Dissertations / Theses on the topic 'Dispersal event'

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Nolan Hertel; Committee Member: Armin Ansari; Committee Member: Chris Wang; Committee Member: Rebecca Howell.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007.
Dr. Armin J. Ansari, Committee Member ; Dr. Farzad Rahnema, Committee Member ; Dr. Rebecca Howell, Committee Member ; Dr. Nolan E. Hertel, Committee Chair.

With increasing encroachment on natural communities by anthropogenic activity, it is important to understand the functions of natural ecosystems in an effort to conserve natural areas. A first-hand study of the population dynamics of South Florida Slash Pine (P. elliottii Engelm. var. densa) following a fire event provided insight to its recovery and dispersal following a fire. A natural fire (lightning-induced) occurred in the spring of 2000 at the T. Mabry Carlton, Jr. Reserve, Sarasota County, providing an opportunity to study aspects of slash pine in relation to fire. One objective of my research was to look at dispersal/recruitment conditions and slash pine dynamics in relation to fire. I looked at the varying degrees of tree mortality due to fire at different stands of slash pines. I also looked at the stands in terms of stand composition and spatial arrangement of surviving adults. Finally, I studied how variable seedling establishment and survival was between stands. Few inferences could be drawn between fire and these individual analyses; however, all analyses revealed that at the scale of this study, pine flatwoods are patchy. I also looked at the dispersal of slash pines following a fire event. I modeled my research after Ribbens et al. (1994) and Clark et al. (1998), who took a phenomenological approach to dispersal modeling. This approach involved using distances between adults and seeds/seedlings and fecundity of adults to create dispersal models based on maximum likelihood estimates (MLE). I found that, while I could predict a model within acceptable parameters for most of the stands, more data was needed to predict models that better fit the data. This finding, along with the fact that I recovered no seed data for analysis, suggests factors are contributing to dispersal and recruitment (e.g. cone-crop) that need to be accounted for in the future.

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Document formatted into pages; contains 78 pages.
Thesis (M.S.)--University of South Florida, 2003.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: With increasing encroachment on natural communities by anthropogenic activity, it is important to understand the functions of natural ecosystems in an effort to conserve natural areas. A first-hand study of the population dynamics of South Florida Slash Pine (P. elliottii Engelm. var. densa) following a fire event provided insight to its recovery and dispersal following a fire. A natural fire (lightning-induced) occurred in the spring of 2000 at the T. Mabry Carlton, Jr. Reserve, Sarasota County, providing an opportunity to study aspects of slash pine in relation to fire. One objective of my research was to look at dispersal/recruitment conditions and slash pine dynamics in relation to fire. I looked at the varying degrees of tree mortality due to fire at different stands of slash pines.
ABSTRACT: I also looked at the stands in terms of stand composition and spatial arrangement of surviving adults. Finally, I studied how variable seedling establishment and survival was between stands. Few inferences could be drawn between fire and these individual analyses; however, all analyses revealed that at the scale of this study, pine flatwoods are patchy. I also looked at the dispersal of slash pines following a fire event. I modeled my research after Ribbens et al. (1994) and Clark et al. (1998), who took a phenomenological approach to dispersal modeling. This approach involved using distances between adults and seeds/seedlings and fecundity of adults to create dispersal models based on maximum likelihood estimates (MLE). I found that, while I could predict a model within acceptable parameters for most of the stands, more data was needed to predict models that better fit the data.
ABSTRACT: This finding, along with the fact that I recovered no seed data for analysis, suggests factors are contributing to dispersal and recruitment (e.g. cone-crop) that need to be accounted for in the future.
