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Mealor, Michael A. "Spatial heterogeneity in ecology." Thesis, University of Stirling, 2005. http://hdl.handle.net/1893/53.
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This project predominantly investigated the implications of spatial heterogeneity in the ecological processes of competition and infection. Empirical analysis of spatial heterogeneity was carried out using the lepidopteran species Plodia interpunctella. Using differently viscous food media, it was possible to alter the movement rate of larvae. Soft Foods allow the movement rate of larvae to be high, so that individuals can disperse through the environment and avoid physical encounters with conspecifics. Harder foods lower the movement rate of larvae, restricting the ability of individuals to disperse away from birth sites and avoid conspecifics encounters. Increasing food viscosity and lowering movement rate therefore has the effect of making uniform distributed larval populations more aggregated and patchy. Different spatial structures changed the nature of intraspecific competition, with patchy populations characterised by individuals experiencing lower growth rates and greater mortality because of the reduced food and space available within densely packed aggregations. At the population scale, the increased competition for food individuals experience in aggregations emerges as longer generational cycles and reduced population densities. Aggregating individuals also altered the outcome of interspecific competition between Plodia and Ephestia cautella. In food media that allowed high movement rates, Plodia had a greater survival rate than Ephestia because the larger movement rate of Plodia allowed it to more effectively avoid intraspecific competition. Also the faster growth rate, and so larger size, of Plodia allowed it to dominate interspecific encounters by either predating or interfering with the feeding of Ephestia. In food that restricts movement, the resulting aggregations cause Plodia to experience more intraspecific encounters relative to interspecific, reducing its competitive advantage and levelling the survival of the two species. Spatial structure also affected the dynamics of a Plodia-granulosis virus interaction and the evolution of virus infectivity. Larval aggregation forced transmission to become limited to within host patches, making the overall prevalence of the virus low. However potentially high rates of cannibalism and multiple infections within overcrowded host aggregations caused virus-induced mortality to be high, as indicated by the low host population density when virus is presented. Also aggregated host populations cause the evolution of lower virus infectivity, where less infective virus strains maintain more susceptible hosts within the aggregation and so possess a greater transmission rate. The pattern of variation in resistance of Plodia interpunctella towards its granulosis virus was found using two forms of graphical analysis. There was a bimodal pattern of variation, with most individuals exhibiting either low or high levels of resistance. This pattern was related to a resistance mechanism that is decreasingly costly to host fitness.
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Smith, M. Alexander. "Spatial ecology of Bufo fowleri." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84844.
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The geographic isolation of populations can result in a metapopulation effect where regional dynamics of extinction and colonization are more important to population viability than local dynamics of individuals' birth or death. When this partial isolation is maintained for many generations genetic variability can be geographically structured. Populations of temperate-zone anuran amphibians are often considered to be geographically isolated on relatively small spatial scales due to the animals presumed high site fidelity and strict dependence on moisture for respiration and breeding. As a result, temperate, pond-breeding anuran amphibian populations are considered likely candidates to test hypotheses of metapopulation theory, movement and phylogeography. Using data from the Fowler's toad, (Bufo fowleri) I test the applicability of metapopulation theory, the likelihood of limited movement and the strength of phylogeographic structure. Specifically, I show that the generalization of the amphibians-as-metapopulations paradigm, due to their limited dispersal capabilities, is not supported (I). Bufo fowleri movement is well described by an inverse power function. Whereas most individuals do not move, some move long distances. There is no sex bias to this movement and I propose the hypothesis that the animals moving the longest distances are aided by the passive action of lake currents (II). B. fowleri juveniles are not a dispersal stage. They move neither farther nor faster than adults. The observation of predominantly juvenile contribution to a dispersal pool is due to their abundance---there are simply many more juveniles than adults (III). My observations of amphibian population turnover do not support the predictions of two specific metapopulation models when parameterized on a local (<10km) or regional scale (~300km) (IV). B. fowleri populations in Canada exhibit both shallow and deep phylogeographic structure. The shallow divisions are geo
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Hendry, Ruth Juliet. "Spatial modelling in plant ecology." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/1126/.
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In this thesis a range of lattice based spatially explicit models of ecosystems are presented and their applicability to various ecological situations is demonstrated with emphasis on plant communities These mechanistic and individual based models which include coupled map lattices and cellular automata aim to produce ecological insights and testable results Models of both short and long term systems are developed with the former being potentially testable in the eld and the latter promoting understanding where experimentation is not feasible A range of graphical and numerical techniques were developed to investigate both plant and animal model ecosystems The starting point is a short term single species coupled map lattice which investigates popula tion structure arising from local competitive interactions The model concludes that increase of size variation with increasing density indicates the presence of competitive intraspecic asymme try This idea is applied to crop data where considerable asymmetry is identied emphasising the need for balancing crop yield and size consistency Multispecies extensions to this model focus on spatial patterning arising from biotic interac tions and various numerical techniques underline the asymmetrical relationship between long and short lived species Environmental heterogeneity is imposed on the plant species in a third version of the model via the incorporation of an explicit resource base The complex inter dependence of community and environment is highlighted and illustrated by a model of the evolution of seed sizes Through the application of cellular automata to forest and epidemiological systems the concept of memory such as age or stage structuring is shown to be vital in the generation of spatial structure in long term ecological systems Analytical investigations generate further insights and again emphasise the crucial role played by spatial extensiveness in the wide range of ecological situations considered here In conclusion lattice models are ideally suited to the study of ecosystems
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Moreno, Michael Raghib. "Point processes in spatial ecology." Thesis, University of Glasgow, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443445.
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Bunwong, Kornkanok. "Spatial modelling in evolutionary ecology." Thesis, University of Warwick, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439642.
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Roslin, Tomas. "Spatial ecology of dung beetles." Helsinki : University of Helsinki, 1999. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/roslin/.
