Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-03-20T15:42:34Z No. of bitstreams: 1 ThiagoLC_DISSERT.pdf: 1446311 bytes, checksum: f9df761557b8cd9c1f4395f10697bdbd (MD5) / Made available in DSpace on 2017-03-20T15:42:35Z (GMT). No. of bitstreams: 1 ThiagoLC_DISSERT.pdf: 1446311 bytes, checksum: f9df761557b8cd9c1f4395f10697bdbd (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Species of the Cichla genus have been introduced in a variety of tropical aquatic ecosystems, thus resulting in a marked reduction in diversity and population size of native fish assemblies due to their predatory behavior. Despite Cichla induced impact the mechanisms by which the species are still poorly known. In this study we compared the functional response of an alien predator fish C. kelberi and a native predator H. aff. malabaricus. More specifically, the tested hypotheses were: 1) both predator species have functional responses of type II on different prey species, and 2) the functional responses of the alien predator were higher for all preys when compared to the native predator. The predators were acclimated in tanks of 500 liters and fed twice daily with preys O. niloticus and L.vannamei for 3 days, 4 preys in the morning and 4 in the afternoon. Hunger levels were standardized after a fast of 48 hours. After the pre-experimental phase an exemplar of C. kelberi was randomly introduced in each tank of O. niloticus with initial prey densities of 2, 4, 8, 16, 25 and 40, and for L. vannamei 2, 4, 8, 16, 32 and 64 (n = 4 per density). After 24 hours the number of prey consumed was counted. This method was repeated for the native predator H. aff. malabaricus. Totaling 48 experimental units. The functional response C. kelberi was greater than or equivalent to the native predator H. aff. malabaricus. There was no difference in consumption between the two species at low densities. The attack rate did not differ between the two predators and handling time was driven by C. kelberi for the species O. niloticus. However, the two species showed functional response type II, thus corroborating with the comparative functional response method to predict the impact on native communities. Functional Comparative Response is a quick and reliable method to predict the ecological impacts of invasive species / Espécies do gênero Cichla têm sido introduzidas em vários ecossistemas aquáticos tropicais, resultando em uma redução na diversidade e tamanho populacional de assembleias de peixes nativos, devido a sua atuação predatória. Os mecanismos de predação pelos quais o tucunaré (Cichla kelberi) permanece pouco conhecido. Nesse estudo foram comparadas as resposta funcionais de um peixe predador alienígena C. kelberi e de um predador nativo Hoplias aff. malabaricus. Especificamente, foram testadas as hipóteses: 1) que ambas as espécies de predador apresentam respostas funcionais do Tipo II, na qual a espécie preda em baixa densidade, sobre diferentes espécies de presas, e que 2) as respostas funcionais do predador alienígena foram maiores para todas as presas, quando comparados com o predador nativo. Os predadores foram aclimatados nos tanques de 500 litros e alimentados duas vezes ao dia com alevinos de Oreochromis niloticus e Litopenaeus vannamei durante 3 dias, 4 presas pela manhã e 4 presas a tarde. Os níveis de fome foram padronizados depois de um jejum de 48 horas. Foi introduzido aleatoriamente um exemplar de C. kelberi em cada tanque de O. niloticus com densidades iniciais de presas de 2, 4, 8, 16, 25 e 40 e para L. vannamei 2, 4, 8, 16, 32 e 64 (n = 4 por densidade), e depois de 24 horas contabilizado o número de presas consumidas. Este método foi repetido para o predador nativo H. aff. malabaricus. Totalizando 48 unidades experimentais. A resposta funcional de C, kelberi foi maior ou equivalente a do predador nativo H. aff. malabaricus. Não houve diferença no consumo entre as duas espécies nas baixas densidades. A taxa de ataque não diferenciou entre os dois predadores e o tempo de manipulação foi impulsionado por C, kelberi para a espécie O. niloticus. As duas espécies apresentaram resposta funcional do tipo II corroborando com o método de resposta funcional comparativa de prever os impactos nas comunidades nativas. Respostas funcionais é um método rápido e confiável para previsão de impactos ecológicos de espécies invasoras / 2017-03-20

Nest survival often is lower at habitat edges than in habitat cores because of greater nest predation and parasitism near edges. I studied nest survival of breeding birds in bottomland hardwood forests of the lower Roanoke River, North Carolina. Nesting success was monitored in two forest width classes: narrow bands of levee forest that were dominated by two edge types, and wide, continuous levee forest stands that have edges but most forest is relatively far from edge. Nest success of Acadian Flycatchers and Prothonotary Warblers was similar in narrow and wide levees; nest success of Northern Cardinals was greater in narrow levees. Results of my study indicate that edge effects are not universal, and that amount of contrast at edges may interact with landscape context to alter ecological processes, such as nest predation. Bird populations are remarkably constant over time relative to other taxa, implying strong regulation. Avian population ecologists, however, have not studied regulatory mechanisms as often as seasonal limiting factors. Conversely, avian behavioral ecologists seldom emphasize the population dynamic consequences of habitat selection and reproductive success. This study describes the intersection of individual behavior and population regulation in the context of a new model of population regulation, site dependence, which is based on characteristics of breeding sites and behavior of individuals. I studied habitat distribution, age structure, reproductive output, and breeding site fidelity of Prothonotary Warblers (Protonotaria citrea) in two different bottomland hardwood forest habitats of the lower Roanoke River in North Carolina. Older males (³ 2 yr old) were equally common in cypress-gum swamps and mixed oak hardwood levee forest. Pairing success and success of first nests indicated that older males occupied the most suitable territories available in each habitat. Bird density was three times greater in swamps, and birds nesting in swamps averaged greater clutch sizes and fledged more young per nest than birds in levees. Greater reproductive output was the result of greater fecundity because nest survival and predation pressure appeared equal in the two habitats. Annual return rates for plot immigrants vs. previous residents did not differ in swamps. In levees, newly arriving birds were less likely to return the following year than previous residents. Immigrants most likely occupied low quality sites and dispersed in an attempt to improve breeding site quality. Habitat-specific demography and density patterns of this study indicate ideal preemptive distribution. Variance in site quality, between and within habitats, and preemptive use of sites are consistent with theory of population regulation via site dependence. Foraging behavior often reflects food availability. For example, in habitats where food availability is high, predators should move more slowly and attack prey more often than in habitats where food availability is low. I studied the foraging behavior of breeding Prothonotary Warblers in two habitat types to assess relative food availability and implications for habitat quality. The two habitats, levee and swamp forest, differ in hydrology, forest structure, and tree species composition. I quantified foraging behavior with focal animal sampling and continuous recording during foraging bouts. I measured two aspects of foraging behavior: 1) prey attacks per minute, using four attack types (glean, sally, hover, strike), and 2) number of movements per minute (foraging speed), using three types of movement (hop, short flight [£ 1 m], long flight [>1 m]). Male warblers made significantly more prey attacks per minute in swamp forest than in levee forest; the same trend was evident in females. Foraging speed, however, was not different between habitats for males or females. Results indicate that foraging effort is similar in swamps and levees, but that warblers encounter more prey in swamps. Greater food availability may be related to greater reproductive success of warblers nesting in cypress-gum swamps than in coastal plain levee forest. / Ph. D.