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The mitochondrial genome is organized as a small circular molecule of DNA, present in hundreds/thousands of copies per cell and characterized by a much greater evolutionary rate than the average nuclear gene. The mitochondrial DNA (mtDNA) is transmitted as a non-recombining unit only through the mother and its variability is originated only by the sequential accumulation of new mutations. During millennia, this process of molecular divergence has given rise to monophyletic units (haplogroups) that are generally restricted to specific geographic areas or population groups. The study of the geographical distribution, the internal variability and the coalescence age of each haplogroup allow us to make inferences about the demographic history of populations, such as dispersals, range expansions, or migrations. During my PhD studies, I analysed the sequence variation of the mtDNA at the highest level of resolution, that of complete sequence (mitogenome), in order to reconstruct the migration events of both human and animal populations. In particular, I mainly focused my research activity on three projects. The first project aimed to date the events that brought to the initial peopling in Sardinia and to clarify the genetic history of Europe. Sardinians are "outliers" in the European genetic landscape and, according to paleogenomic nuclear data, the closest to early European Neolithic farmers. To learn more about the genetic ancestry of Sardinians, we analyzed 3491 modern and 21 ancient mitogenomes from Sardinia and observed that the age estimates of three Sardinian-specific haplogroups are >7800 years, the archeologically-based upper boundary of the Neolithic in the island. This finding supports archeological evidence of a Mesolithic occupation of the island, but also reveals a dual ancestral origin of the first Sardinians. Indeed, one of the Sardinian-specific haplogroups harbors ancestral roots in Paleolithic Western Europe, but the other two are most likely of Late Paleolithic Near Eastern ancestry, and among those that are often assumed to have spread from Anatolia only with the Neolithic. Thus, their ages are compatible with the scenario of a Late Glacial recolonization of Mediterranean Europe from the Near East prior to the migration wave(s) associated with the onset of farming. The second project aimed to further assess the mitogenome variation of Native Americans origin. Specifically, I focused on Ecuador and Peru, two geographical areas of particular interest because of their location along the Pacific coast, in order to shed light on the peopling of South America. Phylogenetic analyses encompassing both novel and previously reported mitogenomes, allowed the identification of 50 new sub-haplogroups and the finding of a number of sub-clades shared with Native Americans from North and Central America, thus increasing the number of founding mtDNA lineages that entered South America from the North. Our phylogeographic analyses confirmed that the North to South expansion was extremely rapid, and most likely occurred along both the Pacific and Atlantic coasts. The third study was aimed to acquire information about the diffusion process of the Asian tiger mosquito Ae. albopictus by analysing the mitogenome variation of representatives from Asia, America and Europe. Phylogenetic analyses revealed five haplogroups in Asia, but population surveys showed that only three of these were involved in the recent worldwide spread. We also found out that a sub-haplogroup, which is now common in Italy, most likely arose in North America from an ancestral Japanese source. During these three years I also contributed to two additional projects whose goals were to reconstruct the ancient migratory events involving the Arabian Peninsula and Eastern Africa by the study of a rare haplogroup named R0a and to acquire new insights on the initial events that brought to the diffusion of domestic cattle (Bos taurus) outside the Near East.

Grâce à l’étude du gastéropode Concholepas concholepas, distribué le long des côtes chiliennes, cette thèse a cherché à contribué au débat concernant l’adéquation entre les structures biogéographiques et phylogéographiques et le rôle de la dispersion contemporaine dans le maintien des structures historiques. Sur un plan historique, les patrons observés, suite à l’analyse d’un fragment de l’ADNmt COI de 14 populations réparties sur 4000 km, témoignent d’un processus d’expansion démographique et géographique très rapide sur l’aire de distribution de l’espèce. Concernant les flux de gènes contemporains, l’étude de 11 microsatellites a permis de montrer que la dispersion efficace ne reflète que partiellement le potentiel de dispersion conféré par une longue phase larvaire pélagique : cette dispersion dépend des contraintes hydro-dynamiques (rétention) et d’habitats (fjords vs. Côte linéaire). Ces données permettront d’affiner les plans de gestion et conservation de C. Concholepas
Based on the study of the marine gastropod Concholepas concholepas, spread along the Chilean coasts, this thesis aimed at examining the correlation between biogeographic and phylogeography patterns and the role played by the present-day dispersal on the maintenance of the historical population structure. On an historical time scale, the analysis of sequences of a mitochondrial DNA gene (COI) on ca. 400 individuals from 14 localities along 4000 km of coastline revealed a rapid demographic and geographic expansion. On a contemporary time scale, the use of 11 microsatellites showed that the effective dispersal represents only a fraction of the potential larval ability previously hypothesized based on the pelagic larval duration: dispersal strongly vary according to hydro-dynamic patterns (retention zone) and habitats (fjords vs. Linear coasts). The results of this thesis have implications on management and conservations policy applied to C. Concholepas

