Made available in DSpace on 2014-06-11T19:25:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-06-30Bitstream added on 2014-06-13T18:26:14Z : No. of bitstreams: 1 souza_vp_me_jabo.pdf: 172982 bytes, checksum: 387d5e08d4531f6eb3f646c6fefcc7b5 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O trabalho teve como objetivos determinar a flutuação populacional de formas aladas e ápteras de Myzus persicae (Sulzer, 1776), Brevicoryne brassicae (Linnaeus, 1758) e Lipaphis erysimi (Kaltenbach, 1843) e avaliar a influência de inimigos naturais, de fatores meteorológicos e a distribuição vertical dos pulgões em couve, Brassica oleracea L. var. acephala DC., em Jaboticabal, SP. A amostragem de formas aladas e ápteras dos pulgões foi efetuada com armadilhas amarelas com água e coleta direta na parte aérea, enquanto os inimigos naturais foram averiguados por procura visual na parte aérea da couve e armadilhas de solo. As formas aladas dos pulgões começaram colonizar a couve em meados de maio, quando prevalesceram temperatura média de 22,6ºC, umidade relativa de 68,5% e ausência de precipitação pluviométrica. A colonização da couve por ápteros de L. erysimi iniciou-se quatro dias após a chegada dos indivíduos alados, para B. brassicae e M. persicae esse intervalo foi de 9 dias e 30 dias, respectivamente. As populações mais elevadas dos pulgões ocorreram na couve de julho a setembro, com os pulgões apresentando baixa atividade durante o verão e outono. Os ápteros de M. persicae predominaram nas folhas medianas da couve, o mesmo acontecendo com B. brassicae nas folhas apicais e L. erysimi nas basais. As aranhas, Cycloneda sanguinea (Linnaeus, 1775), Lebia concinna Brullé, 1837 e Diaeretiella rapae (Mc'Intosh, 1855) foram os inimigos naturais com maior potencial para controlarem as populações dos pulgões. A umidade relativa do ar foi o principal fator meteorológico a atuar sobre alados e ápteros dos pulgões, com a densidade populacional desses insetos diminuindo com o incremento da umidade. / The objectives of this work were to determine the populational fluctuations of alate and apterous Myzus persicae (Sulzer, 1776), Brevicoryne brassicae (Linnaeus, 1758) and Lipaphis erysimi (Kaltenbach, 1843), and to evaluate the influence of natural enemies, meteorological factors and the within-plant distributions of aphids in kale, Brassica oleracea L. var. acephala DC., cultivated in Jaboticabal, São Paulo State. Alate and apterous aphids were sampled by yellow traps of water and visual search, while natural enemies were checked by visual search of the aerial parts of kale and pitfall traps. The alate aphids began to colonize the kale crop in mid May, when prevailed medium temperature of 22.6ºC, relative humidity of 68.5% and absence of rainfall. Apterous L. erysimi began to colonize the kale crop four days after the arrival of first alate individuals, while for B. brassicae and M. persicae that interval were 9 days and 30 days, respectively. The highest populations of the aphids in the crop were observed from July to September, and they showed low activity during the summer and fall. Apterous M. persicae prevailed on the middle leaves of kale, the same were observed for B. brassicae and L. erysimi on top and basal leaves, respectively. The natural enemies that showed the greatest potential to regulate the aphid populations were: spiders, Cycloneda sanguinea (Linnaeus, 1775), Lebia concinna Brullé, 1837 and Diaeretiella rapae (Mc'Intosh, 1855). The relative humidity of the air was the major meteorological factor to act on alate and apterous aphids, the population density of them decreased with the increment of that humidity.

