Dissertations / Theses: 'Population biology'

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Couch, Brett Charles. "Population biology of Sclerotium cepivorum." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ45399.pdf.

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Vella, Adriana. "Primate population biology and conservation." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245184.

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Bohan, David Andrew. "Modelling Steinernema feltiae population biology." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261776.

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Seelig, Frederik. "Population biology of Ixodes ticks." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558849.

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The hard tick Ixodes ricinus is one of the most important species of disease vectors worldwide. It transmits a variety of pathogens, including spirochaetes that are the causative agent of Lyme borreliosis (LB) in humans. This study aimed at analysing different aspects of the ecology, molecular evolution, and microbial associations of I. ricinus. A novel scheme for the phylogenetic analysis and genotyping of I. ricinus was established as part of this study. Phylogeographic clustering of I. ricinus samples fromdifferent European countries was observed, while samples from two different sites inSouthwest England did not show spatial differentiation. The ecology and host abundance in these two habitats was assessed. Differences in the density of questing ticks and in the abundance of rodent hosts were observed. Both sites exhibited low densities of rodents and of ticks infesting them. A blood meal analysis revealed high proportions of mixed feedings and showed artiodactyls to be a main host group for immature I. ricinus ticks from Britain. The prevalence rates of Wolbachia endobacteria in British I. ricinus samples were higher than rates found in samples from other European countries. The unique endosymbiont Midichloria was detected in all female I. ricinus ticks that were screened. A newly developed multi gene analysis of Midichloria samples from six European countries showed a largely coordinated phylogeography with their tick hosts. Taken together, the findings of this thesis demonstrate that British I. ricinus ticks differ from their European counterparts in several ways, which has implications for the epidemiology of infectious diseases transmitted by this vector.

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Silva, Mónica Almeida e. "Population biology of bottlenose dolphins in the Azores archipelago." St Andrews : University of St Andrews thesis, 2007. https://research-repository.st-andrews.ac.uk/handle/10023/215.

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Kennaway, Gabrielle M. A. "The population biology of freshwater phytoplankton." Thesis, Bangor University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236909.

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Vàrkonyi, Gergely. "Population biology of periodic Xestia moths." Helsinki : University of Helsinki, 2003. http://ethesis.helsinki.fi/julkaisut/mat/ekolo/vk/varkonyi/.

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Bottomley, Herbert Christian. "The population biology of multispecies helminth infection." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1445327/.

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Vertebrate hosts are frequently infected with multiple helminth species. There is a body of experimental evidence to suggest that infection with one parasite species can have either an antagonistic or synergistic effect on another species such interactions may occur through parasite establishment, survival and fecundity. The extent to which such interactions are involved in the organization of helminth communities is largely unknown. Mathematical models based on Markov processes are used to explore two themes: 1) The effect of interspecific interactions on the joint distribution of helminth par asites in a population of hosts, and 2) conditions under which interacting species can coexist. To explore the former, models are formulated that describe the pro cess by which helminths of two species are acquired and lost in a cohort of ageing hosts. In these models, the interspecific interaction occurs at the point of parasite establishment within the host such that the rate of establishment depends on the current worm burdens of the two species. The results are used to highlight some of the difficulties associated with inferring interspecific interactions from ecological data. The relationship between competition and species coexistence is investigated us ing models of the long-term dynamics of interacting species. Models are developed in which there is a free-living larval stage whose population size is dependent on the size of the adult worm population. The models are analyzed using 'hybrid' and 'moment-closure' approximations the former involves replacing stochastic com ponents of the model with deterministic approximations, and the latter assumes a functional relationship between higher and lower order moments based on a specified distribution. The Lotka-Volterra model of competition is derived for the case where hosts are equally exposed to parasites of the same species. Coexistence of two compet ing species is promoted by heterogeneous host exposure to each parasite species, provided that the rates of exposure to the two parasite species are not perfectly, positively correlated, and provided that the degree of heterogeneity in host expo sure is similar for both species. In addition, it is shown that the conditions required for coexistence are the same regardless of whether competition occurs at the point of parasite establishment within the host or via parasite fecundity. These results are discussed within the context of helminth community ecology.

