Bacteria are ubiquitous to marine living surfaces, taking on a broad spectrum of roles from mutualistic to pathogenic. Despite their universality, much remains unknown about their basic ecology and interactions with higher organisms. To address this gap, this thesis firstly examines the bacterial communities associated with three co-occurring marine eukaryote hosts from temperate Australia: the demosponge Cymbastela concentrica, the subtidal red macroalga Delisea pulchra and the intertidal green macroalga Ulva australis. Molecular characterisation of the bacterial communities was undertaken using 16S rRNA gene library analysis to compare within-host (alpha) and between-host (beta) diversity for the three microbial communities. This study highlights the potentially substantial contribution host-associated microorganisms could have on marine microbial diversity. The remaining focus for this thesis was on the bacterial community associated with D. pulchra. This alga produces a suite of biologically active secondary metabolites (furanones) that non-toxically inhibit acyl homoserine lactone (AHL)-driven quorum sensing in bacteria, affecting a range of phenotypes including colonisation and virulence traits. The ecology of D. pulchra???s epiphytic bacteria was investigated using a mechanistic approach to explain bacterial colonisation patterns. In particular, concepts and models of ecological succession founded in eukaryote ecology were investigated. The thesis concludes with a study investigating the effect of furanones and elevated temperature on bacteria-induced disease and thallus bleaching of D. pulchra. In the presence of furanones colonisation and infection of two Roseobacter isolates from D. pulchra???s epiphytic bacterial community were inhibited. Ruegeria strain R11 was demonstrated to have temperature regulated virulence, which caused thallus bleaching in furanone-free algae. The implications of elevated sea temperatures resulting from global warming for algal health are discussed.

Floods are major disturbance events for riverine ecosystems, directly and indirectly impacting organisms and their habitat. In this study I investigated the role of riverine floods and flow alteration in regulating aquatic macroinvertebrate population and community structure. I examined this problem using a variety of methods: a meta-analytic review of primary studies from the literature, a mathematical model synthesizing population and flood ecology, a multi-year experimental flood program in an arid-land river, and a field investigation of flood recovery behaviors in a charismatic larval odonate. I found that floods significantly reduced invertebrate abundance in the short term, but had varied effects across particular study sites, microhabitats, and taxonomic groups. I determined that both resistant and resilient capabilities are important to persistence of invertebrate populations after disturbance events, and that these traits may act in a binary fashion. Recovery over time of invertebrate populations may be partially due to "hidden resistance" of spatially displaced individuals in side-channels, benthic substrate, and vegetation or wood. Some invertebrates adapted to flood-prone rivers may possess behavioral adaptations for returning to the main-channel of the river after flood events. This dissertation contributes to riverine disturbance ecology and provides information useful to prediction and management of ecosystem flows in rivers. / Graduation date: 2012

Impacts of ecological competition are reduced when organisms play different roles in their environment. More individuals can survive on varied but finite sets of resources when organisms eat different kinds of prey, live in different places, or are active at different times. Species within an assemblage of small fossorial snakes have ecologies that vary mostly by diet. Different species eat very different things. Species live in different habitats on sand ridges, but the differences are less dramatic than in diet. Disparity in resource use typically varies the most according to species, so that individuals of the same species are more similar to each other than they are to individuals of other species. However, variation exists in resource use within species over time and space. Wide variation exists in dietary resource use in four well-sampled species of comb-eared skinks. However, where species occur at the same study site there are clear distinctions in resource use between species despite the wide variation in diets observed between individuals of the same species. Additionally, strict ecological distances in diet between species are maintained during five censuses that were conducted over a 16-year period. These results illustrate the basic ecological principals of fundamental and realized niches. Here, individuals ate many different food items and species have the potential to overlap in diet but that overlap is reduced because of realized ecological boundaries between species within a single place and time, which result in decreased competition for resources. / text

No description available.

