Дисертації з теми "Ecologic variability"
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Billard, Elodie. "Etude des communautés microbiennes fonctionnelles benthiques impliquées dans le cycle du méthane (Lac du Bourget)." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAA017/document.
Повний текст джерелаBenthic microbial communities are actively involved in organic matter recycling and fact biogeochemical functioning of lake ecosystems. These communities comprise many phyla but their functional diversity is still incompletely known. This study is focused on the benthic microbial communities involved in the methane cycle in lacsutrine suystems. We aimed understanding the structural and abundance changes of functional genes related to the vertical distribution (redox gradient in sediment), the horizontal variability (coastal vs. pelagic benthic zone) and seasonal dynamics related to mixing of the water column (re-oxygenation of benthic interface). The composition of methanotrophic and methanogenic communities was characterized by sequencing analyses.For this study, sedimentary cores were sampled along a transect from coastal to pelagic zone, at different times during an annual cycle. In addition, each sediment core was analyzed in its verticality from the water-sediment interface to 20 cm depth. Microbial communities involved in the cycle of methane (methanogenesis and methanotrophy) were targeted by 2 functional genes (mcrA and pmoA). Furthermore, phylogenetic markers were used to characterize the total bacterial and archaeal communities. These communities are studied in terms of structure (genotyping), diversity (sequencing) and abundance (qPCR, DNA) of their functional genes.The results of the study showed that, on a spatial scale, a low heterogeneity was detected for a given sampling station in terms of structure of microbial communities (total and functional), however, a high variability was detected both at an horizontal scale along a transect (costal vs. pelagic zone), due to contrasted environmental conditions, and at a vertical scale (upper to deeper layers in the core) under the effect of redox conditions. The bacterial community being the most affected in the verticality, with structural changes among all strata studied. In the same study, a comparative analysis of the structure (for all of the communities), between pooled samples and individual samples, demonstrated that the analysis of individual samples provided a greater number of OTU for the majority of microbial communities.Moreover the study of the temporal dynamic of methanogen and methanotroph communities revealed changes in the structure and abundance, mainly at the water - sediment interface, according to the oxygenation levels that varied through time. The analysis of diversity showed a dominance of Methanomicrobiales (Methanoregula mainly) for methanogens, but Methanosarcinales (Methanosarcina) and Methanobacteriales (Methanobacterium) were also identified. The methanotrophs' community was dominated by Methylobacter on deeper stations and by Methylococcus in coastal station. Type II methanotrophs (Methylosinus and Methylocystis) were also identified.This work highlights the importance of taking into account both the spatial variability (horizontal and vertical) and the temporal variability of methanogen and methanotroph communities. Changes on their structures and abundances are significant parameters for understanding the processes involved in the methane cycle
Afán, Asencio Isabel. "Ecological response of marine predators to environmental heterogeneity and spatio-temporal variability in resource availability." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/398990.
Повний текст джерелаAlegre, Norza Sior Ana Renza Paola. "Trophic ecology of jumbo squid and predatory fishes in the Northern Humboldt Current System." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS223/document.
Повний текст джерелаThis work provides a contribution to a better understanding of the trophic ecology of important predators in the Northern Humboldt Current System, the jack mackerel (Trachurus murphyi), the chub mackerel (Scomber japonicus) and the jumbo squid (Dosidicus gigas) by the characterization of the highly variable feeding patterns of these species at different spatiotemporal scales. We provided new knowledge on the comparative trophic behaviour of these species, defined as opportunistic in previous investigations. For that purpose we applied a variety of statistical methods to an extensive dataset of 27,188 non-empty stomachs. We defined the spatial organization of the forage fauna of these predators and documented changes in prey composition according to predators' size and spatiotemporal features of environment. Our results highligh the key role played by the dissolved oxygen. We also deciphered an important paradox on the jumbo squid diet: why do they hardly forage on the huge anchovy (Engraulis ringens) biomass distributed of coastal Peru? We showed that the shallow oxygen minimum zone present off coastal Peru could hamper the co-occurrence of jumbo squids and anchovies. In addition, we proposed a conceptual model on jumbo squid trophic ecology including the ontogenetic cycle, oxygen and prey availability. Moreover we showed that the trophic behaviour of jack mackerel and chub mackerel is adapted to forage on more accessible species such as for example the squat lobster Pleurocondes monodon and Zoea larvae. Besides, both predators present a trophic overlap. But jack mackerel was not as voracious as chub mackerel, contradictorily to what was observed by others authors. Fish diet presented a high spatiotemporal variability, and the shelf break appeared as a strong biogeographical frontier. Diet composition of our fish predators was not necessarily a consistent indicator of changes in prey biomass. El Niño events had a weak effect on the stomach fullness and diet composition of chub mackerel and jack mackerel. Moreover, decadal changes in diet diversity challenged the classic paradigm of positive correlation between species richness and temperature. Finally, the global patterns that we described in this work, illustrated the opportunistic foraging behaviour, life strategies and the high degree of plasticity of these species. Such behaviour allows adaptation to changes in the environment
Kosanic, Aleksandra. "Ecological responses to climate variability in west Cornwall." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/18120.
Повний текст джерелаAlexandre, Carlos Manuel Engeitado. "Ecological impact of streamflow variability in the bio-ecology of freshwater fishes from permanent and temporary mediterranean river systems." Doctoral thesis, Universidade de Évora, 2014. http://hdl.handle.net/10174/14671.
Повний текст джерелаJoyce, Andrew Noel. "Modelling surface climate over complex terrain for landscape ecology." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4245/.
Повний текст джерелаAvois-Jacquet, Carol. "Variabilité spatiale multiéchelle du zooplancton dans un lagoon récifal côtier (Multiscale spatial variability of zooplankton in a coastal reef lagoon)." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00001767.
Повний текст джерелаRamakrishnan, Lakshmikantan. "Environmental variability and ecological dynamics in spatially structured populations /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004361.
Повний текст джерелаALVES, Amanda Lacerda. "Ecologia alimentar de Zoanthus sociatus e Protopalythoa variabilis (Cnidaria: Zoantharia) no litotal de Pernambuco, Brasil." Universidade Federal Rural de Pernambuco, 2015. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5234.