Made available in DSpace on 2015-08-20T17:09:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-20. Added 1 bitstream(s) on 2015-08-20T17:26:36Z : No. of bitstreams: 1 000836155.pdf: 1638926 bytes, checksum: 52f2a08fe8d649d36c3c14e8c319fe60 (MD5) / Considerando a grande importância do Rhipicephalus (Boophilus) microplus, na produção de bovinos, o presente estudo teve como objetivo avaliar a sazonalidade deste artrópode em bovinos mantidos em pastagem de Brachiaria decumbens. Para tanto, foi pesquisada a dinâmica populacional durante 12 meses no município de Formiga, Minas Gerais. Vinte e quatro bovinos com oito a 12 meses de idade foram submetidos à infestação natural pelo carrapato. Contagens de fêmeas parcialmente ingurgitadas, 4,5 a 8,0 mm (partenóginas), foram computadas do lado esquerdo de cada bovino, nos períodos -2,-1 e zero. Utilizando-se as médias das contagens de carrapatos nas referidas datas, efetuou-se a randomização, para obtenção de dois grupos com infestações equitativas, os quais foram mantidos em piquetes separados. Para estudo da sazonalidade, as contagens foram realizadas nos períodos 3, 7, 14, 21, 28, e a cada 14 dias, durante 12 meses. Para verificar a incidência ectoparasitária com os efeitos climáticos, foram colhidos do posto climatológico do município, os seguintes dados: temperatura máxima e mínima, precipitação pluvial e umidade relativa do ar. Tratamentos táticos foram realizados, via tópica (pulverização), com uma formulação contendo Cipermetrina 15% + Clorpirifos 25% + Butóxido de Piperonila 15 + Citronela 1%, em todas as datas nas quais as quantificações de carrapatos ultrapassavam 30 partenóginas, em média. Como coadjuvante ao projeto, foram, ainda, realizadas pesagens dos animais e colheitas de fezes para contagens de ovos por grama de fezes (OPG) a cada 28 dias, sendo os mesmos tratados, com Fosfato de Levamisole injetável, na dose de 4,7 mg/kg, atingindo média de OPG ≥ 300. A carga média parasitária por animal e os desvios padrões do grupo I foi de 18,7(±11,7) e para o grupo II de 25,9 (±22,6), sendo realizados 15 tratamentos carrapaticidas nos dois grupos. As contagens de OPG apresentaram-se mais... / Considering the great importance of Rhipicephalus (Boophilus) microplus in cattle, the present study aimed to evaluate the seasonality of this arthropod in cattle maintained in pastures of Brachiaria decumbens. To that end, were investigated the population dynamics for 12 months in the city of Formiga, Minas Gerais. Twenty-four cattle with eight to 12 months of age were subjected to natural infestation by ticks. Counts of partially engorged females, from 4,5 to 8,0 mm (engorged), were computed on the left side of each animal, at times -2, -1 and zero. Using the mean on those dates tick counts, randomization was executed, to obtain two groups with fair infestations, which were kept in separate paddocks. To study of seasonality, the counts were recorded at 3, 7, 14, 21, 28, and every 14 days for 12 months. To check the ectoparasitic incidence with the climatic effects, were collected from the climatological station of the city, the following data: maximum and minimum temperature, rainfall and relative humidity. Tactical treatments were performed, topically (spray) with a formulation containing Cypermethrin 15 % + Chlorpyrifos 25% + Piperonyl butoxide 15 + Citronella 1% on all the dates on which tick measurements exceed 30 engorged on average. As an adjunct to the project, were also carried weights of animals and faeces samples for egg counts per gram of feces (EPG) every 28 days, and they are treated with injectable Levamisole Phosphate at a dose of 4,7 mg/kg, reaching average of EPG ≥ 300. The mean parasite load per animal and group I standard deviation was 18,7 (± 11,7) and group II 25,9 (± 22,6) and were performed 15 acaricide treatments in both groups. The EPG counts were more elevated in the months of December and May, and made two treatments in each group, a total of four anthelmintic treatments throughout the study. There was no statistical difference between the mean weight of the two analyzed groups (p>0,05), as well ...

