Durante décadas, a visão prevalente em ecologia de microrganismos era de que os fatores ambientais locais seriam os únicos agentes estruturantes das comunidades e dos padrões de coexistência das espécies. Entretando, estudos recentes têm fornecido evidência de que processos ligados a dispersão possam ser tão importantes quanto o ambiente local na estruturação das comunidades, reacendendo o debate em torno da hipótese clássica sobre a ubiquidade dos microrganismos. Neste estudo, nós examinamos os padrões de coexistência do fitoplâncton e os possíveis determinantes da variação espacial na composição das comunidades em 9 lagoas do sul do Brasil. Nós testamos se as espécies fitoplanctônicas apresentam um padrão não aleatório de coexistência através de um modelo nulo e se distância espacial ou a distância ambiental possuem relação com a similaridade na composição das comunidades. Nós também investigamos se as variáveis ambientais locais são bons preditores da abundância das espécies. Na análise de coexistência, nós não observamos um padrão significativo de estruturação dentro das lagoas, mas encontramos um padrão não-aleatório e segregado das espécies ao longo das lagoas, indicando que as espécies coexistem menos do que o esperado ao acaso nesta escala. A similaridade na composição das comunidades mostrou correlação significativa com a distância ambiental, mas não foi correlacionada com a distância geográfica entre os sítios. Além disso, a variação na abundância das espécies apresentou correlação significativa com as variáveis ambientais locais (transparência da água, condutividade, nitrato e ortofosfato). Em conclusão, nossos resultados apoiam a visão de que a variação espacial do fitoplâncton é melhor explicada pelo ambiente local. Nós não testamos a influência de variáveis históricas e filogenéticas sobre esses padrões, que podem ser temas de estudos futuros, a fim de elucidar ainda mais essas questões. / For decades, the main hypothesis in microbial ecology was that local environment would be the only mechanism structuring communities and patterns of species coexistence. However, recent studies have provided evidence that processes related to dispersion can be as important as the local environment for shaping biological communities, stimulating new debates on the classical hypothesis about the ubiquity of microorganisms. In this study, we examined the phytoplankton coexistence patterns and possible determinants of spatial variation in community composition in 9 lakes of southern Brazil. First, we use a null model analysis for tested whether the phytoplankton species show a nonrandom pattern of coexistence. We also tested whether spatial distance or environmental distance act as potential factors controlling community composition. Finally, we investigated whether local environmental variables are good predictors of species abundance. We did not observe a significant pattern of coexistence species in the within-lakes analysis, but we found a nonrandom pattern of coexistence and segregation of species across-lakes analysis, indicating that the species coexist less than expected by chance on this scale. Phytoplankton community composition showed a strong positive correlation with the environmental distance but was not correlated with the geographical distance between sites. Moreover, the variation in the abundance of species showed significant correlation with local environmental variables (water transparency, conductivity, nitrate and orthophosphate). In conclusion, our results support the view that the spatial variation of phytoplankton is best explained by the local environmental conditions. We suggest that the influences of historical and phylogenetic variables on these patterns, here not measured, be analyzed in future studies, to further elucidate these questions.

Coastal dolphins are often exposed to habitat degradation and direct interactions with humans. Major factors that influence dolphin distribution, critical for conservation concerns, are still poorly understood even for the bottlenose dolphin, the best-studied cetacean. To establish the environmental conditions that best predict occurrence of bottlenose dolphins and high feeding densities in Galveston Bay, I conducted a total of 367 boat surveys in five locations of the estuary, totaling 3,814.77 km of search effort. I counted groups of dolphins and measured surface water temperature, salinity, turbidity, total number of boats, shrimp vessels, and number of seabirds. Using geospatial tools, these data -- along with location, distance to the Gulf of Mexico and water depth -- were analyzed on a 500- m resolution grid. Temporal factors at daily and seasonal scales were also examined. Occurrence was modeled using a Generalized Additive Model and core feeding densities (i.e., feeding densities above 2 SD of the mean) were modeled with a Generalized Linear Model. A total of 1,802 dolphins in 262 groups were detected, 56.87% of which were feeding. I found that all factors except warm/cold seasons and turbidity were useful to predict dolphin distribution, which was related non-linearly to most predictors. Fewer variables were relevant in predicting core feeding densities. These were, in decreasing order of relevance, distance to the Gulf of Mexico, surface water temperature, depth, number of boats, and warm/cold seasons. Feeding was highly clustered and the main core areas, less than approximately 3 km2 wide, were stable across time of day and season. The majority of the occurrences (86.2%) and feeding groups (94%) were situated in two bay locations - Galveston Ship Channel (GSC) and Bolivar Roads (BRD) - that amounted to only one- fifth of the surveyed area. Compared to conditions in GSC and BRD when no dolphins were sighted, feeding cores weredeeper and more seabirds were observed. This fine-scale study of bottlenose dolphin distribution may contribute to a better understanding of habitat requirements for coastal dolphins. It also may provide information needed to minimize potential negative impacts to this population caused by human activities.