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This study investigated the feeding ecology of zoanthids Zoanthus sociatus and Protopalythoa variabilis. Colonies of this species were sampled in the infralittoral zone of reefs in northeastern Brazil (may/2013 to february/2014). Polyps (n = 400) were examined the gastric cavity and prey found were counted, measured and identified. We calculated the richness and total abundance of prey items. The GLM test two-way ANOVA was used to compare the abundance and ricness between period and species. The biovolume of preys were calculated to characterize the most important food items in terms of their biomasses. To evaluate the selectivity, zoanthid and plankton samples were collected in the dry season and rainy. The results revealed the occurrence of seven taxa of phytoplankton and zooplankton three, and particulate organic matter. Pennales diatoms were the most abundant and most frequent prey and, together with invertebrate eggs, constituted the most important food items in terms of their biomasses. There were significant differences in abundance and richness among the species and between periods, with a significant interaction between these factors, only for abundance. The mean size of prey items within the polyps of Z. sociatus (26.35 ± 59.10 μm) and polyps of P. variabilis (26.56 ± 54.71 μm) was significantly smaller than in the plankton (54,14 ± 107,25 μm). As for the type prey, Zoanthus sociatus and Protopalythoa variabilis feed predominantly diatoms. The results, the two species are suspensívoras, feeding mainly on small phytoplankton. These results corroborate those previously found for the zoanthid P. caribaeorum in the same place, showing that this group has an important role in energy flow in reefs, transferring biomass of plankton to superiroes groups of the chain. This is fundamental to the Brazilian reefs where coverage of other suspensívoros as coral, is very low.
Este trabalho objetivou estudar a ecologia alimentar dos zoantídeos Zoanthus sociatus e Protopalythoa variabilis. Foram amostradas trimestralmente (maio/2013 a fevereiro/2014) colônias das espécies no infralitoral nos recifes da Praia de Porto de Galinhas (8º 33’ 00’’ a 8°33’33” S ; 35º 00’27’’ a 34º 59’ 00’’ W). Os pólipos (n=400) tiveram a cavidade gástrica examinada e as presas encontradas foram contabilizadas, medidas e identificadas. Foram calculadas a riqueza e abundância total dos itens de presas. O teste GLM two-way ANOVA foi usado para comparar a abundância e riqueza entre período e espécies. A partir das medições das presas, foi calculado o biovolume para caracterizar as presas com maior importância no aporte de biomassa. Para análise de seletividade foram coletadas amostras das espécies de zoantídeos e do plâncton no período seco e chuvoso. Os resultados revelaram a ocorrência de sete taxons do fitoplâncton e três do zooplâncton, além de matéria orgânica particulada. As diatomáceas pennales foram as presas mais abundantes e, juntamente, com ovos de invertebrados constituíram as presas mais importantes no aporte de biomassa. Houve diferença significativa na abundância e riqueza entre as espécies e entre os períodos, havendo interação significativa entre estes fatores, apenas para a abundância. O tamanho médio das presas presentes nos pólipos de Z. sociatus (26,35 ± 59,10 μm) e nos pólipos de P. variabilis (26,56 ± 54,71 μm) foi menor do que no plâncton (54,14 ± 107,25 μm). Quanto ao tipo de presa, Zoanthus sociatus e Protopalythoa variabilis se alimentam predominantemente de diatomáceas. Pelos resultados obtidos, as duas espécies são suspensívoras, alimentando-se principalmente de fitoplancton de pequeno porte. Esses resultados corroboram os anteriormente encontrados para o zoantídeo P. caribaeorum no mesmo local, demonstrando que este grupo tem um papel importantíssimo no fluxo de energia nos recifes, transferindo biomassa do plâncton para elos superiroes da cadeia. Isto é fundamental para os recifes brasileiros onde a cobertura de outros suspensívoros, como corais, é muito baixa.
Gonzalez, Andrew. "Extinction : the role of habitat fragmentation and environmental variability." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/12032.
Повний текст джерелаEvangelista, Charlotte. "Variabilité intraspécifique chez les espèces invasives et ses conséquences sur le fonctionnement des écosystèmes aquatiques." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30233/document.
Повний текст джерелаWhile biological invasions are widely recognized as a major cause of ecosystem changes, the ecological impacts of invasive species could be modulated by intraspecific variability in ecological traits occurring between and within populations. The present work demonstrated, at different geographical scales, the existence of a strong phenotypic variability within two freshwater invaders, Lepomis gibbosus and Procambarus clarkii. In addition, phenotypic responses to environmental conditions was demonstrated to be complex, revealing notably that the methods used to control invasive populations can be counter-productive and that the colonization history of invasive populations is an important driver of phenotype-environment relationships. Experimental approaches also demonstrated that intraspecific variability modulated the intensity of the ecological impacts of invasive species on community structure and ecosystem functioning. These findings strongly support the idea that integrating intraspecific variability in the context of biological invasions is essential to better appreciate their impacts on recipient ecosystem and ultimately improve the efficient of management methods based on the characteristics of invasive populations
Gasmi, Sonia. "Ecologie trophique et reproduction d'une population sauvage d'huître creuse Crassostrea gigas dans un écosystème macrotidal, peu profond : cas du Bassin d'Arcachon." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0626/document.
Повний текст джерелаThe ecological functioning of coastal ecosystems is subjected to the synergistic action of climate change and anthropogenic pressures. In Arcachon Bay, the reproductive cycle of the oyster Crassostrea gigas has changed in recent years (e.g. weak gametogenesis, spawning delay). This pattern seems to be associated with global changes in thermal and trophic conditions. The aim of this work was to characterize the spatio-temporal variability in the reproductive investment of oysters in Arcachon Bay. This variability has been investigated in relation to the origin, quantity and quality of the trophic resources. The results revealed important spatial gradients of variability in gonadal development and trophic signal in C. gigas, between inner parts of the bay influenced by river inputs (south-east and north-east) and the external part of the bay, which is influenced by oceanic inputs. Two hydrodynamic factors explained most of the observed variability: immersion time and oceanic water renewal. A comparison of C. gigas gametogenesis and the nutritional value of available food sources between the south-eastern and north-eastern parts of the bay revealed temporal variability in the composition of phytoplankton. This variability was associated with variability in the amounts of essential fatty acids, necessary for gametogenesis. Changes in energy reserves and gamete release cycle were synchronized with the seasonal nutrient variability. These results constitute a first approach in the development of a model predicting the evolution of the energetic needs of C. gigas under the global change in environmental conditions
Vasseur, David Alan. "Temporal and hierarchical scales mediate environmental and ecological variability in food webs." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102226.
Повний текст джерелаThe approach used herein employs both mathematical models and empirical data which represent food webs responding to environmental variability at different hierarchical scales. Within each of these representative food webs, the influence of environmental variability on the stability of the food web is determined using an approach which accounts for the effects of temporal scale. This thesis demonstrates that the stability of simple model food webs (high hierarchical scale) is tightly linked to environmental variability and the temporal scales at which these changes occur dictate which species in the model are most affected. At lower scales of organisation, empirical data indicate that environmental variability generally has a lesser impact on stability and that only certain temporal scales are responsible for this trend. At these temporal scales some species respond differently to environmental variability, negative changes in one species (or group) are offset by positive changes in another - a process known as compensation. These results highlight the importance of both temporal and hierarchical scale in mediating the response of food webs to environmental variability. Ultimately, they will serve to better understand how models and experiments should scale-up from low to high hierarchical and temporal scales.