Functional response is the framework thorough which we can quantify how predator hunting behaviors such as rate of successful attack and time spent handling prey interact with prey density to determine the rate at which prey are killed. Cheetahs are mesopredators and their behavior can be shaped by the need to avoid larger predators while hunting relatively large bodied and mobile prey. I used data from 34 years of observed cheetah hunts in Serengeti National Park in Tanzania to investigate how reproductive condition, prey density, seasonality, and the proximity of larger predators affect cheetah kill rates, probability of successful attack, and time spent handling prey. Mothers with cubs had an asymptotic Type II functional response where kill rate increased but eventually leveled-off at high prey densities, while cheetahs without cubs had a dome shaped Type IV functional response where kill rates actually declined at high prey density. Probability of successful attack on prey was higher for mothers with cubs, and increased slightly with prey density. Mothers with cubs had different prey handling behavior than other cheetahs. Cheetah mothers spend longer at kills then other cheetahs despite the risk that the carcass can attract lions and hyenas that could steal the carcass and potentially kill her cubs. Mothers must make sure their cubs have sufficient time at the carcass to eat their fill, thus they minimize risk from larger predators by being vigilant. In contrast, cheetahs without cubs are unconcerned with cub predation and can eat quickly to minimize the risk of kleptoparasitism. My results show how the pressures of cub rearing and coexisting with larger carnivores differentially shape the hunting behavior of cheetahs, and suggest that intensity of mesopredator suppression may depend on individual variability. This is the first time the functional response for a large mesopredator, has been quantified and the first time a dome shaped response has been recorded in a mammal. My work shows the value in accounting for individual variability in functional response and how linking of carnivore hunting behavior to multiple species interactions advances our understanding of how classical ecological theory applies to wild ecosystems. / Ph. D.

Background: Venous thromboembolism (VTE), comprising the conditions of deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common acute cardiovascular event associated with increased long-term morbidity, functional disability, all-cause mortality, and high rates of recurrence. Major advances in identification, prophylaxis, and treatment over the past 3-decades have likely changed its clinical epidemiology. However, there are little published data describing contemporary, population-based, trends in VTE prevention and management. Objectives: To examine recent trends in the epidemiology of clinically recognized VTE and assess the risk of recurrence after a first acute episode of VTE. Methods: We used population-based surveillance to monitor trends in acute VTE among residents of the Worcester, Massachusetts, metropolitan statistical area (WMSA) from 1985 through 2009, including in-hospital and ambulatory settings. Results: Among 5,025 WMSA residents diagnosed with acute PE and/or lower-extremity DVT between 1985 and 2009 (mean age = 65 years), 46% were men and 95% were white. Age- and sex-adjusted annual event rates (per 100, 000) of clinically recognized acute first-time and recurrent VTE was 142 overall, increasing from 112 in 1985/86 to 168 in 2009, due primarily to increases in PE occurrence. During this period, non-invasive diagnostic VTE testing increased, vi while treatment shifted from the in-hospital (chiefly with warfarin and unfractionated heparin) to out-patient setting (chiefly with low-molecular-weight heparins and newer anticoagulants). Among those with community-presenting first-time VTE, subsequent 3-year cumulative event rates of key outcomes decreased from 1999 to 2009, including all-cause mortality (41% to 26%), major bleeding episodes (12% to 6%), and recurrent VTE (17% to 9%). Active-cancer (with or without chemotherapy), a hypercoagulable state, varicose vein stripping, and Inferior vena cava filter placement were independent predictors of recurrence during short- (3-month) and long-term (3-year) follow-up after a first acute episode of VTE. We developed risk score calculators for VTE recurrence based on a 3-month prognostic model for all patients and separately for patients without active cancer. Conclusions: Despite advances in identification, prophylaxis, and treatment between 1985 and 2009, the disease burden from VTE in residents of central Massachusetts remains high, with increasing annual events. Declines in the frequency of major adverse outcomes between 1999 and 2009 were reassuring. Still, mortality, major bleeding, and recurrence rates remained high, suggesting opportunities for improved prevention and treatment. Clinicians may be able to use the identified predictors of recurrence and risk score calculators to estimate the risk of VTE recurrence and tailor outpatient treatments to individual patients.