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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Mediators of Fine-Scale Population Genetic Structure in the Black Blow Fly, Phormia regina (Meigen) (Diptera: Calliphoridae)

Charity Grace Owings (7023467) 16 October 2019 (has links)
Population genetic structure is difficult to assess in blow flies (Diptera: Calliphoridae) due to high connectivity and genetic diversity of subpopulations. Previous studies revealed high relatedness among individuals within wild samples of blow fly populations, however broad geographic structure was absent. The aim of this research was to determine if blow fly genetic structure exists at a fine spatiotemporal resolution and, if so, to elucidate the influence of environmental factors and resource availability on fly genetics. Specifically, blow fly population genetic patterns were tested against anull hypothesis that flies adhere to a patchy population model with high genetic diversity (i.e. no structure) and high resource availability. Samples of the black blow fly, <i>Phormia regina</i> Meigen (Diptera: Calliphoridae), were collected at six urban parks in Indiana, USA (=urban) in 2016 and 2017 (N = 14 and 16 timepoints, respectively). Additional sampling in different ecoregions was performed to determine if trends observed at a high-resolution scale were also present at a broad geographic scale. Therefore, <i>P. regina</i> were also collected at four sites within two national parks (the Great Smoky Mountains and Yellowstone National Parks) over a three-day period. Randomly selected females (N = 10) from each sample underwent the following analyses: 1) gut DNA extraction, 2) molecular analysis at 6 microsatellite loci, 3) vertebrate-specific 12S and 16S rRNA sequencing, and, 4) vertebrate fecal metabolite screening. Flies from the national parks and a comparable subset of urban data also underwent stable isotopeanalysis (SIA) to determine larval food source. Overall, strong seasonal population genetic structure was observed over both years in the urban environment (2016 F’<sub>ST</sub>= 0.47, 2017 F’<sub>ST</sub>0.34), however spatial structure was lacking, as seen in previous studies (2016 F’<sub>ST</sub>= 0.04, 2017 F’<sub>ST</sub>0.03). Weather conditions prior to and on the day of blow fly collections, interspecific competition, and resource availability greatly impacted the genetic diversity and kinship of <i>P. regina</i>. A total of 17 and 19 vertebrate species were detected by flies in 2016 and 2017, respectively, and many flies tested positive for vertebrate feces, suggesting that many varied resources are important for maintaining high gene flow among geographic locations. Genetic diversity was non-existent in flies collected from the Smokies (F’<sub>ST</sub>= 0.00), while very slight spatial structure existed in the Yellowstone populations (F’<sub>ST</sub>= 0.07). Environmental factors such as temperature, humidity, and wind speed were all statistically relevant in maximizing fly collections with vertebrate resources. In 720 min of total sampling time in the national parks and a subset of urban data, 28 vertebrate species were identified, and fecal resources appeared to be the most abundant in Yellowstone. Stable isotopeanalysis revealed a majority of larval resources in the national parks were herbivores, with a more even distribution of carnivore and herbivore carcasses present in the urban environment, which likely explains the high genetic diversity of adult flies in these regions. Overall, the null hypothesis that <i>P. regina</i> adheres to a patchy population model could not be rejected for the Smokies populations. However, the urban and Yellowstone populations appear to adhere to a Levins metapopulation model in which variable availability in resources leads to random bottleneck events in the local populations. Overall, environmental conditions, competition, and resource availability are all important factors influencing <i>P. regina </i>population genetic structure in different environments.
22

Modelling the population dynamics and viability analysis of franciscana (Pontoporia blainvillei) and Hector�s dolphins (Cephalorhynchus hectori) under the effects of bycatch in fisheries, parameter uncertainty and stochasticity