La gorgone rouge, Paramuricea clavata (Cnidaire, Octocoralliaire), est une espèce sessile, longévive à faible croissance dont les populations présentent une lente dynamique. Cette espèce est caractérisée par une phase larvaire pélagique qui représente l’unique phase de dispersion potentielle au cours du cycle de vie de cette espèce. P. clavata est une espèce clé des assemblages à coralligène de Méditerranée, qui subit les effets combinés des activités de plongée sous-marine et du changement climatique. Dans ce contexte, il était donc fondamental d’approfondir les connaissances sur les traits d’histoire de vie, la biologie et l’écologie de cette espèce. L’objectif de ce travail était d’étudier, à l’aide d’une approche génétique, les facteurs biologiques et écologiques clés qui devraient être importants pour la réponse de l’espèce aux changements environnementaux. Parmi ces facteurs, la dispersion larvaire joue un rôle fondamental dans la dynamique et la connectivité des populations marines. Dans le contexte actuel des fortes pressions anthropiques, la compréhension des degrés de connectivité entre les populations est primordiale pour évaluer le devenir des populations, face au changement climatique, et pour mettre en place des plans de conservation et des réseaux d’aires marines protégées
The red gorgonian, Paramuricea clavata (Cnidaria, Octocorallia), is a sessile, long-lived and slow growing species which displays slow population dynamics. This species is characterized by a pelagic larval phase that represents the sole potential phase of dispersal during the life cycle of this species. P. clavata is a key species of coralligenous assemblages of the Mediterranean Sea which undergoes the combined effects of diving activities and climate change. In this context, extending the knowledge about life history traits, biology and ecology of the red gorgonian was of fundamental importance. Using a genetic approach, the goal of this work was to study some key biological and ecological factors which should be important for the response of this species to environmental changes. Among these factors, larval dispersal plays a major role in driving marine population dynamics and connectivity. In the current context of strong anthropic pressures, understanding the level of population connectivity is primordial to evaluate population outcome, facing climate change, and to develop conservation plans as well as to design marine reservenetworks

The extraction, processing and smelting of ores has long been responsible for the release of heavy metals into the fluvial environment. As a consequence numerous studies have reported enhanced metal concentrations found in association with the sediments of rivers and in their surrounding floodplains. This thesis investigates the mobilisation, transport and the overbank deposition of sediment-associated heavy metals during flood events on the River Swale, North Yorkshire. This catchment has a prolonged history of mining for lead and zinc which spans approximately 2,000 years. Contemporary overbank sediment deposits for the fbll length of the river system were examined following three flood events that occurred in 2002. The quantity of sediment deposited and concentrations of associated metals were determined as well as the metal deposition flux and speciation, by using various analytical procedures including a nitric acid digestion and the BCR sequential extraction method. Physical characteristics such as sediment grain size, pH, loss on ignition and carbonate content were also investigated. Floodplain sedimentation rates were relatively high during the floods and the patterns in metal concentrations were both spatially and temporally consistent. The locations of most concern were located within the headwaters of the catchment where lead concentrations exceeded 25,000 mg kg'. Investigations into the mobility of the sediment-associated metals revealed that up to 88% of cadmium was found within the exchangeable phase of the sediment, however the concentrations of exchangeable lead and zinc were much higher and surpassed UK Government guidelines for crop growth and grazing livestock. Concentrations of exchangeable lead and zinc reached 19,241 mg kg' and 1,457 mg kg' respectively. Locations of 'exchangeable metal hotspots' with high levels of bioavailable metals were repeatedly found within the upper 21 km of the catchnent, around the confluence of tributaries which drain once intensively mined areas. These very high concentrations potentially pose a risk to flora and fauna that grow or graze on the floodplain surrounding the River Swale if they are taken up or ingested. Remediation measures could be adopted to treat either the source of metals in order to prevent them entering the fluvial system, reduce the concentrations already in the contaminated floodplain, or minimise the area inundated by flood waters. Alternatively, land management strategies could be adopted in order to reduce the potential for metal uptake by plants and animals and subsequently entering into the foodchain.

A molécula de CO2 é a principal responsável pelas consequências negativas do efeito estufa. Os números cada vez maiores associados à emissão de CO2 na atmosfera têm atraído a atenção de cientistas na busca de novos catalisadores para reações de dissociação de CO2. Simultaneamente, vários eventos atômicos podem influenciar as propriedades catalíticas de tal sistema, como o efeito de forte interação metal-suporte (SMSI - Strong Metal-Support Interaction) e o rearranjo atômico nas nanopartículas bimetálicas expostas a atmosferas gasosas. Este trabalho apresenta os resultados de um estudo sobre o comportamento de nanopartículas (NPs) de CuNi1-/CeO2 (0<<1) durante o tratamento de redução em H2 (etapa usada na ativação de catalisadores) seguido da reação inversa de deslocamento gás-água (RWGS - Reverse Water-Gas Shift). As amostras foram inicialmente caracterizadas em termos de suas composições, componentes químicas, arranjo atômico e tamanhos usando as técnicas de espectroscopia de raios X por dispersão em energia (EDS - Energy Dispersive X-ray Spectroscopy), espectroscopia de fotoelétrons excitados por raios X (XPS - X-ray Photoelectron Spectroscopy) e microscopia eletrônica de transmissão (TEM - Transmission Electron Microscopy). Após, as amostras foram aquecidas até 500 ∘C em uma atmosfera de H2. Em 500 ∘C as