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May, Roelof Frans. "Spatial Ecology of Wolverines in Scandinavia." Doctoral thesis, Norwegian University of Science and Technology, Department of Biology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1730.
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Moussy, Caroline Maude Christine. "Spatial ecology of the serotine bat." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13848.
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The spatial ecology of a species underpins an array of important questions about the ecology and evolution of a species, relating for instance to sociality, population dynamics, geographical distribution or genetic partitioning. Furthermore, the understanding of the spatial ecology of a species also has important implications for conservation and for disease management. It is in this context that I have examined the spatial ecology of the serotine bat (Eptesicus serotinus), in Europe, and especially at the northern limit of its distribution in England, using population genetic and stable isotope analyses. Data from nuclear microsatellite markers indicated higher levels of gene flow on the continent than in England. Consistent with this, England was separated into three genetically distinct populations, inter-connected by male-driven gene flow. Substantial asymmetric gene movement over the English Channel was inferred, possibly indicating a northward and westward range expansion. Mitochondrial DNA revealed fast population expansion and strong female philopatry. Moving to finer scale, δ13C in wing tissue and fur revealed that the association of individuals at roosts is flexible and dynamic, possibly reflecting their membership to communities operating at larger geographic scales. Communities of E. serotinus seem therefore to create a network of roosts with individuals continually re-assorting among themselves both within and across breeding seasons. The integration of the genetic and isotopic data highlighted complex spatial, social and temporal interactions in this species. While individual associations within communities seem to be flexible, communities were found to be strongly segregated over the breeding season. In contrast, genetic connectivity operates on a larger geographical scale than the local summer landscape. Together, these findings help explain the apparent absence in the UK of the European Bat Lyssavirus 1 (EBLV-1) for which this species is the main host. Hence, the relative fragmentation of this low-density population may inhibit the virus’ spread. However, with regular immigration from the continent, EBLV-1 could eventually enter the UK.
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Witt, Matthew John. "The spatial ecology of marine turtles." Thesis, University of Exeter, 2007. http://hdl.handle.net/10036/30023.
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Gaining an understanding of the spatial ecology of marine turtles is essential for elucidating aspects of their life history ecology and for effective conservation management. This thesis presents a collection of chapters seeking to investigate the spatial ecology of this taxon. An array of technologies and methodologies are employed to ask both ecological and spatial management questions. Work focuses on foraging and thermal ecology, spatial appropriateness of Marine Protected Areas, movement models to describe habitat utilisation, analysis of data from sightings and strandings schemes and the use of a large synoptic fisheries dataset to describe fisheries patterns and putative risks to marine megavertebrates.
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Jones, Esther Lane. "Spatial ecology of marine top predators." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12278.
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Species distribution maps can provide important information to focus conservation efforts and enable spatial management of human activities. Two sympatric marine predators, grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina), have overlapping ranges but contrasting population dynamics around the UK; whilst grey seals have generally increased, harbour seals have shown significant regional declines. A robust analytical methodology was developed to produce maps of grey and harbour seal usage estimates with corresponding uncertainty, and scales of spatial partitioning between the species were found. Throughout their range, both grey and harbour seals spend the majority of their time within 50 km of the coast. The scalability of the analytical approach was enhanced and environmental information to enable spatial predictions was included. The resultant maps have been applied to inform consent and licensing of marine renewable developments of wind farms and tidal turbines. For harbour seals around Orkney, northern Scotland, distance from haul out, proportion of sand in seabed sediment, and annual mean power were important predictors of space-use. Utilising seal usage maps, a framework was produced to allow shipping noise, an important marine anthropogenic stressor, to be explicitly incorporated into spatial planning. Potentially sensitive areas were identified through quantifying risk of exposure of shipping traffic to marine species. Individual noise exposure was predicted with associated uncertainty in an area with varying rates of co-occurrence. Across the UK, spatial overlap was highest within 50 km of the coast, close to seal haul outs. Areas identified with high risk of exposure included 11 Special Areas of Conservation (from a possible 25). Risk to harbour seal populations was highest, affecting half of all SACs associated with the species. For 20 of 28 animals in the acoustic exposure study, 95% CI for M-weighted cumulative Sound Exposure Levels had upper bounds above levels known to induce Temporary Threshold Shift. Predictions of broadband received sound pressure levels were underestimated on average by 0.7 dB re 1μPa (± 3.3). An analytical methodology was derived to allow ecological maps to be quantitatively compared. The Structural Similarity (SSIM) index was enhanced to incorporate uncertainty from underlying spatial models, and a software algorithm was developed to correct for internal edge effects so that loss of spatial information from the map comparison was limited. The application of the approach was demonstrated using a case study of sperm whales (Physeter macrocephalus, Linneaus 1758) in the Mediterranean Sea to identify areas where local-scale differences in space-use between groups and singleton whales occurred. SSIM is applicable to a broad range of spatial ecological data, providing a novel tool for map comparison.
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Whitney, Karen. "Spatial structure affects landscape ecology function." [Florida] : State University System of Florida, 1999. http://etd.fcla.edu/etd/uf/1999/amp7637/whitney.pdf.
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Thesis (M.S.)--University of Florida, 1999.Title from first page of PDF file. Document formatted into pages; contains viii, 35 p.; also contains graphics. Vita. Includes bibliographical references (p. 27-34).
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Blumenthal, Janice Margaret. "Spatial ecology of Cayman Islands marine turtles." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493645.
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Moyer, Melissa Ann. "Spatial ecology of female Florida black bears." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007441.
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Gilbert, Marius. "Spatial ecology of Dendroctonus micans (Kug.) (Coleoptera: Scolytidae)." Doctoral thesis, Universite Libre de Bruxelles, 2000. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211766.
