Dissertations / Theses on the topic 'Invasione'
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Pizzo, Leonardo <1977>. "Analisi dei processi di invasione di piante esotiche nei paesaggi costieri sabbiosi del Veneto." Doctoral thesis, Università Ca' Foscari Venezia, 2012. http://hdl.handle.net/10579/1204.
Full textThis study analyses the effects of disturbance (mainly human, but also natural) on the process of invasion by alien species in the coastal dune systems of Veneto region. The research has been articulated into two levels, one focusing on morphological and functional traits of coastal dune wild species (natives and aliens) and the other on the plant community level. The results highlight that height, large leaf area and SLA are useful traits for the successful colonisation of the most invasive species along the mobile coastal dunes. Human impact has deeply contributed to the decay of the quality and functionality of coastal ecosystems, reducing the resistance native plant communities are able to oppose the arrival of invasive alien species under less disturbed conditions.
Falvo, Laura. "Analisi dei fattori prognostici nei carcinomi papilliferi della tiroide: ruolo del sottotipo istologico e della istologica invasione vascolare." Doctoral thesis, La Sapienza, 2006. http://hdl.handle.net/11573/917181.
Full textGASPARINI, GIULIA. "Cancer-Glia interaction in perineural invasion in pancreatic cancer: identification of FGF-BP1 as a molecular target." Doctoral thesis, Università Vita-Salute San Raffaele, 2022. http://hdl.handle.net/20.500.11768/122891.
Full textIntroduzione L'invasione perineurale (PNI) è definita come la presenza di cellule cancerose lungo i nervi. La PNI ha la sua più alta incidenza nell'adenocarcinoma duttale pancreatico (PDAC), dove è presente nell'80-100% dei pazienti ed è un fattore negativo associato ad un aumento della recidiva del cancro e ad una ridotta sopravvivenza. Durante la PNI, i nervi e il cancro formano un microambiente unico che promuove sia la crescita del cancro che il rimodellamento neurale. Diverse molecole sono state descritte per promuovere la PNI, come le neurotrofine e le chemochine. Le cellule di Schwann (SC), le principali cellule gliali del sistema nervoso periferico, si infiltrano nel PDAC nelle prime fasi della malattia e forniscono una guida alle cellule tumorali lungo i nervi, oltre a promuovere la neurogenesi intorno al tumore. Nonostante il chiaro contributo delle SC alla PNI, le interazioni tra nervi mielinizzati, SC e PDAC sono state poco studiate. Obiettivi Studiare le interazioni reciproche tra PDAC e cellule nervose e sviluppare un nuovo punteggio per stratificare e analizzare meglio la gravità della PNI nei pazienti. Materiali e metodi: Abbiamo analizzato come interagiscono i nervi mielinizzati e le cellule cancerose e identificato le molecole che governano questa interazione. Abbiamo utilizzato coculture neuronali-SC e cellule tumorali 2D per ricreare la PNI in vitro. Inoltre, per valutare più fisiologicamente queste interazioni, abbiamo sviluppato organoidi pancreatici. Risultati: I nostri risultati hanno mostrato che le cellule neoplastiche possono indurre profonde alterazioni nelle cocolture mielinizzate, sia per contatto diretto che paracrino. Mediante analisi del secretoma, abbiamo selezionato potenziali candidati in grado di indurre la degenerazione della mielina e ci siamo concentrati su FGF-BP1, una molecola coinvolta sia nella progressione del cancro che nella degenerazione dei nervi. Mediante trattamento con FGF-BP1 ricombinante e inibizione del suo segnale, abbiamo proposto che FGF-BP1 possa mediare la degenerazione della mielina indotta dalle cellule tumorali. Inoltre, abbiamo dimostrato che la degenerazione della mielina promuove la crescita, la proliferazione, la migrazione e l'invasione delle cellule tumorali. Per riprodurre questi risultati in un modo più fisiologico, abbiamo sviluppato organoidi e sferoidi pancreatici e coculture di organoidi-nervi. Abbiamo anche stabilito un modello in vivo di PNI trapiantando ortotopicamente sferoidi di tumore che stiamo attualmente convalidando. Infine, abbiamo applicato il nuovo punteggio di PNI ad una popolazione di 507 pazienti sottoposti a resezione chirurgica per PDAC presso l'Ospedale San Raffaele. Conclusioni: abbiamo analizzato rigorosamente le interazioni tra PDAC e nervo e identificato un candidato che potrebbe diventare un nuovo obiettivo terapeutico per i pazienti con PDAC. Inoltre, abbiamo dettagliato il ruolo della PNI specificamente nel PDAC, sollecitando una maggiore attenzione per la PNI in ambito clinico.
David, Noemi. "Slow waves in un modello di crescita tumorale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/12024/.
Full textMasi, Alessia. "Targeting integrins and modulating invasion and metastasis with metal-based drugs." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3615.
Full textDistant metastases of solid tumours are the major cause of cancer death. To improve the effectiveness of chemotherapy, only marginally active on secondary tumours, anti-metastatic agents are needed, i.e. compounds that display the capacity to selectively interfere with metastatic formation and growth. Among metal compounds, NAMI-A, HIm[Ru(III)Cl4Imdmso], has repeatedly shown a peculiar and selective anti-metastatic activity being able to prevent the formation, and to inhibit the growth of established secondary tumours. On these bases, the first phase of the project was aimed to investigate how variations on the NAMI-A chemical structure can influence the anti-metastatic activity. For this purpose, some representative complexes have been chosen: two heterocyclic compounds KP418, HIm[Ru(III)Cl4(Im)2], and KP1019, HInd[Ru(III)Cl4(Ind)2], presenting a different N-donor ligand, and three organometallic compounds, RM175, [(η6-biphenyl)Ru(II)Cl-(ethylendiamine)]PF6, its osmium congener AFAP51, [(η6-biphenyl)Os(II)Cl(ethylene-diamine)]BF4, and RAPTA-T, [RuCl2(η6-toluene)PTA], carrying a PTA ligand instead of ethylendiamine. The effects of the compounds on the interference with some steps of the metastatic progression are evaluated with appropriate in vitro tests, comparing the behaviour of the human MDA-MB-231 highly invasive breast cancer cells to that of human HBL-100 non tumorigenic mammary epithelial cells. To validate the model, the in vitro effects are compared with the in vivo anti-metastatic activity studied in the MCa mammary carcinoma of the CBA mouse. The results obtained highlight the selective activity of the organometallic compound RAPTA-T towards the highly invasive cell line in vitro, accompanied by a selective inhibition of metastasis development in vivo. RAPTA-T seems to act through the modulation of tumour cells-extracellular matrix interactions, and of cell motility. In particular RAPTA-T induces a cytoskeleton remodelling, mainly through the formation of stress fibres, that causes a stiffening of the cell body, particularly evident on MDA-MB-231 cells grown on ECM components. These effects, selectively identified in the highly invasive MDA-MB-231 cells, can be related to the higher ruthenium uptake, detected in this cell line. Cell adhesion, migration and invasion are directly related to actin assembly and disassembly, phenomena regulated by the RhoGTPases. RAPTA-T completely counteracts the increase of trypsin mediated cell detachment induced by the RhoGTPases inhibitor C3 transferase, in MDA-MB-231 cells grown on fibronectin and collagen IV, and on HBL-100 cells grown on collagen IV. These molecular events might stem from the cell surface and involve integrin adhesion molecules, as suggested by the role of ECM components in the functional tests and by the preference of RAPTA-T to bind them, above all, collagen IV, with which RAPTA-T interacts chemically as confirmed by an NMR analysis. The effect of RAPTA-T on cells immediately after the adhesion on the substrate, i.e. mainly adherent with integrinic receptors, suggests that RAPTA-T interacts mainly with integrins in the form already bound with the substrate. Le metastasi dei tumori solidi sono una delle principali cause di morte. Per migliorare l’effetto della chemioterapia, che è attiva solo marginalmente sui tumori secondari, sono necessari agenti anti-metastatici, cioè composti che si mostrino capaci di interferire selettivamente con la formazione e la crescita delle metastasi. Tra i vari composti di sintesi il NAMI-A, HIm[Ru(III)Cl4Imdmso], ha ripetutamente mostrato una selettiva azione anti-metastatica dimostrandosi capace di prevenire la formazione e di inibire la crescita di metastasi già formate. Su queste basi, la prima fase di questo progetto ha avuto lo scopo di indagare come variazioni nella struttura chimica del NAMI-A potessono influenzare l’azione anti-metastatica. A questo scopo sono stati scelti alcuni composti rappresentativi: due composti eterociclici il KP418, HIm[Ru(III)Cl4(Im)2], e il KP1019, HInd[Ru(III)Cl4(Ind)2], e tre composti organometallici, RM175, [(η6-biphenyl)Ru(II)Cl-(ethylendiamine)]PF6, il suo congenere a base di osmio AFAP51, [(η6-biphenyl)Os(II)Cl(ethylene-diamine)]BF4, e RAPTA-T, [RuCl2(η6-toluene)PTA], che al posto dell’etilendiamina presenta il ligando PTA. Gli effetti dei composti sull’interferenza con alcuni step della progressione metastatica sono stati valutati con alcuni test in vitro, paragonando il comportamento della