Secchi, Eduardo Resende, n/a January 2006 (has links)
Incidental mortality in fisheries, especially gillnets, is one of the most important causes of decline of many species of cetaceans around the globe. Local populations of franciscana, Pontoporia blainvillei, and Hector�s dolphins, Cephalorhynchus hectori, have been subject to high levels of mortality in gillnets for several decades. This is due to a combination of extensive overlap in distribution of these coastal dolphins and large numbers of fishing nets. Stage-specific population dynamic models (without environmental stochasticity) suggest that both species have a low potential for population growth of approximately 0.2% (95% CI: -3.7% to 4.2%) to 3.4% (95% CI: 1.6% to 6.4%) for franciscana and 0.85% (95% CI: -1.0% to 2.6%) for Hector�s dolphins. Although the two species have similar population growth rates, they result from different life history strategies. Franciscana has a relatively low adult survival rate (0.86; SD = 0.016) which is compensated by a relatively high reproductive potential. The latter is a combination of early reproduction and high fecundity. Hector�s dolphin has a low reproductive potential, which is a combination of late reproduction and low fecundity, which is probably compensated by a relatively high adult survival rate (0.92; SD = 0.02) Apparent differences in growth rate among franciscana populations are possibly due to a combination of varying population-specific reproductive potential and, in some populations, inaccuracy in parameter estimates. Inaccuracy in estimating natural survival rates is also a cause for the low growth rate of Hector�s dolphins. The estimated low population growth rates of these species are insufficient to compensate for current levels of fishing-related mortality in some local populations, especially when environmental and/or demographic stochasticity is considered. Under these circumstances Banks Peninsula population would have a negative mean population growth rate of 0.54% (95% CI: -2.2% to 0.9%) and would decrease below its initial size in approximately 74% of the simulations. Stochasticity alone would decrease considerably the probability of the Banks Peninsula population to grow and recover from past and current high bycatch levels. Effects of stochasticity were also high for one of the franciscana stocks (i.e. stock from Franciscana Management Area II). In other areas (e.g. West Coast of the South Island; franciscana stock from FMA I) fishing effort and bycatch mortality rate seem not to be impeding population growth. Even in a stochastic environment and under current levels of fishing effort, the West Coast population and the franciscana stock from FMA I would grow at a positive rate of 0.32% (95% CI: -1.2% to 1.8%) and 3.1% (95% CI: 2.2 to 7.2%), respectively. Parameter uncertainty does not change the conclusion that immediate and extreme limitations on fishing practice and effort are necessary to increase the chances of recovery for some local populations/stocks. Fishing effort in New Zealand is regulated by a quota system. The quota system, the low number of fishing boats and the relatively low overlap between fishing nets and dolphins are probably the reasons for the positive population growth of Hector�s dolphins from the West Coast of the South Island. On the other hand, not even the Marine Mammal Sanctuary is sufficient to avoid negative mean population growth rate of Hector�s dolphins under current levels of fishing effort off Banks Peninsula. In Brazil, Uruguay and Argentina, where franciscana occurs, gillnet fisheries are not regulated. In some areas, faced with a declining fish stocks, fishermen have increased fishing effort to compensate for reduced catches, and the bycatch of franciscana has increased as a consequence. Strategies aiming at the conservation of these two species are likely to benefit other components of the ecosystem. Especially in the case of franciscana, reducing fishing effort is likely to promote the recovery of depleted fish stocks.
23

Mechanisms Underlying Frog Occupancy Patterns in a Landscape Mosaic of Tropical Forest and Pasture

Hawley, Tanya Joy 21 April 2008 (has links)
Habitat modification is the primary cause of amphibian population declines worldwide. Some species survive in modified habitats whereas others become restricted to small, isolated forest patches. Although many studies compare species richness and composition between modified and intact habitats, the factors and mechanisms that maintain biodiversity in these landscapes are poorly understood. I asked how life history traits and habitat features influence interspecific variation in frog occupancy patterns in tropical pasture and forest. To identify mechanisms underlying occupancy patterns, I used experiments to examine how abiotic conditions in different habitats influence the vital rates of tadpoles. I also explored whether tadpoles use a carnivorous foraging strategy to improve performance in nutrient-poor, ephemeral pools in pasture. Although modified and intact habitats offer abiotic environments that differ in quality for frogs, pastures contribute to the maintenance of biodiversity in fragmented landscapes. I detected an equal number of species but substantially different assemblage composition in forest and pasture. Species that occurred in pasture had different traits than those in forest, including larger body sizes, larger clutch sizes, larger geographic ranges, and reproductive modes that depend on water. The occurrence of pasture-specialists was associated with habitat features at small spatial scales, whereas the occurrence of forest-specialists was associated with habitat features at small and large spatial scales. An experiment indicated that abiotic conditions in pastures may deter or facilitate adult movements to breeding sites. Behavioral selection of sites by two model species was consistent with tadpole performance. Tadpoles of a pasture-specialist performed well across the pasture-forest gradient, but abiotic conditions in pasture facilitated faster growth and development than in edge or forest. In contrast, tadpoles of a forest-specialist performed well only in edge and forest. Most tadpoles occupying ephemeral pasture pools were facultative carnivores or cannibals of eggs and hatchlings. Tadpoles may contribute to the regulation of assemblages in pasture pools, influencing the relative abundance and composition of species through differential predation on eggs and hatchlings. The study of factors and mechanisms that contribute to population growth or decline of species can facilitate understanding of assemblage-level patterns of amphibian diversity in modified landscapes.
24