amostras foram expostas às atmosferas de H2 e H2+CO2. Durante todos esses tratamentos, as amostras foram caracterizadas in situ pelas técnicas de XPS em pressões próximas à ambiente (NAP-XPS - Near Ambient Pressure X-ray Photoelectron Spectroscopy) com energias de fótons incidentes de 1250 eV e 2000 eV, espectroscopia de absorção de raios X (XAS - X-ray Absorption Spectroscopy) e XAS resolvido no tempo medido no modo transmissão nas bordas K do Cu (8979 eV), K do Ni (8333 eV) e L3 do Ce (5723 eV). As medidas in situ realizadas mostraram uma migração de átomos de Cu (Ni) para a superfície das nanopartículas durante o tratamento em atmosfera de H2 (H2+CO2). Além disso, a população atômica de Cu na superfície é dependente da quantidade de Cu usada no processo de síntese. Uma maior concentração de Cu durante a síntese implica em uma menor população de Cu na superfície durante as reações de redução em H2 e de RWGS. A ocorrência do fator geométrico do efeito SMSI, caracterizado por uma camada de óxido de cério em torno das nanopartículas durante o tratamento de redução, foi observado para algumas nanopartículas, revelando a existência de um limite na concentração de Cu para a ocorrência do efeito. Somente as nanopartículas com grande quantidade de Cu apresentaram o efeito SMSI durante o tratamento de redução em H2. A superfície das nanopartículas apresentando o efeito SMSI retorna ao estado inicial (sem a camada de óxido de cério) após a inserção da atmosfera de CO2. Além disso, a natureza do efeito SMSI foi elucidada pela primeira vez: a camada de óxido de cério interage com os átomos de Cu e Ni através dos estados iniciais Ce3d10O2p6Ce4f0 e Ce3d10O2p6Ce4f1, dependendo do caso estudado. Como consequência do efeito SMSI, os átomos de Cu das nanopartículas reduzem antes (temperaturas mais baixas) do que nanopartículas semelhantes que não apresentam o efeito SMSI. Os resultados de reatividade para a formação de CO através da reação RWGS, associados aos eventos catalíticos a nível atômico observados (efeito SMSI, população atômica de superfície, mudança no estado de oxidação dos catalisadores) levaram à projeção de um catalisador otimizado aplicado à reação RWGS. A camada de óxido de cério do efeito SMSI tem consequência negativa nos resultados de reatividade. A migração de átomos de Ni para a superfície levou a uma diminuição da reatividade catalítica na reação RWGS. Baseado nesses resultados, é proposta a síntese de nanopartículas com uma grande quantidade de Ni visando evitar a ocorrência do efeito SMSI e permitir uma grande população atômica de Cu na superfície durante a reação RWGS, ambos desempenhando um papel fundamental nos resultados de reatividade para a reação RWGS.
The CO2 molecule is the main responsible for the negative consequences of the greenhouse effect. The increasing numbers associated to the amount of CO2 emission in the atmosphere have attracted the attention of scientists aiming the discovery of new catalysts to CO2 dissociation reactions. At the same time, several atomic events may influence the catalytic properties of such systems, like the Strong Metal-Support Interaction (SMSI) effect and atomic rearrangement when the bimetallic nanoparticles (NPs) are exposed to a gaseous atmosphere. This work presents the results of a study about the behavior of CuNi1-/CeO2 (0<<1) NPs during the H2 reduction treatment (step used in the activation of the catalysts) followed by the reverse water-gas shift (RWGS) reaction. The samples were initially characterized in terms of their compositions, chemical components, atomic arrangement and sizes, using the Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) techniques. Afterwards, these samples were heated to 500 ∘C in a H2 atmosphere. At 500 ∘C the samples were exposed to H2 and H2+CO2 atmospheres. During all these treatments, the samples were characterized in situ by Near Ambient Pressure XPS (NAP-XPS) with incident photon energies of 1250 eV and 2000 eV, X-ray Absorption Spectroscopy (XAS) and time-resolved XAS techniques in transmission mode at the Cu K (8979 eV), Ni K (8333 eV) and Ce L3 (5723 eV) edges. The in situ measurements performed showed a copper (nickel) migration to the nanoparticles surface during H2 (H2+CO2) gaseous treatment. Moreover, the Cu surface atomic population is dependent on the Cu amount used in the synthesis process. The higher concentration of Cu during the synthesis implies in a smaller Cu surface atomic population during H2 reduction and RWGS reaction. The occurrence of the geometrical factor of the SMSI effect, characterized by a cerium oxide capping layer surrounding the nanoparticles during reduction treatment, was observed for some of the NPs, revealing the existence of a threshold in the Cu concentration to occur the SMSI effect. Only nanoparticles with high amounts of Cu present the SMSI effect during the H2 reduction treatment. The surface of the nanoparticles presenting the SMSI effect is recovered to the initial state (free of the capping layer) after inserting the CO2 atmosphere. Moreover, the nature of the SMSI effect was elucidated for the first time: the capping layer interacts with the Cu and Ni atoms via Ce3d10O2p6Ce4f0 and Ce3d10O2p6Ce4f1 initial states, depending on the case studied. As a consequence of the SMSI effect, the Cu atoms of the nanoparticles reduce earlier (lower temperature) than similar nanoparticles that do not present the SMSI effect. The reactivity results towards the CO formation in the RWGS reaction, associated to the catalytic events at atomic level observed (SMSI effect, surface atomic population, change on the oxidation state of the catalysts) led to the design of an optimized catalyst applied to this reaction. The capping layer of the SMSI effect has a negative influence on the reactivity results. The migration of Ni atoms to the surface led to a decrease of the catalyst reactivity in the RWGS reaction. Based on these results, it is proposed a synthesis of nanoparticles with a high amount of Ni in order to avoid the SMSI effect and to allow a high Cu surface atomic population during the RWGS reaction, both playing a key role in the reactivity results towards the RWGS reaction.