linea cellulare altamente invasiva MDA-MB-231 proveniente da carcinoma mammario, con quello delle HBL-100 linea cellulare dell’epitelio mammario non tumorigenica. Per validare il modello proposto in vitro gli effetti dei composti sono stati paragonati con la loro azione in vivo studiata sul carcinoma mammario (MCa) dei topi CBA. I risultati ottenuti mettono in luce la selettiva azione del composto organometallico RAPTA-T verso la linea cellulare altamente invasiva in vitro, accompagnata dalla inibizione selettiva dello sviluppo delle metastasi in vivo. Il RAPTA-T sembra agire attraverso la modulazione delle interazioni cellula-matrice extracellulare e della motilità cellulare. In particolare il RAPTA-T induce il rimodellamento del citoscheletro, principalmente attraverso la formazione di fibre da stress, questo genera irrigidimento del corpo cellulare, particolarmente evidente sulle MDA-MB-231 cresciute sui componenti della matrice extracellulare. Questi effetti, selettivamente identificati sulla linea altamente invasiva, MDA-MB-231, possono essere correlati ad un più alto assorbimento di rutenio che è stato rilevato in questa linea cellulare. L’adesione cellulare, la migrazione e l’invasione sono direttamente correlate al rimodellamento del citoscheletro actinico, e questi fenomeni sono regolati dalle RhoGTPasi. Il RAPTA-T reverte completamente l’aumentato distacco conseguente al trattamento con la C3 transferasi, agente che inibisce le RhoGTPasi, nelle MDA-MB-231 cresciute su fibronectina e collagene IV e sulle HBL-100 cresciute sul collagene IV. Questi eventi potrebbero coninvolgere l’adesione integrinica ai substrati, come suggerito dal ruolo dei componenti della matrice extracellulare nei test funzionali presi in considerazione, dalla preferenza del RAPTA-T per il legame con questi, e soprattutto il collagene IV con cui il RAPTA-T interagisce chimicamente, come confermato dall’analisi NMR. L’effetto del RAPTA-T su cellule appena dopo l’adesione al substrato, quindi prevalentemente legate attraverso i recettori integrinici, suggerisce che il RAPTA-T interagisca principalmente con le integrine nella forma già legata i substrati.
XXII Ciclo
1978
White, Laura Linsey Fallaize. "Mechanisms underlying marine macroalgal invasions : understanding invasion success of Sargassum muticum." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23713.
Full textShucksmith, Richard. "Biological invasions : the role of biodiversity in determining community susceptibility to invasion." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485655.
Full textMiller, Nathaniel P. "Invasions of Secondary Forest by a Nonnative Grass Species: Microstegium vimineum {Nees}(Poaceae)." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1307047314.
Full textMedvecz, Erin. "Resisting Invasion: Grassland Plant Responses to an Invasive Legume, Lespedeza cuneata." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2123.
Full textNati, Julie Jeanne Helene. "Invasion physiology : do physiological characteristics facilitate the spread of invasive fish species?" Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/8104/.
Full textPorter, Erica. "The roots of invasion: Belowground traits of invasive and native Australian grasses." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/134392/1/Erica_Porter_Thesis.pdf.
Full textHeger, Tina. "Zur Vorhersagbarkeit biologischer Invasionen : Entwicklung und Anwendung eines Modells zur Analyse der Invasion gebietsfremder Pflanzen /." Berlin : Inst. für Ökologie der Techn. Univ, 2004. http://www.gbv.de/dms/bs/toc/472604457.pdf.
Full textNdwayana, Hamilton Ncedo. "A sustainable development approach in the control of alien invasion vegetation." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1020803.
Full textCarol, Bruguera Joaquim. "Ecology of an invasive fish (Silurus glanis) in Catalan reservoirs." Doctoral thesis, Universitat de Girona, 2007. http://hdl.handle.net/10803/7870.
Full textThe aim of this thesis is to provide the first data on the ecology of European Catfish (Silurus glanis) introduced to the Iberian Peninsula and to appraise its ecological impact on native biota. We sampled the fish assemblage of 14 Catalan reservoirs (Spain). The European catfish is nowadays introduced in four Iberian river basins: in the Ebro river basin for 30 years, in the Ter and Tajo river basin for a few years and we report the first record for the Llobregat river basin. We demonstrate the utility of comparing early and late invasion stages to understand the ecological changes caused by invasive species: recent introductions of catfish had smaller and younger catfish with growth rates higher than old and native populations and preying on fish instead of crayfish for old introductions. We also report the first published telemetry data for catfish.
Moodley, Desika. "Determinants of introduction and invasion success for Proteaceae." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79851.
Full textENGLISH ABSTRACT: Successful biological invasions take place when species introduced to regions outside their natural dispersal range overcome several barriers and establish, persist, proliferate and spread potentially resulting in major threats to biodiversity. The success of invasive alien plants depends on species-specific traits and characteristics of the introduced environment. In this thesis I explore which species traits are important and which environmental barriers need to be overcome for an invasion to occur using Proteaceae as a test case. Firstly, I assessed the global introduction history and invasion ecology of Proteaceae - a large plant family with many taxa that have been widely disseminated by humans, but with few known invaders. This revealed that at least 402 species (i.e. 24% of 1674 species in this family) are known to have been moved by humans out of their native ranges, 58 species (14%) have become naturalized and 8 species (2%) are invasive. The probability of naturalization was greatest for species with large native range sizes, low susceptibility to Phytophthora root-rot disease, larger seeds, mammal-dispersed seeds and those with the capacity to resprout after fire or other disturbances. The probability of naturalized species becoming invasive was greater for species with larger range sizes, species used as barrier plants, taller species, species with smaller seeds, serotinous species, and those that regenerated mainly through re-seeding. Secondly, I looked at mechanisms underlying naturalization on a regional scale, using species which are not already classified as major invaders. At least 26 non-native Proteaceae species have been introduced to, and are cultivated in, South Africa. Propagule pressure facilitated the naturalization of Hakea salicifolia populations in climatically suitable areas, but in suboptimal climates human-mediated land disturbance and land management activities are important for naturalization. Similar drivers are important for naturalization of other alien Proteaceae: a long residence time, fire regimes, poor land management, and propagule pressure were important mechanisms for naturalization. Thirdly, I determined whether reproduction, which in part drives propagule pressure, serves as a barrier for naturalization. I examined several Australian Proteaceae species introduced to South Africa and observed that all species were heavily utilized by native nectar-feeding birds and insects. The five Banksia species that were assessed are self-compatible but four species have a significantly higher reproductive output when pollinators visit inflorescences. Fruit production in H. salicifolia does not differ between naturally-pollinated and autonomously-fertilized flowers. Moreover, no significant difference in fruit production was observed between the five pollination treatments (i.e. natural, pollen-supplementation, autonomous, hand-selfed and hand-crossed treatments) and naturalized and non-naturalized populations. However, pollen limitation was detected in non-naturalized populations which received fewer pollinator visits than naturalized populations. Thus, reproduction limits but is not a fundamental barrier to invasion for H. salicifolia. I conclude that reproductive success of the studied Proteaceae, which is a key barrier determining invasiveness, is not limited by autonomous seed set or mutualisms in the introduced range. In this thesis I highlight biogeographical characteristics, a set of life-history traits and ecological traits as important determinants of invasiveness. These traits are in turn dependent on the stage of invasion. Characteristics of the recipient environment are also important drivers of invasions. This study provides a better understanding of plant invasions in general, but the patterns and processes of invasions highlighted in this thesis will be particularly useful for the current and future management of alien Proteaceae in South Africa and elsewhere, as well as, other species that are adapted to Mediterranean and nutrient poor ecosystems. For example, combining traits of invasiveness and susceptible environments will help to identify which non-native species pose a high risk of becoming invasive (e.g. species with large home ranges and barrier plants) and which conditions in the target area are likely to facilitate or exacerbate invasions (e.g. strong climate match and high propagule pressure).