The degree to which biotic interactions influence invasion success may partly depend on the evolutionary relationship between invaders and native species. In particular, since host-use by enemies such as invertebrate herbivores and fungal pathogens tends to be phylogenetically conserved, exotic plants that have close native relatives in the invaded range should be more likely to interact with enemies. In this thesis, I explore this idea using a series of experiments and field surveys at nested taxonomic levels. My results indicate that exotics from multiple plant families experience lower damage if their average phylogenetic distance from locally co-occurring native family members is higher. I then demonstrate that within the Asteraceae, foliar and capitular damage are lower on exotic compared to native species. Both damage types had a relatively large phylogenetic component, but did not decline with phylogenetic distance to native or exotic confamilials. Finally, I show that communities with versus without close relatives are unlikely to differ in resistance to the novel invader, Solidago virgaurea: biotic resistance imposed by competitors, generalist vertebrates, and specialist invertebrates resulted in similar patterns of damage and mortality regardless of the presence of congeneric natives. In some cases, effects of biota were positive: growth of S. virgaurea seedlings in soils collected near congeneric natives was enhanced more than in soils from communities where congenerics were absent. Overall, these results suggest that biotic interactions between exotic and native species can be phylogenetically structured, although trends based on distance measures tend to be weak. In some cases, damage does decline with phylogenetic distance to native species; however this trend is unlikely to be a strong force limiting invasion or structuring plant communities. These results have significant implications for current theories of invasion biology including the "Enemy Release Hypothesis" and "Darwin's Naturalization Hypothesis", as well as for community phylogenetics.

Bacteria are ubiquitous to marine living surfaces, taking on a broad spectrum of roles from mutualistic to pathogenic. Despite their universality, much remains unknown about their basic ecology and interactions with higher organisms. To address this gap, this thesis firstly examines the bacterial communities associated with three co-occurring marine eukaryote hosts from temperate Australia: the demosponge Cymbastela concentrica, the subtidal red macroalga Delisea pulchra and the intertidal green macroalga Ulva australis. Molecular characterisation of the bacterial communities was undertaken using 16S rRNA gene library analysis to compare within-host (alpha) and between-host (beta) diversity for the three microbial communities. This study highlights the potentially substantial contribution host-associated microorganisms could have on marine microbial diversity. The remaining focus for this thesis was on the bacterial community associated with D. pulchra. This alga produces a suite of biologically active secondary metabolites (furanones) that non-toxically inhibit acyl homoserine lactone (AHL)-driven quorum sensing in bacteria, affecting a range of phenotypes including colonisation and virulence traits. The ecology of D. pulchra???s epiphytic bacteria was investigated using a mechanistic approach to explain bacterial colonisation patterns. In particular, concepts and models of ecological succession founded in eukaryote ecology were investigated. The thesis concludes with a study investigating the effect of furanones and elevated temperature on bacteria-induced disease and thallus bleaching of D. pulchra. In the presence of furanones colonisation and infection of two Roseobacter isolates from D. pulchra???s epiphytic bacterial community were inhibited. Ruegeria strain R11 was demonstrated to have temperature regulated virulence, which caused thallus bleaching in furanone-free algae. The implications of elevated sea temperatures resulting from global warming for algal health are discussed.

