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Dissertations / Theses on the topic 'Population ecology'
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Folk, Travis Hayes Grand James Barry. "Population ecology of northern bobwhites." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/FOLK_TRAVIS_11.pdf.
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Shea, Katriona. "Matrix models in population ecology." Thesis, Imperial College London, 1994. http://hdl.handle.net/10044/1/10133.
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Matrix theory is a powerful tool in the study and description of populations. This study commences by discussing the theory relevant to ecological studies, before reviewing recent uses of matrix models in population dynamics. Stage-structured and multistate matrix models are then developed to describe populations of Cirsium palustre in the U.K. and of Carduus nutans in New Zealand. These models were parameterized using field data and provide information on transient dynamics, long-term growth rates, reproductive contributions and eventual stable distributions. Sensitivity and elasticity analyses allow the robustness of the models and the relative contributions of the various life history stages to the population growth rate to be assessed. In the case of C. nutans, a major weed pest ofpasture land, this allows ontogenetic states vulnerable to control by mechanical, chemical or biological means to be targeted. These models are further refined to include the effects of environmental stochasticity. For C. palustre, lack of information on the existence and persistence of a seed bank limited the model construction, and so field and greenhouse experiments were conducted to provide additional information about seed viability and the factors affecting seedUng recruitment and survival. In addition, a theoretical critique of the use in comparative ecology of elasticity analysis to detect trade-offs in life history strategies is presented. Simulation and analytical studies indicate that this approach is not valid. Finally, the use of matrix models in evolutionary demography and management strategy formulation is discussed. As a whole, this thesis illustrates the strength and versatility of matrix models used in population ecology.
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Persson, Jens. "Population ecology of Scandinavian wolverines /." Umeå : Swedish University of Agricultural Sciences, 2003. http://diss-epsilon.slu.se/archive/00000205/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003.Appendix includes reproductions of five papers and manuscripts, some co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix of papers.
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Hens, H. (Hilde). "Population genetics and population ecology in management of endangered species." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215853.
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Abstract Knowledge of the determinants of the viability of populations is essential in order to undertake effective conservation and management of endangered species. In this study, long-term demographic data was combined with genetic data to study the viability of an endangered orchid species, Epipactis atrorubens. The genetic analyses revealed low levels of genetic variation and the presence of population genetic differentiation independent of the spatial scale. Low levels of seed-mediated gene flow, possibly linked to low seedling recruitment, is the likely cause of the low levels of gene flow. Indications of slow post-glacial colonisation rates were found, which together with the low gene flow predict a limited capacity of the species to shift its range to more suitable habitats after environmental change. Low genetic variation as a proxy for low evolutionary potential also suggests that the species has limited capacity to adapt to new environmental conditions. Furthermore, poor seedling recruitment lowers population viability in small populations, as highlighted by the low population growth rates. In addition, we found a strong effect of stochasticity that limits the viability of populations. Both the genetic and demographic analyses indicated low viability of the studied species and that seedling recruitment could be the main determinant for the viabilityTiivistelmä Luonnonsuojelun perusta on populaatioiden elinkykyyn vaikuttavien tekijöiden tuntemus. Tässä väitöskirjatyössä tutkittiin uhanalaisen orkidean, tummaneidonvaipan (Epipactis atrorubens), elinkykyyn vaikuttavia tekijöitä yhdistämällä pitkäaikaisseurannoilla kerätyt demografiset aineistot geneettisin menetelmin kerättyihin aineistoihin. Lajin populaatioiden geneettisen muuntelun määrän havaittiin olevan pieni ja populaatioiden todettiin olevan geneettisesti erilaistuneita maantieteellisestä skaalasta riippumatta. Geneettisen erilaistumisen syy voi olla alhainen geenivirta, joka on seurausta vähäisestä siemendispersaalista ja huonosta taimettumisesta. Populaatioiden evolutiivista historiaa tutkittaessa havaittiin merkkejä hitaasta jääkauden jälkeisestä kolonisaatiosta, mikä yhdessä alhaisen geenivirran kanssa ennustaa, että lajilla on huono kyky siirtyä sille sopivammille alueille, jos ympäristö muuttuu. Huonoa evolutiivista potentiaalia kuvastava vähäinen geneettinen muuntelu ennustaa, että lajilla on huono kyky sopeutua uusiin ympäristöoloihin. Tämän lisäksi huono taimettuminen laskee elinkykyä etenkin pienissä populaatioissa, mikä näkyy muun muassa pienten populaatioiden matalina kasvukertoimina. Stokastinen vaihtelu vaikutti elinkykyä alentavasti, mikä pitäisikin huomioida nykyistä paremmin elinkykyanalyyseissä. Sekä geneettiset että demografiset analyysit osoittivat taimettumisen mahdollisesti olevan määräävä tekijä tummaneidonvaipan populaatioiden elinkyvylle
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Bill, Adam. "Nonnegative feedback systems in population ecology." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.698987.