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This research investigates the present-day metropole (Metropolitan Area of Campinas) focusing on the dispersed urbanization and the urbanization process, as a part of which themall Shopping Iguatemi was built in the city of Campinas, considering it an indicator of regional sca/e dynamics, but with deep implications to the city and the local environment. Since Iguatemi opened its doors, almost three and a half decades ago, some changes have been happening in the city's dynamics, as much in the population profile as in its behavior, such as purchasing habits, culture and local and regional trade. There's an upper and middle class consumer displacement from downtown to the ma 11, as well as the pendulum-like motion of the Metropolitan Area of Campinas' population in pursue of new consumption options. Given this migration from downtown and Metropolitan Area of Campinas to the margins of the urban area (city expansion zone), some residential enterprises and business have a/so been built around Iguatemi. Since its opening, Iguatemi has been through five expansions and will soon build a residential complex as part of a larger project aiming the densification of its surroundings. The enterprise's primary expansions have been defined, in a way, by the new re/ationships amongst the city and the Metropolitan Area of Campinas, by the need to innovate in order to attract the consumer given the implementation of another eight malls in the c?ty, and the new consumption habits defined by the contemporary life in constant search for entertainment, leisure and specialized trade. This research is based on bibliographica/, documental and joumalistic sources, and it addresses how Shopping Iguatemi has been backing the dispersion of the eastem zone of Campinas in the last thirty-five years, given the rapid changes in the characterization of the urban environment. It a/so analyzes how entrepreneurs have identified market opportunities in this new consumer society, offering new leisure altematives to fulfill the demando This process has been happening since the 80s and it has been changing its outlines since the late 20th century.
Este trabalho investiga a metr?pole contempor?nea (Regi?o Metropolitana de Campinas) com enfoque na urbaniza??o dispersa e no processo de urbaniza??o no qual se insere o Shopping Iguatemi na cidade de Campinas, considerando este como ind?cio de din?micas na escala regional, mas com profundas implica??es para a cidade e para o contexto local. Nota-se que, a partir da inaugura??o do Shopping Iguatemi, ocorrida h? quase tr?s d?cadas e meia, algumas mudan?as foram ocorrendo na din?mica da cidade, tanto no perfil da popula??o, como nos costumes, com novos h?bitos de consumo, cultura e no com?rcio local e regional. Percebe-se um deslocamento do p?blico consumidor das classes alta e m?dia das ?reas centrais para o shopping, bem como a mobilidade pendular da popula??o da Regi?o Metropolitana de Campinas em busca de novas formas de consumo. Com essa migra??o do centro e da Regi?o Metropolitana de Campinas para as adjac?ncias da malha urbana (?reas de expans?o da cidade), alguns empreendimentos residenciais e estabelecimentos comerciais tamb?m come?aram a despontar na regi?o pr?xima ? localiza??o do Iguatemi. Desde a sua origem, o Shopping Iguatemi passou por cinco expans?es e em breve implantar? um novo complexo residencial como parte de um projeto maior para adensamento do seu entorno. As principais amplia??es do empreendimento foram determinadas, em parte, pelas novas formas de relacionamento entre a cidade e a Regi?o Metropolitana de Campinas, pela necessidade de inova??o para atrair o p?blico consumidor frente as implanta??es de mais oito shoppings no munic?pio e pelos novos h?bitos de consumo definidos pela vida contempor?nea em busca de alternativas de entretenimento, lazer e com?rcio especializado. Esta pesquisa foi embasada em fontes bibliogr?ficas, documentais e jornal?sticas e aborda como o Shopping Iguatemi vem contribuindo para a dispers?o da regi?o leste da cidade de Campinas nos ?ltimos trinta e cinco anos, tendo em vista as aceleradas mudan?as na configura??o do espa?o urbano. Analisa tamb?m como os empreendedores?investidores identificaram as oportunidades de mercado nessa nova sociedade de consumo oferecendo eventos de lazer para atender a demanda. Esse processo vem ocorrendo desde a d?cada de 1980 e atinge novos contornos no final do s?culo XX e na atualidade.