Les écosystèmes tropicaux, en particulier les écosystèmes amazoniens, sont connus pour abriter une importante diversité d'organismes, terrestres ou aquatiques. Cependant, les causes et les processus responsables de cette grande diversité dans les assemblages de poissons d'eau douce restent encore peu connus, et leur identification est un fort enjeu dans l'évaluation future des impacts des perturbations humaines qui sont grandissantes dans ces milieux. Nous avons étudié les processus qui façonnent la diversité et la structure des assemblages de poissons d'eau douce de Guyane dans les petits cours d'eau et les fleuves non impactés par les activités humaines. La diversité au sein des assemblages de petits cours d'eau augmente le long du gradient amont/aval et dans les milieux où l'habitat est plus diversifié. L'identité des espèces change le long de ce gradient, définissant des zones le long du cours d'eau. Les relations spatiales entre les assemblages et leur isolement ont aussi un fort effet sur les assemblages. En incorporant les informations sur les traits des espèces (diversité fonctionnelle) et leur relation de parenté (diversité phylogénétique), nous avons montré que la diversité au sein des assemblages n'était pas influencée par l'environnement ou les interactions entre les espèces. Nous avons aussi confirmé le fort effet de la limite à la dispersion entre les assemblages, en lien avec l'histoire passée des bassins versants, dans les petits cours d'eau et dans les fleuves. De telles études sur les processus structurant les assemblages nécessitent l'acquisition de données biologiques plus complètes, et donc le développement d'une nouvelle méthode d'échantillonnage qui soit exhaustive et non invasive. Pour cela, nous avons testé le metabarcoding environnemental (l'identification moléculaire des espèces présentes à partir d'un échantillon d'eau). Cette méthode donne des résultats complémentaires aux pêches traditionnelles et nécessite encore un travail de développement et des tests supplémentaires pour améliorer son efficacité et permettre son utilisation pour identifier les processus structurant les assemblages. Ces travaux, aussi bien pratiques que théoriques, sont nécessaires au développement d'un meilleur cadre conceptuel sur la structure des assemblages de poissons tropicaux, et dans la construction d'indicateurs d'impacts d'activités humaines sur les écosystèmes. / Tropical ecosystems, especially Amazonian ecosystems, host a great diversity of terrestrial and aquatic organisms. However, the causes and the processes behind this high diversity for freshwater fish assemblages are little known, but their identification will be an asset in the assessment of anthropogenic impacts that are increasing in these regions. We studied the processes that shape the diversity and the structure of freshwater fish assemblages of non-impacted streams and rivers located in French Guiana. Within-assemblage diversity increased along an upstream/downstream gradient and was higher in sites where the habitat was diversified. Species identity changed along this gradient, which created zones along the stream. Spatial relationships between assemblages and their isolation also greatly impacted species assemblages. Using information about species traits (functional diversity) and their phylogenetic relationships (phylogenetic diversity), we showed that within-assemblage diversity was not influenced by the environment or by species interactions. We also confirmed that dispersal limitation, linked with the past history of drainage basins, had a strong effect on assemblage structure in both streams and in rivers. Future investigations on the processes structuring fish assemblages will need to acquire more exhaustive biological data, and therefore to develop an efficient, and non-destructive sampling method. To this aim, we evaluated the efficiency of environmental metabarcoding applied to aquatic assemblages (the molecular identification of species present from a water sample) and compared it to traditional sampling methods. Currently, metabarcoding gives complementary information to traditional sampling. It thus needs developments and further tests to increase its efficiency and allow its use for assembly processes studies. Pursuing the formalization of a conceptual framework to investigate assembly rules together with the development of an efficient fish sampling protocol are now needed to better understand the structure of tropical fish assemblages. Those theoretical and practical developments will contribute to better evaluate anthropogenic disturbances on aquatic ecosystems.