AFRIKAANSE OPSOMMING: Suksesvolle biologiese indringing vind plaas wanneer ʼn spesie geïntroduseer word in ʼn area buite sy natuurlike verspreidings area, sekere versperrings oorkom, vestig, bly voortbestaan, vermenigvuldig en versprei en potensieel ʼn groot bedreiging inhou vir biodiversiteit. Die sukses van uitheemse indringer plante hang af van spesifieke kenmerke van die spesie en kenmerke van die omgewing waarin dit geïntroduseer word. In hierdie tesis maak ek gebruik van Proteaceae om te ondersoek watter kenmerke is belangrik en watter omgewing versperrings moet oorkom word vir indringing om plaas te vind. Ten eerste assesseer ek die wêreldwye introduksie geskiedenis en indringers ekologie van Proteaceae – ʼn groot plant familie wat wyd gebruik word deur mense, maar met min indringer spesies. Dit het gewys dat mense ten minste 402 spesies (dus 24% van die 1674 spesies in die familie) uit die inheemse areas verskuif het, 58 spesies (14%) genaturaliseer het en 8 spesies (2%) indringers geword het. Die moontlikheid van naturalisasie was die grootste vir spesies met ʼn groot inheemse streek, lae vatbaarheid vir Phytophthora wortelvrot, groter sade, dier verspreide sade en die met ʼn vermoë om weer uit te spruit na ʼn vuur of ander versteuring. Die moontlikheid van genaturaliseerde spesies om indringers te word, was groter vir spesies met groter streek grootte, spesies wat as versperring plante gebruik word, hoër spesies, spesies met kleiner sade, serotiniese spesies, en die wat hoofsaaklik voortbestaan as saadspruiters. Tweedens, het ek gekyk na onderliggende meganismes op ʼn regionale skaal, deur gebruik te maak van spesies wat nie alreeds as belangrike indringers geklassifiseer is nie. Ten minste 26 nie-inheemse Proteaceae spesies is alreeds geïntroduseer en word gekultiveer in Suid Afrika. Propaguul druk fasiliteer die naturalisering van Hakea salicifolia populasies in areas met geskikte klimaat, terwyl in areas met ʼn sub optimale klimaat, versteurings deur mense en grond bestuurs aktiwiteite belangrik is vir naturalisering. Die selfde drywers is belangrik vir die naturalisering van ander uitheemse Proteaceae: lang verblyftyd, vuur bestel, swak land bestuur en propaguul druk. Derdens het ek bepaal of reproduksie, wat gedeeltelik propaguul druk dryf, ʼn versperring is vir naturalisasie. Ek het gekyk na verskeie Australiese Proteaceae spesies wat geïntroduseer is in Suid Afrika, en het gevind dat al die spesies besoek word deur inheemse nektar etende voëls en insekte. Die vyf Banksia spesies wat geassesseer is, kan self bestuif, maar vier van die spesies het ʼn betekenisvolle hoër reproduksie wanneer bloeiwyses deur bestuiwers besoek word. Vrug produksie verskil nie tussen natuurlik bestuifde en self bestuifde blomme in H. salicifolia nie. Verder was daar geen verskil tussen vrug produksie van die vyf bestuiwings behandelinge (naamlik: natuurlik, stuifmeel bygevoeg, self, hand self en hand kruis) en tussen genaturaliseerde en nie genaturaliseerde populasies. Ewenwel, stuifmeel beperking is gevind in nie-genaturaliseerde populasies wat egter ook minder besoeke ontvang het dan die genaturaliseerde populasies. Dus, reproduksie kan die verspreiding beperk maar is nie ʼn fundamentele versperring vir indringing van H. salicifolia nie. My konklusies is dat die reproduktiewe sukses, wat andersins ʼn sleutel versperring is vir indringing, in die bestudeerde Proteaceae nie beperk word deur outonomiese saad produksie of mutualismes in die geïntroduseerde gebied nie. In hierdie tesis beklemtoon ek die biogeografiese karakters, lewens geskiedenis kenmerke en ekologiese kenmerke as belangrike bepalers van indringing. Hierdie kenmerke is op hulle beurt weer afhanklik van die stadium van indringing. Karakters van die ontvangende omgewing is ook belangrike dryfvere van indringing. Hierdie studie verbeter hoe ons plant indringing in die algemeen verstaan, maar die patrone en prosesse van indringing wat beklemtoon word in hierdie tesis sal besonder bruikbaar wees vir huidige en toekomstige bestuur van uitheemse Proteaceae in Suid Afrika en op ander plekke, asook vir ander spesies wat aangepas is tot Mediterreense en nutriënt arm ekosisteme. Byvoorbeeld, die kombinasie van kenmerke van indringing en vatbare omgewings sal help om te identifiseer watter uitheemse spesies ʼn hoë risiko inhou om ʼn indringer te word (byvoorbeeld spesies met ʼn groot streek grootte en versperring spesies) en watter kondisies in die teiken area die waarskynlikste indringing fasiliteer of vererger (byvoorbeeld sterk klimaat ooreenstemming en hoë propaguul druk).
Carmona, Catot Gerard. "Explaining the invasive success of the eastern mosquitofish (Gambusia holbrooki): the role of temperature." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/129501.
Full textLa gambúsia (Gambusia holbrooki) és un dels peixos continentals més àmpliament distribuït i més invasors. Se sap que no s’ha pogut establir al nord d’Europa ni a trams alts de rius, on la temperatura és massa baixa per a la supervivència i la reproducció. Aquesta tesi analitza com afecta la temperatura a la capacitat competitiva i a les característiques del cicle vital de la gambúsia. Es van mostrejar gradients latitudinals i al llarg de rius i es va trobar que la gambúsia que vivia a ambients més favorables (és a dir, latituds menors i zones baixes dels rius), presentava un major esforç reproductiu i una menor condició corporal però que aquests patrons de variació eren febles i depenien de l'edat dels peixos. També es va portar a terme un experiment en què es va demostrar que a mesura que puja la temperatura la gambúsia incrementa la seva capacitat de competència pels recursos i el comportament agressiu contra el fartet (Aphanius iberus), endemisme ibèric en perill d'extinció. Els nostres resultats impliquen que el canvi climàtic afavorirà l'èxit invasor de la gambúsia i augmentarà el seu impacte en els peixos natius
Barrios-O'Neill, Daniel. "Consumer-resource interactions and biological invasions : insights from an invasive Ponto-Caspian study system." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680885.
Full textPujol, Buxó Eudald. "Biological invasions: a temporal, spatial and plastic point of view: the case of Discoglossus pictus in Europe = Invasions biològiques: un punt de vista temporal, espaial i plàstic : el cas de Discoglossus pictus a Europa." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/456898.