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Li, Yifei. "Nonlinear diffusion in mathematical biology." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/234381/1/Yifei_Li_Thesis.pdf.

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Reaction-diffusion models with nonlinear diffusion are widely used for studying population dynamics in biology and ecology. Yet, the relationship between nonlinear diffusion mechanisms in populations and the behaviours of individuals is hard to be intuitively interpreted in classical models. To address this problem, we develop a discrete-continuum modelling framework, where the movement of individuals influenced by crowding effects is connected to the nonlinear diffusivity functions in a well-defined continuum limit. Using this framework, we explore the influence of nonlinear diffusion on population extinction, and analyse the existence and stability of travelling waves in continuous equations which model the invasion process.

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Banks, John E. "The effects of landscape heterogeneity on insect populations : a study of pattern and scale /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5166.

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Adkins, Suzanne Craig. "Population Biology and Restoration of Intertidal Cockle Beds." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/7794.

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There is evidence that infaunal bivalves in New Zealand are not as abundant as they once were with overfishing and habitat modification contributing to the decline in density and health of cockles. The population biology and abundance of the bivalve Austrovenus stutchburyi (tuangi) in eight beds in four estuaries was assessed both seasonally (13 seasons) and annually (7 years) as little is known about the cockle beds in the Canterbury region of New Zealand. As with populations of similar species worldwide, there were site specific differences in population structure (density and size ranges) with the highest densities at Takamatua (>1500/m²), and the lowest at Port Levy (<350/m²). Gonad indices varied between male and female cockles. Male reproductive cycles were similar at all sites with male cockles being reproductively active year round, while females were more active in spring and summer. Temporal and spatial site specific differences occurred in cockle condition with high salinity sites having higher condition indices (CI) than low salinity sites. There were spatial and temporal variations in salinity (3-35ppt), sediment structure (fine sand through to predominantly silt), water temperature (6-20°C), nutrient supply (total volatile solids (TVS) 0.002- 0.15mg/L) and contaminant levels. Metal pollution indices (MPI) ranged between 3 and 11. Three cockle transplant trials were undertaken both within and between estuarine systems. Caged cockles survived well, and cage design needed to allow vertical movement of the bivalves within the substrate to reduce mortality. At the end of the 12 month trial, approximately 45% of the cockles remained in the plots. The condition of transplanted cockles was similar to naturally occurring cockles. Recommendations are made to optimise the success of cockle transplants. Large scale, un-caged placement of 25-30mm length cockles in the mid-low tide region of areas with stable, but not necessarily uncontaminated substrate, moderate salinity and temperature and with a reliable nutrient supply is recommended. The results from the thesis research can be applied to other infaunal bivalves in New Zealand allowing more successful restoration processes leading to increased species diversity and ecosystem functioning.

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Rahoo, G. M. "Biology and population dynamics of sawflies on Ribes." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356791.

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Carter, Jonathan Philip. "Population biology of Trichoderma spp. used as inoculants." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329046.

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Creasey, Simon Spencer. "Population genetics and biology of deep-sea crustacea." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243161.

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Gurney, Mark. "Population genetics and conservation biology of Primula elatior." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249052.

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Johansson, Mats E. "Population biology of the clonal plant Ranunculus lingua." Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 1992. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-111108.