Made available in DSpace on 2014-06-11T19:30:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-29Bitstream added on 2014-06-13T18:40:11Z : No. of bitstreams: 1 romao_arr_me_botib.pdf: 1517142 bytes, checksum: 9847478643094b18e301318681e42e82 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo analisa a anautogenia em moscas-varejeiras e sua influência sobre a dinâmica populacional dos insetos. O estudo foi dividido em duas partes. Na primeira, os experimentos de laboratório foram realizados para analisar o desenvolvimento ovariano de Chrysomya albiceps, C. megacephala e C. putoria. No segundo, um modelo matemático foi empregado para analisar padrões a partir de dados pré-existentes de Lucilia cuprina. Os resultados obtidos para a comparação entre as diferentes fases do desenvolvimento ovariano em diferentes espécies, Chrysomya albiceps, C. megacephala e C. putoria e densidades crescentes foram analisados com modelo linear generalizado binomial. O espaço paramétrico dos parâmetros do modelo proposto por Readshaw & Cuff (1980) foi investigado com recorrências a partir de reduções nos valores do substrato protéico para L. cuprina, espécie utilizada para modelar o sistema. Os resultados sugerem que C. putoria é a espécie que mais foi influenciada negativamente pela densidade de adultos. C. megacephala mostrou ser a espécie que menos foi atingida pela densidade. As reduções nos valores dos parâmetros do modelo matemático produziram mudanças qualitativas e quantitativas nos padrões ecológicos de oscilação nas simulações com L. cuprina, com relevância para o contexto de dinâmica e persistência populacional de moscas. / This study analyses the anautogeny in blowflies and its influence on the population dynamics of insects. The study was separated in two parts. In the first one, a laboratory experiment was conducted to analyze the ovarian development of Chrysomya albiceps, C. megacephala and C. putoria. In the second part, a mathematical model was employed to investigate patterns from data previously obtained with Lucilia cuprina. Results were compared in different species, Chrysomya albiceps, C. megacephala and C. putoria and in increasing densities by using binomial generalized linear model. The parametrical space of the Readshaw & Cuff (1980) model parameters was investigated with recurrences by reducing the protein substrate values for L. cuprina, the species used to model the system. The results suggest that C. putoria was the most negatively influenced species for adult densities. C. megacephala was the least influenced species for density. The reductions of model parameters values produced qualitative and quantitative changes in the ecological patterns of oscillations in L. cuprina, with relevance to the context of dynamics and persistence of flies.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam. / Science, Faculty of / Zoology, Department of / Graduate

Climatic variation is an important driver of avian life history and population dynamics. Climate change models predict increased variability for many regions and to predict the effects on species, we need to examine how their life history characteristics influence their response to climate. I studied how environmental conditions influenced the ecology of white-tailed (Lagopus leucura) and rock ptarmigan (L. mutus) in tundra habitats of the southern Yukon Territory. Although sympatric in the study area, breeding territories were generally segregated, with white-tailed ptarmigan selecting steep, rocky slopes at higher elevations and rock ptarmigan preferring lower elevation sedge meadows. For both species, cold spring temperatures delayed the onset of breeding, resulting in smaller clutch sizes and fewer hatched young per female. However, delayed breeding led to a stronger reduction in these rates for rock ptarmigan, suggesting a lower resilience to extend reproductive effort in colder years. White-tailed ptarmigan were also more likely to re-nest following failure and had higher daily nest survival, both of which contributed to greater annual productivity compared to rock ptarmigan. Annual adult survival showed the opposite pattern to productivity as rock ptarmigan survival was 24 percent higher than white-tailed ptarmigan. This finding suggested a reproduction-survival trade-off exists for the two species, which may be driven by differing susceptibility to environmental factors in the region. Life history theory predicts that if the likelihood of future breeding opportunities is low, individuals should increase current reproductive effort, which may explain why white-tailed ptarmigan have longer breeding seasons and higher reproductive effort under unfavourable climatic conditions. Population models showed that growth rates (λ)were approximately stable for rock ptarmigan (λ=1.01), but declining for white-tailed ptarmigan (λ=0.96). Simulations showed that warmer spring temperatures over the next few decades would elevate λ by ~0.05 for both species, but the extent of increase in λ may be reduced with more variable spring conditions. Population growth will also depend on how changing winter conditions influence survival for each species. Model simulations suggest that if juvenile and adult survival are positively correlated, rock ptarmigan would be more resilient to severe years that simultaneously depress reproduction and survival. / Forestry, Faculty of / Graduate

In this thesis, I present two methods of fast variable elimination in stochastic systems. Their application to models of population dynamics from ecology, epidemiology and population genetics, is explored. In each application, care is taken to develop the models at the microscale, in terms of interactions between individuals. Such an approach leads to well-defined stochastic systems for finite population sizes. These systems are then approximated at the mesoscale, and expressed as stochastic differential equations. It is in this setting the elimination techniques are developed. In each model a deterministically stable state is assumed to exist, about which the system is linearised. The eigenvalues of the system's Jacobian are used to identify the existence of a separation of timescales. The fast and slow directions are then given locally by the associated eigenvectors. These are used as approximations for the fast and slow directions in the full non-linear system. The general aim is then to remove these fast degrees of freedom and thus arrive at an approximate, reduced-variable description of the dynamics on a slow subspace of the full system. In the first of the methods introduced, the conditioning method, the noise of the system is constrained so that it cannot leave the slow subspace. The technique is applied to an ecological model and a susceptible-exposed-infectious-recovered epidemiological model, in both instances providing a reduced system which preserves the behaviour of the full model to high precision. The second method is referred to as the projection matrix method. It isolates the components of the noise on the slow subspace to provide its reduced description. The method is applied to a generalised Moran model of population genetics on islands, between which there is migration. The model is successfully reduced from a system in as many variables as there are islands, to an effective description in a single variable. The same methodology is later applied to the Lotka-Volterra competition model, which is found under certain conditions to behave as a Moran model. In both cases the agreement between the reduced system and stochastic simulations of the full model is excellent. It is stressed that the ideas behind both the conditioning and projection matrix methods are simple, their application systematic, and the results in very good agreement with simulations for a range of parameter values. When the methods are compared however, the projection matrix method is found in general to provide better results.