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We develop and adapt absolute stability results for nonnegative Lur'e systems, that is, systems made up of linear part and a nonlinear feedback in which the state remains nonnegative for all time. This is done in both continuous and discrete time with an aim of applying these results to population modeling. Further to this, we consider forced nonnegative Lur'e systems, that is, Lur'e systems with an additional disturbance, and provide results on input-to-state stability (ISS), again in both continuous and discrete time. We provide necessary and sufficient conditions for a forced Lur'e system to have the converging-input converging-state (CICS) property in a general setting before specializing these results to nonnegative, single-input, single-output systems. Finally we apply integral control to nonnegative systems in order to control the output of the system with the key focus being on applications to population management.
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Rees, Mark. "The population ecology of annual crucifers." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47630.
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Ignacio, Espinoza Julio C. "Functional and Population Based Viral Ecology." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/347118.
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Viruses represent the most abundant biological entities on earth where, they are able to interact with all kingdoms of life. Yet their diversity, ecology and evolutionary aspects are only beginning to be fully elucidated, mainly due to technical limitations. The vast majority of the microbial world remains elusive to culture; more than 90% of genome sequenced viral isolates infect only 5 of the 54 prokaryotic phyla that are currently recognized. In contrast, viral metagenomics bypasses the need for cultures by directly sequencing fragmented genetic material of environmental viral communities. This dissertation uses viral metagenomics by applying well-tested bioinformatic protocols and expanding them to compare and contrast patterns of diversity, richness and specialization of large viral metagenomic datasets, in both local and global scales. First I demonstrate the utility of a functional-based perspective by adopting the protein cluster environment to estimate global viral diversity. Then, I use this PC approach to analyze metagenomes from two ecologically different environments, which by uncovering local gene specialization showcases the adequacy of a gene-centered workflow. Then I continue to expand upon this PC framework to study the Tara Oceans virome analyses of these data reveal patters of diversity that support a seed bank model. Finally, in search of a more meaningful ecological unit, I move from a gene-centered standpoint towards a population-based frame. We adopted a novel metagenomic technique that allowed me to uncover the discontinuity in the genomic sequence space, thus empirically defining a population. This final contribution will allow to sort and count viral communities, the first step to applying ecological and evolutionary theory.
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Klaoudatos, D. "Reproductive ecology, population genetics and population dynamics of selected Decapod crustaceans." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637807.
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The reproductive ecology of three species of Decapod crabs, the shore crab (Carcinus maenas), the velvet crab (Necora puber) and the edible crab (Cancer pagurus), were studied in Swansea Bay and South Gower. Spawning occurs over winter and spring (shore crab), winter (edible crab), and summer (velvet crab). Berried females occur in spring and summer (shore crab), winter spring and summer (edible crab), summer and autumn (velvet crab). Eggs hatch in spring and summer (shore crab, edible crab), summer and winter (velvet crab). Copulation occurs in summer and autumn (shore crab), summer, autumn and winter (edible crab, velvet crab). Shore crabs from Swansea Queen’s Dock have a different reproductive cycle compared to the shore crabs from Tawe Barrage Impoundment and Mumbles Pier. More than one spawning periods or an extended spawning period was indicated for the shore crabs in the Docks. The genetic makeup of the shore crab populations present in Swansea Queen’s Dock and Mumbles Pier was compared using SSCP and cloning analysis of the 16S rRNA. Four different haplotypes were identified all of which were present in the Docks and one in the Pier, with low level of genetic divergence, and close relationship of the identified haplotypes with published shore crab haplotypes. AMOVA showed no significant difference between the study populations and published shore crab haplotypes. However, all identified haplotypes were different from published shore crab haplotypes, indicating a degree of reproductive isolation of the Swansea shore crab populations. Analysis of the permit return data for 1980-2002 of the edible and velvet crab fishery for the South Wales Sea Fisheries Committee District indicated that a combination of factors including overfishing, environmental conditions, and the “Sea Empress” oil spill in 1996 have contributed to a decline in landings that continues to date with limited signs of recovery.
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Woods, John G. "Ecology of a partially migratory elk population." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/32392.
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In this thesis I investigate the ecology of a partially migratory (<100% of the animals migrate) population of elk (Cervus elaphus) in the Canadian Rockies. I radio-tagged elk in a 330 km² area of the Bow River valley (BRV) in Banff National Park, Alberta and followed them for 36 months. Elk movements to adjacent watersheds expanded the study area to 2900 km². My goals were to describe the seasonal movements made by BRV elk and to reach some understanding of the causes of these movements.
The M/R (migrant/resident) ratios for adult bulls and adult cows were 4.3 and 0.5 respectively. Classified ground counts revealed that adult bulls made up only 11% of the population and that the overall M/R ratio for the population was 0.6. Migrations did not take elk beyond the foraging range of timber wolves (Canis lupus), their principal predator. Three cows changed migration status between years and some migrants were sympatric with residents during the rutting (breeding) season. These observations are consistent with the hypothesis that migration in elk is a conditional ESS (evolutionarily stable strategy).
Although 1 adult radio-tagged bull dispersed, individual annual home-ranges of the remaining elk overlapped from year-to-year. Elk were strongly philopatric to winter, summer, and rutting ranges. There were no differences detected in the relative philopatry of bulls and cows, or of migrants and residents.
