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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Efeito potencial de mudanças climáticas sobre a distribuição de Phyllomedusa centralis (Anura : Hylidae)

Arruda, Luana Aparecida Gomes de 02 December 2014 (has links)
Submitted by Valquíria Barbieri (kikibarbi@hotmail.com) on 2018-04-05T22:00:26Z No. of bitstreams: 1 DISS_2014_Luana Aparecida Gomes de Arruda.pdf: 854132 bytes, checksum: e5dce680d3fc443608aec08b5e456321 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2018-04-23T18:21:48Z (GMT) No. of bitstreams: 1 DISS_2014_Luana Aparecida Gomes de Arruda.pdf: 854132 bytes, checksum: e5dce680d3fc443608aec08b5e456321 (MD5) / Made available in DSpace on 2018-04-23T18:21:48Z (GMT). No. of bitstreams: 1 DISS_2014_Luana Aparecida Gomes de Arruda.pdf: 854132 bytes, checksum: e5dce680d3fc443608aec08b5e456321 (MD5) Previous issue date: 2014-12-02 / Pesquisas em campo voltadas para conservação de espécies são necessárias, porém muitas vezes são limitadas, onerosas e trabalhosas. Uma ferramenta que pode ser utilizada para minimizar estes problemas é a Modelagem Preditiva de Distribuição Potencial de Espécies (MPDPE), que permite estimar áreas potenciais de ocorrência atuais e futuras e que vem recebendo destaque em estudos conservacionistas, pois pode ser utilizada com espécies raras ou que estão sofrendo algum grau de ameaça. No presente estudo, a MPDPE foi utilizada para conhecer a distribuição e prever o efeito potencial de mudanças climáticas sobre a distribuição da perereca Phyllomedusa centralis, que possui distribuição conhecida restrita a poucas localidades no estado de Mato Grosso, Brasil. Os modelos foram desenvolvidos com o método de entropia máxima com o auxilio do programa MaxEnt, utilizando variáveis bioclimáticas atuais e futuras. Os modelos de predição de distribuição atual e de cenários futuros obtiveram elevados valores da área sob a curva operador-receptor e a validação apontou alta precisão na qualidade do modelo. Em todos os modelos, a variável ambiental com maior porcentagem de contribuição foi a precipitação. Todos os modelos apresentaram previsão de aumento nas áreas de distribuição potencial em comparação com o modelo atual de distribuição. Apesar de apresentar limitações, o modelo de distribuição potencial é relevante e pode ajudar no planejamento e gestão de reservas, descoberta de novas populações e manejo de espécies, identificação de áreas prioritárias para conservação e definição de onde é necessária a restauração de habitats. / Field surveys aimed at the conservation of species are necessary, but are often limited, costly and onerous. A tool that can be used to minimize these problems is the Predictive Modeling of Potential Species Distribution (PMPSD), which allows estimating current and future areas of potential occurrence and has received attention from conservationists studies, because it can be used with rare species or who are suffering some degree of threat. In the present study PMPSD was used to determine the distribution and predict the potential effect of climate change on the distribution of tree frog Phyllomedusa centralis, which has restricted distribution to a few localities in the state of Mato Grosso, Brazil. The models were developed with maximum entropy method with the aid of the MaxEnt program using current and future bioclimatic variables. The prediction models of current distribution and future scenarios had higher Area Under the receiver-operator Curve values and the validation showed high accuracy of the model quality. In all models the environmental variable with highest percentage of contribution was precipitation. All models showed increased areas of potential distribution compared with the current distribution model. Despite the limitations, the model of potential distribution is important and can help in planning and management of reserves, discovery of new populations, identification of priority areas for conservation, and definitions of regions to habitat restoration.
72

Bombus terrestris chegará ao Brasil? Um estudo preditivo sobre uma invasão em potencial / Will Bombus terrestris reach Brazil? A predictive study about a potential invasion