Verdy, Ariane. "Dynamics of marine zooplankton : social behavior, ecological interactions, and physically-induced variability." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43158.
Повний текст джерелаIncludes bibliographical references (p. [221]-232).
Marine ecosystems reflect the physical structure of their environment and the biological processes they carry out. This leads to spatial heterogeneity and temporal variability, some of which is imposed externally and some of which emerges from the ecological mechanisms themselves. The main focus of this thesis is on the formation of spatial patterns in the distribution of zooplankton arising from social interactions between individuals. In the Southern Ocean, krill often assemble in swarms and schools, the dynamics of which have important ecological consequences. Mathematical and numerical models are employed to study the interplay of biological and physical processes that contribute to the observed patchiness. The evolution of social behavior is simulated in a theoretical framework that includes zooplankton population dynamics, swimming behavior, and some aspects of the variability inherent to fluid environments. First, I formulate a model of resource utilization by a stage-structured predator population with density-dependent reproduction. Second, I incorporate the predator-prey dynamics into a spatially-explicit model, in which aggregations develop spontaneously as a result of linear instability of the uniform distribution. In this idealized ecosystem, benefits related to the local abundance of mates are offset by the cost of having to share resources with other group members. Third, I derive a weakly nonlinear approximation for the steady-state distributions of predator and prey biomass that captures the spatial patterns driven by social tendencies. Fourth, I simulate the schooling behavior of zooplankton in a variable environment; when turbulent flows generate patchiness in the resource field, schools can forage more efficiently than individuals.
(cont.) Taken together, these chapters demonstrate that aggregation/ schooling can indeed be the favored behavior when (i) reproduction (or other survival measures) increases with density in part of the range and (ii) mixing of prey into patches is rapid enough to offset the depletion. In the final two chapters, I consider sources of temporal variability in marine ecosystems. External perturbations amplified by nonlinear ecological interactions induce transient ex-cursions away from equilibrium; in predator-prey dynamics the amplitude and duration of these transients are controlled by biological processes such as growth and mortality. In the Southern Ocean, large-scale winds associated with ENSO and the Southern Annular Mode cause convective mixing, which in turn drives air-sea fluxes of carbon dioxide and oxygen. Whether driven by stochastic fluctuations or by climatic phenomena, variability of the biogeochemical/physical environment has implications for ecosystem dynamics.
by Ariane Verdy.
Ph.D.
Pouder, Jessica Anne. "Using Human Footprint Models and Land-Cover Variability to Predict Ecological Processes." W&M ScholarWorks, 2014. https://scholarworks.wm.edu/etd/1539626953.
Повний текст джерелаScheuerell, Mark David. "Environmental drivers of spatial and temporal variability in lakes /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/5144.
Повний текст джерелаMcCarthy, Megan Campbell. "Plant Biomass Allocation: Understanding the Variability within Size Constraints." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194007.
Повний текст джерелаMOURA, Carina Carneiro de Melo. "Ecologia e conservação dos testudines, Nordeste do Brasil." Universidade Federal Rural de Pernambuco, 2013. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5410.
Повний текст джерелаMade available in DSpace on 2016-08-19T15:39:02Z (GMT). No. of bitstreams: 1 Carina Carneiro de Melo Moura.pdf: 2573558 bytes, checksum: 252687e022e5525fdfa76d18da7b8ef2 (MD5) Previous issue date: 2013-02-26
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Studies that aimed investigating the ecology and genetic diversity of populations of Testudines are essential to evaluate the response of aquatic communities of Testudines to human impacts and changes in the habitats of these animals. Research on this subject are few in the ecosystem of Caatinga and Atlantic Forest. Thus, in order to fill a gap in knowledge about these species, the present study aimed to investigate the conservation status of the Testudines populations located in the area of morphoclimatic Caatingas, Environmental Protection Area in the Araripe, Semi Arid region, Ceará, Northeast Brazil, regarding their population structure and genetic heterogeneity, and compile scientific actions related to the subject Testudines in northeastern Brazil. We used two traps convergence specific to clade Testudine called Covo (trap with bait), six days a month, for one year (August 2011 to July 2012). Each specimen captured was marked, sexed, had registered their biometric data and biological samples were collected for genetic analysis. For comparison of the genetic variability of populations of P. geoffroanus were used samples of Testudines collected at two points domain morphoclimatic Atlantic Forest, the Forest of Privê in Camaragibe and the Forest of Rio Paratibe in Paulista. Were captured in the area of Caatinga 63 individuals representing three species, 44 of Phrynops geoffroanus, nine of Kinosternon scorpioides and ten of Mesoclemmys tuberculata. Population size estimated by the Jolly-Seber method was 49.28±11 for K. scorpioides, 56±16.3 for M. tuberculata and 301.5 ± 67.09 for P. geoffroanus.The index of sexual dimorphism calculated the mean carapace of males and females was 1.06 (diverted for females) for P. geoffroanus and 1.04 (deflected males) for K. scopioides. We could not infer about sexual dimorphism and sex ratio for the species M. tuberculata, because only females were captured. Analysis of genetic diversity showed that the population of Caatinga showed similar genetic diversity of the populations of Atlantic forest, with genetic distance no significantly different between groups (Caatinga and Atlantic Forest), which may be the result probably of a population explosion or intense flow gene, demonstrating that despite the adverse conditions of the semi arid, the population studied in this environment presents similar adaptive capacity that populations of Atlantic Forest.