Full textLes invasions biològiques estan essent aparentment infrautilitzades com a laboratoris naturals per investigar certs aspectes teòrics fonamentals de la biologia. En aquest sentit, els nou estudis presentats en aquesta tesi – ordenats en tres blocs temàtics – intenten donar un punt de vista evolutiu – a part d'ecològic – sobre la invasió de la granota pintada (Discoglossus pictus) a Europa. Aquesta granota es va introduir des d'Algèria a Banyuls de la Marenda (Catalunya Nord) fa aproximadament un segle, arribant ara des de Montpeller fins a Sant Celoni, colonitzant contínuament noves àrees. A la "PART A: variabilitat intraespecífica al llarg de la distribució invasora de Discoglossus pictus" observem que la granota pintada no forma un conjunt uniforme de poblacions en la seva distribució invasora europea, ni fenotípica ni genòmicament: la mida i els trets de la història vital dels adults es relacionen amb la precipitació mitjana de cada zona, mentre que la diferenciació genètica entre poblacions ha estat molt probablement creada pel procés d'expansió en sí. A la "PART B: Competència intra-gremi en capgrossos de Discoglossus pictus" veiem que la granota pintada representa, fisiològicament, una addició única al gremi local de capgrossos, caracteritzada per un creixement molt ràpid i orientat al consum, amb bones capacitats d'augmentar la qualitat i quantitat de la ingesta d'aliments quan n'hi ha possibilitats. Pel que fa a la freqüent relació de competència entre Epidalea calamita i Discoglossus pictus, podem observar que els capgrossos autòctons que han tingut un major nombre de generacions de contacte amb els invasors són capaços d'infligir un major estrès competitiu en aquests. Els dos competidors també difereixen lleugerament en les seves preferències de cria, però semblen estar obligats a acabar competint molt sovint a nivell de bassa. Dins d'aquestes, la posició tròfica d'ambdues espècies pot respondre tant a patrons evolutius com a patrons ecològics amb les dades recollides fins ara. Finalment, a la "Part C: Capgrossos de Discoglossus pictus com a presa per depredadors aquàtics autòctons" veiem que la granota invasora presenta un patró de defenses induïbles que s'emmotlla al que s'esperaria per a un anur autòcton, responent a tots els depredadors nadius eficaçment, mancant respostes davant de depredadors introduïts. La complexa història evolutiva dels conjunts d'anurs del mediterrani occidental posa la granota pintada com un cas molt particular d'espècie invasora, on no ses poden descartar els efectes d'una història co-evolutiva prèvia entre espècies similars.
Crider, Kimberly Kay. "BIOLOGICAL CONTROL: EFFECTS OF TYRIA JACOBAEAE ON THE POPULATION DYNAMICS OF SENECIO JACOBAEA IN NORTHWEST MONTANA." The University of Montana, 2010. http://etd.lib.umt.edu/theses/available/etd-03092010-140634/.
Full textBiological control, using introduced, specialist insects is a common strategy for controlling plant invasions. However, the efficacy of biological control agents in controlling their host plants is rarely quantified population level. I quantified the impact of a specialist biological control agent, the cinnabar moth (Tyria jacobaeae) on its host plant, tansy ragwort (Senecio jacobaea) in northwest Montana. Cinnabar moth damage and its effects on important plant vital rates were tested with and without specialist herbivores. The presence of moth larvae corresponded to a reduction in population growth rates to less than one, compared to herbivore-free controls, indicating the potential for successful biological control by this insect. However, delayed effects of cinnabar moth herbivory on tansy ragwort vital rates were realized during the year following moth herbivory, after the moths had disappeared from the system. Individual damage to flowering plants in 2005 led to increased survival of these plants in the following year compared to controls, by reverting back to a vegetative state. In addition, seed set was reduced in plants that were damaged as juvenile rosettes in 2005 that went on to flower in 2006. When these delayed effects were combined in matrix models, gains in adult survival did not outweigh the decreases in fecundity or transition rates in terms of population growth and our initial conclusions remained unchanged. However, further study revealed that moth larvae were more likely to be depredated by carpenter ants in xeric sites suggesting that moth populations may not be sustained in these areas. Cinnabar moth larvae can be effective in this system provided they consume a large number of seeds (>90%) in consecutive years, but requires that moth populations are established and sustained from year to year. While herbivores do show the ability to control an invasive plant species, this relationship is strongly contextual in this system. This work emphasizes the importance of recognizing the influence of habitat context on the outcome plant-herbivore interactions, specifically in invaded ecosystems.
Seyed, Sadr Mohamad. "SLIT proteins inhibit malignant brain tumour cell invasion via downregulation of pro-invasive genes." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110340.
Full textLa transformation d'une tumeur primaire en tumeur maligne et métastatique, s'éloignant du point d'origine, est souvent la principale cause de décès chez le patient. Les tumeurs cérébrales malignes tel les glioblastomes et les médulloblastomes sont parmi les plus invasives cancers humains. La voie de signalisation de Slit-Robo a été largement caractérisée et montre l'implication de Slit-Robo dans la répulsion des axones et cellules neuronales. Dans cette étude, nous avons étudié la possibilité que Slit-Robo pourraient repousser les cellules cancéreuses invasives cérébrales. Le premier chapitre de cette thèse présente une introduction approfondie du rôle de la famille des protéines Slit-Robo dans le contexte du cancer et de la biologie des tumeurs cérébrales. Le deuxième chapitre présente des preuves de l'implication des protéines Slit et leur rôle dans l'inhibition de l'invasion des cellules de tumeurs cérébrales. Aussi, la caractérisation de la voie de signalisation employée par les protéines Slit dans l'inhibitionde l'invasion des cellules cancéreuses a été montrée. De plus, cette étude présente des résultats qui suggèrent que les protéines Slit diminuent l'expression de la transcription degènes pro-angiogénique et pro-invasif des cellules tumorales. Nous avons aussi identifié MMP14 comme une protéase des protéines Robo et dont l'expression est influencée par les protéines Slit. Finalement, nous proposons un modèle démontrant qu'une diminution de l'expression de MMP14 induit une réduction de l'invasion des cellules tumorales du cerveau.
Robinson, Todd Peter. "Application of advanced techniques for the remote detection, modelling and spatial analysis of mesquite (prosopis spp.) invasion in Western Australia." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/620.
Full textLesieur, Vincent. "Invasion de la punaise américaine Leptoglossus occidentalis en Europe : une contribution à la compréhension des invasions fulgurantes." Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2045/document.
Full textDuring the last decades, biological invasions were observed to increase exponentially, at an unprecedented rate and magnitude, in direct relation with the human activities, especially globalization. In this context, some invasive species spread very quickly in the area of introduction. The European invasion of Leptoglossus occidentalis is a good example of this phenomenon. This study aimed at testing some hypotheses to explain the rapidity of this invasion. To reach this goal, we used a multidisciplinary approach combining population genetics (analyzing samples from native and invaded areas) with a study of biological and ecological characteristics of the invasive populations. Through the use of molecular markers and Bayesian methods (ABC), we confirmed previous suspicions and demonstrated that the European invasion proceeded from multiple introductions in distant geographic areas. Our results also indicated that a primarily invaded area of Eastern North America acted as a bridgehead for the invasion in Europe. Moreover, population genetics, combined with an experimental measurement of the bug flight capabilities using flight mills, revealed that the intrinsic capacities of dispersion of this species are particularly high. The environmental conditions of the newly invaded areas in Europe did not constitute a barrier to the invasion of L. occidentalis. Its high degree of polyphagy was confirmed on European conifers, quite all species being susceptible to be exploited, thus favoring population establishment. . Furthermore, this study highlights the ecological threat represented by this insect which can affect the native flora in Europe. Actually, bug damage which can be important, seems to be additive to those of native insects exploiting cone and seed resources, thus decreasing the potential of natural regeneration. This work contributes to improve knowledge on biological invasions, especially to understand the reasons underlying the rapid spread observed in some invasive species, and highlights phenomenon underestimated until recently such as the Bridgehead scenario
Allen, Victoria. "Uncovering Pathways Regulating ILC Metastasis Through miRNA Expression Analysis and Generation of Novel Invasive ILC Models." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39616.
Full textDonaldson, Jason Ernest. "The invasion ecology of Acacia elata (A. Cunn. Ex Benth.) with implications for the management of ornamental wattles." Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85808.