Bulls had average 1-way migrations of 30 km horizontally and 840 m vertically. Cows had average 1-way migrations of 36 km horizontally and 1079 m vertically. The net energy and time investments for these movements were calculated and judged to be trivial. Elk on both high and low elevation ranges ate primarily grasses and sedges during the autumn, winter, and spring, and the leaves of deciduous shrubs during the summer. Similarities outweighed differences between high and low elevation ranges.
Elk population characteristics (numbers, composition, survival, recruitment, predation, parasites, animal morphology) were measured during 1985-91 and compared with similar data gathered during 1944-69. In most respects, the population has not changed over these years and little is known of density-dependent processes.Science, Faculty of
Zoology, Department of
Graduate
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Haak, Christian. "The concept of equilibrium in population ecology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ57352.pdf.
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Cuddington, Kim Michelle Dibble. "Math, metaphor and meaning in population ecology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61888.pdf.
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Gregory, Richard D. "Host-parasite interactions : population and community ecology." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276582.
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Rigby, Emma Louise. "Population ecology and behaviour of Daubenton's bat." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531517.
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Knell, Robert James. "The population ecology of two insect pathogens." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284218.
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Sands, Richard James. "The population ecology of oak processionary moth." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/427138/.
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The oak processionary moth (Thaumetopoea processionea; OPM) is an invasive pest species that was introduced to West London in 2006. Its gregarious larvae pose a risk to forestry and public health by defoliating oak trees and shedding toxic setae. It is not known how OPM populations will spread or what impact they will have in the UK, therefore the aim of this thesis was to explore the population ecology of oak processionary moth in West London. The thesis focuses on three key topics. Firstly how habitat influences the temporal and spatial distribution of OPM populations. Secondly, the development of molecular methods to identify the parasitoids of OPM. Thirdly, the characterisation of interactions between OPM and its main parasitoid, Carcelia iliaca. These topics were addressed by a combination of a two-year field study at three sites in West London and lab based molecular techniques. Oak processionary moth was found to have a strong spatially and temporally stable habitat preference for open woodland containing a high proportion of oak trees. Fieldwork and molecular techniques revealed a new tachinid fly in the UK, C. iliaca, a major parasitoid of OPM. Carcelia iliaca was responsible for the mortality of around 37% of moth pupae on average, suggesting that currently parasitism is not having a stabilising effect on OPM populations. OPM exhibited similar habitat preferences to continental populations as well as other processionary moths, likely driven by tree apparency. It is not clear how parasitism of OPM would respond in an outbreak and current parasitism rates are lower than those in continental populations. This may be a result of OPM nest removal, which was common management practice at the time of the study. The findings of this study have been used to recommend that nests remain in situ for longer, to allow C. iliaca numbers to increase. Other OPM management options include tree felling, pesticide application and biocontrol. This study found no evidence that OPM control currently warrants tree felling. Biocontrol could be augmented with the use of specific parasitoids such as the newly discovered C. iliaca or entomopathogenic agents identified in Chapter 3, and may be the favoured management option for stakeholders and managers, but is difficult to manage in the long term.
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Matos, Dalva Maria da Silva. "Population ecology of Euterpe edulis Mart. (Palmae)." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296949.
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1- The ecology of a population of the tropical palm tree Euterpe edulis Mart. was studied at the Municipal Reserve of Santa Genebra, Campinas (Sao Paulo, Brazil). This palm has been intensively exploited due to the quality of its heart of palm (palmito). The heart of palm corresponds to the apical meristem of the plant together with the developing new leaves. 2- The indiscriminate exploitation that this palm has been subject to over recent years in southern Sao Paulo may result in it becoming extinct in many forest fragments. The biodiversity of large animals in these forests has declined as a consequence of hunting, and the overexploitation of E. edulis has also led to a decline in the number of large frugiverous birds. The financial benefits generated by the sustainable exploitation of palmito can exceed those from a single extraction or those from forest conversion to agriculture. 3- The seed and seedling ecology of the population of E. edulis was examined. On average each plant produced approximately 1500 fruits and, there was a tendency for plants of intennediate size to be slightly more fecund. Most seeds were found in close proximity to adult plants; the distance of dispersal could be described by a negative power curve. Five species of birds belonging to the Family Turdidae were observed to feed on the fruits of E. edulis while on the tree, while subsequent dispersal along the gro':lnd was found to occur by water. The probability of surviving and growing to the next Sl~ class was inversely related to the number of seedlings. The maximum survival of seedlIngs and growth to the next size class occurred approximately 4 m from adult plants, indicating that the survival and growth of seedlings was suppressed in the immediate vicinity of conspecific adults. 4- The spatial pattern of the population of E. edulis, in the Municipal Reserve of Santa Genebra, was significantly clumped. The data indicate that the spatial distribution of individuals becomes less clumped with time as individuals develop. 5- The transition matrix analysis of the population revealed that the population is increasing at a rate of 14% year-I. The highest sensitivity was observed in the transition from size-class 1 (0-10 mm diameter) to class 2 (10.1 - 20 mm). According to the elasticity analysis, most of the value of the finite rate of population increase is accounted for by the probability of surviving and remaining in the same size class. The results from the haryesting simulations, indicate that it is possible to harvest E. edulis sustainably when harvesting is restricted to size class 6 plants (Le. reproductive adults). 6- The density-dependence observed for survival and growth of plants in the smallest size class was s~ong enough to affect the population dynamics of E. edulis. Elasticity analysis of the transItion matrix shows that the position of populations of E. edulis in G-L-F space moves towards the L apex of the demographic triangle as the density of plants increases.