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The scope of this thesis was to identify, describe and quantify important life-history traits for the pseudoannual aquatic plant Ranunculus lingua in different ecological settings, by comparing populations from geographically marginal vs. central habitats. Results from a four-year field study showed that abiotic factors (water-level fluctuations and associated processes) tended to have a greater influence in marginal populations, whereas biotic factors (competition, insect grazing and fungal infections) dominated in central populations. This was reflected in different depth distribution of ramet numbers and ramet sizes between the areas, and In different dynamic patterns, with a higher flux of ramets in marginal populations. In a reciprocal transplant experiment, marginal ramets produced more but smaller rhizomes, whereas central ramets produced Individually larger but fewer rhizomes, irrespective of transplant site. A possible selection for genotypes producing large rhizomes in the central habitat was supported by the fact that initially smaller ramets were more likely to be diseased by the fungal pathogen Peronospora gigantea and damaged by insect grazing. In the marginal population, where density-independent mortality factors tend to dominate, a high reproductive output, expressed in production of high numbers of rhizomes, was suggested to be a favoured life-history trait. In a glasshouse experiment, ramets from marginal and central populations were grown in low and high densities and under three contrasting nutrient levels. The allocation to sexual structures was generally very low, and did not incur any costs in terms of reduced rhizome production. Rhizome production showed strong positive allometrical relationships to mother ramet size. Increasing mother ramet size resulted in a larger increase in rhizome numbers for the marginal than for the central population, whereas the increase in mean rhizome mass was more pronounced for the centred population. Both populations showed similar reductions in rhizome production in response to increased density and lowered nutrient levels, which could not be explained by size-dependent effects adone. The dispersal, dynamics and distribution of R. lingua were studied in a marginal river population in northern Sweden, where the only means of dispersal is by vegetative diaspores, i.e. floating rhizome fragments. Stranding occurred mainly in river curves and at obstacles, and the distribution of established stands was also highly correlated with these features. Relative changes in ramet numbers were correlated with water-level fluctuations during the present and previous growing seasons, with winter low-water, and with duration of spring-flood. The predictability of change was high within but low between stands. It was concluded that the patterns and mechanisms of dispersal are fundamental for local distribution patterns as well as variation in regional abundance in R. lingua

Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 4 uppsatser

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Xu, Yiyang. "Topics in population genetics and mathematical evolutionary biology." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682366.

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Part A studies the optimal strategies of seed germination problems where the population has a class structure under a fluctuating environment . In particular, a multidimensional age-class model is studied using a dynamical programming method. Numerical results about the so-called optimal stochastic strategy which consists of information about previous environmental states are computed. Comparing the optimal stochastic strategy with the optimal population-based strategy shows that the optimal stochastic strategy is highly effective in genera.l. A potentially useful diffusion approximation for the seed germination problem is also derived with numerical results. For part B, a multi-dimensional Moran model is studied using a diffusion approximation approach. The scaling limit and corresponding governing stochastic partial differential equations (SDEs) are derived. An expansion method is used to approximate the stationary distribution of the SDEs. An approximation formula for the effective migration rate is then derived.

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Zahn, Laura. "Population dynamics of the gynodioecious Boutelouachondrosioides (Poaceae)." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/279959.

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This dissertation investigated the evolution and ecology of male sterility in the gynodioecious Bouteloua chondrosioides (Poaceae) by studying the distribution, inheritance, phenotypes of male sterility, mitochondrial DNA polymorphisms, and the distribution and effect polyploidy has on sex type expression in B. chondrosioides. B. chondrosioides has two male sterile types, one of which is described for the first time in this dissertation. Field studies determined that the proportion of male sterility was highly variable among populations and non-randomly distributed within populations. Investigations of the progeny of individuals of known sex type rejected models of simple nuclear recessive and dominant inheritance of male sterility. Examination of characters that may affect reproduction demonstrated that there were few significant reproductive differences explaining the maintenance of the two male sterile forms. In order to investigate if male sterility is due to cytoplasmic factors, mitochondrial DNA restriction fragment length polymorphisms were examined to determine if there were correlations between unique restriction fragment patterns and male sterile forms. These studies demonstrated that some, but not all, male sterile individuals do have unique mitochondrial restriction fragments. In addition to these investigations, the distribution of polyploidy was characterized and investigations performed to determine if there are correlations between sex type and ploidy level and if polyploidy has evolved once or multiple times in B. chondrosioides. Flow cytometry resulted in data that demonstrated no correlation between male sterility and ploidy level, and that while most populations are either only diploid or tetraploid, some populations had both diploid and polyploid individuals. The examination of the relationships of cpDNA sequences from individuals of known ploidy level demonstrated that polyploidy appears to have originated and established more than once in the history of B. chondrosioides. The results from these three studies exhibit patterns that are in accord with the hypothesis that male sterility in B. chondrosioides is due to cytoplasmic male sterility.