Estudos que visem investigar a ecologia e diversidade genética das populações de testudines são essenciais para avaliar a resposta das comunidades aquáticas dos testudines aos impactos antrópicos e as modificações nos habitats destes animais. Pesquisas relativas a este tema são consideravelmente poucos nos ecossistemas de Caatinga e Mata Atlântica. Desta forma, no intuito de preencher uma lacuna no conhecimento sobre estas espécies, o presente estudo objetivou investigar o status de conservação das populações de testudines localizadas no domínio morfoclimático das Caatingas, na Área de Proteção Ambiental Chapada do Araripe, região de Semi Árido, Ceará, Nordeste do Brasil, no que se refere as suas estruturas populacionais e heterogeneidade gênica, além de compilar as ações cientificas referentes ao tema Testudines no nordeste do Brasil. Foram utilizadas duas armadilhas de convergência específicas para o clado Testudine, denominada Covo (armadilha com isca), seis dias por mês, durante um ano (agosto de 2011 a julho de 2012). Cada espécime capturado foi marcado, sexado, teve seus dados biométricos registrados e foram coletadas amostras biológicas para análise genética. Para efeito de comparação da variabilidade genética das populações de P. geoffroanus foram utilizadas amostras de testudines coletadas em dois pontos do domínio morfoclimático de Mata Atlântica, Mata do Privê em Camaragibe e Mata do Rio Paratibe em Paulista. Foram capturados na área de Caatinga 63 indivíduos, representando três espécies, 44 Phrynops geoffroanus, nove Kinosternon scorpioides e dez Mesoclemmys tuberculata. O tamanho da população estimado pelo método de Jolly-seber foi de 49.28±11 para K. scorpioides ,56±16.3 para M. tuberculata e 301.5±67,09 para P. geoffroanus. O índice de dimorfismo sexual calculado com a média dos valores da carapaça dos machos e fêmeas foi de 1.06 (desviado para fêmeas) para P. geoffroanus e 1.04 (desviado para machos) para K. scopioides. Não foi possível inferir a cerca de dimorfismo sexual ou razão sexual para a espécie M. tuberculata, pois foram capturadas apenas fêmeas. A análise da diversidade genética demonstrou que a população da Caatinga apresentou diversidade genética semelhante a das populações de Mata Atlântica, não havendo distância genética significativamente diferente entre os grupos (Caatinga e Mata Atlântica), que pode ser resultado provavelmente de uma explosão populacional ou intenso fluxo gênico, demonstrando que apesar das condições adversas da caatinga, a população estudada neste ambiente apresenta semelhante capacidade adaptativa que as populações da Mata Atlântica.
Papacostas, Katherine J. "Spatial and Temporal Variability in Marine Invasion and Trophic Dynamics." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/305874.
Повний текст джерелаPh.D.
Species interactions are central to the study of community ecology, but these interactions can change with context. For instance, predator-prey interactions can vary with species introductions, spatial scale and temporal scale, and we are still learning how such factors can influence the strength of these interactions. Studying species interactions via multifaceted approaches and at different scales aids in the understanding of local and large scale processes, and can lead to predictions of how our ecosystems will persist in the face of continued anthropogenic alteration of the globe. The present series of studies sought to explore spatial and temporal variability in marine predator-prey interactions and invasion dynamics. The first objective was to assess biogeographic variability in predator invasions in the field. The second examined spatial variation in niche breadth via field collections, laboratory dissections, and database development, and the third involved a series of laboratory and field experiments as well as population modeling to examine temporal variability in native and non-native behavioral interactions. Specifically for the first objective, I examined the strength of marine invasive species-induced trophic cascades across latitude, hypothesizing that a non-native tertiary consumer could facilitate non-native basal prey establishment through the consumption of a native secondary consumer. I further predicted that the ecological importance of this cascade may be reduced in the subtropics relative to the temperate zone due to stronger predation pressure at lower latitudes. I found evidence of a trophic cascade in both regions, but it was only maintained under ambient predation pressure in the temperate zone. My results also suggest that strong predation pressure on the non-native intermediate predators in the subtropics may explain the weakened cascade under ambient conditions. For the second objective, I tested the hypothesis of increased specialization at lower latitudes using Brachyuran crabs as a model system and diet as my measure for niche breadth, while controlling for range size, body size and evolutionary relatedness. I compiled a dataset on 39 crab species' diets from existing studies and conducted my own diet analyses on species collected in a temperate, subtropical and tropical region, resulting in a global comparison. I found that latitudinal position was correlated with range size for temperate species, but not for tropical species, and found no correlation between the other focal variables and latitude. These results suggest that ecological mechanisms (i.e. competition strength) may be driving patterns of niche breadth in the temperate zone, while evolutionary mechanisms may be more important in predicting niche breadth patterns in tropical systems. For the third objective, I examined the influence of native and non-native prey naïveté on intermediate predator invasion success. I hypothesized that 1) naïveté is greatest in earlier stages of invasion across all trophic levels, decreasing the longer a non-native species is established in a system, 2) Native prey naïveté results in resource effects which increases invasion success, or 3) predator effects on non-native species would outweigh the importance of basal native prey naïveté, preventing an increase in non-native population growth. Through laboratory trials, I found support for naïveté being stronger at earlier stages of invasion, for both native basal prey and non-native intermediate predators. I also found weak predation on the more recently established intermediate predator in the field. However, my population model predicted that growth independent of basal prey naïveté. These results suggest that physiological traits, such as conversion efficiency and growth rates of the invasive crab may be driving its population growth more-so than foraging benefits. My studies surrounding the variability of species interactions are the first to examine the strength of invasive species-induced trophic cascades across latitude, one of very few marine empirical studies to examine diet breadth at a large spatial scale, and the first to examine multi-trophic behavioral effects on invasion success respectively. They highlight the importance of studying multi-trophic interactions, as examining more pieces of the food web is increasingly important in developing a broader understanding of interactions and adaptations within invaded communities. My research also highlights the importance of studying interactions from a macroecological perspective. Tracking both invasions and native species interactions through space and time provides insight into marine community dynamics and may elucidate possible mechanisms of species coexistence.
Temple University--Theses
Hellberg, Erik. "Historical variability of deciduous trees and deciduous forests in northern Sweden : effects of forest fires, land-use and climate /." Umeå : Dept. of Forest Vegetation Ecology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s308.pdf.
Повний текст джерелаChadburn, R. G. "An investigation into the genetics and ecology of a closed semi-natural population of Drosophila melanogaster." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377122.
Повний текст джерелаMcNeil, Brenden E. "Spatial variability of foliar nitrogen in the Adirondack Park, New York." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
Повний текст джерелаPatino, Victor. "Ecological study of factors associated with homicide rate variability in El Salvador, 2016." Thesis, Biostatistics program, 2021. https://hdl.handle.net/2123/25585.
Повний текст джерелаFava, Federica <1978>. "Spatial and temporal variability and ecological processes in the epibenthic assemblages of the northern Adriatic Sea." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3677/1/Fava_Federica_Tesi.pdf.
Повний текст джерелаFava, Federica <1978>. "Spatial and temporal variability and ecological processes in the epibenthic assemblages of the northern Adriatic Sea." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3677/.
Повний текст джерелаZapata, Martha J. Zapata. "Spatial and temporal variability in aquatic-terrestrial trophic linkages in a subtropical estuary." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515139504483898.