Full textENGLISH ABSTRACT: This thesis explores how human dictated methods of introduction and species-specific traits interact to define spatial patterns in invasive plant populations using Acacia elata as a model species. I initially asked whether the relatively small invasive extent (when compared to congeners introduced for forestry or dune stabilization) of a species used widely for ornamental purposes (A. elata) is due to low rates of reproduction in South Africa. Results indicate that A. elata has similar traits to other invasive Australia Acacia species: annual seed input into the leaf litter was high (up to 5000 seeds m-2); large seedbanks develop (>20 000 seeds m-2) in established stands; seed germinability is very high (>90%); seeds accumulate mostly in the top soil layers but can infiltrate to depths of 40cm; and seed germination appears to be stimulated by fire. I argue that the current limited distribution of invasive A. elata populations is not attributable to species-specific reproductive traits. Following on from this I addressed the relative importance of species traits, the recipient environment, and introduction dynamics using species distribution models and spread models defined using a range of parameters representative of invasive Australian acacia species. Results indicate that in the early stages of simulated invasions, the number of trees introduced was the most important parameter influencing abundance and extent, while the placement of introduction foci in urban areas associated with ornamental introductions limited the extent and abundance of invasive populations. I suggest that conditions relating to human-mediated introduction events initially mask the influence of intrinsic species traits and help to explain the failure and success of species associated with specific human-shaped pathways. Third, I used scale-area curves to determine how these human-dictated introduction conditions influenced the spatial structure of populations. The fractal dimension (Dij) of A. elata populations indicates plot scale (2.5-25m) spread with high densities that are increasing. Artefacts of introduction history were observed at the regional scale (2.5-25km) - populations are contiguous around introduction foci such as towns and roads. Moreover, fragmentation of A. elata populations at local to landscape scales (0.25-2.5km) is due to a combination of the haphazard regional placement and limited secondary dispersal vectors, both of which can be linked to their introduction history. In summary, this study used a combination of field-based data, modelling techniques and broad-scale sampling methods to assess how intrinsic species traits and introduction conditions mediate invasive spread. I conclude that introduction history can have a long-lasting (100+ years) influence on the spatial structure and distribution of invasive plants, which can mask the influence of individual species traits.
AFRIKAANSE OPSOMMING: Alhoewel menigte plant spesies deur mense ingevoer word, word slegs 'n klein hoeveelheid van plante indringers. Die beperkte aantal spesies wat in nuwe habitatte vestig en versprei, kan grotendeels toegeskryf word aan die omgewing en mensgemaakte hindernisse ten opsigte van oorlewing, voortplanting en verspreiding. In hierdie tesis gebruik ek Acacia elata as ʼn model spesie om te ondersoek hoe die invoeringsproses sowel as spesie spesifieke eienskappe die ruimtelike struktuur van indringende populasies bepaal. Aanvanklik was my vraag of die relatiewe klein indringingsarea van ʼn spesie wat ingevoer is vir ornamentele doeleindes (Acacia elata), teenoor die groot indringingsareas van Australiese Acacia-spesies wat ingevoer is vir bosbou of duin stabilisering, die gevolg is van lae voortplantings tempo in Suid-Afrika. Resultate dui daarop dat A. elata soortgelyke eienskappe as ander indringende Australië akasia spesies het: jaarlikse saad produksie is hoog (tot 5000 sade m - 2); groot ontwikkelde saadbanke (> 20 000 sade m - 2); hoë saad ontkieming (> 90 %); saad versamel in die boonste grondlae, alhoewel dit kan infiltreer tot 'n diepte van 40 cm; laastens, ontkieming word deur vuur gestimuleer. Hierdie resultate stel voor dat die huidige beperkte verspreiding van indringende A. elata populasies nie die gevolg is van spesie spesifieke voortplantings eienskappe nie. Gevolglik het ek 11 indringende Australiese akasia-spesies ondersoek om die relatiewe belangrikheid van spesie eienskappe, die area waar hul geplant is, asook invoerings aspekte te ondersoek. Resultate wys dat die aantal bome wat ingevoer is, die belangrikste eienskap was ten opsigte van digtheid en verspreiding van ʼn indringende spesie, terwyl invoering naby fokuspunte in stedelike gebiede weer spesie digtheid en verspreiding beperk. Hierdie resultate toon dat spesies eienskappe aanvanklik nie ʼn groot invloed het op hul sukses nie, maar dat hul sukses eerder afhang van waar hul geplant word. Derdens, gebruik ek skaal - area kurwes om te bepaal hoe die invoering van A. elata die ruimtelike struktuur van populasies beïnvloed het. Die fraktale dimensie (Dij) van A. elata bevolkings dui op verspreiding by die plaaslike vlak (2,5 - 25m), wat voorstel dat verspreiding nie op hierdie skaal beperk is nie. Eienskappe van die rede/metode van invoering was wel waargeneem op die groter skaal (2.5 - 25km) waar populasies digter was naby dorpe en paaie. Die intermediêre skaal (0,25 - 2.5km) dui daarop dat A. elata populasies huidiglik beperk word deur 'n kombinasie van lukrake plasing en beperkte sekondêre verspreiding, albei wat gekoppel kan word aan hul invoer geskiedenis. Hierdie studie maak dus gebruik van 'n kombinasie van veld gebaseerde data, modellerings tegnieke en breë skaal steekproefmetodes om te evalueer hoe algemene spesies eienskappe en invoer toestande verspreiding bepaal. Sodoende verskaf ek ʼn raamwerk om die invloed van invoer toestande op die ruimtelike struktuur en verspreiding van ornamentele plant indringers te verstaan.
Boubou, Angham. "Apport de l'approche évolutive pour l'étude de l'invasion de l'acarien rouge de la tomate, Tetranychus evansi." Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0018.
Full textThe red tomato spider mite Tetranychus evansi (Tetranychidae) is regarded as an invasive species having an important economic impact on solanaceous crops. It was first discovered in Brazil in 1954, where it probably originated. Based on historical records, T. evansi was first reported in Africa and more recently in Europe and Asia. This work aims at reconstructing the colonization routes of T. evansi and identifies the scenario that best describes the evolutionary history of the invasion. To do this, we first analyzed samples collected from most parts of the world where the mite is currently known to occur. We used sequence variation of a fragment of the mitochondrial Cytochrome Oxidase I (COI) sub-unit I gene and the ITS1-5.8S-ITS2 of the nuclear ribosomal DNA. Our results were consistent with the hypothesis of a South American origin of this species. They also suggested that the invasion of south Europe resulted from multiple cryptic introductions from two genetically divergent lineages originated from two distant geographical regions in Brazil. These two lineages seem to have a differential invasive potential. Despite the high genetic divergence, crosses between mites stemming from the two lineages do occur both in the laboratory and in nature. Second, we used 16 microsatellite loci that we developed for this study and in association with Approximate Bayesian Computation (ABC) methods; we reconstructed the historical events of the cryptic invasion of the pest. ABC results challenge the invasion scenario captured by historical data only. They suggest that T. evansi first arrived to Europe in Southern Spain (Andalusia) long before historic records. Thus, Andalusia seems to have served as a source for colonization of new areas in Africa and other Mediterranean regions. The results obtained in this thesis provide an interesting framework to further study and understand why some populations of an exotic species might become invasive
Selge, Sebastian. "Public and scientific discourses on biological invasions : social representations of invasive non-native species in Scotland." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=183833.
Full textCamacho-Cervantes, Morelia. "Heterospecific social interactions of the invasive guppy (Poecilia reticulata) : a potential trait to enhance invasion success." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6561.
Full textRiley, Leslie Anne. "Estimating invasive species impact interaction strengths, abundance and the role of productivity in a freshwater invasion /." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/l_riley_111808.pdf.
Full textBerry, Katharine M. "The role of parasites in the invasion ecology of Harmonia axyridis." Thesis, University of Stirling, 2017. http://hdl.handle.net/1893/27336.
Full textYapi, Thozamile Steve. "An assessment of the impacts of invasive Australian wattle species on grazing provision and livestock production in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/95455.