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Larsson, Jobs Karl. "Population Fragmentation and Genetic Variation in Grouse." Doctoral thesis, Uppsala University, Department of Ecology and Evolution, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6006.

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In this thesis the genetic variation of two grouse species, the Chinese grouse (Bonasa sewersowi) and the Black grouse (Tetrao tetrix) was examined with neutral genetic markers: microsatellites. Habitat fragmentation and isolation leads to structuring among and loss of genetic variation within populations.

The Chinese grouse in a small population in Lianhuasan nature reserve was found to have undergone a population bottleneck and as a result of isolation and possible inbreeding showed genetic impoverishment hereof.

The Black grouse populations in Europe face various different conditions from widely distributed areas of suitable habitat in the northern and eastern parts of its range to highly naturally and anthropogenically fragmented habitat landscapes in the west.

Structure among populations was found in Great Britain where Wales, Scotland and England showed characteristics of three different genetic entities, indicating very little or no geneflow between these populations.

The Dutch population showed signs of loss of genetic variation as to be expected from a population that has historically decreased in population size from several thousands to tens of individuals in a matter of decades. However the possibility to spot signs of a bottleneck was impaired due to the short time-window in which this can be observed in a population with such a low effective population size (N_E).

The sampled populations in Europe clustered into five different groups of genetic identities. The different clusters were: Great Britain-, the Netherlands-, Fenno-Scandian-, Alpine- and lowland German-Austrian populations. The level of genetic variation when compared over all these different populations decreased as a sign of isolation and small N_E. However it was not feasible to separate the impact of these two factors.

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Allen, J. B. "Geographical variation and population biology in wild Theobroma cacao." Thesis, University of Edinburgh, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384148.

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Grünig, Christoph. "Population biology of the tree-root endophyte Phialocephala fortinii /." [Zürich], 2003. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15313.

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Wong, Jia Yih. "The population biology of 'Fusarium oxysporum' f. sp. 'asparagi'." Thesis, University of Kent, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429653.

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Rieger, Mary Alice. "Horticultural management and population biology of several Banksia species." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phr554.pdf.

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Bibliography: leaves 159-205. This research aims to improve understanding of the control of flowering in relation to photoperiod and temperature to increase knowledge of the floral initiation trigger for Banksia. An exploration of the population biology in relation to genetic variation present in commercial and natural populations of Banksia will provide information on the gene pool for breeding programs. Molecular biology techniques have been used to explore areas such as pollen competition and gene flow.

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Cullen, Sean Anthony. "Population biology of eared grebes in naturally fragmented habitat." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq37507.pdf.

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Silva, Monica Almeida. "Population biology of bottlenose dolphins in the Azores archipelago." Thesis, University of St Andrews, 2007. http://hdl.handle.net/10023/215.

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The ranging behaviour, habitat preferences, genetic structure, and demographic parameters of bottlenose dolphins living in the Azores were studied using data collected from 1999 to 2004. Only 44 dolphins out of 966 identified were frequently sighted within and between years and showed strong site fidelity. The remaining individuals were either temporary migrants from within or outside the archipelago, or transients. Estimates of home range size were three times larger than previously reported for this species, possibly as a result of the lower availability of food resources. Mitochondrial DNA sequences showed very high gene and nucleotide diversity. There was no evidence of population structuring within the Azores. The Azorean population was not differentiated from the pelagic population of the Northwest Atlantic, suggesting the "unproductive" waters of the Atlantic do not constitute a barrier to dispersal. Population size, survival and temporary emigration rates were estimated using open-population models and Pollock's robust design. A few hundreds of dolphins occur in the area on a given year, though the majority should use it temporarily, as suggested by the high emigration rates. Bottlenose dolphins preferentially used shallow areas with high bottom relief. Temporal and spatial persistence of dolphin-habitat associations documented in this study further supports the idea of a close relationship between certain bathymetric features and important hydrographic processes and suggests the occurrence of prey aggregations over these areas may be, to some extent, predictable. Several results of this study suggest there are no reasons for concern about the status of this population. Yet, the resident group may be negatively affected by increasing pressure from the whale watching activity. Although the proposed Marine Park constitutes important habitat for resident dolphins, at present, the area is clearly insufficient to satisfy their spatial requirements and its conservation value may be limited.