Em um cenário de aumento de competitividade, crescente expectativa por inovações do produto e necessidade de atender diferentes perfis de consumidores, o conceito de gerenciamento de cadeias de suprimentos globais (GSCM) surge como uma estratégia para coordenar mais eficazmente as atividades dispersas geograficamente dos sistemas produtivos. Na adoção do GSCM, as organizações devem lidar com rupturas que impactam no gerenciamento das suas atividades, tais como a interrupção de vias de transporte, pane no fornecimento de energia, desastres naturais e até ataques terroristas. Nesse contexto, o trabalho introduz um procedimento sistematizado para modelagem das cadeias de suprimentos visto como um sistema a eventos discretos e sua análise por simulação das atividades do GSCM baseada em técnicas formais como a rede de Petri (PN) e o Production Flow Schema (PFS). Um exemplo é também apresentado para ilustrar e comprovar as vantagens do método proposto na análise do GSCM.
In a context of increasing competition, rising of expectations for product innovations and need to satisfy different consumer needs, the concept of global supply chain management (GSCM) emerges as a strategy to more efficiently coordinate the geographically dispersed activities of production systems. Adopting GSCM, organizations have to deal with external disruptions that impact management activities, such as transport interruption, power supply failure, natural disasters and terrorist attacks. In this way, a systematized procedure for modeling supply chains as a discrete event system and simulation analysis of GSCM activities based on formal techniques, such as Petri net (PN) and Production Flow Schema (PFS) is introduced. An example is also presented to illustrate and confirm the advantages of the proposed method for GSCM analysis.

The potential restriction to effective dispersal and gene flow caused by habitat fragmentation can apply to multiple levels of evolutionary scale; from the fragmentation of ancient supercontinents driving diversification and speciation on disjunct landmasses, to the isolation of proximate populations as a result of their inability to cross intervening unsuitable habitat. Investigating the role of habitat fragmentation in driving diversity within and among taxa can thus include inferences of phylogenetic relationships among taxa, assessments of intraspecific phylogeographic structure and analyses of gene flow among neighbouring populations. The proposed Gondwanan clade within the chironomid (non-biting midge) subfamily Orthocladiinae (Diptera: Chironomidae) represents a model system for investigating the role that population fragmentation and isolation has played at different evolutionary scales. A pilot study by Krosch et al (2009) indentified several highly divergent lineages restricted to ancient rainforest refugia and limited gene flow among proximate sites within a refuge for one member of this clade, Echinocladius martini Cranston. This study provided a framework for investigating the evolutionary history of this taxon and its relatives more thoroughly. Populations of E. martini were sampled in the Paluma bioregion of northeast Queensland to investigate patterns of fine-scale within- and among-stream dispersal and gene flow within a refuge more rigorously. Data was incorporated from Krosch et al (2009) and additional sites were sampled up- and downstream of the original sites. Analyses of genetic structure revealed strong natal site fidelity and high genetic structure among geographically proximate streams. Little evidence was found for regular headwater exchange among upstream sites, but there was distinct evidence for rare adult flight among sites on separate stream reaches. Overall, however, the distribution of shared haplotypes implied that both larval and adult dispersal was largely limited to the natal stream channel. Patterns of regional phylogeographic structure were examined in two related austral orthoclad taxa – Naonella forsythi Boothroyd from New Zealand and Ferringtonia patagonica Sæther and Andersen from southern South America – to provide a comparison with patterns revealed in their close relative E. martini. Both taxa inhabit tectonically active areas of the southern hemisphere that have also experienced several glaciation events throughout the Plio-Pleistocene that are thought to have affected population structure dramatically in many taxa. Four highly divergent lineages estimated to have diverged since the late Miocene were revealed in each taxon, mirroring patterns in E. martini; however, there was no evidence for local geographical endemism, implying substantial range expansion post-diversification. The differences in pattern evident among the three related taxa were suggested to have been influenced by variation in the responses of closed forest habitat to climatic fluctuations during interglacial periods across the three landmasses. Phylogeographic structure in E. martini was resolved at a continental scale by expanding upon the sampling design of Krosch et al (2009) to encompass populations in southeast Queensland, New South Wales and Victoria. Patterns of phylogeographic structure were consistent with expectations and several previously unrecognised lineages were revealed from central- and southern Australia that were geographically endemic to closed forest refugia. Estimated divergence times were congruent with the timing of Plio-Pleistocene rainforest contractions across the east coast of Australia. This suggested that dispersal and gene flow of E. martini among isolated refugia was highly restricted and that this taxon was susceptible to the impacts of habitat change. Broader phylogenetic relationships among taxa considered to be members of this Gondwanan orthoclad group were resolved in order to test expected patterns of evolutionary affinities across the austral continents. The inferred phylogeny and estimated divergence times did not accord with expected patterns based on the geological sequence of break-up of the Gondwanan supercontinent and implied instead several transoceanic dispersal events post-vicariance. Difficulties in appropriate taxonomic sampling and accurate calibration of molecular phylogenies notwithstanding, the sampling regime implemented in the current study has been the most intensive yet performed for austral members of the Orthocladiinae and unsurprisingly has revealed both novel taxa and phylogenetic relationships within and among described genera. Several novel associations between life stages are made here for both described and previously unknown taxa. Investigating evolutionary relationships within and among members of this clade of proposed Gondwanan orthoclad taxa has demonstrated that a complex interaction between historical population fragmentation and dispersal at several levels of evolutionary scale has been important in driving diversification in this group. While interruptions to migration, colonisation and gene flow driven by population fragmentation have clearly contributed to the development and maintenance of much of the diversity present in this group, long-distance dispersal has also played a role in influencing diversification of continental biotas and facilitating gene flow among disjunct populations.