Durante décadas, a visão prevalente em ecologia de microrganismos era de que os fatores ambientais locais seriam os únicos agentes estruturantes das comunidades e dos padrões de coexistência das espécies. Entretando, estudos recentes têm fornecido evidência de que processos ligados a dispersão possam ser tão importantes quanto o ambiente local na estruturação das comunidades, reacendendo o debate em torno da hipótese clássica sobre a ubiquidade dos microrganismos. Neste estudo, nós examinamos os padrões de coexistência do fitoplâncton e os possíveis determinantes da variação espacial na composição das comunidades em 9 lagoas do sul do Brasil. Nós testamos se as espécies fitoplanctônicas apresentam um padrão não aleatório de coexistência através de um modelo nulo e se distância espacial ou a distância ambiental possuem relação com a similaridade na composição das comunidades. Nós também investigamos se as variáveis ambientais locais são bons preditores da abundância das espécies. Na análise de coexistência, nós não observamos um padrão significativo de estruturação dentro das lagoas, mas encontramos um padrão não-aleatório e segregado das espécies ao longo das lagoas, indicando que as espécies coexistem menos do que o esperado ao acaso nesta escala. A similaridade na composição das comunidades mostrou correlação significativa com a distância ambiental, mas não foi correlacionada com a distância geográfica entre os sítios. Além disso, a variação na abundância das espécies apresentou correlação significativa com as variáveis ambientais locais (transparência da água, condutividade, nitrato e ortofosfato). Em conclusão, nossos resultados apoiam a visão de que a variação espacial do fitoplâncton é melhor explicada pelo ambiente local. Nós não testamos a influência de variáveis históricas e filogenéticas sobre esses padrões, que podem ser temas de estudos futuros, a fim de elucidar ainda mais essas questões. / For decades, the main hypothesis in microbial ecology was that local environment would be the only mechanism structuring communities and patterns of species coexistence. However, recent studies have provided evidence that processes related to dispersion can be as important as the local environment for shaping biological communities, stimulating new debates on the classical hypothesis about the ubiquity of microorganisms. In this study, we examined the phytoplankton coexistence patterns and possible determinants of spatial variation in community composition in 9 lakes of southern Brazil. First, we use a null model analysis for tested whether the phytoplankton species show a nonrandom pattern of coexistence. We also tested whether spatial distance or environmental distance act as potential factors controlling community composition. Finally, we investigated whether local environmental variables are good predictors of species abundance. We did not observe a significant pattern of coexistence species in the within-lakes analysis, but we found a nonrandom pattern of coexistence and segregation of species across-lakes analysis, indicating that the species coexist less than expected by chance on this scale. Phytoplankton community composition showed a strong positive correlation with the environmental distance but was not correlated with the geographical distance between sites. Moreover, the variation in the abundance of species showed significant correlation with local environmental variables (water transparency, conductivity, nitrate and orthophosphate). In conclusion, our results support the view that the spatial variation of phytoplankton is best explained by the local environmental conditions. We suggest that the influences of historical and phylogenetic variables on these patterns, here not measured, be analyzed in future studies, to further elucidate these questions.