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Walker, Martin. "The population biology of Ascaris lumoricoides infections in humans." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523751.

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Slooten, Elisabeth. "Population biology, social organization and behaviour of Hector's Dolphins." Thesis, University of Canterbury. Zoology, 1990. http://hdl.handle.net/10092/5800.

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Hector's dolphins are threatened with local extinction by entanglement in coastal gillnets. This thesis provides data on population biology, social organization and behaviour of Hector's dolphins that help assess human impacts on their populations. To estimate population growth, I integrated anatomical studies which estimated longevity and age at first reproduction, with photographic field studies which estimated reproductive rate and survival rate. Sixty incidentally caught and beach-cast dolphins were aged from the growth layers in their teeth. Maximum age was 19 years for females and 20 for males. Females gave birth to their first calf at 7 to 9 years old, and thereafter had one calf every 2 to 3 years. Population models using these data predicted maximum population growth rates of 1.8 to 4.4% per year. These rates were exceeded by the number of Hector's dolphins recently killed in gillnets in the Pegasus Bay-Canterbury Bight area. Survival rates (including gillnet mortality) estimated using photographic identification, also suggested that this population was unable to cope with recent gillnet entanglement levels. Population models using these survival rates (0.797 to 0.865 after the first year of life), even in combination with the most optimistic reproductive rates, resulted in a decreasing population. The population models were also used to explore the likely consequences of management strategies which reduce entanglement mortality. Population and population growth rate fluctuated markedly for several decades after a significant reduction in entanglement mortality, especially if the age structure of the population was biased towards younger individuals. A study of social organization and behaviour pointed to another potential conservation risk. The social organization of Hector's dolphins was studied using photographic identification. Each individual associated loosely with a relatively large number of others, rather than with a few close associates, and groups frequently joined other groups and exchanged members. Sequence analysis was used to classify Hector's dolphin behaviour into five categories: 'feeding', 'sexual" 'aggressive', 'play' and 'aerial', using behaviour sequence analysis. The number of sexual behaviours per individual was highest in groups of 11-15 dolphins, and tended to increase after groups came together. The fluid association patterns and increase in sexual behaviours after groups come together suggest that Hector's dolphins have a promiscuous mating system in which males search for rather than monopolize females. Such a mating system has the potential to reduce fertilization rates in areas of low abundance.

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Gibson, C. C. "The population and community biology of Rhinanthus minor L." Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376354.

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Lindner, Robert. "The population biology of the Common Guillemot, Uria aalge." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322917.

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Hatchwell, Benedict L. "Population biology and coloniality of common guillemots Uria aalge." Thesis, University of Sheffield, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241796.

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Smith, Edward Mark. "Population biology of Staphylococcus aureus on dairy cattle farms." Thesis, University of Warwick, 2004. http://wrap.warwick.ac.uk/73120/.

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A total of 450 isolates of Staphylococcus aureus were typed using multilocus sequence typing (MLST). They were isolated from the cattle and environment of a UK organic dairy farm, 43 dairy herds in the USA, the mammary glands of cattle in Chile and the UK, and also included the reference strain Newbould 305 (NCIMB 702892). Strains were compared to investigate differences between isolates from varying sites of isolation and the population detected on a single farm. MLST was suitable for the differentiation of bovine associated S. aureus, and thirty different sequence types were detected. These contained a number of novel alleles detected at each loci, agreeing with previous reports of host-specialisation, and indicating localised strain evolution. MLST was also able to discriminate between isolates detected in milk and on teat skin. The N ewbould 305 strain was significantly (p<0.05) associated with teat skin, and this may have important implications for future studies. The majority of isolates (87.4%) were present within one previously undescribed clonal complex (CC97), which contained representatives from all three geographic locations. Analysis of isolates from a single farrri demonstrated the clonality of the organism, supporting the theory of cow-to-cow spread of disease. No isolates were detected in heifer mammary secretions, suggesting transmission to these animals did not occur. Typing of multiple colonies from a single sample demonstrated strain heterogeneity within individual quarters. Environmental isolates were detected, though it is unlikely that they formed a significant reservoir of infection on the farm studied.