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Bennett, Andrew Thomas Deakin. "The ecology of spatial memory in European jays." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302845.
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Marino, Jorgelina. "Spatial ecology of the Ethiopian wolf, Canis simensis." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403578.
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Gough, Lauren. "The spatial ecology of an endemic desert shrub." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/13267/.
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Using spatial patterns to infer biotic and abiotic processes underlying plant population dynamics is an important technique in contemporary ecology, with particular utility when investigating and shrub population dynamics, for which experimental and observational methodologies are rarely feasible. Using a novel one-class classification technique, the locations of over 17,000 Spartocytisus supranubius individuals were mapped from aerial imagery generating a spatially extensive (162 ha), yet accurate, dataset. The recent rapid increase in studies using pattern-process inference has not been accompanied by a rigorous assessment of the behaviour of these techniques, nor an appraisal of their utility in addressing ecological research questions. The first part of the thesis addresses these concerns, investigating whether current methodologies are adequate to test hypotheses concerning spatial interactions. A literature review reveals a preponderance of studies of small, little-replicated plots. The results of the research raise concerns about the utility of spatial point pattern analyses as currently applied in the literature. To avoid inaccurate description of fine-scale spatial structures it is recommended that researchers increase plot replication. Furthermore, studies of spatial structure and population dynamics should account for spatial environmental gradients, whatever plot size is used. The second part of the thesis presents a rigorous investigation, incorporating a priori inference and the application of fine-scale spatial statistical and modelling techniques, of the biotic and abiotic mechanisms underlying the spatial structure and population dynamics of S. supranubius, a leguminous shrub species endemic to the Canary Islands. The spatial structure of S. supranubius populations is consistent with the operation of clonal reproduction and intra-specific competition. However, the results indicate that spatial environmental heterogeneity (from small to broad scales), in particular topography, can interact with biotic processes to generate quantitatively different S. Supranubius patterns in different locations. Future research into the spatial and temporal dynamics of interactions between abiotic and biotic processes is recommended.
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Irvine, Michael Alastair. "Pattern formation and persistence in spatial plant ecology." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/67166/.
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The main aim of the thesis is to explore the interaction between pattern and process in vegetation ecology using a variety of mathematical and statistical methods. Of particular interest is what information about the dynamics of the underlying system can be gained through a single spatial snapshot, such as an aerial photograph or satellite image. The hypotheses are related to seagrass ecology, whose growth is primarily clonal and broadly exists as a monoculture and thus makes it an ideal candidate to study these interactions. The thesis broadly concerns two forms of spatial pattern and the underlying dynamics that give rise to them. The first concerns regular pattern formation, where the pattern has a characteristic length scale. Examples are abundant in natural systems, such as mussel beds, semi-arid ecosystems as well as seagrass. The developments concerned with regular pattern formation include methods of detection in a large spatial dataset, a novel stochastic model of vegetation that produces regular pattern with plausible mechanisms, the development of a new methodology to fit regular spatial pattern data to the model and the impact as well as evolutionary mechanisms of regular patterning in the presence of disease. The second form of spatial pattern exhibited in a wide variety of sessile species is scale-free or fractal patterning. Certain scaling heuristics, such as the boundary dimension of a vegetation cluster or the power-law exponent of the patch-size distribution have been used to infer properties of the dynamics. We explore these heuristics using a variety of plausible models of vegetation growth and find the circumstances under which there is a clear relationship between the spatial heuristics and the dynamics. These are then supplemented by viewing vegetation growth as an aggregation process. A novel model of vegetation aggregation with death is produced to find the origin of the ubiquitous power-law patch-size distribution found in nature. Finally the impact of scaling on the spread of disease is explored.
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Chapman, Daniel. "Spatial ecology of the tansy beetle (Chrysolina graminis)." Thesis, University of York, 2006. http://etheses.whiterose.ac.uk/14079/.
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Victorsson, Jonas. "Community Assembly and Spatial Ecology of Saproxylic Coleoptera." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88765.
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Schmidt, Jill Lisa. "Spatial ecology of bacteria in surficial marine sediments /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/11058.
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Hanrahan, Alexander. "Spatial Ecology Of River Otters In Southern Illinois." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2413.
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Social behavior and habitat selection of river otters (Lontra canadensis) are highly variable among populations and there is limited information on how space use of this mustelid changes in human-modified environments. Understanding the spatial ecology of river otters is important for efforts focused on habitat management and preventing human-wildlife conflicts. My objectives were to quantify: (1) home ranges and core areas, (2) second- and third-order habitat selection, and (3) relationships between home-range size and intensity of human development for river otters in southern Illinois. VHF transmitters were used to track river otters during 2014-2016. Home-range and core-area sizes then were compared between males (n = 8) and females (n = 10), as was home-range overlap. I also compared the frequency individuals were located <25 m from a conspecific between sexes. Habitat selection at the second and third orders was analyzed with an eigen-analysis of selection ratios. Male river otters had larger home ranges and core areas than females. Home ranges of males overlapped frequently; lack of core-area overlap among females suggested they may be territorial. Males also were located <25 m from a conspecific more frequently than females (P = 0.023), and male-male dyads shared space more than male-female and female-female dyads (P = 0.002). Herbaceous and wooded wetlands were most strongly selected for at both second- and third-order scales, but streams and ponds also were selected. Regarding terrestrial cover types, river otters selected land with vegetative cover over areas with impervious surface (e.g., parking lots and shopping centers). Forests were selected over crop fields at the third-order, but not second-order, scale. Use of urbanized land was uncommon for river otters, and there was a positive relationship (P = 0.004) between home-range size and the percentage of home range within developed open space (e.g., roads and residential lawns). The habitat selection and sociality of river otters in southern Illinois varied among individuals, as it does among river otter populations throughout North America. By recording sex differences in social behavior and selection of aquatic and upland habitat, my study provides wildlife biologists with a better understanding of river otter space use throughout a rural-urban gradient.