Full textENGLISH ABSTRACT: I investigated the impacts of the invasive wattle species (Acacia mearnsii, A. dealbata, A. decurrens), on the ecological function and productivity of rangelands in South Africa and their ability to sustain livestock production. More specifically, this study set out to: (1) assess grazing areas at a national scale; (2) identify evidence of progressive impacts of these species on livestock production across a selection of magisterial districts; (3) determine the effects of A. mearnsii density on growth form dominance of indigenous plant species, and highlight how this translates into impacts in forage quality and quantity; (4) determine the effects of A. mearnsii invasion on soil resources and conditions (key determinates of ecological function) required to support grazing production; and finally (5) determine to effects that clearing operations have had on the provision of grazing resources. My results indicate that the level of overlap between wattle invasion and areas with a high grazing potential, at the national scale, is relatively low (2.9%). However, at a magisterial district scale, areas with a high grazing potential have a moderate (approximately 35.1% high grazing potential area under wattle invasion for highest invaded district) level of invasion. Scattered and moderate levels of invasion currently dominate or characterise these species invasion patterns. Both light and dense A. mearnsii invasions reduce grazing capacity. Dense invasion had the most severe effect reducing grazing capacity from 2 ha, required to support one large stock unit, to 8 ha. The clearing of this species was found to improve grazing capacity within 5 years. The reduction in grazing capacity following invasion was largely due to reduced basal cover and herbaceous biomass. The clearing of invaded sites was found to increase both basal cover and herbaceous biomass to pre-invasion levels. Acacia mearnsii invasion was found to affect certain soil properties. Under an A. mearnsii canopy, plant litter, carbon content of the soil and nitrogen concentrations were all found to be elevated. Overall, this study demonstrates that Acacia invasions have a significant effect on grazing resources at a local or site scale, and that for the eastern region of South Africa, these effects are ultimately scaled up to a district level. This is likely to have important financial and human well-being repercussions. However clearing and restoration programs are clearly able to reverse or mitigate these effects. This study therefore lends support to or complements other ecosystem service provision arguments for clearing alien invasive species.
AFRIKAANSE OPSOMMING: Die impak van die indringer- wattelbome spesies ( A. mearnsii , A. dealbata , A. decurrens) , op die ekologiese funksie en produktiwiteit van weivelde in Suid-Afrika en hul vermoë om vee produksie te onderhou was ondersoek. Meer spesifiek, is hierdie studie uiteengesit om: (1) ondersoek in te stel na die mate van oorvleueling tussen indringing deur wattelbome spesies en belangrike weidingsgebiede op 'n nasionale skaal; (2) bewyse te verskaf van die progressiewe impak van hierdie spesies op vee-produksie oor 'n seleksie van politieke distrikte, (3) die gevolge van A. mearnsii digtheid op groei vorm en oorheersing van inheemse plante te wys, en hoe dit voer kwaliteit en kwantiteit affekteer; (4) die gevolge van A. mearnsii indringing op grond hulpbronne sowel as die kondisie (sleutel bepalende faktore van ekologiese funksie) wat benodig word om weiding produksie te ondersteun vas te stel, en uiteindelik (5) om die gevolge van skoonmaak bedrywighede op die voorsiening van weiding hulpbronne te bepaaal. My resultate dui daarop dat die vlak van oorvleueling tussen die wattelbome indringing en gebiede met 'n hoë weiding potensiaal, by die nasionale skaal, relatief laag is (2’9 %). Maar op 'n landdrosdistrik skaal, het gebiede met 'n hoë weiding potensiaal 'n matige (ongeveer 35.1 % weiding potensiaal area onder wattelbome indringing vir die hoogste binnegevalde distrik ) vlak van indringing. Verspreide en matige vlakke van indringing oorheers tans of kenmerk hierdie spesies se indringings patrone. Beide lig en digte A. mearnsii besettings verminder dravermoë. Digte inval het die mees ernstige uitwerking en verminder dravermoë van 2 ha, wat nodig is om een grootvee-eenheid te ondersteun na 8 ha. Bevindinge wys dat die verwydering van hierdie spesies weiding kapasiteit kan verbeter binne 'n tydperk van 5 jaar. Die afname in dravermoë na indringing is grootliks te wyte aan die afname in basale bedekking en kruidagtige biomassa. Na die skoonmaak van indringer persele is bevind dat beide basale bedekking en biomassa weer verhoog tot voor- indringings vlakke. Acacia mearnsii indringing beïnvloed sekere grondeienskappe. Onder A. mearnsii blaredak, is alle blaarafval, koolstof-inhoud van die grond en stikstof konsentrasies verhef. In die algeheel, toon hierdie studie dat die Acacia indringings 'n beduidende uitwerking op weidings hulpbronne by 'n plaaslike of perseel skaal het, en vir die oostelike streek van Suid-Afrika, is hierdie effekte ook uiteindelik vertaalbaar tot 'n distrik vlak. Dit sal waarskynlik belangrike finansiële en menslike welsyn gevolge hê, maar die skoonmaak en herstel programme is duidelik daartoe instaat om die gevolge te keer of te verminder. Hierdie studie leen dus ondersteuning aan of komplimenteer ander ekostelsel dienslewering argumente (soos dié van die Werk vir Water program) vir die verwydering van indringerspesies.
Robinson, Todd Peter. "Application of advanced techniques for the remote detection, modelling and spatial analysis of mesquite (prosopis spp.) invasion in Western Australia." Curtin University of Technology, Department of Spatial Sciences, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=118290.
Full textThese three modules of research are summarised hereafter. To examine the rates and patterns of mesquite invasion through space and time, canopies were extracted from a temporal series of panchromatic aerial photography over an area of 450 ha using unsupervised classification. Non-mesquite trees and shrubs were not discernible from mesquite using this imagery (or technique) and so were masked out using an image acquired prior to invasion. The accuracy of the mesquite extractions were corroborated in the field and found to be high (R2 = 0.98, P<0.001); however, accuracy varied between classes (R2 = 0.55 to 0.95). Additional sampling may be required in some of the wider class intervals, particularly the moderate density class (30 to 90%) as sampling frequency was poor within the range of 60 to 90%. This is a direct result of there being relatively few quadrats available to be randomly selected in this class. That is, quadrats with between 60-90% cover were only evident in 4% of the test area. A more robust approach would, therefore, be to split this class into two (e.g. 30-60% and 60-90%) and select an additional 15 quadrats in the 60-90% range. The resolution of the imagery (1.4 m) precluded mapping shrubs smaller than 3 m2. Rates and patterns were compared to mesquite invasions in its native range.
It was determined that: (i) the shift from grass to mesquite domination had been rapid, with rates of increase in canopy cover comparable to invasive populations where it is native; (ii) rate of patch recruitment was high in all land types (stony flats, red-loamy soils and the riparian zone), but patch expansion and coalescence primarily occurred over the riparian zone and redloamy soils; (iii) mesquite had been spread by sheep and macropods and the recent switch to cattle is likely to exacerbate spread as it is a far more effective dispersal vector; and (iv) early successional patterns, such as high patch initiation followed by coalescence of existing stands are similar to where mesquite is native, but patch mortality did not occur. A knowledge based model was used to predict which parts of the Pilbara region are most at risk. Several limitations of models often employed in predicting suitability ranges of invasive plants were identified and include: (i) an inability to incorporate the notion that within a suitability range there is likely to be a scale of favourability; (ii) an inability to assign greater importance to evidence that is likely to have more importance in defining the areas suitable for invasion; and (iii) an inability to control the level of conservatism in the final results. These three shortcomings were mitigated through the use of: (i) fuzzy membership functions to derive a range of favourability from poor to best; (ii) pairwise comparison to derive higher weights for layers perceived to be more important and vice versa; and (iii) the use of ordered weighted averaging to directly control the level of conservatism (or risk) inherent in the models produced.
Based on the outcomes of the historical reconstruction of spatial rates and patterns, data sources included land types, land use, and the derivation of a steady state wetness index from spot height data. Model outputs were evaluated using two methods: the area under the curves (AUC) produced from relative operating characteristic (ROC) plots and by the maximum Kappa procedure. Both techniques agreed that the model most representative of the validation data was the one assuming the most risk. To create a Boolean output representing areas suitable/not suitable for invasion, optimal cut-points were derived using the point closest to the top left hand corner of the ROC plot and by the maximum Kappa method. Both methods obtained identical cut-points, but it is argued that the coefficient produced by the maximum Kappa method is more easily interpreted. The highest AUC was found to be 0.87 and, based on the maximum Kappa method, can be described as good to very good agreement with the validation records used. Digital multispectral imagery (DMSI), acquired in the visible and near infrared portions of the spectrum (3 visible bands, 1 near infrared) with a spatial resolution of 1 m and hyperspectral imagery (126 bands, 3 m spatial resolution) was acquired to assess the potential of developing a reliable and repeatable mapping tool to facilitate the monitoring of spread and the effects of control efforts. Woody vegetation was extracted from the images using unsupervised classification and grouped into patches based on contiguity. Various statistics (e.g. maximum, minimum, median, mean, standard deviation, majority and variety) were assigned to these patches to garner more information for species separation.