Durante décadas, a visão prevalente em ecologia de microrganismos era de que os fatores ambientais locais seriam os únicos agentes estruturantes das comunidades e dos padrões de coexistência das espécies. Entretando, estudos recentes têm fornecido evidência de que processos ligados a dispersão possam ser tão importantes quanto o ambiente local na estruturação das comunidades, reacendendo o debate em torno da hipótese clássica sobre a ubiquidade dos microrganismos. Neste estudo, nós examinamos os padrões de coexistência do fitoplâncton e os possíveis determinantes da variação espacial na composição das comunidades em 9 lagoas do sul do Brasil. Nós testamos se as espécies fitoplanctônicas apresentam um padrão não aleatório de coexistência através de um modelo nulo e se distância espacial ou a distância ambiental possuem relação com a similaridade na composição das comunidades. Nós também investigamos se as variáveis ambientais locais são bons preditores da abundância das espécies. Na análise de coexistência, nós não observamos um padrão significativo de estruturação dentro das lagoas, mas encontramos um padrão não-aleatório e segregado das espécies ao longo das lagoas, indicando que as espécies coexistem menos do que o esperado ao acaso nesta escala. A similaridade na composição das comunidades mostrou correlação significativa com a distância ambiental, mas não foi correlacionada com a distância geográfica entre os sítios. Além disso, a variação na abundância das espécies apresentou correlação significativa com as variáveis ambientais locais (transparência da água, condutividade, nitrato e ortofosfato). Em conclusão, nossos resultados apoiam a visão de que a variação espacial do fitoplâncton é melhor explicada pelo ambiente local. Nós não testamos a influência de variáveis históricas e filogenéticas sobre esses padrões, que podem ser temas de estudos futuros, a fim de elucidar ainda mais essas questões. / For decades, the main hypothesis in microbial ecology was that local environment would be the only mechanism structuring communities and patterns of species coexistence. However, recent studies have provided evidence that processes related to dispersion can be as important as the local environment for shaping biological communities, stimulating new debates on the classical hypothesis about the ubiquity of microorganisms. In this study, we examined the phytoplankton coexistence patterns and possible determinants of spatial variation in community composition in 9 lakes of southern Brazil. First, we use a null model analysis for tested whether the phytoplankton species show a nonrandom pattern of coexistence. We also tested whether spatial distance or environmental distance act as potential factors controlling community composition. Finally, we investigated whether local environmental variables are good predictors of species abundance. We did not observe a significant pattern of coexistence species in the within-lakes analysis, but we found a nonrandom pattern of coexistence and segregation of species across-lakes analysis, indicating that the species coexist less than expected by chance on this scale. Phytoplankton community composition showed a strong positive correlation with the environmental distance but was not correlated with the geographical distance between sites. Moreover, the variation in the abundance of species showed significant correlation with local environmental variables (water transparency, conductivity, nitrate and orthophosphate). In conclusion, our results support the view that the spatial variation of phytoplankton is best explained by the local environmental conditions. We suggest that the influences of historical and phylogenetic variables on these patterns, here not measured, be analyzed in future studies, to further elucidate these questions.

Ample research explores individual factors associated with sexual violence, yet individual, dyadic, and environmental influences on intimate partner sexual violence (IPSV) occurring in the larger context of non-intimate partner violence (NIPSV) remain relatively unexplored. The current study aimed to determine the extent to which county-level indicators in combination with individual and dyadic factors are associated with sexual violence across relationship types. Reported IPSV and NIPSV cases were obtained from the Tennessee Bureau of Investigation’s (TBI) online incident-based reporting system. County-level variables indicative of neighborhood physical disorder, violent crime, income inequality, firearm prevalence, and community alcohol use patterns were retrieved from the online resource County Health Rankings and Roadmaps. Using a nested case–control design, we determined significant sexual violence risk within younger cohorts and across relationship types, finding three significant county-level factors: 1) income inequality, 2) rate of firearm fatalities, and 3) percentage of female residents. Suggested prevention and intervention efforts include targeting younger age groups for IPSV and NIPSV education, developing resources for a range of relational partners, improving legal access and law enforcement training for reporting, and continued examination of the role of firearms.

Avian malaria (Plasmodium spp.) is a popular model system to study the ecology and evolution of parasite-host-vector interactions in the wild. These studies have historically focused mostly on the avian hosts and the malaria parasites. Knowledge regarding the role of vectors is essential to our understanding of these wild systems, but has only very recently started to accumulate. This thesis aimed to contribute to this field by assessing mosquito-malaria-host associations for British mosquitoes and the role of mosquito ecology in shaping these parasite systems in a British woodland study site, using molecular, field ecology and statistical modelling methodologies. From the 12 mosquito species or species groups found, I showed that the Cx.pipiens/torrentium mosquito group is likely to have a major role in avian malaria transmission in Great Britain, while Cs. annulata may be transmitting P. circumflexum. I also demonstrated a positive spatial association between mosquito density per host and avian malaria prevalence, in accordance with theoretical expectations for malaria transmission. Findings here provide evidence that avian malaria transmission in British woodlands is limited mainly to June-August, being preceded by relapse of previous infections or, alternatively, by maintenance of chronic blood parasitaemia through the colder months; this agrees with theoretical expectations and findings elsewhere for temperate climates. This thesis also described local-scale spatial heterogeneity and seasonal variation in adult mosquito abundance within a British woodland where avian malaria is endemic, with differing patterns found between species or species groups. Spatially, variation in adult mosquito abundance was associated with microclimatic and landscape variables such as distances to mosquito breeding sites, microclimate and canopy height; seasonally, variation in mosquito abundance was associated with temperature and rainfall, alongside calendar date. The heterogeneity in mosquito parameters and associations with environmental variables found at a site where avian malaria is endemic highlights the need to anticipate such complexity when trying to understand Plasmodium transmission. By doing so, we further extend the potential of these parasite systems to improve our knowledge regarding the ecology and evolution of parasite-host-vector associations.