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BONACCHI, ANDREA. "Spatial ecology of Apodemus flavicollis in Central Italy." Doctoral thesis, Università di Siena, 2019. http://hdl.handle.net/11365/1092627.
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Acquiring knowledge on the spatial behaviour of rodents is crucial to understand their key ecological role in forested habitats. This achievement requires investigations through different habitat types and spatial scales, given that the structure and species composition of vegetation are known to influence considerably the small mammal community. Woodlands actively managed for coppice, with their mosaic of stands differing markedly in plant structure and, to a lesser extent, composition, provide an excellent model for studying the impact of such variation on small mammal spatial ecology.
In this light, we planned a study aiming at facilitating the comprehension of factors driving the spatial ecology of the yellow-necked mouse Apodemus flavicollis, a ground-dwelling rodent inhabiting a coppiced sub-Mediterranean deciduous oak forest in central Italy.
The first part of the thesis (Chapter 1) relied on radio-tracking to investigate some components of A. flavicollis spatial behaviour in two oak stands coppiced in different years and contrasting in terms of both resource availability (i.e. plant food and cover) and intra- and inter-specific population densities. Our study suggests that A. flavicollis home range and core area size was not influenced by sex but rather by season and habitat type, whereas ranges overlap depended on both sex and season. In particular we found mice to have smaller home ranges in recently coppiced area, suggesting that these areas can represent for this species a high-quality habitat.
The second part of the thesis (Chapter 2) consists of a multiscale analysis of A. flavicollis captures over three years of live-trapping to reveal the environmental factors driving the occurrence of the species. More specifically, at the macrohabitat level this chapter aimed to individuate which environmental factors drive A. flavicollis site occupancy dynamics (i.e. local extinction and colonization probabilities) in coppiced stands differing in their structural and compositional characteristics. Furthermore, inside each stand, microhabitat features most likely ruling mice captures at the single trap-site were pointed out. Macrohabitat analyses results suggested that in our study area A. flavicollis shows a clear preference for woods at early stages, with a local probability of extinction gradually growing with time since last coppicing and a lower colonization probability in stands with a more complex and thick vertical structure of the vegetation. In addition, microhabitat analyses revealed that A. flavicollis seems to be mostly conditioned by the resources available at ground level, being a mainly terricolous species.
Finally, important issues related to the principal objectives of this thesis were addressed in Appendix A and B. The former investigated by cafeteria experiments the potential role of fruits of several shrub species as a trophic resource for A. flavicollis, while the latter explored the existence of intra- and inter-specific social tolerance in these rodents through the analysis of live-trapping secondary data.
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Pereira, de Felipe Fernanda. "Sexual segregation in spatial and feeding ecology of seabirds." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/668678.
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Sexual Segregation (SS) is a phenomenon that occurs across a wide range of animal species, and that had been broadly categorized in spatial/habitat segregation and social segregation. SS of a given species is often related quantitatively to its Sexual Size Dimorphism (SSD), which frequently drives to sexual differences that can work as a mechanism to avoid competition between individuals of opposite sex. SS has been widely studied among terrestrial birds. The few existing studies on SS involving pelagic seabirds have focused on the breeding period, and the extent of SS in relation to environmental conditions and fisheries and its persistence during the non-breeding period remains poorly understood in this taxa.
In this thesis, we aimed to understand the causes and consequences of SS in spatio-temporal distribution (inferred through geolocation and GPS-tracking data), migratory phenology (inferred through light-level data from geolocators), behaviour (inferred through immersion data from geolocators) and feeding ecology (inferred through Stable Isotope Analysis (SIA)) of three closely-related shearwaters: Scopoli’s, Cory’s and Cape Verde shearwaters (Calonectris diomedea, C. borealis, and C. edwardsii, respectively). To assess and understand potential sex differences within or between breeding (for Scopoli’s shearwater) and non-breeding periods (for the three Calonectris shearwaters), we adopted a multidisciplinary approach combining geolocation, immersion data, GPS-tracking, spatial modelling and SIA.
Our findings pointed out that during the breeding period, females of Scopoli’s shearwater seem to be outcompeted by males and forced to increase their foraging effort, especially under unfavourable conditions. This result suggests unfavourable conditions induced an inter-sexual competition for limiting resources, and males forced females to forage further from the colony. Furthermore, males interacted with fishing vessels to a greater extent, profiting from discards more than females. Otherwise, during the non-breeding period, both sexes of the three Calonectris shearwaters shared the same non-breeding areas, suggesting competitive exclusion does not promote spatial segregation throughout the annual cycle. Sexual differences in the migratory phenology were subtle for the three species, with males consistently returning earlier to breeding colonies, and male Cory’s shearwaters remaining resident in a larger proportion than females, likely due to sex-specific reproductive roles at early stages of the breeding period. For both breeding and non-breeding periods, males consistently feed on higher trophic levels (inferred from higher δ15N) than females, suggesting that sexual differences in diet may persist year-round. For the breeding period, we found an increase of δ15N values correlated with fishing vessel attendance, indicating that sexual differences observed may mostly emerge from differential fishing vessel attendance and consumption of fishery discards between males and females. However, the influence of SSD in bill size in determining differences in diet remains unclear.
Overall, we found consistent differences in foraging movements, migratory phenology, and resource use between sexes, indicating a robust SS during breeding and non-breeding periods in shearwater species. Furthermore, our results indicated that SS in foraging strategies of Scopoli’s shearwater may lead to unbalanced exposure of males and females to bycatch in the North-Western Mediterranean, which could reduce effective population size and compromise the population viability of the species.