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Hancock, Andrew. "The biology and fishery of Roe's abalone Haliotis roei Gray in south-western Australia, with emphasis on the Perth fishery /." Connect to this title, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0068.

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Laine, Kari. "Long-term variations in plant quality and quantity in relation to cyclic microtine rodents at Kilpisjärvi, Finnish Lapland." Oulu, Finland : University of Oulu, 1988. http://catalog.hathitrust.org/api/volumes/oclc/18696609.html.

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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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Supriatna, Asep K. "Optimal harvesting theory for predator-prey metapopulations /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phs959.pdf.

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Bruegl, Hilary A. "Remotely Administered Immunocontraception as an Effective and Humane Management Tool for Feral Horses (Equus caballus) in Overpopulated Rangelands." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/scripps_theses/329.

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Since the advent of world travel and exploration, humans have been introducing animals to new countries and environments to which they were not native. Wild horses in North America are protected by the Wild Free-Roaming Horses & Burros Act, and their growing populations can damage native species and ecosystems. These feral horses organize themselves into harems consisting of several mares, a dominant stallion, and occasionally subordinate stallions. In the breeding season, a peak in stallion libido and mare ovulation elicit distinct reproductive behaviors. Population numbers of feral horses (Equus caballus) need to be humanely controlled without the disruption of these key behaviors. The Adopt-A-Horse program, a current program consisting of roundup and public adoption for a fee, is not effective on its own. The proposed study examines two minimally-invasive immunocontraceptive methods that may be effective in reducing population growth: Gonadotropin releasing hormone (GnRH) agonists, antibodies that prevent mares from entering estrous, and porcine zona pellucida (PZP), an antibody that changes the conformation of ova sperm receptors to prevent fertilization. This potential study proposes that 8 independent populations of feral horses will be tracked for 4 years to assess normal behavior. After 4 years, populations will undergo one of four treatments: control (n=1), roundup and adoption (n=1), mares treated with 2-year remotely administered PZP vaccine (n=3), and mares treated with 2-year remotely administered GnRH agonist (n=3). Urinalysis will be used to test for pregnancy, and behavior of mares will be monitored over the course of 4 years after administration. Combined observations of behavioral effects and growth rates will be used to determine the most efficient and humane method of population control. Both chemical methods of fertility control should greatly reduce the overall number of foals produced. Where PZP will potentially be the better choice for immunocontraception due to its minimal interference with the endocrine system of feral horses, GnRH agonists are likely to affect normal behavior and may not be suitable for implementation in wild rangelands. Efforts to control populations will be most effective when the current Adopt-A-Horse program is combined with administration of PZP every second year. Success of an immunocontraception program for feral horses in overpopulated rangelands may pave the way for more invasive populations to be controlled in this manner.

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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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38

Poetter, Karl. "Molecular population and evolutionary genetics of Rickettsiae /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu148767034687517.

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39

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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40

Sminkey, Thomas R. "Age, growth and population dynamics of the sandbar shark, Carcharhinus plumbeus, at different population levels." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539616858.