Os afloramentos rochosos ferruginosos denominados bancadas lateríticas podem ser considerados uma paisagem peculiar no Centro-Oeste do Brasil, próximos às cidades de Corumbá e Ladário, MS. Embora situada em uma região populosa, próxima a fazendas e sítios urbanos, esta vegetação ainda é desconhecida. Neste estudo avaliamos a composição florística e a estrutura da comunidade, bem como suas relações florísticas com outros afloramentos rochosos. O levantamento foi conduzido em três locais - Banda Alta (19°08´S, 57°34´W, 85 m altitude); São Sebastião do Carandá (19°06´S, 57°31´W, 90 m) e Monjolinho (19°16´S, 57°31´W, 65-150 m). A vegetação encontrada nestes afloramentos rochosos ocorre como uma cobertura contínua sobre o substrato rochoso ou como ilhas de solo. Para o estrato contínuo, a vegetação foi amostrada em parcelas de 1 m² distribuídas aleatoriamente. A própria ilha de solo foi considerada uma unidade amostral. A composição de espécies e os valores de cobertura foram avaliados em cada parcela ou ilha de solo. Avaliaram-se 199 parcelas e 164 ilhas de solo neste estudo. Além da abundância das espécies o tamanho e outras características das ilhas de solo foram incluídas neste levantamento. Os dados foram explorados através de tabelas fitossociológicas e de técnicas estatísticas de classificação e ordenação. As relações florísticas foram exploradas nos níveis taxonômicos de famílias e gêneros pela comparação de listas de espécies publicadas de outros afloramentos. Foram amostradas 188 espécies pertencentes a 58 famílias nas três bancadas lateríticas. Deste total, 66 espécies foram encontradas nas parcelas e 181 nas ilhas de solo. A estrutura da comunidade é influenciada, principalmente, pela presença de fina camada de substrato e pela área insular. Processos envolvendo competição exclusiva e diferentes respostas ao regime hídrico aparentemente podem ser as maiores fontes da separação espacial e padrões de abundância. A flora das bancadas lateríticas mostrou similaridade com a flora de afloramentos graníticos da Caatinga, em nível de famílias e gêneros. Condições climáticas e outros fatores podem influenciar as disjunções florísticas observadas mas o substrato rochoso parece ser o fator determinante, com exceção das bancadas lateríticas. Esperava-se que as bancadas fossem similares a outros afloramentos ferruginosos mas isto não ocorreu, sugerindo um importante efeito da história paleoclimática da plataforma continental nos padrões de composição e abundância de espécies da comunidade vegetal das bancadas lateríticas. / The ironstone outcrops called bancadas lateríticas can be considered a peculiar feature of the Central Brazil landscape nearby the cities of Corumbá and Ladário (MS). Although situated in a populated region, near farmlands and cities, the vegetation occurring on these outcrops is completely unknown. In this work we aim to explore the species composition, the floristic relations with other rock outcrops and the community structure of the vegetation thriving on the ironstone surface of the bancadas. The survey was conducted in three outcrops - Banda Alta (19°08´S, 57°34´W, 85 m altitude); São Sebastião do Carandá (19°06´S, 57°31´W, 90 m) and Monjolinho (19°16´S, 57º31´W, 65-150 m). The vegetation found on the rock outcrops occurred as a continuous cover or in groups called soil-islands. In the continuous formation, the vegetation cover was sampled by random Quadrats of 1 m2. A single soil island was taken as a sample unit. The species composition and correspondent cover value was evaluated for each quadrat and soil island. A total of 199 random quadrats and 164 soil islands was used in this work. Along with the abundance of species, the size and other features of each soil islands were included in the survey. The data was explored by the construction of phytosociological tables and statistical classification and ordination techniques. The floristic relations were explored at the level of families and genera by comparisons with published species lists from other outcrops. We detected 188 species belonging to 58 plant families on the three Bancadas outcrops. From this total, 66 species were found in random quadrats and 181 in soil islands. The community structure is primarily influenced by the substrate thickness and the soil island area. Processes involving apparent species competitive exclusion and different responses to water regime can be major sources of the overall spatial disjunction and abundance patterns. The bancadas flora showed similarities with the flora of granite outcrops in the Caatinga formation at the level of genera and families. Climate and other factors can play a role in the floristic disjuntions observed but the rock substrate poses as a dominant factor with the exception of the Bancadas. The departure from the expected similarity with other ironstone outcrops suggests an important effect of Paleoclimatic history of the continental shelf in the patterns of species composition and abundance in the Bancadas plant community.

abstract: Identifying the ecological role, or niche, that a species occupies within their larger community elucidates environmental adaptability and evolutionary success. This dissertation investigates the occupied niche of chimpanzees (Pan troglodytes schweinfurthii) living in an open, dry savanna-woodland environment by examining patterns of resource use and interspecific interactions. Data were collected October 2010--November 2011 at Issa, in the Ugalla region of western Tanzania, which is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. Unlike most primatological studies which employ methods that include focal follows, this study focused instead on observing 'resource patches' for chimpanzees. Patch focals allow for the observation of all animals within a study area; capture resources that are not used by the study species; and are particularly well suited for unhabituated communities. In order to better understand relationships between environment and behavior, data collected at Issa are compared with published data from other chimpanzee populations. Issa chimpanzees were expected to have broader resource use than forest chimpanzees, as well as increased competition with other fauna, due to fewer available resources. However, in contrast to the assumption of food scarcity in dry habitats, dietary resources were available throughout the year. Like other populations, the diet of Issa chimpanzees consisted of mostly fruit, but unlike at other sites, the majority of plants consumed were woodland species. Additionally, although chimpanzees and other fauna shared spatial and dietary resources, there was only nominal overlap. These results point to extremely low levels of indirect competition between chimpanzees and other fauna. Despite extensive study of forest chimpanzees, little is known about their role within their faunal community in open, dry habitats, nor about how greater seasonality affects resource use. This project addresses both of these important issues and fosters novel approaches in anthropological studies, especially in reference to chimpanzee ecology and evolution. Understanding current chimpanzee behavioral relationships with their environments shapes hypotheses about their pasts, and also informs predictions about behaviors of similar taxa in paleo-environments. Lastly, examining the ecological role of chimpanzees within their larger communities will influence the formation of, as well as evaluate, conservation strategies. / Dissertation/Thesis / Ph.D. Anthropology 2013