André Luis Acosta 24 June 2015 (has links)
A abelha Bombus terrestris é um eficiente polinizador, prestando importantes serviços ecossistêmicos na Europa e adjacências, onde é nativa. Suas colônias têm sido criadas em larga escala para polinização agrícola, as quais são comercializadas internacionalmente, inclusive em países fora de sua área de ocorrência nativa. Deliberada ou acidentalmente a espécie tem sido introduzida em ambientes alóctones, em muitos casos tornando-se invasora. Quando invasora, a espécie é um potencial vetor de doenças e um competidor com outras abelhas; vários impactos têm sido relatados em áreas invadidas ao redor do mundo. Na América do Sul, a espécie foi inicialmente introduzida em ambientes naturais no Chile, mas rapidamente a invasão se espalhou; atualmente é encontrada ocupando ambientes naturais na Argentina. A elevada capacidade invasiva da espécie e a alta velocidade de sua expansão, conforme tem sido relatada por pesquisadores, levantou a possibilidade de a espécie alcançar o Brasil por meio de corredores ambientais favoráveis que se conectam com áreas já invadidas, gerando preocupações sobre potenciais impactos aos sistemas naturais e agrícolas. Esta pesquisa empregou uma abordagem interdisciplinar, integrando uma variedade de métodos analíticos oriundos de diferentes áreas da ecologia e os mais avançados recursos de sistemas de informações geográficas para detectar globalmente as áreas susceptíveis à invasão por Bombus terrestris, considerando-se também as mudanças climáticas. Para o sul da América do Sul foram identificados os corredores de invasão que poderão permitir a espécie se espalhar e alcançar Brasil a partir de locais invadidos. Para o Brasil, foram identificados os municípios mais vulneráveis à entrada da espécie, e também aqueles que estão na rota de expansão da invasão Brasil adentro. Para os municípios brasileiros, por sua vez, foram verificadas as culturas agrícolas e as espécies de Bombus nativas que a invasora poderá interagir ao longo da rota de invasão potencial; com estas informações foram apontadas áreas prioritárias, subsidiando o planejamento de monitoramento e ações de controle do processo de invasão, mas também medidas preventivas e mitigadoras de impactos ambientais e econômicos após a invasão, caso venha a ocorrer. / The bee Bombus terrestris is an efficient pollinator, providing important ecosystem services in Europe and surrounding areas, where it is a native species. Their colonies have been reared in large-scale for agricultural pollination, which are internationally traded, including for countries outside its native range. The species has been deliberately or accidentally introduced into non-native environments, becoming invasive in many cases. When invasive, the species is a potential vector of diseases and competes with other bees for resources; many impacts have been reported in invaded countries around the world. In South America, the species was introduced in natural environments of Chile at first, but the invasion was quickly spread; nowadays it is found living in natural environments of Argentina. The high invasiveness of the species and the high speed of its invasive expansion, as has been reported by researchers, raised the possibility of the species reach Brazil through suitable environmental corridors that are connected with areas already invaded, raising the concerns about potential impacts to natural and agricultural systems. An interdisciplinary approach was used in this research, composing a variety of analytical methods from different areas of ecology and applying the most advanced resources of geographic information systems to detect areas susceptible to invasion by Bombus terrestris at global scale, considering also climate change. For the southern South America, the corridors of invasion that could allow the spreading of the species and that potentially reach Brazil were identified. For Brazil, the most susceptible municipalities at the entrance of the species have been identified, and also those that are on the route of expansion inside the country. For Brazilian municipalities, crops and native species of Bombus that the invasive species can interact with along the potential invasion route were verified; with this information, priority areas were identified, supporting the planning of monitoring and control actions of the invasion process, but also preventive and mitigating measures of environmental and economic impacts after the invasion, if it eventually occurs.
73