This thesis increase our knowledge about SS in Calonectris species, and show that species with slight SSD also present well-marked SS and that intrinsic and extrinsic factors can promote inter-sexual differences throughout the annual cycle. Furthermore, we highlight that SS in distribution and foraging behaviour of Scopoli’s shearwater, and probably in other seabird species, should be taken into consideration when implementing specific conservation plans in the marine environment.La segregación sexual (SS) es un fenómeno habitual en animales, como consecuencia de diferencias entre sexos en la distribución espacio-temporal, el comportamiento o la ecología trófica. En aves marinas, el estudio de la SS se ha centrado principalmente en el período reproductivo. En cambio, su alcance e implicaciones en relación a las condiciones ambientales, así como su ocurrencia fuera del período reproductivo, han sido menos estudiadas. Nuestro objetivo fue comprender las causas y consecuencias de la SS en la distribución, fenología migratoria, comportamiento y ecología trófica de tres especies emparentadas: la pardela cenicienta mediterránea, cenicienta atlántica y de Cabo Verde (Calonectris diomedea, C. borealis y C. edwardsii, respectivamente). Para ello evaluamos las diferencias sexuales en el periodo reproductivo (en la pardela cenicienta mediterránea) y de invernada, y discutimos si dichas diferencias se extienden a lo largo del ciclo anual. Para el periodo reproductivo, nuestros resultados indicaron que las hembras de pardela cenicienta mediterránea son menos competitivas que los machos, viéndose obligadas a incrementar el esfuerzo de búsqueda de alimento, especialmente ante condiciones ambientales desfavorables. Además, los machos fueron más proclives a interaccionar con barcos pesqueros, haciendo mayor uso de descartes, pero exponiéndose a un mayor riesgo de captura accidental, lo que podría comprometer el tamaño efectivo de la población y su viabilidad en el Mediterráneo noroccidental. Fuera del periodo reproductivo, ambos sexos compartieron las zonas de invernada en las tres especies, indicando que la exclusión competitiva no causa, al menos a escala espacial, SS a lo largo del año. Ambos sexos se alimentaron en diferentes niveles tróficos, sugiriendo que la segregación trófica persiste a lo largo del año. Encontramos sutiles diferencias en el calendario migratorio, siendo los machos los primeros en retornar a las colonias, y un mayor porcentaje de machos que de hembras de la pardela cenicienta atlántica no migró, probablemente como estrategia ventajosa de cara a las etapas iniciales del periodo reproductivo. En general, encontramos evidencias de SS en los movimientos de búsqueda de alimento, fenología migratoria y ecología trófica, tanto durante el período reproductivo como en el período de invernada en las tres especies de pardela.
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Ieraci, Luciano A. "Spatial intermittency, biodiversity, and multifractals." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33411.
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Ecosystems involve highly non-linear interactions between species and their environments over wide ranges of scales. These interactions give rise to population number densities that are highly intermittent in both space and time. The simplest hypothesis about the variability of individual density fields is that they are scale invariant in space-time. For some cases, such as plankton, this has been demonstrated empirically. In addition, at a fixed space-time location there is a well-established information theory approach for treating the density statistics for different species. In this "species space", there are already two scaling biodiversity models: the (mono) fractal model and the lognormal model.The simplest treatment combining real and species space scaling is obtained by considering an anisotropic multifractal cascade in a (5-D) species-space-time space. With the help of a unique data base involving nearly three hundred different species densities, each over a spatial range of approximately 40, 0.5m x 0.5m samples from six underwater sites in the Saint Lawrence Estuary, this simple "superscaling" model is tested. It is shown that the scaling of all species densities is compatible with a "bilinear" multifractal model, where an "elliptical dimension" parameter characterises the anisotropy of species-real space. This information is then used to numerically simulate the spatial variability of joint species densities, and it is discussed how this framework can be used to define scale invariant measures of biodiversity.
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White, Andrew. "Temporal and spatial dynamics of ecological systems." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338459.
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Purves, Drew William. "Local spatial structure and plant population dynamics." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251813.
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Thomas, Christopher Francis George. "The spatial dynamics of spiders in farmland." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358257.
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Audorff, Volker. "Vegetation ecology of springs ecological, spatial and temporal patterns." Bayreuth Bayreuth Center of Ecology and Environmental Research, 2009. http://d-nb.info/99933087X/34.
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Keeling, Matthew James. "The ecology and evolution of spatial host-parasite systems." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/30/.
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All ecological and epidemiological systems are embedded in space and composed of individuals; these facts often have a profound effect on the dynamics and means many tools and definitions require reformulation. Modelling has always been about taking highly complex dynamical systems, such as the natural environment, and attempting to simplify them to a leve that can be conceptualised, in the process losing all the features that are not understood or not anticipated. The individual based spatial models which form the basis of this work start from the simple rules for individuals and build up to a complex system, allowing new, unexpected phenomenon to arise naturally. The local interactions in spatial models lead to short scale correlations and self-induced spatial heterogeneity as the small fluctuations of environmental noise are amplified into macro-scale patterns. These spatial patterns can lead to ephemeral refuges for hosts from where they can disperse stabilising the dynamics. After discussing the importance and variety of host-parasite interactions several techniques to be used in this work are developed and explained on simple examples. Chapters III and IV introduce a caricature host-pathogen model and how how this deviates from the standard mean field theory approximations. Attention is then turned to host-parasitoid systems and the spatially extended Nicholson-Bailey equations; probems with this coupled map lattice are highlighted and an alternative artificial ecology is formulated. Remaining with the Nicholson-Bailey equations these are forced to be integer based by utilising stochastic events, this greatly stabilises the dynamics hence the method was applied to the persistence of measles epidemics in small populations (=500000). Chapter VII demonstrates how the inclusion of space enhances the effects of parasitism in increasing the evolutionary advantage of sexual hosts over asexual ones. Finally general techniques are developed to implicitly model the effects of spatial correlations and stochastic individual based interactions.