Effects of parasite exchange between wild and farmed salmon

Ashander, Jaime Unknown Date
No description available.
25

Effects of parasite exchange between wild and farmed salmon

Ashander, Jaime 11 1900 (has links)
Human food production activities can dominate natural systems, altering ecological and evolutionary aspects of the environment. Disease-mediated interactions are of particular concern. For example, parasites may "spill-over'' from farms to wildlife. Parasites isolated on farms can evolve resistance to treatment chemicals , but "spill-back'' from wildlife to farms may alter evolutionary dynamics. Here, we consider exchange of parasites (Lepeophtheirus salmonis) between wild (Oncorhynchus gorbuscha) and farmed salmon. We derive and analyze discrete-time models that implicitly include wild salmon migrations. First, we extend a standard fisheries model to show parasite exchange affects "line-dominance'' in the population ecology of salmon. Second, we extend a classic population genetics model to show that wild salmon can theoretically provide an "ecosystem service'' by delaying the onset of chemical resistance in parasites on farms. This service, however is affected by a nonlinear feedback if farm parasites spill-back to affect wild salmon. / Applied Mathematics
26

Modelling the population dynamics and viability analysis of franciscana (Pontoporia blainvillei) and Hector�s dolphins (Cephalorhynchus hectori) under the effects of bycatch in fisheries, parameter uncertainty and stochasticity

Secchi, Eduardo Resende, n/a January 2006 (has links)
Incidental mortality in fisheries, especially gillnets, is one of the most important causes of decline of many species of cetaceans around the globe. Local populations of franciscana, Pontoporia blainvillei, and Hector�s dolphins, Cephalorhynchus hectori, have been subject to high levels of mortality in gillnets for several decades. This is due to a combination of extensive overlap in distribution of these coastal dolphins and large numbers of fishing nets. Stage-specific population dynamic models (without environmental stochasticity) suggest that both species have a low potential for population growth of approximately 0.2% (95% CI: -3.7% to 4.2%) to 3.4% (95% CI: 1.6% to 6.4%) for franciscana and 0.85% (95% CI: -1.0% to 2.6%) for Hector�s dolphins. Although the two species have similar population growth rates, they result from different life history strategies. Franciscana has a relatively low adult survival rate (0.86; SD = 0.016) which is compensated by a relatively high reproductive potential. The latter is a combination of early reproduction and high fecundity. Hector�s dolphin has a low reproductive potential, which is a combination of late reproduction and low fecundity, which is probably compensated by a relatively high adult survival rate (0.92; SD = 0.02) Apparent differences in growth rate among franciscana populations are possibly due to a combination of varying population-specific reproductive potential and, in some populations, inaccuracy in parameter estimates. Inaccuracy in estimating natural survival rates is also a cause for the low growth rate of Hector�s dolphins. The estimated low population growth rates of these species are insufficient to compensate for current levels of fishing-related mortality in some local populations, especially when environmental and/or demographic stochasticity is considered. Under these circumstances Banks Peninsula population would have a negative mean population growth rate of 0.54% (95% CI: -2.2% to 0.9%) and would decrease below its initial size in approximately 74% of the simulations. Stochasticity alone would decrease considerably the probability of the Banks Peninsula population to grow and recover from past and current high bycatch levels. Effects of stochasticity were also high for one of the franciscana stocks (i.e. stock from Franciscana Management Area II). In other areas (e.g. West Coast of the South Island; franciscana stock from FMA I) fishing effort and bycatch mortality rate seem not to be impeding population growth. Even in a stochastic environment and under current levels of fishing effort, the West Coast population and the franciscana stock from FMA I would grow at a positive rate of 0.32% (95% CI: -1.2% to 1.8%) and 3.1% (95% CI: 2.2 to 7.2%), respectively. Parameter uncertainty does not change the conclusion that immediate and extreme limitations on fishing practice and effort are necessary to increase the chances of recovery for some local populations/stocks. Fishing effort in New Zealand is regulated by a quota system. The quota system, the low number of fishing boats and the relatively low overlap between fishing nets and dolphins are probably the reasons for the positive population growth of Hector�s dolphins from the West Coast of the South Island. On the other hand, not even the Marine Mammal Sanctuary is sufficient to avoid negative mean population growth rate of Hector�s dolphins under current levels of fishing effort off Banks Peninsula. In Brazil, Uruguay and Argentina, where franciscana occurs, gillnet fisheries are not regulated. In some areas, faced with a declining fish stocks, fishermen have increased fishing effort to compensate for reduced catches, and the bycatch of franciscana has increased as a consequence. Strategies aiming at the conservation of these two species are likely to benefit other components of the ecosystem. Especially in the case of franciscana, reducing fishing effort is likely to promote the recovery of depleted fish stocks.
27