Establishing conservation management for avian threatened species

Ponnikas, S. (Suvi) 18 February 2014 (has links)
Abstract The protection of endangered species requires knowledge about the habitat requirements and the genetic issues related to the population viability. In this doctoral thesis, I defined the breeding habitat features of the Finnish populations of the Golden Eagle (Aquila chrysaetos) and the Peregrine Falcon (Falco peregrinus) by applying habitat suitability modelling. Secondly, I studied the conservation genetic issues of the Finnish population of the White-tailed Eagle (Haliaeetus albicilla) and the two Reed Bunting subspecies Emberiza schoeniclus witherbyi and E.s. lusitanica met in the Iberian Peninsula. All study populations are classified as threatened according to IUCN classification and they have experienced declines in population sizes in recent history. My results from habitat suitability models showed that human-induced changes in habitat threaten the Golden Eagle in Finland. The relative suitability for the species presence dropped to zero when the proportion of human altered landscape (agricultural or urbanized areas) in the core of the breeding habitat (4 km2) was more than 5%. Models further showed that habitat structure influences breeding habitat selection of the Peregrine Falcon, as it favours well-connected areas of open peatlands. Therefore, fragmentation (i.e., decreasing the connectivity) of open peatlands decreases the habitat quality for the species. The White-tailed Eagle has recovered mainly through local growth, but my results suggest that gene flow from neighbouring populations has had an impact as well, and has enhanced the genetic viability of the Finnish population. The current structure of the two subpopulations (one along the Baltic Sea coast line and another inland in Northern Finland) results mainly from the species’ ecology (i.e., philopatric behaviour), not from the recent population bottlenecks. The effective population size estimate of the coastal subpopulation of White-tailed Eagle was below the critical size needed to maintain evolutionary potential. The estimates of the effective population sizes for E.s. lusitanica and E.s. witherbyi and inland subpopulation of White-tailed Eagle were close or below the critical level of 50, which makes them prone to losing fitness due to inbreeding depression in the short term. Therefore, these study populations need to increase in size in order to secure population viability in the future. / Tiivistelmä Ihmisen aiheuttamat elinympäristöjen muutokset uhkaavat biodiversiteettiä kasvattamalla yhä useampien eliölajien sukupuuttoriskiä. Tehokkaat suojelutoimenpiteet edellyttävät tietoa uhanalaisten lajien elinympäristövaatimuksista sekä populaation elinkyvylle keskeisistä geneettisistä tekijöistä. Tarkastelen väitöskirjatyössäni maakotkan (Aquila chrysaetos) sekä muuttohaukan (Falco peregrinus) Suomen populaatioiden pesimäympäristön piirteitä maisemaekologisen mallinnuksen avulla. Toiseksi tarkastelen Suomen merikotkapopulaation (Haliaeetus albicilla) sekä Iberian niemimaalla esiintyvien pajusirkun alalajien Emberiza schoeniclus witherbyin ja E.s. lusitanican suojelun kannalta tärkeitä geneettisiä tekijöitä. Kaikki tutkimuspopulaatiot ovat uhanalaisia ja ne ovat kärsineet voimakkaista kannan pienenemisistä. Maisemaekologiset mallit osoittivat maakotkan välttävän ihmisen muokkaamaa ympäristöä (maatalousalueet ja rakennetut alueet). Lajin esiintymistodennäköisyys laski nopeasti nollaan, kun ihmisen muokkaaman ympäristön osuus nousi yli 5 prosenttiin pesimäympäristön ydinalueella (4 km2). Mallit osoittivat maiseman rakenteen vaikuttavan muuttohaukan habitaatinvalintaan, sillä se suosi pesimäympäristönään kytkeytyneitä avosoita. Avosoiden pirstoutuminen (l. kytkeytyneisyyden väheneminen) vähentää näin ollen muuttohaukan pesimäympäristön laatua. Merikotkapopulaatio on toipunut pääosin paikallisen kasvun myötä, mutta tulokseni viittaavat myös siihen, että geenivirta naapurimaiden populaatioista on lisännyt Suomen populaation geneettistä muuntelua. Nykyinen rakenne (rannikon ja Lapin alapopulaatiot) on seurausta lajin synnyinpaikkauskollisuudesta, ei niinkään populaatiokoon romahduksista. Rannikon merikotkapopulaation efektiivinen koko jäi alle kriittisen rajan, joka tarvitaan evolutiivisen potentiaalin säilymiselle. Pajusirkun alalajien sekä Lapin merikotkapopulaation efektiiviset populaatiokoot olivat lähellä kriittisenä pidettyä 50:tä tai jäivät alle, joten ne ovat vaarassa menettää kelpoisuutta sukusiitosdepression seurauksena lyhyellä aikavälillä. Sekä pajusirkun alalajien että merikotkapopulaatioiden tulee sen vuoksi kasvaa säilyäkseen elinvoimaisina tulevaisuudessa.
74