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The objectives of my research were to test the hypothesis that compensatory (density-dependent) growth of sandbar shark (Carcharhinus plumbeus) occurred after severe population reduction, to describe the juvenile sandbar shark fauna present in the Chesapeake Bay during 1980-81 and 1990-93, and to perform demographic analyses to examine potential population growth. Age and growth of sandbar sharks were investigated by counting rings in vertebral samples collected in 1980-81 and 1991-92. Age at maturity was 15-16 years for both sample periods and both sexes. For sexes combined, the von Bertalanffy growth parameters were L&\sb{lcub}\infty{rcub}& = 199 cm precaudal length (PCL), K = 0.057, t&\sb{lcub}\rm o{rcub}& = &-&4.9 years for the 1980-81 sample and L&\sb{lcub}\infty{rcub}& = 164 cm PCL, K = 0.089, t&\sb{lcub}\rm o{rcub}& = &-&3.8 years for the 1991-92 sample. Significant differences in size at age and annual incremental growth of juveniles suggest a small increase in juvenile sandbar shark growth rate between the two sampling periods. Annual catches of sharks &>&105 cm PCL declined substantially between survey periods. Males and females were present in a 1:1 ratio. During 1980-81 juveniles ranged in age from 0-7 yr, but in 1990-93 few sandbar sharks over age 4 were taken. Based on the best estimate of fishing mortality the population ranged from 10,087 to 8509 sharks from 1989-1993. Annual year-class size was variable but all estimates were within one order of magnitude. Juvenile sandbar sharks declined in abundance by approximately 15% between 1989 and 1993. The annual population growth rate was highest under a scenario of natural mortality (M) = 0.05 and maximum age of 30 yr, but was only 11.9%/yr. at higher juvenile mortality rates and adult M fixed at 0.10, the best estimate of M for sandbar sharks, population growth rate was only 2.6%/yr. Adding fishing mortality (F) at immature ages caused the population to decline unless F levels were &<&0.10 and 0.05 at maximum age = 30 and 60 yr, respectively. It is apparent that sandbar shark populations will decline under any substantial fishing mortality on immature ages, and mature fish can only be exploited at very low levels of fishing mortality.

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41

Murphy, John F. "The ecology and population biology of two litter decomposing basidiomycetes." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06302009-040233/.

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42

Mavraganis, Katherine. "The reproductive ecology & population biology of Aquilegia canadensis (Ranunculaceae)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ31229.pdf.

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43

Gravenor, Michael Brynley. "The population biology of Plasmodium falciparum within the human host." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260744.

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44

Wang, Chun-Neng. "Systematics, developmental biology and population genetics of Titanotrichum oldhamii (Gesneriaceae)." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/13188.

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45

Van, Der Merwe Nicolaas Albertus. "Phylogeography and population biology of Chrysoporthe austroafricana and allied species." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/79193.

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46

Sumpton, Wayne Donald. "Population biology and management of snapper (Pagrus auratus) in Queensland /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16381.pdf.

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47

Van, der Merwe Nicolaas Albertus (Albie). "Phylogeography and population biology of Chrysoporthe austroafricana and allied species." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/30863.

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Chrysoporthe canker is an important stem disease of commercially planted eucalypts in the tropics and sub-tropics. The disease is caused by several species of Chrysoporthe, which appear to have continental distributions and also occur on native hosts in each of their respective areas. The primary aim of this thesis was to elucidate the phylogeography and population biology of Chrysoporthe spp. that are important to commercial forestry. This was achieved by using several modern DNA based techniques, including multigene phylogenetic analyses, population genetic determinations using polymorphic microsatellite markers, and phylochronometric estimations. It was found that Chrysoporthe cubensis from South America is genetically distinct from C. cubensis occurring in Southeast Asia. The Asian form of the fungus was thus described as Chrysoporthe deuterocubensis. Calibrated chronometric phylogenies showed that the genus Chrysoporthe was approximately 7 million years old, placing its emergence well after the breakup of the Gondwana supercontinent. Therefore, continental drift did not play a role in the establishment of current geographic distributions of Chrysoporthe species. In Africa, C. austroafricana resulted from the subsequent allopatric speciation process. This fungus occurs on native Syzygium trees and two non-native trees, including Eucalyptus. Population genetic data showed that populations of C. austroafricana from Syzygium were more diverse than those on the other hosts, while a chronometric phylogeny also showed this population to be the oldest. Therefore, Syzygium represents the formative host of C. austroafricana, i.e., the host on which the fungus evolved, while the other hosts have been colonized via host jumping. This capability was also investigated in a population of C. cubensis from Colombia, occurring on Eucalyptus and Miconia hosts. Population genetic estimates showed that this population is continually jumping between hosts, but it was not possible to determine if either of these hosts represented a formative host. Taken together, this study considerably advanced the understanding of population and phylogeographic processes that shaped the evolution of C. cubensis, C. austroafricana and C. deuterocubensis.
Thesis (PhD)--University of Pretoria, 2012.
Genetics
PhD
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48

Wilson, Maya. "Biology and conservation of the endangered Bahama Swallow (Tachycineta cyaneoviridis)." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96264.