These statistics were explored for their ability to separate mesquite from coexisting species using Tukey’s Honestly Significantly Different (HSD) test and, to reduce redundancy, followed by linear discriminant analysis. Two approaches were taken to select the patch statistics offering the best discrimination. The first approach selected patch statistics that best discriminated all species (named “overall separation”). This was compared to a second approach, which selected the best patch statistics that separated each species from mesquite on a pairwise basis (named “pairwise separation”). The statistics offering the best discrimination were used as input in an Artificial Neural Network (ANN) to assign class labels. An incremental cover evaluation, whereby producer’s accuracy was computed from mesquite patches grouped into various size-classes, showed that identification of mesquite patches smaller than 36 m2 was relatively low (43-51%) regardless of the method used for choosing between the patch statistics or image type. Accuracy improved for patches >36 m2 (66-94%) with both approaches and image types. However, both approaches used on the hyperspectral imagery were more reliable at capturing patches >36 m2 than the DMSI using either approach. The lowest omission and commission rates were obtained using pairwise separation on the hyperspectral imagery, which was significantly more accurate than DMSI using an overall separation approach (Z=2.78, P<0.05), but no significant differences were found between pairwise separation used on either media.
Consequently, all methods and imagery types, except for DMSI processed using overall separation, are capable of accurately mapping mesquite patches >36 m2. However, hyperspectral imagery processed using pairwise separation appears to be superior, even though not statistically different to hyperspectral imagery processed using overall separation or DMSI processed using pairwise separation at the 95% confidence level. Mapping smaller patches may require the use of very high spatial resolution imagery, such as that achievable from unmanned airborne vehicles, coupled with a hyperspectral instrument. Alternatively, management may continue to rely on visual airborne surveys flown at low altitude and speed, which have proven to be capable at mapping small and isolated mesquite shrubs in the study area used in this research.
Meffin, Ross. "Invasion success and impacts of Hieracium lepidulum in a New Zealand tussock grassland and montane forest." Lincoln University, 2010. http://hdl.handle.net/10182/1808.
Full textSaulnier, Ronald Betnoit. "Analysis of integrins and cell adhesion on invasive tumor cell lines using an in vitro invasion assay." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30317.
Full textMedicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate
Kempf, Hannah Lowe. "Comparisons of Ecosystem Dynamics Before and After Invasion Reveal Consequences of Invasive Species in Benthic Marine Communities." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1524830000208304.
Full textRamakrishnan, Alisa Paulsen. "Genetic patterns of dispersal and colonization during initial invasion and spread of an invasive grass, Brachypodium sylvaticum." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/355.
Full textMurphy, Jennifer E. "The Beginning and Legacy of Rosa multiflora Invasions: Understanding the Mechanisms that Drive Its Success Across Stages of Invasion." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1561484787925341.
Full textKelley, Amanda. "The Effect of Temperature on Phenotypes of the Invasive European Green Crab: Physiologic Mechanisms that Facilitate Invasion Success." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1004.
Full textMastalerz, Allison. "The role of ornamental gardening in forest plant invasions across an urban-rural gradient in Southwestern Ohio." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866412.
Full textVardien, Waafeka. "Molecular ecology and invasive species management: unravelling the dynamics of Lantana camara invasions in the Kruger National Park, South Africa using a molecular approach." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20378.
Full textENGLISH ABSTRACT: Non-native species are recognized as a major component of global environmental change. Their ecological impacts are numerous and include the alteration of whole ecosystem processes as well as the loss of native biodiversity. As such, understanding the processes that drive the invasion of non-native species is essential for the control and management thereof. Numerous research approaches have been used to provide insight on the history and ecology of non-native species invasions. However, recent approaches employing molecular techniques have greatly helped in solving taxonomic issues associated with some of these species; identifying sources of invasions; and shedding light on colonization dynamics. Lantana camara, a globally invasive and highly variable species complex, is one of the most notorious plant invaders in South Africa. The species has been associated with negative impacts in agricultural areas, decreased invertebrate diversity, livestock mortality, and where it occurs along riparian areas- decreased water quality and obstruction to accessing water sources. This project aimed to review L. camara invasions in South Africa and to unravel patterns of spread in L. camara along the Sabie-Sand catchment in South Africa’s flagship protected area, the Kruger National Park, using a molecular approach. The findings of the first part of the study highlight that L. camara has successfully spread across South Africa with only four known introduction events, and this can be attributed to the species’ broad ecological tolerance, its use in the horticultural industry, and a variety of dispersal vectors (birds, humans and rivers). Furthermore, although sale of the species is prohibited in the country, it will continue to spread naturally and also has the potential to expand its distribution under changing climate scenarios. The second part of the study highlights that spread along the Sabie-Sand catchment is primarily river-driven and that the Sand tributary is the invasion source in the system. Because the Sand tributary originates outside the Kruger National Park, and only a small portion is under park management, the implications for spread are important.
AFRIKAANSE OPSOMMING: Nie-inheemse spesies word erken as 'n belangrike komponent van die globale omgewing verandering. Hulle ekologiese impak is talle en sluit in die verandering van ekosisteem prosesse asook die verlies van inheemse biodiversiteit. As sodanig, die begrip van die prosesse wat lei tot die inval van 'n nie-inheemse spesies is noodsaaklik vir die beheer en bestuur daarvan. Talle navorsingsbenaderings is gebruik om insig te gee oor die geskiedenis en ekologie van nie-inheemse spesies invalle. Onlangse benaderings soos die gebruik van molekulêre tegnieke, help in die oplossing van taksonomiese kwessies wat verband hou met 'n paar van hierdie spesies,in die identifisering van bronne van invalle, en om lig te werp op die kolonisasie dinamika. Lantana camara, 'n wêreldwye indringende en spesie kompleks, is een van die mees berugte plantindringer in Suid-Afrika. Die spesie is geassosieer met negatiewe gevolge in landbou gebiede, afgeneem ongewerwelde diversiteit, vee mortaliteit, en waar dit voorkom saam oewer gebiede - afgeneem kwaliteit van die water en obstruksie tot waterbronne. Hierdie projek is daarop gemik om om L. camara invalle in Suid-Afrika te hersien en patrone van verspreiding te ontrafel in L. camara langs die Sabie-Sand-opvanggebied in Suid-Afrika se vlagskip beskermde gebied, die Kruger Nasionale Park, met behulp van 'n molekulêre benadering. Die bevindinge van die eerste deel van die studie wys dat L. camara het suksesvol versprei oor die hele Suid-Afrika met slegs vier bekende inleiding gebeure, en dit kan toegeskryf word aan die spesie se breë ekologiese verdraagsaamheid, die gebruik daarvan in die hortologie bedryf, en 'n verskeidenheid van die verspreiding vektore (voëls, mens en riviere). Verder, hoewel die verkoop van die spesie in die land verbied word, sal dit natuurlik voortgaan om te versprei en het ook die potensiaal om uit te brui onder veranderende klimaat scenario's. Die tweede deel van die studie wys dat versprei langs die Sabie-Sandopvanggebied hoofsaaklik rivier-gedrewe is en dat die Sand sytak die inval bron is. Omdat die Sand sytak buite die Kruger Nasionale Park ontstaan, en slegs 'n klein gedeelte onder park bestuur is, is die implikasies vir verspreiding belangrik.
Financial support from the DST-NRF Centre of Excellence for Invasion Biology and the Working for Water (WfW) Programme through their collaborative project on “Research for Integrated Management of Invasive Alien Species” and Stellenbosch University’s Subcommittee B Young Researcher's Fund
Parker, John D. "Plant-herbivore interactions : consequences for the structure of freshwater communities and exotic plant invasions." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/9460.
Full textOlsson, David. "USA:s invasion av Irak : EN studie av hur Bushadministrationen motiverade invasionen av Irak 2003, och hur motiveringen förhåller sig till FN-stadgan." Thesis, Försvarshögskolan, Krigsvetenskapliga avdelningen (KVA), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-2701.
Full textBrown, Carly. "Applications of DNA-barcoding in the identification and understanding of grass invasions in Southern Africa." Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/4650.