Early life history of Haliotis asinina: A model for haliotid aquaculture and molluscan research

Counihan, R. T. Unknown Date (has links)
No description available.
28

Energetics and foraging behaviour of the Platypus Ornithorhynchus anatinus

Bethge, P January 2002 (has links) (PDF)
In this work, behavioural field studies and metabolic studies in the laboratory were conducted to elucidate the extent of adaptation of the platypus Ornithorhynchus anatinus to its highly specialised semiaquatic lifestyle. Energy requirements of platypuses foraging, resting and walking were measured in a swim tank and on a conventional treadmill using flow-through respirometry. Foraging behaviour and activity pattern of platypuses in the wild were investigated at a sub-alpine Tasmanian lake where individuals were equipped with combined data-logger-transmitter packages measuring foraging activity or dive depth and ambient temperature. Energy requirements while foraging in the laboratory were found to depend on water temperature, body mass and dive duration and averaged 8.48 W kg-1. Mean rate for subsurface swimming was 6.71 W kg-1. Minimum cost of transport for subsurface swimming platypuses was 1.85 J N-1m-1 at a speed of 0.4 m s-1. The metabolic rate of platypuses resting on the water surface was 3.91 W kg-1 while minimal RMR on land was 2.08 W kg-1. The metabolic rate for walking was 8.80 and 10.56 W kg-1 at speeds of 0.2 and 0.3 m s-1, respectively. Minimal cost of transport for walking was predicted to be 2.13 J N-1m-1 at a speed of 1.7 m s-1. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body mass, dive duration and water temperature. Activity patterns of platypuses in the wild were highly variable. Forty percent of the platypuses studied showed patterns, which deviated considerably from the nocturnal pattern generally reported for the species. Some animals showed diurnal rhythms while others temporarily followed the lunar cycle. Foraging trips lasted for an average of 12.4 h of continuous foraging activity per day (maximum: 29.8 hours). There were significant differences in diving behaviour between sexes and seasons. Activity levels were highest between August and November and lowest in January. While foraging, platypuses followed a model of optimised recovery time, the optimal breathing theory. Mean dive duration was 31.3 seconds with 72 % Energetics and foraging behaviour of the platypus 6 of all dives lasting between 18 and 40 seconds. Mean surface duration was 10.1 seconds. Mean dive depth was 1.28 m with a maximum of 8.77 m. Up to 1600 dives per foraging trip with a mean of 75 dives per hour were performed. Only 15 % of all dives were found to exceed the estimated aerobic dive limit of 40 seconds indicating mainly aerobic diving in the species. Total bottom duration per day was proposed as a useful indicator of foraging efficiency and hence habitat quality in the species. In contrast to observations made earlier in rivers, temporal separation was found to play a vital role for social organisation of platypuses in the lake system that was investigated. It is suggested that high intra-specific competition as well as limited burrow sites and a limited number of at the same time highly productive foraging locations were responsible for this observation. Mean burrow temperature in the wild was 17.5 and 14.2ºC in summer and winter, respectively, and was fairly constant over the platypus's resting period. In the cooler months, burrow temperature was up to 18ºC higher than ambient air temperature. By combining both field and laboratory data, a time-energy budget for the platypus was created. Mean field metabolic rate was 684 kJ kg-1 day-1 and was significantly higher in the winter months. Mean food requirement was 132 g fresh matter kg-1 day-1. Feeding rates were 68 % higher in winter than in summer. While platypuses in the swim tank were found to expend energy at only half the rate of semiaquatic eutherians of comparable body size, cost of transport at optimal speed as well as field metabolic rates were in line with findings for eutherians. These patterns suggest that locomotor efficiency of semiaquatic mammals might have reached a limit for energetic optimisation. The semiaquatic lifestyle seems to pose comparable energetic hurdles for mammals regardless of their phylogenetic origin.
29

Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae) / Demography and dispersal ability of the Alpine Longhorn \kur{Rosalia alpina} (Coleoptera: Cerambycidae)

DRAG, Lukáš January 2011 (has links)
This Master Thesis brings results of study on endangered species Alpine Longhorn Rosalia alpina in beech forest of National Nature Reserve Maly and Velky Bezdez and Slatinne Hills. We used mark-recapture method to study the population size, longevity and dispersal ability of this species. We also assessed the distribution pattern of the species on another 15 habitat patches in the Ralska Upland.
30