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In order to prevent species extinctions, conservation strategies need to incorporate the identification and mitigation of the root causes of population decline with an assessment of vulnerability to genetic and stochastic factors affecting small populations. Species or populations with small ranges, such as those on islands, are particularly vulnerable to extinction, and deficient knowledge of these species often impedes conservation efforts. The Bahama Swallow (Tachycineta cyaneoviridis) is an endangered secondary cavity-nester that only breeds on three islands in the northern Bahamas: Abaco, Grand Bahama, and Andros. I investigated questions related to population size and distribution, genetic diversity and population structure, breeding biology, and ecological interactions of the swallow, with the goal of informing the conservation and management of the species. Using several population survey methods on Abaco, I found that swallow site occupancy and density is higher in southern Abaco, especially near roads and pine snags. Future research should prioritize identifying the causes of variable and low population densities in parts of the swallow's range. I used microsatellite markers and morphometrics to assess differences between populations on Abaco and Andros. We found a lack of genetic differentiation (G'ST = 0.03) between populations, but differences in morphology suggest that gene flow might be low enough to enable traits under selection to diverge. By locating and monitoring nests, I found that swallows rely on woodpecker-excavated cavities in pine snags and utility poles, and that swallows nesting in pine snags had higher fledging success (92%) than those nesting in utility poles (50-62%). Using a cavity nest-web approach, I assessed how swallows interact with cavity-nesting birds and resources on Abaco. Hairy Woodpeckers (Dryobates villosus) primarily excavated pine snags, while West Indian Woodpeckers (Melanerpes superciliaris) excavated utility poles in non-pine habitat. Only swallows and La Sagra's Flycatchers (Myiarchus sagrae) used nest sites in the pine forest. Swallows in non-pine habitat face competition for cavities with American Kestrels (Falco sparverius), and non-native House Sparrows (Passer domesticus) and European Starlings (Sturnus vulgaris). These results highlight the importance of pine forest and the Hairy Woodpecker for the persistence of the swallow.
Doctor of Philosophy
In order to prevent species extinctions, conservation strategies need to identify and resolve the problems that cause species to decline, as well as address issues characteristic of small populations. Species or populations with small ranges, such as those on islands, are particularly vulnerable to extinction, and lack of knowledge of these species often impedes conservation efforts. The Bahama Swallow is an endangered species that only breeds on three "pine islands" in the northern Bahamas. The swallow is a secondary cavity-nester, which means that it nests in a cavity, usually either a natural tree hole or a hole created by another bird species. In this study, I investigated where swallows are found on the islands, the genetics and body sizes of populations, nesting biology, and connections with other species, with the goal of providing information for the conservation and management of the species. On Abaco, I found that there are more swallows in the southern part of the island, especially near roads and the dead standing pine trees (pine snags) used for nesting. Future research should assess why there are fewer birds in other parts of the swallow's range. I tested whether the genetics and body sizes of populations on Abaco and Andros are different from each other. Populations were genetically similar, but may be separated enough to result in body size differences. I located swallow nests on Abaco, and found that swallows rely on cavities made by woodpeckers in pine snags and utility poles. By visiting some nests repeatedly, I found that swallows nesting in pine snags were more successful than those nesting in utility poles. I also assessed how swallows interact with the other bird species that create and use nesting cavities. Hairy Woodpeckers usually create cavities in pine snags, while West Indian Woodpeckers use utility poles outside of the pine forest. Swallows nesting in the pine forest compete with fewer bird species for cavities than swallows nesting in other habitats. These results show that managing the forest to retain pine snags and Hairy Woodpeckers is important for the conservation of the swallow.

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49

Valentinsson, Daniel. "Fisheries biology of the whelk (Buccinum undatum) : population biology, estimation uncertainty and consequences of management alternatives /." Göteborg : Göteborg University, 2002. http://catalogue.bnf.fr/ark:/12148/cb39905470n.

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50

Paltiel, Charles J. "An analysis of the 1994-1996 northern Strait of Georgia oyster survey." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ51440.pdf.

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Dissertations / Theses on the topic 'Population biology'

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