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Osborne, Meave Catherine. "The spatial ecology of phytopathogenic zoospores in the rhizosphere." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369560.
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This thesis is concerned with an analysis of swimming of oomycete zoospores, particularly in relation to the hypothesis that electrotaxis mediated host root colonisation. A correlation was found between the electrotactic behaviour of zoospores of Phytophthora palmivora and Pythium aphanidermatum and their localisation relative to anodic or cathodic regions of the majority of non-host roots. Cathodotropic P. aphanidermatum zoospores were found to be attracted to the cathode generated at the wound site on monocotyledonous and dicotyledonous plant roots studied. Zoospores of P. aphanidermatum were also found to become gradually less attracted to these wound sites as they dissipated over time. Anodotropic P. palmivora zoospores were found to be repelled by the cathodic wound sites on roots of all plants investigated, with the exception of Petunia hybrida. In addition to this zoospores of P. aphanidermatum were found not exhibit chemotaxis or encystment in gradients of the wound-specific metabolite acetosyringone. This suggests that electrotaxis and chemotaxis both operate in directing zoospore accumulation around roots. This reduction of the conductivity of the bathing medium by the addition of different concentrations of sodium chloride salts did not appear to affect the accumulation of both zoospore species around roots of rye grass. The results of this study supports the hypothesis that zoospores use electrotaxis as one means to locate new plant hosts in the rhizosphere. However, chemotaxis may still augment the regulation of zoospore colonisation and encystment.
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Bal, Harit Kaur. "Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528.
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Wen, Yuming. "Spatial diffusion model for simulation of urban land cover change /." View online ; access limited to URI, 2004. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3147805.
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Hoss, Shannon Kelleigh. "Spatial ecology of the Eastern diamond-backed rattlesnake (Crotalus adamanteus)." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/HOSS_SHANNON_17.pdf.
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Jensen, Olaf P. "Spatial ecology of blue crab (Callinectes sapidus) in Chesapeake Bay." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1989.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis 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.
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O'Neill, K. P. "Dispersal and spatial ecology in woodmice living in pastoral farmland." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368476.
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Tuck, Joanne Michelle. "Effects of spatial heterogeneity on the ecology of terrestrial isopods." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368185.
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Simpson, Samantha. "Spatial ecology and fisheries interactions of Rajidae in the UK." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/427037/.
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The spatial occurrence of a species is a fundamental part of its ecology, playing a role in shaping the evolution of its life history, driving population level processes and species interactions. Within this spatial occurrence, species may show a tendency to occupy areas with particular abiotic or biotic factors, known as a habitat association. In addition some species have the capacity to select preferred habitat at a particular time and, when species are sympatric, resource partitioning can allow their coexistence and reduce competition among them. The Rajidae (skate) are cryptic benthic mesopredators, which bury in the sediment for extended periods of time with some species inhabiting turbid coastal waters in higher latitudes. Consequently, identifying skate fine-scale spatial ecology is challenging and has lacked detailed study, despite them being commercially important species in the UK, as well as being at risk of population decline due to overfishing. This research aimed to examine the fine-scale spatial occurrence, habitat selection and resource partitioning among the four skates across a coastal area off Plymouth, UK, in the western English Channel. In addition, I investigated the interaction of Rajidae with commercial fisheries to determine if interactions between species were different and whether existing management measures are effective. First using a combination of research surveys, conventional and electronic tagging I investigate the fine-scale spatial ecology of four sympatric skates. Second I use stable isotope analysis of Rajidae eye lenses to provide an insight into juvenile feeding and spatial ecology. Finally this research used commercial landings data and conventional tagging to investigate fisheries interactions and current management efficacy. Results show that Rajidae were not randomly distributed at fine-scales within the coastal zone but instead associated with particular locations and depths. In addition, only one of the four species inhabited both marine and brackish habitats. I present evidence demonstrating inter- and intra-species groups partitioned by both habitat and diet along with evidence for active habitat selection. Habitat partitioning between these four species influenced their interaction with commercial fisheries and the degree of protection offered by existing Marine Protected Areas (MPAs). I also demonstrate that legislation specifically designed to protect skates may not be effectively enforced and indicate where further investigation will be required to ensure that the conservation of skates is realised.
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Nicholson, Kerry Lynn. "Spatial Movements and Ecology of Mountain Lions in Southern Arizona." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194192.
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Managing wildlife in urban areas is increasingly necessary for wildlife conservation. Large carnivores like mountain lions (Puma concolor) present a particular challenge to managers because of public safety and the polarizing emotional reactions to human-lion encounters. Intensive development and conversion of large open spaces to small properties and subdivisions has caused increased habitat loss, fragmentation and encroachment. Preserving movement corridors for access to habitat patches is important in maintaining landscape connectivity to ensure viable populations adjacent to urban areas. Because mountain lion habitat is often adjacent to urbanization in Arizona and lions traverse large landscapes, mountain lions are ideal models to examine how human alteration of habitats influences their life history characteristics and ability to adapt to a variety of environments. The objective of this study was to examine the ecology and spatial movements of mountain lions surrounding urban areas. We studied habitat selection, urban use by mountain lions, spatial movements and overlap, genetic relatedness, feline disease, and ectoparasites of mountain lions in southern Arizona.
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Whitman, Elizabeth Rose. "Factors Affecting Green Turtle Foraging Ecology Across Multiple Spatial Scales." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3870.
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The hierarchical levels at which resource selection occurs can have important consequences for individual and population energy budgets and structure the impacts of a forager on its ecosystem. Assessing factors affecting resource selection of large marine herbivores across scales is important because of their potentially large impacts on seagrass community dynamics and historical and current changes in their population sizes and those of their potential predators. I explored the factors (predation risk, resource abundance, quality and identity) affecting resource use of large marine herbivores (green turtles, Chelonia mydas) from the scale of habitat patches to forage species within patches. I used a combination of in-water surveys, aerial drone video transects, baited camera surveys, and seagrass community and nutrient content analyses to provide insights into resource use by turtles in multiple ecological contexts.