Dispersal is one of the most fascinating processes in human evolutionary history. This complex process is directly connected to ecological, climatic, and environmental changes affecting animal communities and humans as its indivisible part. By itself species are responding to the changes differently, and their survival depends on the strategy species choose, expressed in the niche breadth and its demography. Inspired by the fact that humans are and always have been part of the nature, I propose a paleontropological and ecological integrated scenario and aim at understanding the environmental/ecosystem dynamics of Homo species dispersal out of Africa into Eurasia. The dispersal of humans was spurred by both intrinsic population factors (demography) and by climatic/environmental conditioning(biogeographic barriers, unsuitable climates). Yet, within any given community competitive relationships and species interaction in general affect species liability to survive the change. Species over evolutionary times, either adapts to the change, disperse into favourable territories where the environmental conditions are suitable as their former habitats, or worse become extinct. It is currently believed that the presence of humans didn’t have profound effects on the herbivore populations until very recently (Pushkina and Raia, 2008). This may be well true because dense herbivore populations are not controlled by predation. Conversely, humans had a strong influence on the distribution of carnivores, either by interference of competitive exclusion (Pushkina and Raia, 2008). Around 2 million years ago, when Homo first arose, the relationship between humans and carnivores begun to change, slowly at the beginning but much faster later, humans changed their strategy to earn food, from occasional scavenging towards full predatory activity (Hladik and Pasquet, 2002). The initial stasis but eventually the exponential increase in morphology, and the quality and technology of tool implements seems to borne this out. This process passed through strong environmental/climatic changes and faunal turnovers, and intermingles with major migrations and speciation events. On such changes humans were reacting in several ways, either by demographical or cultural shifts displayed by niche breadth and environmental preferences deviations. My main goal is to examine human dispersals ecology from a paleogeographical perspective, to evaluate the effects of competitive relationships (influence of humans on carnivores and vice versa), and the influence of environmental (climatic) changes on their populations and distributions. Modern evolutionary sciences about human evolution and dispersal are plenty of controversies. Evidence of early Pleistocene hominid dispersal outside Africa is scant and still object of debate. Before discoveries of earliest Eurasian Pleistocene sites, most of the early evidences appeared to support a relatively late initial dispersal after around 1 Ma, suggesting 6 Acheulean technological innovation as decisive aspect. Thanks to discoveries of Dmanisi (Lordkipanidze et al. 2013) and Chinese (Zhu, 2008) sites today it is suggested that the first dispersal happened around 1.9 Ma. If that evidence is correct, such an early dispersal may be better envisioned as driven more strongly by biological and ecological factors (Shipman at al. 1989; Anton et al. 2002) than by technological breakthroughs (Gabunia at al. 2002). Now there is general agreement that Homo erectus evolved in Africa, and then spread to Eurasia (Templeton, 2002). First dispersals of this species were accompanied by well-known climatic-environmental (faunal) changes (deMenocal, 2004; Norton and Braun, 2010; O'Regan, 2011). Although paleoanthropologists generally agree that modern humans evolved from Homo erectus, they disagree in their interpretations of the evolutionary mechanisms that controlled the human lineage evolutionary process. Two decades ago these interpretations were based on limited information and often emphasized on unique fossil discoveries, missing the support of natural sciences, but the growing body of multidistiplinary research gave a possibility to produce several evolutionary models, explaining the origins of modern Homo sapiens. Following two main opposing models such are “Recent African Origin” and “Multiregional Evolution” appeared other two models “Hybridization and Replacement model” and “Assimilation Model” (Strienger, 2002). In contrast of Multiregionalism (Fryer 1993), which denies existence of any particular region as a cradle of human origins (Thorne and Wolpoff, 1992), more balanced "Recent African Origin", which is slightly different from so called "splitter" views (Tattersal and Schwartz, 2008), proposes that a second wave of human dispersal out of Africa happened around 1 Ma, the new human species known as Homo heidelbergensis gave rise to Homo neanderthalensis in Eurasia, and Homo sapiens in Africa (Stringer, 2002; Rightmire, 2008), this event also was accompanied by major climatic-environmental turnovers. Finally, modern humans originated in Africa crowned dispersal about 