Orientadores: Maurea Nicoletti Flynn, Gisela de Aragão Umbuzeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-26T21:07:30Z (GMT). No. of bitstreams: 1 Alegretti_Lucas_M.pdf: 2378258 bytes, checksum: db1360024f2abd7e9ffc0aedfe3f1777 (MD5) Previous issue date: 2015 / Resumo: As respostas de populações ao estresse ambiental têm sido avaliadas em relação a efeitos na taxa de crescimento da população, na capacidade suporte do meio, na densidade e viabilidade populacional. Os objetivos deste trabalho englobam a descrição da estrutura e da dinâmica de uma população natural de Parhyale hawaiensis através da confecção de tabela de vida idade-específica para obtenção de parâmetros vitais populacionais, além de fornecer recomendações metodológicas para testes de toxicidade crônica, conhecido como LTRE (Life Table Responde Experiment). A estrutura populacional, a classe etária, a evolução da densidade, a razão sexual, a curva de sobrevivência, a taxa líquida de reprodução, o tempo de geração e a taxa per capita de crescimento foram estabelecidos para uma população da região entre marés do cinturão de algas, em Poço de Anchieta, Itanhaém - SP. A estratégia de vida identificada para a espécie está associada a um padrão de dinâmica populacional consistente com o comportamento adotado por espécies costeiras em ambientes fisicamente controlados e sujeitos a frequentes perturbações, e sugerem tendências relacionadas à latitude, produtividade e previsibilidade que podem ser resumidas nas hipóteses de seleção r-K relacionadas à longevidade, maturidade e fecundidade da espécie. A abordagem experimental aqui recomendada procura delinear um experimento com período de 12 semanas com a espécie teste P. hawaiensis, com o objetivo de obter respostas a agentes estressores em nível populacional, utilizando com endpoints as estatísticas demográficas: o potencial reprodutivo (R0), a taxa intrínseca de crescimento (r) e o tempo de geração (T). Os valores guias estimados foram respectivamente R0 = 1.45 ± 1.01, r = 0.057 ± 0.169 e T = 3.510 ± 1.305 / Abstract: Population¿s responses to environmental stress have been evaluated for effects on parameters such as population growth rate, environment carrying capacity, population density and viability. The objectives of this study are to describe the structure and dynamics of a natural population of Parhyale hawaiensis by constructing age-specific life tables to obtain population vital parameters and provide methodological recommendations for chronic toxicity tests, known as LTRE (Life Table Response Experiments). The population structure, age group, temporal evolution of the density, sex ratio, survival curve, net reproductive rate, generation time and per capita growth rate were established for a population of the intertidal belt algae, in Poço de Anchieta, Itanhaém - SP. The life strategy identified for the species is associated with a pattern of population dynamics consistent with the behavior adopted by coastal species in physically controlled environments and subject to frequent disruptions, suggesting trends related to latitude, productivity and predictability summarized by rK selection related to longevity, maturity and fecundity of the species. The experimental approach recommended here seeks to outline an experiment with 12-week period with the test species P. hawaiensis, in order to get answers to stressors at the population level, using endpoints with demographic statistics: the reproductive potential (R0), the intrinsic growth rate (r) and the generation time (T). The estimated guide values were respectively R0 = 1.45 ± 1.01, r = 0.057 ± 0.169 and T = 3.510 ± 1.305 / Mestrado / Ambiente / Mestre em Tecnologia

Alpine plants are assumed to be in particular danger as the climate changes rapidly worldwide. Specialist alpine species in Norrbotten County, northern Sweden have been surveyed over the last 20 years, providing insight to population dynamics and how the plants might respond to the changing climate. The main current threat to the species is habitat destruction as the climate changes. Variation in the number of plants among populations and years, and correlations with environmental variables were examined. Some species had increased while others had decreased over the years. No uniform relationship for all species and populations were discovered, but some of the species exhibited relationships between population size changes and temperature and precipitation. However, if the future climate in Norrbotten County changes according to the predictions, the habitats of the specialist alpine plants may be severely altered, leaving the species with no alternative places to establish and grow.

