1) Within the native range, the study focuses on the Lower Limpopo and the Changane sub-drainage (Mozambique). Introgression patterns involving the three co-occurring species were detected, but the frequency of hybrid is low and their geographic expansion is limited. These results provided rather good auspices for the conservation of O. mossambicus, and they allowed to identify two zones of high conservation priorities. The parasitological survey reveals high parasite richness and low prevalences among sites of low conservation values. This last pattern could favour the success of alien introduced species and their hybrids. 2) Among the invasive range of O. mossambicus, both AFLP and mtDNA support a strong genetic homogeneity and a low genetic diversity, a pattern interpreted as resulting from a strong population bottleneck preceding the events of global dispersion. A pattern of population structure related to large scale geography (New Caledonia, Guadeloupe, Jamaica) is nevertheless detected. Body shape variation is also primarily structured at large geographical scale, suggesting a role for genetic constrains on contemporary morphological diversification. The total absence of monogenean parasites in the populations of New Caledonia could result from a founding event and is suggested as a potential factor that could have favoured the O. mossambicus’ success. In conclusion, a low genetic diversity does not likely constraint a strong invasive potential and a rapid phenotypic diversification in tilapias.
19

Invasion success and impacts of Hieracium lepidulum in a New Zealand tussock grassland and montane forest

Meffin, Ross January 2010 (has links)
Invasive species represent a major concern; they can result in serious ecological and economic losses and are recognised as one of the most serious threats to global species diversity. Plant invasions are of particular concern in New Zealand, which has high proportions of both naturalised and endemic plant species. In this thesis I focussed on the invasive plant Hieracium lepidulum, an exotic weed introduced from Europe to New Zealand prior to 1941. It is invasive in a variety of habitats in the South Island, where it has steadily increased in distribution and abundance over the last 50 years, and is thought to have detrimental impacts on native plant communities. I investigated factors influencing its invasion success and tested for impacts on native plant communities, making extensive use of existing plots into which H. lepidulum was experimentally introduced in 2003. I examined how community richness, turnover, resource availability and propagule pressure of the invader interacted to determine the invasion success of H. lepidulum. Results differed markedly above and below treeline. Above treeline, plots with higher richness and turnover were more invaded; below treeline, plots with higher available light were more invaded. In both habitats, these findings were modified by the influence of propagule pressure; at low propagule pressure, site characteristics were non-significant in explaining invasion success, while at higher propagule pressure these effects became significant. To test for impacts resulting in altered community composition and structure, I looked for changes in community richness, diversity and evenness subsequent to H. lepidulum introduction. As impacts may be more apparent at fine spatial scales, I made measurements at a 5 x 5 cm cell scale in addition to the established 30 x 30 cm plot scale. Plot species richness increased from 2003 to 2009 and a component of this increase was associated with H. lepidulum density. Other relationships between the plant community and H. lepidulum were generally non-significant. Results showed that H. lepidulum has had no negative effects on community richness, evenness or diversity. Despite being able to opportunistically colonise grassland sites with high turnover, and forest sites subject to canopy disturbance, dependant on propagule pressure, it appears H. lepidulum has not impacted community composition or structure.
20

Determinants of native and exotic plant species diversity and composition in remnant oak savannas on southeastern Vancouver Island

Lilley, Patrick Ledford 05 1900 (has links)
Many regional and local factors can influence the distribution of native and exotic species in ecological communities. I examined the regional- and local-scale determinants of native and exotic vascular plant species richness and composition in a highly fragmented oak savanna ecosystem on southeastern Vancouver Island. In sharp contrast to most reported results, I found a negative relationship between native and exotic richness at the regional scale, and no relationship at the local scale. Two extrinsic factors, surrounding road density and climate, best explained the regional-scale relationship by each affecting natives and exotics in opposite ways. Road density and climate were also the dominant predictors of native and exotic composition at the regional scale. Patterns in the patch occupancy of individual species confirmed the importance of these factors but I found that low surrounding road densities and cool, wet conditions predicted the presence of many natives and the absence of many exotics. Environmental factors explained variation in richness and composition at the local scale, but these factors were different for natives and exotics. My results suggest that natives and exotics respond to roads and climate in fundamentally different ways. Roads increase both exotic propagule pressure and disturbance, which may facilitate exotic invasion. In contrast, disturbance from roads may increase the likelihood of local extinction for particular natives. Differing climatic preferences within the native and exotic species pools may also partially explain the observed patterns. There was no evidence that native diversity directly affects exotic diversity (or vice versa). Surprisingly, I found that connectivity was not an important predictor of richness or composition despite the high degree of habitat fragmentation in this ecosystem.

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