Hydraulic Geometry and Fish Habitat in Semi-Alluvial Bedrock Controlled Rivers

Ferguson, Sean January 2016 (has links)
The cross-sectional form of semi-alluvial bedrock channels was investigated. Channel geometry data were collected from a variety of streams in Ontario and Québec, Canada to develop empirical downstream scaling relationships. The relationships revealed that bedrock, mixed, and alluvial channels scale at similar rates with respect to discharge. The widest channels were formed in low-relief sedimentary bedrock with minimal alluvial cover. Channels influenced by resistant igneous/metamorphic bedrock produced a strong scaling relationship, whereas channels influenced by weak sedimentary bedrock produced a weak scaling relationship. Alluvial cover appeared to exhibit more control on channel width in low-relief settings in comparison to high-relief settings, with increased alluvial cover promoting channel narrowing. Channels influenced by igneous/metamorphic bedrock produced identifiable thalwegs, presumably due to well-defined bedload transport pathways. Channels influenced by sedimentary bedrock tended to have planar beds. Additionally, fish habitat was investigated at one semi-alluvial bedrock stream in Ontario, Canada. Fish sampling was conducted at proximate bedrock and alluvial sections followed by a survey of physical habitat parameters to evaluate habitat preferences. Adult logperch (Percina caprodes), juvenile white sucker (Catostomus commersonii), adult round goby (Neogobius melanostomus), and adult longnose dace (Rhinichthys cataractae) demonstrated preference toward alluvial substrate, whereas juvenile logperch and adult banded killifish (Fundulus diaphanus) demonstrated preference toward bedrock. Juvenile silver shiner (Notropis photogenis) and juvenile yellow perch (Perca flavescens) were indifferent to substrate type. Empirical depth and flow velocity habitat suitability indices (HSIs) were developed for each fish species. This study presents the first fish habitat suitability criteria developed from a small semi-alluvial bedrock stream and may provide valuable information for fisheries management endeavours in such environments.
75

Development of an integrated GIS-based simulation tool to support ecologically sound water management in the Amudarya river delta

Schlüter, Maja 03 November 2003 (has links)
Extensive use of the Amudarya river waters for irrigation has severely impacted semi-natural ecosystems along its course and in its delta region. Currently, new strategies are searched for multi-user and multi-objective water management to mitigate ecological and socio-economic deterioration. The GIS-based modeling framework, TUGAI, has been developed to support exploration of alternative water management strategies for the Amudarya river delta and to analyze their ecological implications. Available information of heterogeneous type and quality on resource availability and habitat demands of deltaic ecosystems has been integrated into a comprehensive tool by a hybrid approach. A multi-objective water allocation model, AmuEPIC, has been combined with simple, spatially-explicit statistical and rule-based models of landscape dynamics, AmuGIS, and an ecological assessment procedure based on a fuzzy habitat suitability index model for riverine Tugai forests, TugaiHSI. Users can develop scenarios of alternative water management strategies for a time period of up to 30 years and compare their ecological effects. The tool facilitates a first quick assessment of the response of the delta environment to water management measures in a problem-oriented way. It assists in structuring the problem of water allocation to the environment, facilitates analysis of tradeoffs and uncertainties, fosters discussion between stakeholders and supports a goal finding process. Results of scenario analysis demonstrate solutions to given management tasks, which can serve as goals for implementation of measures in reality. First testing results indicate that there is a potential for increase of water discharge for environmental needs, while, at the same time, providing irrigation and other water users with sufficient water.
76