100 Ka from where they spread around the world and replaced aboriginal archaic human populations in other areas of Eurasia by little hybridization with these groups. Ultimate genetic studies during the past ten years were very successful for genetic sciences; amazing discoveries were made in modern human origin studies. Extracted hominine DNA sequences demonstrated and proved fossil record-based presumptions (Trinkaus 2007; Smith, 2011) about genetic flow and admixture between Neanderthals and modern humans (Green et al., 2010; Trinkaus, 2005; Rak, 1998;). That information is reflected in "Hybridization and Replacement" model as a variant of the recent African origin model. It is based on the same fundament, but uses more of hybridization between the migrating population and the indigenous pre-modern populations (Bräuer et al., 2004) in turn "Assimilation Model" with multiregional approach recognizes African origin of modern humans (Smith, 1992), but refuses population dispersal, as a major factor in the origins of modern humans, emphasized the importance of gene flow resulting phenotypic change (Aiello, 1993). After processing information the methodological structure of the research was constructed, 7 the aim is fourfold: Hypothesis creation, definition of variables, database formation, and statistical analysis. First I proposed several basic hypotheses associated with dispersal of Pleistocene humans and its accompanying environmental-climatic changes. The hypotheses were divided in time and the space, and in terms of ecology gradually described the steps of human lineage evolutionary history. As a following step in research were involved several fauna-related ecological variables as are: climatic variables reconstructed by taxon-free (Damuth, 1992) ecomophological variables (herbivores teeth crown characters: Hypsodonty, Loph) (Liu et al. 2013; Eronen, 2010), presence/absence of faunal entities and incorporated them with geographical and time-related variables. I formed database encompassing whole this information using online accessible databases, which were controlled trough the scientific literature and then we opted several statistical and geostatistical analysis as are: simple and multivariate Generalized linear models (GLM), bootstrap resampling, principal component analysis (PCA), geostatistical interpolation method of Kriging, Least-cost path and rout calculation and species distribution modeling (SDM), via R (Cran) software. Finally, I will interpret these long-term characteristics for each dispersal event, estimate the effect of humans on the fauna through time and vice versa, and identify corridors of human dispersal, and their coincidence with moments of climatic change.

Theoretical and empirical work has shown that community diversity and composition can be influenced by both local conditions and dispersal from a regional species pool. This may be especially true shortly after environmental disturbances, because perturbations can provide spatial or temporal niche opportunities for dispersers to establish. Theory predicts that after environmental disturbances tolerant functionally-redundant dispersing species can establish in disturbed communities, maintaining local community diversity and ecosystem function; however, this model relies on the successful establishment of dispersers (i.e., the community must be invasible). Invasibility is expected to decline as time-since-disturbance increases because the local community can use freed resources and increases in abundance. Although studies have acknowledged that timing may influence invasibility, very few studies have focused on how dispersal timing influences the role of dispersal in community response to disturbance. My thesis was conducted to test the role of crustacean zooplankton dispersal timing in the establishment success, and subsequent influence on diversity and ecosystem function of dispersers. To assess this, a field mesocosm study was completed in Churchill, Canada to test the effects of disturbance (nutrients and salinity) and immigration timing (from 51 regional ponds/pools) on invasibility, local community structure and ecosystem functioning (i.e., chl-a). Results show that invasibility was initially high following disturbance, but decreased with time- since-disturbance as the resident community exerted priority effects over dispersers. As a result community diversity was most influenced by immigration when dispersers were added shortly after disturbance. Many coarse measures of diversity were resistant to disturbance, but community composition and the relative abundance of functional groups shifted, and likely influence ecosystem function (i.e., chl-a). When dispersers were added to disturbed communities ecosystem function was recovered to undisturbed levels. Overall, my results suggest that dispersal timing can influence the role of dispersal in communities and the ability of species to capitalize on windows of invasion opportunity will influence their ability to establish in favorable local patches.
Thesis (Master, Biology) -- Queen's University, 2012-09-17 12:18:16.015