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Lai, Yi Ming. "Stochastic population oscillators in ecology and neuroscience." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:f12697fb-23fa-4817-974e-6e188b9ecb38.
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In this thesis we discuss the synchronization of stochastic population oscillators in ecology and neuroscience. Traditionally, the synchronization of oscillators has been studied in deterministic systems with various modes of synchrony induced by coupling between the oscillators. However, recent developments have shown that an ensemble of uncoupled oscillators can be synchronized by a common noise source alone. By considering the effects of noise-induced synchronization on biological oscillators, we are able to explain various biological phenomena in ecological and neurobiological contexts - most importantly, the long-observed Moran effect. Our formulation of the systems as limit cycle oscillators arising from populations of individuals, each with a random element to its behaviour, also allows us to examine the interaction between an external noise source and this intrinsic stochasticity. This provides possible explanations as to why in ecological systems large-amplitude cycles may not be observed in the wild. In neural population oscillators, we were able to observe not just synchronization, but also clustering in some pa- rameter regimes. Finally, we are also able to extend our methods to include coupling in our models. In particular, we examine the competing effects of dispersal and extrinsic noise on the synchronization of a pair of Rosenzweig-Macarthur predator-prey systems. We discover that common environmental noise will ultimately synchronize the oscillators, but that the approach to synchrony depends on whether or not dispersal in the absence of noise supports any stable asynchronous states. We also show how the combination of correlated (shared) and uncorrelated (unshared) noise with dispersal can lead to a multistable steady-state probability density. Similar analysis on a coupled system of neural oscillators would be an interesting project for future work, which, among other future directions of research, is discussed in the concluding section of this thesis.
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Hazlerigg, Charles Rupert Edward. "Fish population ecology and ecological risk assessment." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9678.
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Density-dependent processes are crucial in the regulation of fish populations and strongly influence their resilience to exploitation and exposure to toxic chemicals. Multiple density-dependent processes occur at different stages in the life-cycle of fish, and a general pattern of such processes in the ontogeny of fish has been suggested but not clearly demonstrated in natural populations. This thesis aimed to provide a detailed experimental assessment of density-dependent processes through the entire life-cycle, using laboratory and semi-natural populations of zebrafish, Danio rerio, and to explore the implications of these processes for the ecological risk assessment of endocrine disrupting chemicals using an individual-based population model. Results clearly demonstrate the importance of density-dependent mortality in the early juvenile life-stage and density-dependent growth in the late juvenile and adult life-stages consistent with evidence from wild populations of much larger wild species, suggesting the existence of general ontogenetic patterns of density dependence that are invariant to maximum size. Patterns of density dependence found in populations of zebrafish under semi-natural conditions in Bangladesh were similar to those observed in the laboratory, except that the absolute strength of density dependence was higher and consequently, carrying capacity lower, by about two orders of magnitude in the semi-natural populations. A conclusion from these studies is that these patterns of density dependence are applicable generally across the teleost taxa due to developmental similarities. The population model incorporating these patterns of density dependence showed that density dependence compensated for reasonably high levels of disruption for many individual-level endpoints currently used in risk assessment, including fecundity and sex ratio. This indicates that current risk assessment practices are highly conservative and the inclusion of population models such as developed here for zebrafish, could enhance the scientific basis and ecological realism of laboratory derived data used in risk analysis.
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White, Gregory G. "Population ecology of the prehistoric Colusa Reach /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Romanowski, Helena Piccoli. "Population ecology of Pleuroptya ruralis (Scopoli) (Pyralidae:Pyraustinae)." Thesis, University of Leeds, 1991. http://etheses.whiterose.ac.uk/905/.
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A natural population of Pleuroptya ruralis has been studied for three years with the following aims: (1) to elucidate its life history; (2) to study the variations in the larval and adult densities; (3) to identify the mortality factors acting upon them; (4) to investigate possible relationships between the intensity of the mortality factors and the spatial distribution (horizontal and vertical) of P. ruralis ; (5) to describe the role of the major mortality factors in determining the size of the population studied; (6) to assess the potential of the system for further studies about the mechanism of population regulation. P. ruralis caterpillars were individually labelled and followed throughout their development on a natural growth of their food plant, Urtica dioica (the nettle), near Leeds, Yorkshire, United Kingdom. Parasitism and predation as well as the distribution and movements of the larvae on the host plant were assessed. Caterpillars were also collected and reared in the laboratory for identification of the parasitoid species and to provide support for the field results. Adults were studied in the field by the mark- release- recapture method. Potential female fertility was investigated in the laboratory. The population suffered a dramatic decline in numbers during the period of this study. The main factors determining the observed population levels were the interactions between the weather, time spent in development, deviations in the sex ratio, bird predation towards the completion of pre-adult development and parasitization by a braconid (Macrocentrus grandii). Other parasitoids also had some effect, notably Diadegma sp. Predation also had a strong impact on the population of M. grandii. Birds appear to concentrate their attack in the part of the plant in which they are more likely to find the prey. Weather also influenced adult activity and availability of nectar sources in the field, and starvation of females reduced fecundity in the laboratory. Thus, egg shortfall may also have been important in the decrease of population size. The field method used with the caterpillars provided detailed and valuable information about individual and spatial variation and it is suggested that the system 'nettles / P. ruralis / natural enemies' can be a powerfull tool for studies on the mechanisms of population regulation.