Advancing our understanding of animal dispersal and functional connectivity in human-altered landscapes: conceptual considerations and their empirical and simulation-based demonstration

Pflüger, Femke 17 December 2019 (has links)
No description available.
77

A Multi-Scale Analysis of Jaguar (Panthera onca) and Puma (Puma concolor) Habitat Selection and Conservation in the Narrowest Section of Panama.

Craighead, Kimberly A. 02 May 2019 (has links)
No description available.
78

Habitat Characteristics and Nesting Ecology of Golden Eagles in Arizona

Losee, Michele J. 15 July 2019 (has links)
No description available.
79

Mapping Potential Butterfly Weed (Asclepias Tuberosa) Habitat in Mississippi Using Geographical Information Systems (GIS)

Neigel, Emma Rose 10 August 2018 (has links)
Butterfly weed (Asclepias tuberosa) is a primary larval food source for the monarch butterfly (Danaus plexippus). Planting more butterfly weed may stimulate declining monarch populations. To that end, a habitat suitability map was created for Mississippi in GIS using soil pH, soil texture, and land cover. Herbarium data were derived from the Southeast Regional Network of Expertise and Collections (SERNEC) database. Environmental data were from the USDA National Resource Conservation Service geospatial data gateway. Frequency analysis was used to assign scores to environmental variables of SERNEC occurrences using a suitability index. Global positioning systems (GPS) locations of butterfly weed were collected to validate the model. The most suitable model with 78.9% of GPS points in medium to high suitability was a weighted sum overlay with land cover 50%, soil pH 25%, and soil texture 25%. The suitability map may enable conservationists to identify suitable sites for butterfly weed in Mississippi.
80

Non-Native Species and Urbanization in the Context of Butterfly Communities

Rivest, Stephanie 09 January 2023 (has links)
Biodiversity is being lost around the world and anthropogenic activities, like non-native species introductions and urbanization, are among the leading causes of decline. Broadening our understanding of human-driven impacts on biodiversity can lead to more effective solutions and contribute towards stemming biodiversity losses. In this thesis, I explored the impacts of non-native species introductions and urbanization on butterfly-plant communities. I evaluated potential factors influencing the range expansion of a newly introduced species (Chapter 1), examined the role of urbanization in structuring biological communities (Chapter 2), and identified important ecological interactions between native and non-native species (Chapter 3). In my first chapter, I found that the newly introduced European Common Blue butterfly (Polyommatus icarus) was more abundant in urban and disturbed habitat that was unmown and where their preferred larval host plant (Lotus corniculatus), a non-native species, was present. I also found that P. icarus was not a strong flier relative to other butterfly species, suggesting that adult dispersal may not be a driving factor in range expansion. Instead, this species could expand its range in the future by colonizing habitats in developed regions across Canada given the association I found between P. icarus and disturbed habitat. In my second chapter, I found that urbanization led to the biotic homogenization of butterfly communities around Montréal, QC, favouring a few, highly abundant, non-native species. Homogenization was detected at both the taxonomic and functional levels and was driven by increases in P. icarus abundance in the more urban sites. In my third chapter, I found that non-native plants were well integrated into native butterfly nectar diets in an at-risk oak savanna ecosystem on Vancouver Island, BC and that usage of non-native plants increased when they were more available during the season. I also found that native butterflies visited non-native plants more often than flower availability predicted on its own, suggesting that butterflies may even prefer non-native nectar. Findings from my thesis research broaden our understanding of the ways in which butterfly communities can be influenced by human activities like urbanization and the introduction of non-native species, informing conservation efforts and directing future research needs.

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