Deslocamento ao longo da noite e outros aspectos da biologia do opilião Serracutisoma pseudovarium no Parque Estadual Intervales, São Paulo, Brasil / Displacement throughout the night and other aspects of the biology of the harvestman Serracutisoma pseudovarium in the Intervales State Park, São Paulo, Brazil

Alessandra Zola Ramin 19 November 2014 (has links)
Uma população do opilião Serracutisoma pseudovarium utiliza a Pousada Esquilo do Parque Estadual Intervales (PEI), São Paulo, Brasil, como abrigo. Os animais se escondem em frestas na edificação e saem à noite para forragear, principalmente pelas paredes da construção. Essa situação constituiu uma oportunidade única de se realizar um estudo detalhado de forrageio e uso do espaço por opiliões, sendo este o primeiro objetivo deste trabalho. Além deste local, também foram acompanhados mensalmente, ao longo de 15 meses, outros quatro locais do PEI: Pousada Onça-Pintada, Castelinho, Toca dos Meninos e Gruta Detrás. Em cada um destes locais (com exceção do Castelinho), os animais foram marcados individualmente e foram realizadas medidas corpóreas. Desta forma, foi possível efetuar também um estudo populacional, que constituiu o segundo objetivo deste trabalho. Para analisar o forrageio em detalhes, um croquis da edificação foi elaborado, no qual os animais foram anotados de hora em hora, ao longo de uma noite, em cada um dos meses de coleta. Além do posicionamento do animal, também foram registrados sua marca e o comportamento exibido no momento da observação. Assim, o terceiro objetivo foi realizar um estudo comportamental através de um etograma com dados obtidos em campo, ao longo do ano inteiro. No total, 380 indivíduos foram marcados, sendo 192 na Pousada Esquilo, população foco do estudo. Destes, 71 foram fêmeas, 71 foram machos e 50 foram jovens. O tamanho estimado da população, pelos modelos de Fisher-Ford e Jolly, variou de 36 a 95 indivíduos. A análise dos deslocamentos ao longo do forrageio mostrou que os animais mesclam uma estratégia de emboscada com períodos de deslocamento, em que podem encontrar ativamente uma presa. Não foram encontradas relações entre a frequência de utilização destas estratégias e o sexo, idade ou estado nutritivo/reprodutivo dos animais. Porém, o mesmo indivíduo tendeu a repetir a mesma estratégia em diferentes noites de forrageio. Da mesma forma, a direção do deslocamento tendeu a ser repetida, embora os animais não utilizem trilhas marcadas individualmente ou coletivamente. Etogramas obtidos com dados de campo são raros, e possuem a vantagem de não serem influenciados por fatores como maior densidade de animais e disponibilidade de alimento, comuns em estudos em cativeiro. A comparação de etogramas de machos, fêmeas e jovens não mostrou grandes diferenças de comportamento entre os grupos / A population of the harvestman Serracutisoma pseudovarium uses a building (Pousada Esquilo in the Intervales State Park) as a shelter. The animals hide in crevices of the building during the day and leave at night to forage, walking mainly on the walls of the same building, which is situated inside the forest. This situation appeared to be an unique opportunity to perform a detailed study of foraging dynamics and use of space by harvestmen, which constituted the first objective of this study. In addition to Pousada Esquilo, four other places of the Park were monthly monitored during 15 months, namely: Pousada Onça-Pintada, Castelinho, Toca dos Meninos cave and Detrás cave. In each of these places (except Castelinho) the animals were marked individually and body measurements were taken. This also allowed the conduction of a population study, as the second objective of this study. In order to examine the foraging dynamics in detail, we made a croquis of the building, in which the animals were recorded hourly during one night of each sampling event. In addition to the position of the animal, its individual mark and behavior at the moment of the observation were also recorded. This behavioral study led to the third objective, which was the construction of an ethogram based on the field data collected throughout the year. A total of 380 individuals were marked. In Pousada Esquilo, the target population of the study, 192 animals were marked, being 71 females, 71 males, and 50 juveniles. The size of the population estimated by both Fisher-Ford and Jolly models varied from 36 to 95 individuals. The study of displacement during foraging showed that the animals combine an ambush strategy with periods of walking, when they might actively find a prey. No relation was found between the frequency of usage of each strategy and sex, age or nutritional/reproductive condition of the animals. However, the same individual tended to repeat a strategy in different nights. In a similar way, the direction of the movement tended to be repeated, although the animals did not use individually or collectively marked trails. Ethograms elaborated with field data are rare in the literature, and they have the advantage of not being influenced by factors as higher animal density and food availability, which are common in studies made in captivity. The comparison among ethograms of males, females and juveniles did not show great behavioral differences between the groups

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