Повний текст джерелаMellado, Díaz Andrés. "Ecología de las comunidades de macroinvertebrados de la Cuenca del Río Segura (SE de España). Factores ambientales, variabilidad espacio-temporal, táxones indicadores, patrones de diversidad, rasgos biológicos-ecológicos y aplicaciones para la evaluación biológica. The Ecology of Stream Macroinvertebrate Assemblages from the Segura River Basin (SE Spain): Environmental factors, spatio-temporal variability, indicator taxa, diversity trends, biological-ecological traits and applications for bioassessment." Doctoral thesis, Universidad de Murcia, 2005. http://hdl.handle.net/10803/10777.
Повний текст джерелаCavraro, Francesco <1982>. "Genetica, ecologia e comportamento di un biomonitore della variabilità di sistemi acquatici di transizione." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3041.
Повний текст джерелаTransitional waters play a key role in the functioning of marine ecosystems. In the Italian coastal areas there is only one killifish, Aphanius fasciatus (Valenciennes, 1821), which spents its entire life cycle in these habitats. This project explored the possibility of using Aphanius fasciatus as "biomonitor" of environmental variability to which salt marsh systems within the Venice lagoon are subjected, investigating the adaptive responses of the species to environmental pressures at the level of genetic structure, demography, life history traits and behaviour, articulating the analysis on different spatial scales. While there were no significant differences in the genetic structure of the populations at lagoon scale, the species showed a high phenotypic plasticity. In fact, populations differ in demographic parameters, morphometry and in variations of life history traits related to reproductive investment as a response of the species to different environmental pressures and to the structure of the habitat.
Andolina, Cristina <1986>. "Trophic niche variability of fish populations and communities as a response to ontogeny, habitat heterogeneity and restoration." Doctoral thesis, Università Ca' Foscari Venezia, 2016. http://hdl.handle.net/10579/10331.
Повний текст джерелаMell, Florian. "Expertise en patinage en hockey sur glace : effet des contraintes de tâche." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR108/document.
Повний текст джерелаBased on the theoretical framework of Ecological Dynamics, the aim of this PhD thesis is to analyse the motor behaviour of expert ice-hockey players in relation to a set of interacting constraints. Based on this theoretical framework, our research investigates the performance indicators in order to understand how ice-hockey expert players’ behaviour emerges, persists and is reorganised when the individuals interacts with a set of constraints. We conduced our work in two stages: i) a qualitative research analysing semi-structured interviews of ice-hockey expert coaches and ii) a biomechanics analysis of forward skating. Analysing 10 ice-hockey expert coaches interviews reveals that coaches used ‘operative knowledge’ organized into three main categories (arm movement, lower limb kinematics and posture). This study allowed us to improve our understanding of performance indicators of expert forward skating. It also helped us to design a more representative biomechanics research protocol of forward skating. The second part of this thesis consists of an analysis of low-order and high-order parameters under task constraints manipulation during 20m forward sprints. Our results showed a strong stability of forward skating pattern at the low-order parameters scale as well as a stable catch-up coordination between the two feet and a stable symmetry in the lower limbs movement coordination when expert player weren’t under puck dribbling situation. When they had to run with the puck, experts’ behaviour revealed a significative variability in skating pattern organisation suggesting flexibility of experts’ behaviour in order to improve their adaptability to tasks constraints
Recalde, Salas Angela Paola. "Variability in Baleen Whale Acoustical Ecology: Implications for Optimal Monitoring Using Passive Acoustics." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/80627.
Повний текст джерелаLehnebach, Romain. "Etude de la variabilité ontogénique du profil ligneux chez quelques espèces forestières tropicales de Guyane Française." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS021/document.
Повний текст джерелаWood is a multifunctional tissue involved in sap conduction, storage of water and reserves as well as mechanical support. Tree during its development experiments various constraints due to its environment and its growing size. In response to these constraints, wood functional performances are adjusted by variations of property values, which are dependent on the xylogenesis product. However, wood properties may be modified by the deposition of chemical extractives during heartwood formation. Thus heartwood properties are the result of xylogenesis, heartwood formation and their interactions. This work gave rise to the term 'wood profile', designating all variations of wood properties at different scales and in an ontogenetic dimension, resulting from both processes described above. The diversity of shade tolerance (heliophilic to sciaphilic) strategies species suggests a diversity of wood profile expressions. The description of these different expressions could be a way to better understand plant strategies. Understanding and characterizing wood profile and variations in heartwood quantity in tree, is an economical issue since the Guyanese timber industry has been identified as a promising sector. The analysis of the diversity of wood profile—using a bottom-up approach, from the individual level to the interspecific level—proves to discriminate shade tolerance strategies efficiently. Wood specific gravity variation is especially relevant. However, its relevance is based on (1) combinations of both radial and vertical variations and (2) integration of heartwood that may impact range and direction of the gradient and shape of the profile as well. Effect of heartwood formation on wood specific gravity variations is suggestive of shade tolerance strategy as well as quality and/or quantity of chemical extractives. Relevant characterization of shade tolerance strategies by wood profile is the result of the integration of diverse processes and properties. To the view of growth allocation shift (from trunk to crown) observed in Dicorynia guianensis and of previous studies on tree growth, a potential link between wood profile diversity and growth allocation strategies may exist
Prudden, H. J. "Determinants of population variability in HIV across West Africa : ecological and mathematical modelling analyses." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2016. http://researchonline.lshtm.ac.uk/2634790/.
Повний текст джерелаBi, Yan. "Impact of socio-ecological variability on the transmission of malaria in Yunnan Province, China." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/64151/1/Yan_Bi_Thesis.pdf.
Повний текст джерелаAkter, Rokeya. "Exploring the effects of socio-ecological factors and climate variability on dengue in Australia." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/209682/1/Rokeya_Akter_Thesis.pdf.
Повний текст джерелаSalgado, Hernanz Paula Maria. "Patterns of phytoplankton and primary production variability in the Mediterranean Sea based on remote sensing data." Doctoral thesis, Universitat de les Illes Balears, 2019. http://hdl.handle.net/10803/667024.