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Converse, Paul E. "The Population Ecology, Molecular Ecology, and Phylogeography of the Diamondback Terrapin (Malaclemys terrapin)." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470399169.
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Milligan, Paul. "Population dynamics of African trypanosomiasis." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306017.
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Glass, Kevin Anthony. "The design and implementation of a multiple resolution modeling framework with applications to population modeling /." view abstract or download file of text, 2003. http://wwwlib.umi.com/cr/uoregon/fullcit?78049.
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Thesis (Ph. D.)--University of Oregon, 2003.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 205-209). Also available for download via the World Wide Web; free to University of Oregon users.
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Mäki-Petäys, H. (Hannaleena). "Conservation and management of populations in a fragmented forest landscape:behavioural ecology meets population genetics." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514283482.
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Abstract
The effects of habitat loss and fragmentation on the genetic structure and vulnerability of populations strongly depend on the behaviour of a particular species. In this thesis, I examined the effects of forest fragmentation on genetic population structure with the aim of identifying and evaluating the different genetic and behavioural factors important for species conservation and management on different geographical scales. The species studied were the mound building red wood ants Formica lugubris and F. aquilonia, and a lekking bird, the capercaillie, Tetrao urogallus.
Habitat loss and fragmentation affected the genetic structure in both wood ants and capercaillie. In general, the effects were related to the time since fragmentation and to the level of habitat loss and isolation from the other existing populations. The loss of genetic diversity due to population fragmentation was less observable than the differences in population structure. The response to habitat fragmentation was further dependent on species characteristics such as dispersal and mating behaviour. Sociality affected the genetic vulnerability of wood ant populations by decreasing gene diversity, increasing inbreeding depression and restricting gene flow between subpopulations. The results on the capercaillie in turn suggested that lekking behaviour restricts dispersal of both sexes, thus elevating the occurrence of inbreeding between individuals.
The present study provided important information on species conservation and management in terms of better understanding species' biology and behaviour, as well as increased knowledge concerning the genetic issues that should be taken into account when planning conservation actions. By examining the genetic structure of the species it was possible to clarify the conservation status including the effective population size, the question of origin, and the genetic vulnerability (genetic diversity, inbreeding and inbreeding depression) of the populations and/or species. Overall, the results emphasised the importance of preserving the effective population size and the connectivity of habitat patches when planning species specific management strategies. There were great differences in conservation needs among the species, which should be taken into account especially in local management actions.
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Claridge, Diane E. "Population ecology of Blainville's beaked whales (Mesoplodon densirostris)." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3741.
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Quantifying population demographics is necessary to analyse the status of wildlife populations and to support effective conservation and management. Such a need exists for beaked whales which are vulnerable to anthropogenic noise, including navy sonar. Here, population demographics were estimated for Blainville's beaked whales (Mesoplodon densirostris) in The Bahamas and the potential population-level effects of sonar investigated. Mark-recapture models were fitted to photo-identification data collected at the US Navy's Atlantic Test and Evaluation Centre (AUTEC) where sonars were used regularly and 170 km away at Abaco where sonar use was limited, with the exception of a navy exercise correlated with a stranding of beaked whales in 2000. Life history data collected from 1997-2011 revealed that onset of sexual maturity occurred at age nine for both males and females and minimum longevities were 23 years. The annual turnover of individuals at Abaco was supported by the estimation of a larger parent population. However, adult females showed high site fidelity and survival, while adult males' occupancy patterns were different, making survival of males difficult to separate from permanent emigration. Average annual abundance was lower at AUTEC when compared to a same-sized area at Abaco. Despite a similar number of adult females at both sites, a higher female:calf ratio was found at AUTEC, suggesting lower recruitment through births may have contributed to lower abundance. Population demographics in Abaco changed after the 2000 stranding; abundance and temporary emigration increased then returned to pre-2000 levels remaining stable thereafter. Two stranded whales re-floated in 2000 were later re-sighted having survived exposure to sonar and the physiological stresses related to stranding. This work provides evidence of a possible population-level effect of sonar use at a navy range and during a multi-ship exercise, emphasising the valuable role that longitudinal studies play in monitoring impacts of anthropogenic activities.
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Ng, Sai-chit, and 吳世捷. "Hong Kong's rhododendrons: ecology, population genetics and conservation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B43894343.
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Jones, S. M. "Population ecology of the damselfly Pyrrhosoma nymphula (Sulzer)." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235323.
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Manlove, R. J. "On the population ecology of Avena fatua L." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377141.
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Billington, H. L. "Population ecology and genetics of Holcus lanatus L." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372677.
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Mazzetta, Chiara. "Bayesian estimation of temporal dynamics in population ecology." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613030.
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Duquette, Jared F. "Population Ecology of Badgers (Taxidea taxus) in Ohio." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1222187943.