Full textThe spread of invasive species is one of the greatest threats to global biodiversity. Alien plant invasions also have serious economic impact in terms of the delivery of ecosystem goods and services. Studies of biological invasions in southern Africa have tended to overlook grasses (family Poaceae), although there are many naturalised species in the region. Only a few of these, all perennials, have been officially categorised as invasive in South Africa, but in the winter rainfall region of the Western Cape, grass invasion especially by Mediterranean European annuals have also been noted. These grasses can be difficult to identify. DNA barcoding has been suggested as an alternative method of identifying grasses in the hope of facilitating identification of existing invaders and preventing future invasions. In this study a list of all known naturalised grasses in South Africa was compiled, and a DNA barcoding reference database was assembled for these naturalised grass species as well as for native southern African grass species. The two official markers for plant DNA barcoding (rbcLa + matK) were used in barcoding and phylogenetic analyses, both individually and in combination. The barcoding data was assessed for identification efficacy using three distance-based metrics and one tree-based metric in the R package SPIDER, both including and excluding singleton data. This study lists 128 naturalised grass species and subspecies found in South Africa. In the DNA barcoding analyses, matK was found to perform better as a single barcode than rbcLa, with identification success rates of up to 84% for matK and 76% for rbcLa, using the most successful metric which was the Nearest Neighbour criterion for both of these markers in the data sets without singletons. The combined rbcLa + matK data set performed better than either of the two individual markers, with identification success rates of up to 91% in the data without singletons, with the most successful metric again being the Nearest Neighbour criterion. The combined rbcLa + matK data would therefore be the recommended DNA barcode for southern African grasses of the three data sets tested, based on the results of this study. Phylogenetic trees were constructed with the DNA barcoding data using Bayesian Inference (BI) and Maximum Parsimony (MP) to assess the usefulness of the data in phylogenetic studies and to confirm the efficacy of this grass DNA barcoding data when using tree-based methods of identification. Both the matK and combined datasets resolved all of the grass tribes represented in this study as monophyletic, but the rbcLa data did not.
Soria, Carvajal Monica Cecilia. "Avian seed dispersers of the invasive Rubus niveus (Rosaceae) in Santa Cruz Island, Galapagos, Ecuador." Diss., St. Louis, Mo. : University of Missouri--St. Louis, 2006. http://etd.umsl.edu/r1761.
Full textRichards, Jeannine Hyde. "From 'useful and interesting' to 'evil invaders': evolving perceptions of non-native species in the United States." Thesis, Boston University, 2002. https://hdl.handle.net/2144/27749.
Full textPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
2031-01-02
Alba, Castellón Lorena 1984. "Snail1 expression in mesenchimal cells promotes tumorigenesis and tumor progression." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/403887.
Full textEl factor de transcripción Snail1 es necesario para iniciar la transición epitelio-mesénquima. En cáncer, este proceso provee a las células epiteliales tumorales con características invasivas. En esta tesis demostramos que la función de Snail1 en fibroblastos y en células madre mesenquimales (MSCs) también contribuye a la progresión tumoral. En tumores de origen mesenquimal la expresión de Snail1 en MSCs es necesaria para mantener sus capacidades tumorigénicas e in vivo es necesaria para la formación del tumor. En tumores de origen epitelial, la expresión de Snail1 en los fibroblastos del estroma es necesaria para promover la invasión de las células tumorales. Los fibroblastos son activados de manera dependiente de Snail1 gracias a factores liberados por las células epiteliales del tumor; por ejemplo TGF-. Uno de los efectos de esta activación es la secreción de prostaglandina E2 la cual contribuye a la invasión tumoral. En consecuencia, la depleción de Snail1 en modelos tumorales in vivo reduce la invasión a tejidos adyacentes y disminuye la aparición de metástasis. Estos resultados sugieren un rol clave de Snail1 durante la progresión tumoral que no está limitado a su expresión en células epiteliales.
Devine, Kevin Patrick. "INITIAL RESPONSE OF INVASIVE EXOTIC PLANT SPECIES TO TIMBER HARVESTING IN SOUTHEASTERN KENTUCKY FORESTS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/650.
Full textBohl, Kerry. "An investigation of the factors leading to invasion success of non-native plants using a system of native, introduced non-invasive, and invasive Eugenia congeners in Florida." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4442.
Full textFletcher, David. "Biological invasion risk assessment, considering adaptation at multiple scales : the case of topmouth gudgeon Pseudorasbora parva." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG029/document.
Full textIn this thesis I set out to quantify the risk of invasion from the invasive freshwater fish, Pseudorasbora parva, at a global extent, using traditional correlative ecological niche modelling approaches with the integration of surrogate data representing introduction likelihood (Chapter I). These correlative approaches rely upon key assumptions relating to the presence or absence of local or regional adaptations, and so I subsequently tested for evidence of such adaptations in genetic lineages and in individual populations. This was achieved through analyzing climatic niche differentiation of key genetic lineages in the native and invasive ranges (Chapter II) and by conducting lab experiments comparing thermal responses of important life history traits in populations from contrasting climates (Chapter III). The initial risk assessment did not account for a key factor in invasions; namely, natural dispersal. Natural dispersal has been observed to be subject to selection in vanguard populations of invasive species, and adaptation of dispersal traits can infer additional invasive vigor, allowing the species to spread across the landscape quicker. For this reason, I quantified dispersal, activity and morphological differences, often associated with differential dispersal ability, in populations along a distance-gradient from an invasion front, in order to identify if P. parva is capable of such adaptations.The initial risk mapping study showed that large areas, beyond the current distribution of the species, are climatically suitable. These areas are mainly in North and South America, Australia and New Zealand, and constitute significant scope for spread and impact of this species. When introduction likelihood was included, N. America appears most at risk. I found no evidence to suggest that native genetic lineages represented local adaptations to their respective native climates - there was little or no differentiation of the lineages’ climatic niches in the invasive range. It was also apparent, from the niche comparisons, that the climatic niche in the invaded range constituted a significant shift, compared to the native range. The thermal responses of P. parva life history traits did not differ significantly between populations from a strongly seasonal continental climate and a mild temperate maritime climate. The overall reproductive output of females did not vary according to breeding season temperature, however, temporal reproductive strategy showed a strong response, with lower temperatures inducing a protracted breeding season and higher temperatures inducing rapid and intense reproductive output. The dispersal and morphology-related study identified a strong gradient of morphological change, corresponding with distance from invasion front. This demonstrates a high degree of plasticity in P. parva’s morphology in an invasion context, however this was not linked to either dispersal or activity levels, neither of which was significantly linked to distance from invasion front. Dispersal was best explained by body size, with larger fish more likely to disperse further.Whilst I found no evidence to suggest that the model predictions (Chapter I) were hampered by differentiation at either lineage or population levels, the findings of Chapter II do highlight the uncertainties surrounding the degree of conservatism in such predictions, mainly owing to the fact that past, native, distribution did not accurately predict the current invaded distribution. The results of Chapters II-IV show broad tolerances and great plasticity in P. parva, which likely underpin this species success as a pan-continental invader. The knowledge produced in this thesis provides a useful new resource for the development of management strategies for P. parva and could be usefully enhanced by the additional of analogous studies on native populations, which could help elucidate the source of the observed plasticity
Thompson, Glen Andrew. "Mechanisms of invasion and persistence of the invasive kelp Undaria pinnatifida (Harvey) Suringar within intertidal areas of southern New Zealand." Thesis, University of Canterbury. Zoology, 2004. http://hdl.handle.net/10092/6875.
Full textEssemyr, Moa, and Frida Persson. "INVASION DIREKTMARKNADSFÖRING." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-732.
Full textDirect marketing is an area within marketing that is growing rapidly. Many companies has realised the benefits of using direct marketing, such as receiving direct response from customers and gaining a better customer relation. The growth within direct marketing means that traditional mass marketing today face harder competition than ever.
This thesis examines and look in to three well recognised Swedish companies use of direct marketing. Our main purpose is to establish how companies spend their marketing budget between direct marketing and traditional marketing activities. In this purspose, we aim to look in to the companies marketing activities over the last few years. In relation to this, we also want to establish the main reasons for why companies has increased their direct marketing.