Повний текст джерела[spa] La presente tesis doctoral tiene como objetivo evaluar los patrones espaciales y temporales de la variabilidad del fitoplancton marino y la producción primaria en las aguas superficiales del mar Mediterráneo. La investigación se organiza en tres estudios y se basa principalmente en el uso de datos de satélite del color del océano adquiridos durante el período 1998-2015. Asimismo, datos complementarios (por ejemplo, temperatura superficial del mar, índices climáticos, datos meteorológicos o concentración de polvo atmosférico) son utilizados para abordar cuestiones específicas. El primer estudio tiene como objetivo analizar la contribución de las componentes estacionales y no estacionales de la variabilidad del fitoplancton en la cuenca del mar Mediterráneo. La componente estacional se aborda mediante la caracterización de la fenología del fitoplancton; es decir, mediante la parametrización de los ciclos estacionales su periodo de floración (bloom). Para ello, se ha utilizado un algoritmo basado en detección de umbrales de crecimiento de la biomasa de fitoplancton que ha sido ejecutado píxel a píxel. Los resultados demuestran que la variabilidad debida a la componente estacional puede suponer hasta el 80% de la varianza total de clorofila (Chl) en áreas oceánicas, mientras que en las regiones de plataforma continental la variabilidad de alta frecuencia puede dominar y representar hasta un 49% de dicha variabilidad total de Chl. Las variaciones estacionales típicamente se caracterizan por un período de crecimiento del fitoplancton que se produce en primavera y abarca en promedio 170 días en la cuenca oeste u occidental y 150 días en la cuenca este u oriental. Además, en la cuenca occidental se observa una tendencia positiva en la biomasa de Chl y un aumento en la amplitud y duración del período de floración del fitoplancton. Por otro lado, en la cuenca oriental (y más oligotrófica) las tendencias en la concentración de Chl son generalmente despreciables, pero el valor máximo de Chl alcanzado durante el bloom y la duración del periodo de crecimiento si muestran una disminución. A nivel de toda la cuenca del mar Mediterráneo, las tendencias en el fitoplancton y en la fenología, estimadas en este estudio durante el período 1998-2014, no revelan en promedio ni una disminución/aumento general significativo en la concentración de Chl ni un avance/retraso del valor máximo de biomasa estacional. Sin embargo, sí se detectan grandes variaciones regionales, sugiriendo que la respuesta del fitoplancton a las variables ambientales y climáticas pueda ser compleja y local. El segundo estudio aborda los patrones regionales de variabilidad interanual en series temporales de Chl derivadas de datos de satélites. Se utiliza una clasificación de redes neuronales de aprendizaje no supervisado basada en el análisis de Mapas de Autoorganización (SOM, de las siglas en inglés Self-Organizing Maps) ejecutados en el dominio temporal, con el objetivo de discernir regiones donde la variabilidad temporal de la Chl sea similar en el mar Mediterráneo. Los patrones temporales característicos extraídos a través del análisis SOM muestran diferentes escalas de variación que pueden relacionarse con las características oceanográficas y con la variabilidad biogeoquímica presente en el mar Mediterráneo. Se observan claras diferencias entre las regiones ubicadas en la cuenca occidental y el mar Adriático, donde se sabe que los ríos, la mezcla de invierno y los vientos impulsan variaciones en la producción primaria a escala regional; y también en las regiones ubicadas en la cuenca oriental, representadas por una gran región bastante homogénea. El estudio sugiere que el índice climático North Atlantic Oscillation (NAO) tiene una influencia mayor en las variaciones de Chl ubicadas en la cuenca occidental, mientras que el índice El Niño Southern Oscillation (ENSO) muestra un mayor impacto en la cuenca central del Mediterráneo, principalmente apreciable durante su fase positiva. Tanto NAO como ENSO muestran coherencia no estacionaria con la variabilidad de la Chl en el Mediterráneo. El análisis también revela un cambio brusco producido durante los años 2004-2007, cuando el índice NAO cambió de valores positivos a negativos. Este cambio afectó particularmente a la biomasa de fitoplancton en invierno y es un claro indicador del impacto climático sobre el ecosistema del mar Mediterráneo. El tercer estudio se centra en las tasas de producción primaria en las aguas costeras del mar Mediterráneo estimadas mediante datos de satélites. El estudio revela que aproximadamente el 20% del total de la producción primaria de la cuenca Mediterránea proviene de áreas situadas en la plataforma continental (<200 m de profundidad) y que, además, la mayor parte (~80%) constituye producción regenerada. Casi el 50% de esta producción ocurre en las aguas costeras de la cuenca oriental, mientras que las plataformas occidental y Adriática contribuyen con el 28 y el 24% respectivamente. Se observa una gran variabilidad a escala regional que varía desde zonas muy productivas que superan 350 gC m-2 al año, típicamente situadas en las áreas más productivas asociadas con descargas de ríos importantes, a zonas altamente improductivas (<50 PgC m-2 al año) situadas principalmente en el sureste Mediterráneo. La variabilidad de la producción primaria a largo plazo está dominada por variaciones interanuales que se correlacionan inversamente con datos de temperatura superficial del mar y, del mismo modo, aunque en menor grado, con los índices climáticos NAO y Mediterranean Oscillation Index (MOI). A escala regional, la mayoría de las áreas costeras presentan tendencias de producción primarias no significativas o con un débil declive. No obstante, se observan tendencias de producción primaria altamente positivas en el mar Adriático. Para finalizar el estudio, se ha hecho una clasificación en 18 regiones costeras con valores medios de producción primaria que pueden quintuplicarse entre regiones. Además, el análisis permite la identificación de dos grupos de aguas costeras: por un lado, regiones que muestran una baja variabilidad a lo largo de la costa, ubicadas principalmente en áreas donde la plataforma continental es estrecha; y por otro lado regiones que muestran fuertes gradientes a lo largo de la costa, situadas en regiones donde la plataforma continental es típicamente más ancha y/o existen descargas de ríos. Aproximadamente el 50% de la producción primaria mundial tiene lugar en el océano y, en consecuencia, el fitoplancton marino desempeña un papel fundamental en los flujos globales de carbono. Estudiar la variabilidad espacial y temporal del fitoplancton, así como estimar los factores que determinan esta variabilidad, es esencial para comprender la dinámica, la productividad y los ciclos biogeoquímicos del océano, y para anticipar los efectos del cambio climático en el ecosistema marino. Se espera que esta tesis doctoral pueda contribuir a una mejor comprensión de estos cambios en el mar Mediterráneo.