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Ng, Sai-chit. "Hong Kong's rhododendrons : ecology, population genetics and conservation /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21482743.
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Greenberg, Daniel. "Population dynamics of a declining amphibian." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121577.
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With concern rising over the global decline of amphibian populations, identifying the onset of declines and the factors driving them is paramount. Amphibian populations are naturally characterized by large fluctuations in abundance, which makes separating natural fluctuations from true declines very difficult. By improving our understanding of the natural dynamics of amphibian populations, we can separate normal fluctuations from altered dynamics associated with decline. I apply this principle to an endangered population of Fowler's toads (Anaxyrus [=Bufo] fowleri) in Long Point, Ontario which appears to have gradually declined in abundance. With over two decades of mark-recapture data, I investigate what factors, intrinsic and extrinsic, drive growth in this population. Over this same period, there have been considerable changes to the toads' habitat, as an invasive strain of the common reed, Phragmites australis, has overtaken the wetlands used by toads for breeding. I show that the expansion of this reed has altered the dynamics of the toad population, causing progressive decline due to breeding habitat loss. Prior to 2002, the population of toads was driven by density-dependent growth and overwinter mortality. After 2002, at which point the reeds had eliminated most of the open water habitat, the population of toads responded only to extrinsic factors, particularly the water level of Lake Erie. I then ask whether the expansion of invasive Phragmites has changed not just the quantity of larval habitat, but also its quality, through the release of secondary compounds. I hypothesize that Fowler's toad larvae, as obligate gill breathers, will experience reduced survival, growth, and development in the presence of gill damaging secondary compounds from the invasive Phragmites and native Typha. In contrast, the sympatric Northern leopard frog (Lithobates [=Rana] pipiens) should exhibit similar performance as tadpoles in the presence of secondary compounds, as a facultative gill breather. Contrary to my expectations, I found that Fowler's toad tadpoles had a similar performance across treatments, despite the presence of secondary compounds. Furthermore, the native plant, Typha, but not the invasive Phragmites, appeared to impede growth in Leopard frog tadpoles. Based on these results, I conclude that the expansion of invasive Phragmites has the potential to impact species through changes to available habitat, but not by reducing larval habitat quality. By incorporating population dynamics into the study of amphibian declines we can improve our ability to infer causal links between population declines and the mechanisms that drive them.Alors que le déclin de la population amphibienne mondiale est de plus en plus préoccupant, il est primordial d'identifier les facteurs qui en sont la cause. Puisqu'une certaine fluctuation de population est normale, il est difficile de déterminer si une variation donnée est naturelle ou symptomatique d'un déclin réel. Une meilleure compréhension des fluctuations de la population amphibienne pourrait servir à distinguer entre les facteurs naturels de variation et une altération de dynamique associée à un déclin. Voilà l'idée directrice de cette étude d'une espèce à risque, le crapaud de Fowler (Anaxyrus [=Bufo] fowleri) de Long Point en Ontario, dont la population semble diminuer graduellement. À partir de l'information recueillie sur deux décennies de marquage-recapture, j'ai examiné les facteurs, internes et externes, de variation de leur population. Au cours de la période, leur habitat de reproduction a été considérablement détérioré par la présence d'une espèce envahissante de roseau commun, le Phragmites australis. J'explore le lien entre cette altération de dynamique et le déclin progressif des crapauds de Fowler. Avant 2002, leur population était régulée par des facteurs internes comme la croissance en fonction de la densité et la mortalité hivernale. Depuis, les roseaux communs ont éliminé la plupart de l'habitat en eau libre des crapauds de Fowler, dont la population ne répond plus qu'à des facteurs externes d'influence, en particulier le niveau de l'eau du lac Érié. Ensuite, je cherche à voir si la présence de l'espèce envahissante a influencé, non seulement la quantité d'habitat de reproduction du crapaud de Fowler, mais aussi la qualité de ce qui reste, par la production de composés secondaires. L'hypothèse explorée est que les composés secondaires nuisibles aux branchies, produits autant par l'espèce envahissante Phragmites que par l'espèce native Typha, réduisent les chances de survie, la croissance et le développement des crapauds de Fowler, qui respirent nécessairement par leurs branchies. En toute logique, l'espèce sympatrique grenouille léopard du Nord (Lithobates [=Rana] pipiens), qui respire par ses branchies de façon facultative, devrait être affectée de façon similaire. Cependant, ce n'est pas le cas ; j'ai remarqué que les têtards de crapauds de Fowler n'étaient pas affectés par la présence de composés secondaires. De plus, c'est l'espèce native Typha qui semblait nuire à la croissance des crapauds de Fowler, plutôt que l'espèce envahissante Phragmites. J'en conclus que l'expansion de cette dernière peut influencer plusieurs espèces par une réduction de l'habitat disponible, mais pas par la détérioration de la qualité de son habitat larvaire. En étudiant le déclin amphibien à partir de la dynamique de population, nous pouvons améliorer notre capacité à établir des liens entre le déclin de populations d'espèces et les mécanismes qui y contribuent.
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Morin, Benjamin R. "The Effect of Static and Dynamic Spatially Structured Disturbances on a Locally Dispersing Population Model." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/MorinBR2006.pdf.