In Abaco, The Bahamas I found relatively intact shark populations, including apex predators, relative to other parts of the Caribbean. In the context of healthy predator populations in Abaco, I tested a priori predictions rooted in Ideal Free Distribution (IFD) theory. Green turtles off Abaco deviated from predictions of an IFD determined by the standing stocks of seagrass. Instead, distributions are consistent with predictions of the foraging arena hypothesis with turtles largely restricted to safe habitat patches and selecting locations within these where seagrass N content is relatively high.
Marine invasive species can have detrimental effects on coastal ecosystems and economies. Therefore, understanding the effects of, and factors influencing the rate of spread of the invasive seagrass Halophila stipulacea in the Caribbean is important. In the French West Indies (Guadeloupe, Martinique and St. Martin), I investigated foraging preferences for native versus invasive seagrass species and whether green turtles might facilitate or attenuate the invasion through their choice of habitats and feeding patterns. Green turtle distributions were correlated with native seagrass distributions. Also, despite similar nutrient contents, turtles preferred feeding on native seagrasses irrespective of their relative abundance within a patch. These results suggest that, as predicted by the Enemy Release Hypothesis, green turtles likely facilitate the invasion and spread of the invasive seagrass that may reduce energy flow into turtle populations.
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Feldman, Richard. "Toward a theory of abundance at large spatial scales." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104707.
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Fundamentally, ecology is the study of the diversity, distribution, and abundance of organisms. Recent advances in technology coupled with expanding research goals have lead to studies of how the first two of these properties vary over large spatial scales. There has been relatively few cases documenting large scale spatial variation in abundance and very little theoretical development explaining such variation. Yet a general pattern exists: a species is abundant in very few places and rare in most places in its range. Current theory suggests that such a pattern of abundance reflects underlying spatial variation in the environment. In this thesis, I used observational, experimental, theoretical, and statistical approaches to test the type of environmental variation and how such environmental variation combines with interspecific competition to generate spatial variation in abundance. For two species of hummingbirds, I found that different environmental factors related to abundance than to occupancy. Interspecific competition altered spatial variation in abundance in different ways depending on the niche differences among competing species. Interspecific competition also mediated the effect of the environment on abundance by influencing the relative costs and benefits of different hummingbird foraging strategies. I also found that abundance data can be used to predict species' response to climate change because statistical models minimize the noise inherent in abundance datasets. Despite my findings, a theory of abundance is still in its infancy. It is not known whether there is generality in the number and identity of large scale environmental gradients that affect abundance. Similarly, more work needs to be done connecting the small scale interplay between environment, species traits, behaviour, and competition to a broader geographic context. There are also dispersal and non-niche based approaches to spatial variation in abundance that need to be reconciled with current theory. In this way, a more general theory relating macroevolutionary dynamics to macroecological patterns can be developed.L'écologie est l'étude de la diversité, des distributions et des abondances des organismes vivants. Les avancées technologiques récentes couplées à une expansion des objets de recherche ont permis à une étude approfondie de la variation de ces deux premières propriétés sur de très grandes échelles spatiales. Les variations en abondance sont, quant à elles, peu documentées aux grandes échelles spatiales et les développements théoriques correspondant restent limités. Il existe pourtant un pattern prévalent : une espèce donnée est généralement abondante dans une partie extrêmement réduite de sa zone géographique et rare partout ailleurs. Cette observation est aujourd'hui communément expliquée par une variation environnementale sous-jacente. Cette thèse s'appuie sur des approches à la fois empiriques et expérimentales, statistiques et théoriques pour tester le type de variation environnementale ainsi que les interactions entre environnement et compétition interspécifique pouvant générer les variations spatiales en abondances observées. Il est montré que présence-absence et abondance sont affectées par des facteurs environnementaux distincts. Il apparaît en outre que l'effet de la compétition interspécifique dépend des différences de niches entre espèces et module l'impact de l'environnement sur l'abondance en modifiant des coûts et bénéfices relatifs des différentes stratégies d'acquisition des ressources. Finalement, la possibilité de prédire les réponses aux changements climatiques grâce aux données d'abondance et à des modèles statistiques minimisant le bruit inhérent à ce type de données est démontrée. Pour autant, une véritable théorie des distributions d'abondance reste à développer. Le nombre, et a fortiori l'identité, des gradients environnements affectant les abondances à grande échelle spatiale sont encore mal connus. Un effort de recherche considérable est ainsi nécessaire pour améliorer la compréhension du lien entre phénomènes locaux, dont l'interaction entre environnement, traits, comportement et compétition, et patterns à grandes échelles. Par ailleurs, l'unification entre approches basées sur la dispersion, négligeant les différences de niches, avec la théorie actuelle doit encore être accomplie pour qu'une véritable théorie générale des dynamiques macro-évolutive et patterns macro-écologiques puisse voir le jour.
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Turnbull, Lindsay Ann. "The role of spatial processes in a limestone grassland." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286743.
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Ramakrishnan, 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.
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Dick, David Allen. "Spatial heterogeneity of soil nutrients, nitrogen dynamics and vegetation in a 3rd order stream floodplain in southwestern West Virginia." Huntington, WV : [Marshall University Libraries], 2003. http://www.marshall.edu/etd/descript.asp?ref=339.
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Thesis (M.S.)--Marshall University, 2003.Title from document title page. Document formatted into pages; contains ix, 140 p. including illustrations. Includes vita. Includes bibliographical references (p. 104-108).