[cat] La present tesi doctoral té com a objectiu avaluar els patrons espacials i temporals de la variabilitat del fitoplàncton marí i la producció primària a les aigües superficials de la mar Mediterrània. La investigació s'organitza en tres estudis i es basa principalment en l'ús de dades de satèl·lit del color de l'oceà adquirides durant el període 1998-2015. Així mateix, dades complementàries (per exemple, temperatura superficial de la mar, índexs climàtics, dades meteorològiques o concentració de pols atmosfèrica) són utilitzats per abordar qüestions específiques. El primer estudi té com a objectiu analitzar la contribució dels components estacionals i no estacionals de la variabilitat del fitoplàncton en el conjunt de la mar Mediterrània. El component estacional s'aborda mitjançant la caracterització de la fenologia del fitoplàncton; és a dir, a costa de la parametrització dels cicles estacionals del seu període de floració (bloom). Per aconseguir-ho, s'ha utilitzat un algoritme fonamentat en la detecció de frontera que ha estat executat píxel a píxel. Els resultats assenyalen que la variabilitat deguda al component estacional pot suposar fins al 80% de la variància total de clorofil·la (Chl) en zones oceàniques, mentre que a les regions de plataforma continental la variabilitat d'alta freqüència pot dominar i representar fins a un 49% d'aquesta variabilitat total de Chl. Les variacions estacionals típicament es caracteritzen per un període de creixement del fitoplàncton que es produeix a la primavera i presenta de mitjana 170 dies a la conca oest o occidental i 150 dies a la conca est o oriental. A més, en la conca occidental s'observa una tendència positiva en la biomassa de Chl i un augment en l'amplitud i duració del període de floració del fitoplàncton. D’altra banda, en la conca oriental (i més oligotròfica) els canvis en la concentració de Chl són generalment menyspreables, però si que el valor màxim de Chl assolit durant el bloom s'ha reduït, alhora que la duració del període de creixement també ha disminuït. En referència a tota la conca de la mar Mediterrània, les tendències en el fitoplàncton i en la fenologia, estimades en aquest estudi durant el període 1998-2014, no mostren de mitjana cap disminució/augment general significatiu en la concentració de Chl ni tampoc un avanç/retard del màxim estacional. No obstant això, si que es detecten grans variacions regionals, suggerint que la resposta del fitoplàncton als forçaments ambientals i climàtics pugui ser complexa i local. El segon estudi aborda els patrons regionals de variabilitat interanual en sèries temporals de Chl derivades de dades de satèl·lits. S'utilitza una classificació de xarxes neuronals d'aprenentatge no supervisat basada en l'anàlisi de Mapes d' Autoorganització (SOM, de les sigles en anglès Self-Organizing Maps) executats en el domini temporal, amb l'objectiu de discernir regions on la variabilitat temporal de la Chl sigui similar a la mar Mediterrània. Els patrons temporals característics extrets mitjançant l'anàlisi SOM mostren diferents escales de variació que poden relacionar-se amb les característiques oceanogràfiques i amb la variabilitat biogeoquímica present en la mar Mediterrània. S'observen clares diferències entre les regions situades a la conca occidental i el mar Adriàtic, on se sap que els rius, la barreja d’aigües que passa al mar a l'hivern, i els vents impulsen variacions en la producció primària a escala regional; i també en les regions situades a la conca oriental, representades per una gran regió bastant homogènia. L'estudi suggereix que l'índex climàtic North Atlantic Oscillation Index (NAO) té una influència més gran en les variacions de Chl ubicades a la conca occidental, mentre que l'índex El Niño Southern Oscillation (ENSO) mostra un major impacte en la conca central de la Mediterrània principalment apreciable durant la seva fase positiva. Tant NAO com ENSO mostren coherència no estacionària amb la variabilitat de la Chl a la Mar Mediterrània. L'anàlisi també revela un canvi sobtat produït durant els anys 2004- 2007, quan l'índex NAO va canviar de valors positius a negatius. Aquest canvi va afectar particularment la biomassa de fitoplàncton a l'hivern i és indicatiu clar de canvis en el nivell de l'ecosistema impulsats pel clima en la mar Mediterrània. El tercer estudi se centra en les taxes de producció primària a les aigües costaneres de la mar Mediterrània estimades mitjançant dades de satèl·lits. L'estudi revela que aproximadament el 20% del total de la producció primària de la conca mediterrània prové d'àrees situades a la plataforma continental (<200 m de profunditat) i que, a més, la major part (~80%) constitueix producció regenerada. Gairebé el 50% d'aquesta producció es produeix en les aigües costaneres de la conca oriental, mentre que les plataformes occidental i Adriàtica contribueixen amb el 28 i el 24% respectivament. S'observa una gran variabilitat a escala regional que varia des de zones molt productives que superen 350 gC m-2 a l'any, típicament situades a les àrees més productives generalment associades amb descàrregues de rius importants, fins a províncies altament improductives (<50 PgC m-2 al any) situades principalment al sud-est mediterrani. La variabilitat de la producció primària a llarg termini és dominada per variacions interanuals que es correlacionen inversament amb dades de temperatura superficial del mar i, de la mateixa manera encara que en menor mesura, amb els índexs climàtics NAO i Mediterranean Oscillation Index (MOI). En l’àmbit regional, la majoria de les àrees costaneres presenten tendències de producció primàries no significatives o amb un lleuger declivi, encara que, si bé s'observen tendències de producció primària altament positives al mar Adriàtic. S'han classificat les aigües costaneres en 18 regions amb valors mitjans de producció primària que poden variar fins a cinc vegades d’unes regions a altres. L'anàlisi permet la identificació de dos grups d'aigües costaneres: d'una banda, regions que mostren una baixa variabilitat al llarg de la costa, situades principalment en àrees on la plataforma continental és estreta; i d'altra banda regions que mostren forts gradients al llarg de la costa, situades en regions on la plataforma continental és típicament més ampla i/o hi ha descàrregues de rius. Aproximadament el 50% de la producció primària mundial té lloc a l'oceà i, en conseqüència, el fitoplàncton marí té un paper fonamental en els fluxos globals de carboni. Estudiar la variabilitat espacial i temporal del fitoplàncton, així com estimar els factors que determinen aquesta variabilitat, és essencial per comprendre la dinàmica, la productivitat i els cicles biogeoquímics de l'oceà, i per anticipar els efectes del canvi climàtic en l'ecosistema marí. S'espera que aquesta tesi doctoral pugui contribuir a una millor comprensió d'aquests canvis a la Mediterrània.
Yu, Songyan. "Spatio-temporal dynamics and hydro-ecology of intermittent streams in eastern Australia." Thesis, Griffith University, 2019. http://hdl.handle.net/10072/389088.
Повний текст джерелаThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
Wu, Jin. "How do Amazonian Tropical Forest Systems Photosynthesize under Seasonal Climatic Variability: Insights from Tropical Phenology." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594653.
Повний текст джерелаSchrag, Anne Michelle. "Climate variability and treeline dynamics in Yellowstone and Grand Teton National Parks." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/schrag/SchragA1206.pdf.
Повний текст джерелаWethington, Susan Marie. "Some effects of variability in nectar renewal-rates on the hummingbird-foraging/plant-pollination mutualism." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284254.
Повний текст джерелаTeixeira, José Reinaldo Paranaíba Vilela Alves. "High spatial variability of carbon emission and gas exchange coefficient in three tropical reservoirs." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/5656.