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Lang, Alison. "Individual behaviour and population ecology : developing an individual based model for the Svalbard population of barnacle geese." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302157.
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Mills, Cheryl Anne. "Conservation and ecology of the hazel dormouse, Muscardinus avellanarius." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3907.
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Conservation biologists require information on the distribution, ecology, behaviour and genetic diversity of endangered species in order to identify threatened populations, determine which mechanisms are driving populations closer to extinction, and design appropriate mitigating solutions. The hazel dormouse, Muscardinus avellanarius, is declining across much of its northern range. Dormice are detrimentally affected by habitat degradation, loss and fragmentation. Despite extensive studies and conservation work on hazel dormice, there remain many gaps in our understanding. This thesis aims to fill some of those gaps. Hazel dormice are elusive, and therefore difficult to monitor in the wild. I demonstrate the utility of novel monitoring techniques for the rapid determination of dormouse presence, and provide algorithms for the objective verification of species identity from small mammal footprints. I design and utilise genetic microsatellite markers to investigate molecular ecology in this species. In one of the first studies of hazel dormouse population genetics, I describe high levels of population differentiation and genetic isolation across the southwest UK range. I find a powerful signal of reduction in genetic diversity, and an increase in differentiation between core and peripheral populations. I consider rival hypotheses for the mechanisms driving this population genetic pattern, and place the results in the context of conservation strategies for UK dormice. Further, I use molecular data to investigate the prevalence of multiple paternity in wild dormouse populations. Results contradict a recent estimate of very high rates of polyandry, but remain high at 50%. I investigate the effect of food availability on the hibernation behaviour of dormice. My findings, which demonstrate dormice are variable and flexible in their response to winter diet, increases our understanding of the trade-offs dormice must make in order to survive winter periods. I hope that the research undertaken for this thesis will add to the understanding and conservation of an iconic British mammal, ultimately contributing to the persistence of this species.
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Weir, D. A. "The population ecology and clonal structure of two grasses." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353346.
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Melling, T. M. "The ecology and population structure of a butterfly cline." Thesis, University of Newcastle upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377453.
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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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Durban, John William. "Bayesian methods for marine mammal population assessment." Thesis, University of Aberdeen, 2002. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602316.
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Policy-makers increasingly need to use scientific data that are imprecise. This problem is particularly apparent for marine mammal management issues, where practical research constraints leave scientists and managers with the problem of drawing inference from sparse data. Effective use of such data therefore places great demands on our methods of data analysis and statistical inference. In this thesis I introduce novel Bayesian methods for the analysis of data on marine mammal abundance and trends. Bayesian methods are applied to a suite of case studies to inform current management issues of importance both in the UK and overseas. These include estimating the probability of density dependence in the growth of a killer whale (Orcinus orca) population inhabiting the inshore waters of Washington State; estimating the size of a widespread population of bottlenose dolphins (Tursiops truncatus) in the Bahamas; and assessing the population status and abundance trends of bottlenose dolphins within a newly designated Special Area of Conservation in the Moray Firth, NE Scotland. Each of these case studies uses model-based analysis of individual photo- identification data to make inference about unknown population parameters of interest. Specifically, Bayesian inference, based on "posterior" probability distributions and statements, is used to facilitate scientific reporting in the face of uncertainty about these unknowns. Additional issues addressed are the selection of alternative statistical models for inference based on posterior model probabilities; incorporating model selection uncertainty into inference through the estimation of model-averaged parameter estimates; and the use of random effects prior distributions to model the relatedness between unknown parameters and increase estimate precision. The application of these methods is accomplished through the use of Markov chain Monte Carlo sampling methods, which are implemented using the WinBUGS software.
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Gate, Imogen Mary. "Population ecology of the beech scale (Cryptococcus fagisuga Ldgr.)." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/8831.
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Fryxell, John M. "Resource limitation and population ecology of white-eared kob." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25795.
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In this study I examine the effect of seasonal resource limitation on the behaviour and population dynamics of white-eared kob, Kobus kob leucotis, in the Boma region of the southern Sudan. This population, numbering over 800,000, migrates seasonally between savannah grasslands in areas with low rainfall and ephemerally swamped grasslands in areas with high rainfall. The aims of the study were: (1) to examine whether kob migration tracks ephemeral distributions of food or water resources, (2) to test the hypothesis that the Boma kob population is limited by food availability, (3) to determine if calf production is cued to seasonal peaks in food abundance, and (4) to evaluate the effect of breeding synchrony on lekking behavior and male competition.
Seasonal climatic changes produced pronounced changes in the distribution and abundance of both green forage and water supplies. Dry season migration primarily tracked limited supplies of water. Within the dry season range, kob aggregated at high densities (over 1,000 per km²) in low-lying meadows that supported grass re-growth when little green grass was available elsewhere in the ecosystem. However, southerly movements in the wet season were not explainable by the resource hypothesis, since both food and water were widely distributed during the wet season. I suggest that kob may move southward in order to avoid surface flooding during the wet season.