We consider a class of partial differential equations whose solutions are elements of a space of measures. The motivation for modeling with measures is that sometimes selection-mutation models or models of for example population dynamics or opinion-formation are designed to describe not functions, but rather evolving distributions which can be described by measures. We present a way to prove wellposedness for a particular class of models. Additionally, we briefly discuss a couple of ways to perform the numerical approximation of the evolving measures so that their expected behaviour can be captured. / Vi undersöker en klass av partiella differentialekvationer vars lösningar tillhör rum av mått. Motivationen för att modellera med mått är att selektion-mutations modeller och modeller inom till exempel populationsdynamik och opinionsformation ibland inte beskriver funktioner utan snarare tidsberoende distributioner som kan beskrivas av mått. Vi presenterar ett sätt att bevisa att en specifik klass av dessa modeller är välställda. Vi diskuterar även lite om ett par sätt att använda numeriska approximationer för att visa det förväntade beteendet av de tidsberoende måtten.

Thesis advisor: Pankaj Mehta / Thesis advisor: Ziqiang Wang / Nature has revealed an astounding degree of phylogenetic and physiological diversity in natural environments -- especially in the microbial world. Microbial communities are incredibly diverse, ranging from 500-1000 species in human guts to over 1000 species in marine ecosystems. Historically, theoretical ecologists have devoted considerable effort to analyzing ecosystems consisting of a few species. However, analytical approaches and theoretical insights derived from small ecosystems consisting of a few species may not scale up to diverse ecosystems. Understanding such large complex ecosystems poses fundamental challenges to current theories and analytical approaches for modeling and understanding the microbial world. One promising approach for tackling this challenge that I develop in my thesis is to adapt and expand ideas from statistical mechanics to theoretical ecology. Statistical mechanics has helped us to understand how collective behaviors emerge from the interaction of many individual components. In this thesis, I present a unified theoretical framework for understanding complex ecosystems based on statistical mechanics, random matrix theories, and convex optimization. My thesis work has three key aspects: modeling, simulations, and theories. Modeling: Classical ecological models often focus on predator-prey relationships. However, this is not the norm in the microbial world. Unlike most macroscopic organisms, microbes relie on consuming and producing small organic molecules for energy and reproduction. In this thesis, we develop a new Microbial Consumer Resource Model that takes into account these types of metabolic cross-feeding interactions. We demonstrate that this model can qualitatively reproduce and explain statistical patterns observed in large survey data, including Earth Microbiome Project and the Human Microbiome Project. Simulations: Computational simulations are essential in theoretical ecology. Complex ecological models often involve ordinary differential equations (ODE) containing hundreds to thousands of interacting variables. Typical ODE solvers are based on numerical integration methods, which are both time and resource intensive. To overcome this bottleneck, we derived a surprising duality between constrained convex optimization and generalized consumer-resource models describing ecological dynamics. This allows us to develop a fast algorithm to solve the steady-state of complex ecological models. This improves computational performance by between 2-3 orders of magnitude compared to direct numerical integration of the corresponding ODEs. Theories:Few theoretical approaches allow for the analytic study of communities containing a large number of species. Recently, there has been considerable interest in the idea that ecosystems can be thought of as a type of disordered systems. This mapping suggests that understanding community coexistence patterns is actually a problem in "spin-glass'' physics. This has motivated physicists to use insights from spin glass theory to uncover the universal features of complex ecosystems. In this thesis, I use and extend the cavity method, originally developed in spin glass theories, to answer fundamental ecological questions regarding the stability, diversity, and robustness of ecosystems. I use the cavity method to derive new species backing bounds and uncover novel phase transitions to typicality. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.