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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
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Reservoirs are significant sources of carbon emission to the atmosphere. However the magnitude of this emission has huge uncertainties, partly related to the methods of sampling and partly related to the unconsidered spatial-temporal variability. Here we examined the spatial variability and its drivers of partial pressure, gas exchange coefficient and diffusive flux of CO2 and CH4 in three tropical reservoirs. We observed high spatial variability in CO2 and CH4 concentration and flux within the reservoirs. Our results suggest that all reservoirs were supersaturated in both gases, even considering that some areas were CO2 sinks. A large spatial variability in k600 for CO2 and CH4, and consistently observed k600CH4 values higher than k600CO2 were also observed in all reservoirs. We could explain the high spatial variability of CO2 and CH4 by a combination of parameters such as dissolved oxygen, pH, chlorophyll, wind speed and bathymetry. Finally, we suggest a minimum sampling effort required to representatively cover a study site. Our results illustrate the first specially-resolved analysis of CH4 emissions in reservoirs, and we suggest that in large systems (area ≥ 1,000 km²) and small systems (area ≤ 100 km²), 600 and 200 measurements sites, respectively, are need for a representative dry period carbon flux estimates.
Deng, Ying [Verfasser], and Oliver [Akademischer Betreuer] Bossdorf. "Ecological and evolutionary relevance of plant responses to environmental variability / Ying Deng ; Betreuer: Oliver Bossdorf." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1189654059/34.
Повний текст джерелаWard, Catherine Dale. "Climate variability in social-ecological systems of the Southern Cape: integrating farming and fishing perspectives." Doctoral thesis, Faculty of Science, 2018. http://hdl.handle.net/11427/30088.
Повний текст джерелаNye, Janet Ashley. "Bioenergetic and ecological consequences of diet variability in Atlantic croaker (Micropogonias undulatus) in Chesapeake Bay." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8140.
Повний текст джерелаThesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Gulish, Matthew C. "SEASONAL VARIABILITY OF AQUATIC AND TERRESTRIAL INVERTEBRATES IN A FORESTED STREAM ECOSYSTEM." Kent State University Honors College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1544453804036894.
Повний текст джерелаMillan, Mathieu. "Analyse de la variabilité des traits architecturaux des formes de croissance dans les communautés végétales." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT151.
Повний текст джерелаThe growth forms of plant have been studied many times but they still represent nowadays a fuzzy set, often modified because of the inconsistency and the heterogeneity of the methods used in their analysis. This lack of precision often leads to an inconsistency of the use of the growth forms as a trait in the studies of plants communities and their dynamics. We tried to remedy this situation by applying to some of them the architectural analysis initiated by Hallé and Oldeman, which has been relevant for the understanding of the tree growth form.This study aimed to 1) interpret these growth forms and their variability by means of architectural concepts, 2) study architectural traits variation within roadsides plants communities during succession and in a mowing context. Our resultats show that 1) the architectural concepts and traits are applicable to herbaceous, treelet and bush grosth forms, 2) the expression of the reiteration is the main source of structural variation of growth forms at specific and intraspecific levels and 3) that traits values are changing during succession within the communities : Plants living at early successionnal stages got a simple architectural unit and reiterate at the base of the individual while plants living at late successional stages got complex architectural unit and acrotonic reiteration.These resultats lead us to discuss the holistic value of the architectural analysis for growth forms charaterisation, of biological processes allowing for growth form variation and the interest of the use of architectural traits in plant communities studies
Rosam, Jodie Ray. "Assessment of light quality, variability, and seedling presence in Hawaiian lowland wet forests." Thesis, University of Hawai'i at Hilo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1596447.
Повний текст джерелаHawaiian lowland wet forest (HLWF) plant species are light-limited, yet no information exists on how the understory light varies in relation to species invasion, or if patterns of seedling regeneration and light are linked. I measured the red-to-far-red ratio (R:FR) of light to assess light quality and quantified diurnal variability in three forest types: native-dominated, partially-invaded, and fully invaded by strawberry guava (Psidium cattleianum). I asked: (1) how does understory light quality vary relative to invasion? (2) Are there differences in light quality moving vertically among forest types? (3) Are patterns of seedling regeneration and understory light related? Native-dominated forests had the greatest light quality (highest R:FR), and Psidium cattleianum-dominated forests had the lowest. While I predicted that native seedlings would prefer high-quality light sites, all seedlings preferred medium quality environments. In invaded HLWF, native seedling regeneration is hindered, and restoration efforts should focus on non-native understory removal.
Saunders, Ryan Alexander. "Ecological investigations of euphausiids at high latitudes." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/347.
Повний текст джерелаAccoroni, Stefano. "Ecology, morphological variability and life cycle stages of the toxic benthic dinoflagellate Ostreopsis cf. ovata." Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242557.
Повний текст джерелаThe benthic dinoflagellate Ostreopsis cf. ovata causes massive blooms along the Mediterranean coasts, associated with noxious effects on human health and with mortality of marine organisms, due to the production of palytoxins. The O. cf. ovata life cycle was studied in order to evaluate if sexual reproduction occurred in homothallic and/or heterothallic conditions. Sexual reproduction occurred in both conditions, although heterothally seems to be the preferential way. Nutrient limitation seems to stimulate sexual stages. Different morphotypes have been identified: gametes, planozygotes, different maturation stages of hypnozygotes, and non-dormant cysts. Gamete mating occurred following two mechanisms: (i) vegetative cells joined by epitheca and (ii) gametes mating with cingula laterally aligned, producing a biflagellate planozygote, which was for observed the first time in O. cf. ovata. The ecology of O. cf. ovata bloom was investigated from 2006 to 2010 in the Conero Riviera (N Adriatic Sea) to evaluate the role of environmental factors and substratum. Maximum was always observed in late-summer (106 cells g-1 fw). Significantly higher abundances were observed on rocks than on seaweeds, suggesting that some interactions may occur between Ostreopsis and their living hosts. Hydrodynamism plays a major role in Ostreopsis blooms: abundances were significantly higher in sheltered than in exposed sites. Temperature and nutrients do not seem to have a key role on the bloom dynamics. A high morphometrical variability was shown (DV:18.5-75 μm; W:12.5-60 μm; AP: 10-31.25 μm). O. cf. ovata showed DV significantly lower in sheltered sites compared with exposed ones, suggesting that the former represent favorable sites for intense O. cf. ovata proliferation. The dimensions of Ostreopsis cells in the water column were significantly higher than those of epiphytic ones, suggesting that resuspended cells in the water column probably derived from a mature benthic population.
Mead, Michael Phillip. "The Theory of Planned Behavior and Sleep Opportunity: An Ecological Momentary Assessment of Intra-Individual Variability." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31927.
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