Kob mortality during the dry seasons of 1982 and 1983 was considerably higher than estimated mortality during the wet season. Unusual rainfall during the dry season of 1982 provided a "natural experiment" to test the food limitation hypothesis. Adult mortality was significantly lower during the dry season of 1982 than during the more typical dry season of 1983. Calf mortality did not vary significantly between years. Adult mortality rates were related to dry season duration. Dry season mortality was related to sub-maintenance food intake and declining fat reserves. The age structure of the kob population in 1983 suggests that large-scale mortality (ca. 40%) occurred in the 1980 drought that immediately preceded this study. These findings support the food limitation hypothesis.
Kob exhibited a 4 month period of calf production during the late wet season, when food availability was highest. As a consequence, females continued lactation through the dry season period of food scarcity. I suggest that kob reproductive phenology may result from an obligatory delay during which females restore their fat reserves prior to calving or selection pressures imposed by predation during the vulnerable post-partum period.
Synchronous breeding in the Boma kob was related to
increased rates of aggression between males and increased color
dimorphism, in comparison to the asynchronous breeding Uganda kob, Kobus kob thomasi. Male aggression served not only to establish dominance relations between males on leks, but also disrupted the mating activities of neighboring males. Young adult males suffered higher age-specific mortality than females, possibly resulting from injuries incurred during strenuous fighting on leks.
In order to analyze the age structure of the kob population, I devised a new method for estimating age-specific mortality rates that is free of the restrictive assumptions that underlie most conventional techniques. The proposed method has somewhat greater sampling variation, but is considerably more robust, than two current methods. Moreover, the proposed method permits calculation of age-specific mortality at frequent intervals during periods of population fluctuation and, under some circumstances, population numerical trends may be directly determined from age structure.Science, Faculty of
Zoology, Department of
Graduate
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Watson, D. "Aspects of the population ecology of Senecio vulgaris L." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382119.
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Whiting, Arthur. "Population ecology of the western chorus frog, Pseudacris triseriata." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80896.
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The relationship between habitat preferences and rates of dispersal and directional orientation across different vegetations was investigated using captures from an array of drift fences for Pseudacris triseriata , at a breeding pond near Boucherville, Quebec. Growth rates for juveniles were similar across the study area, suggesting that food was not limiting and movement is related to habitat preference. Frog residence time in habitat enclosures, and between fence arrays was significantly longer for frogs in humid prairie vegetation compared to those in shrubby vegetation. The number of frogs caught per metre of fence in humid prairies was also on average higher than either shrubby or arid prairie vegetations. Together both migration rates and captures per metre of fence suggest that the preferred habitat for P. triseriata is humid prairie vegetation (e.g. Phalaris grass). Target-oriented dispersal may explain why similar numbers of P. triseriata were captured in both shrubby and humid prairie vegetation, despite the perceived preference for humid prairies over shrubby vegetation. The continued persistence of this population appears to be based on the recruitment of juveniles from the larval stage, and is also sensitive to the fecundity of the first time breeders.
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Douglas, Alexander. "Population ecology and behaviour of juvenile bitterling (rhodeus sericeus)." Thesis, Queen Mary, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404561.
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McCarthy, Dominic. "Robustness tools for population ecology : theory algorithms and applications." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496146.
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Sanderson, Fiona Jean. "Population ecology and monitoring of the dormouse Muscardinus avellanarius." Thesis, Royal Holloway, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407422.
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Phillips, Richard A. "Population ecology of Arctic skuas Stercorarius parasiticus, on Foula." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294176.
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Aboud, Mariam Atta El Mannan. "Ecology and population structure of Anopheles arabiensis in Sudan." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275042.
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Hoelzel, A. Rus. "Behavioural ecology and population genetics of the killer whale." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235855.
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Field observations were collected to assess the social behaviour and foraging strategies of free-ranging killer whales from the eastern North Pacific (near Vancouver Island, Canada) and the western South Atlantic (near Peninsula Valdez, Argentina). The Vancouver Island study concentrated on the environmental correlates of group size and the behavioural dynamics of social groups. There were no correlations between foraging behaviour and small-scale habitat use, however both group size and the spatial distribution of groups were correlated with foraging behaviour. In Argentina the subject whales intentionally stranded to capture pup sea lions. It was possible to observe details of prey choice and foraging strategy. Three social groups were observed in the study area. Area use suggested that the different groups were employing different strategies. Whales within social groups shared prey, but one group would exclude another from the best hunting areas. Whales invested the greatest effort in the area of highest yield, and on the prey-type that required the least effort to catch. Energetic calculations suggested that the rate at which these whales captured sea lion prey was just sufficient to sustain them. Two genetic components, the hypervariable 'minisatellite' loci, and the mitochondrial genome were investigated for each study population. In addition, further samples from Iceland and other populations near the sites at Peninsula Valdez and Vancouver Island were analysed. Whales within social groups at Peninsula Valdez were more closely related than between social groups. In general, whales within local populations had very high levels of genetic similarity compared to between population comparisons. This implies inbreeding within and genetic isolation between populations. Two genetically isolated populations (both near Vancouver Island) were sympatric, and the degree of genetic isolation was equal to the level seen for comparisons between the Atlantic and Pacific. A hypothesis is presented on the role of resource exploitation in the structuring of social groups, and the consequences for the genetic structuring of populations.