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Oshima, Júlia Emi de Faria. "Movement ecology and spatial distribution of Tayassu pecari in heterogeneous tropical landscapes /." Rio Claro, 2019. http://hdl.handle.net/11449/183519.
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Orientador: Milton Cezar RibeiroResumo: Modificações da cobertura do solo, perturbações antropogênicas e mudanças climáticas na região Neotropical têm sido associadas à crise da biodiversidade. Nesta tese, o objetivo principal foi investigar os efeitos que a estrutura da paisagem (incluindo a perturbação antropogênica) e a qualidade do habitat têm na distribuição espacial, nos padrões de movimento e na seleção de habitat da queixada - Tayassu pecari. Esta espécie é o único ungulado florestal Neotropical que forma grandes bandos e é uma espécie-chave nos ecossistemas florestais, pois sua extinção local pode causar perdas adicionais de biodiversidade por meio de efeitos em cascata. Ainda assim, pouco se sabe sobre uso do espaço e movimentos de queixadas em escala fina. Para tanto, estudamos a distribuição e movimentação da espécie em diferentes escalas e biomas do Brasil, investigando quais variáveis de paisagem influenciaram a mesma em diferentes escalas e ordens de seleção. Nossos resultados mostram fortes efeitos negativos da modificação da paisagem e fragmentação do habitat na distribuição de queixadas, restando apenas 47% do território brasileiro com áreas adequadas para a espécie. Verificamos que menos da metade de todas as áreas protegidas nos biomas Cerrado e Mata Atlântica têm um habitat adequado para a queixada. Para a análise do movimento, rastreamos 30 indivíduos com colares de GPS de julho de 2013 a outubro de 2016 no Pantanal e no Cerrado do estado do Mato Grosso do Sul. Nossos principais resultados mos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Land cover modifications, anthropogenic disturbances and climate change in the Neotropical region have been linked to the biodiversity crisis. This thesis proposal was to investigate the effects that landscape structure (including anthropogenic disturbance) and habitat quality have in the spatial distribution, in the movement patterns and in the habitat selection of the white-lipped peccary - Tayassu pecari (WLP). This species is the only Neotropical forest ungulate that forms large herds, and it is a keystone species in forest ecosystems because its local extinction may cause additional biodiversity losses through cascading effects. Still, little is known about WLPs space use and fine-scale movement. For that aim we studied the species distribution and movements in different scales and biomes of Brazil, investigating which landscape variables would influence the species in different scales and orders of selection. Our findings show strong negative effects of landscape modification and habitat fragmentation on white-lipped peccary distribution, with only 47% of the Brazilian territory with suitable areas for the species. We also found that less than half of all protected areas in the Cerrado and the Atlantic Forest biomes have suitable habitat for WLP. For the movement analysis we tracked 30 individuals with GPS collars from July 2013 to October of 2016 in the Pantanal and in the Cerrado of Mato Grosso do Sul state. Our main results showed a positive selection of WLP for fore... (Complete abstract click electronic access below)
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Gouhier, Tarik Claude. "Causes and consequences of population fluctuations in spatial ecological systems." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92227.
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Frost, Matthew. "Large-Scale spatial patterns of sandy beach macrofauna community composition." Thesis, University of Plymouth, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289587.
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Mahdi, Abdul-Khaliq Saleh. "The plant ecology of limestone grassland community : spatial organization and coexistance." Thesis, University of Sheffield, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358966.
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Moore, Cordelia Holly. "Defining and predicting species-environment relationships : understanding the spatial ecology of demersal fish communities." University of Western Australia. Faculty of Natural and Agricultural Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0002.
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[Truncated abstract] The aim of this research was to define key species-environment relationships to better understand the spatial ecology of demersal fish. To help understand these relationships a combination of multivariate analyses, landscape analysis and species distribution models were employed. Of particular interest was to establish the scale at which these species respond to their environment. With recent high resolution surveying and mapping of the benthos in five of Victoria's Marine National Parks (MNPs), full coverage bathymetry, terrain data and accurate predicted benthic habitat maps were available for each of these parks. This information proved invaluable to this research, providing detailed (1:25,000) benthic environmental data, which facilitated the development and implementation of a very targeted and robust sampling strategy for the demersal fish at Cape Howe MNP. The sampling strategy was designed to provide good spatial coverage of the park and to represent the park's dominant substrate types and benthic communities, whilst also satisfying the assumptions of the statistical and spatial analyses applied. The fish assemblage data was collected using baited remote underwater stereo-video systems (stereo- BRUVS), with a total of 237 one-hour drops collected. Analysis of the video footage identified 77 species belonging to 40 families with a total of 14,449 individual fish recorded. ... This research revealed that the statistical modelling techniques employed provided an accurate means for predicting species distributions. These predicted distributions will allow for more effective management of these species by providing a robust and spatially explicit map of their current distribution enabling the identification and prediction of future changes in these species distributions. This research demonstrated the importance of the benthic environment on the spatial distribution of demersal fish. The results revealed that different species responded to different scales of investigation and that all scales must be ix considered to establish the factors fish are responding to and the strength and nature of this response. Having individual, continuous and spatially explicit environmental measures provided a significant advantage over traditional measures that group environmental and biological factors into 'habitat type'. It enabled better identification of individual factors, or correlates, driving the distribution of demersal fish. The environmental and biological measures were found to be of ecological relevance to the species and the scale of investigation and offered a more informative description of the distributions of the species examined. The use of species distribution modelling provided a robust means for the characterisation of the nature and strength of these relationships. In addition, it enabled species distributions to be predicted accurately across unsampled locations. Outcomes of the project include a greater understanding of how the benthic environment influences the distribution of demersal fish and demonstrates a suite of robust and useful marine species distribution tools that may be used by researcher and managers to understand, monitor, manage and predict marine species distributions.
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Rew, Lisa J. "Spatial and comparative aspects of arable field margin flora." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333656.
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