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No. of bitstreams: 2 Tese Rodrigo Assis de Carvalho -2014.pdf: 3328420 bytes, checksum: a1e02cfe43c98e24427c7466b7570d2d (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-03-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Species richness became a classical descriptor of biological communities, however, this concept does not encompass functional differences among species which may be linked to the functioning and the maintenance of ecosystem processes. For example, species with similar ecological traits should play similar ecological functions while species with distinct traits should play different functions. Understanding functional patterns of communities and how ecological processes act on their structuring is a challenge to ecologists, mainly in environments poorly known as tropical freshwater systems. In this context, the main goals of this thesis are to: i) test if the functional structure of headwater fish assemblages are influenced by drainage area and/or environmental components of basins; ii) comprehend the functional structure of river and headwater stream fish assemblages and evaluate the role of environment and spatial components on this structure; iii) test if functional diversity and species diversity patterns, besides spatial priorities for their conservation, are spatially congruent. The first objective was evaluated with a set of 25 headwater streams distributed in the Araguaia (13) and Tocantins (12) River basins. We tested for (dis)similarities among Araguaia and Tocantins fish assemblages with an analysis of similarities (ANOSIM), and we evaluated the role of space and environment on fish assemblages functional structure with RLQ and Fourthcorner analyses. We found a functional dissimilarity between fish assemblages of Araguaia and Tocantins (R = 0.09, p = 0.03) and RLQ was significant for trait/environment relationships (p = 0.005), although spatially structured environment also seems to be relevant. Altitude, channel depth, water temperature, turbidity and conductivity are environmental variables that influenced: body mass, water column position, substrate preference, parental care, foraging location and migratory habits. In this ways, fish assemblages' functional structure of Araguaia and Tocantins River basins are delimited is influenced by both space and local conditions of the environment. For evaluating the second objective, we calculate the net relatedness index (NRI) of 22 rivers and 27 headwater stream of Tocantins-Araguaia basin and related them with environmental variables of each watercourse. We used a variation partitioning for understanding how much of NRI variation could be explained by environment and/or space. The spatial pattern of NRI indicated that fish assemblages from headwater streams tend to be functionally clustered and from rivers overdispersed, and their separation is associated with four environmental variables: depth, width, water velocity and dissolved oxygen. However, variation partitioning indicated a lower influence of the environment on NRI variation when compared with the spatial components. Therefore, the functional structure of rivers and headwater streams is associated with neutral processes such as the dispersal limits of each species through the space. We evaluated the third objective using 21 units formed by the combination of one river and one headwater stream. Utilizing null models, we verified if units with higher species richness also have higher functional diversity. We created conservation scenarios for species richness and functional diversity with an algorithm of complementarity. No unit had higher functional diversity than expected by it species richness, which might indicate the possibility of developing a single conservation strategy for them. However, the congruence between conservation scenarios for species richness and functional diversity seems to be the result of the algorithm used that selects areas harboring species with restricted spatial occurrence, independently of other criteria used. / A riqueza de espécies é um descritor clássico das comunidades biológicas, porém, seu conceito não engloba as diferenças ecológicas entre as espécies que podem estar ligadas à manutenção de processos ecossistêmicos. Por exemplo, espécies com características ecológicas semelhantes devem desempenhar funções ecológicas similares enquanto as de características distintas desempenhariam funções diferentes. Entender os padrões funcionais das comunidades e os processos que atuam sobre a sua estruturação é um desafio para os ecólogos, principalmente em ambientes pouco conhecidos como os de água doce tropicais. Dentro deste contexto, os objetivos desta tese são: i) testar se a estrutura funcional das assembleias de peixes de riachos pode ser influenciada pelos limites da área de drenagem e/ou pelos componentes ambientais das bacias hidrográficas; ii) compreender a estruturação funcional das assembleias de peixes em rios e riachos de cabeceira e avaliar o papel do ambiente e do espaço sobre esta estruturação; iii) testar se os padrões de diversidade funcional e de riqueza de espécies das assembleias de peixes, além das prioridades espaciais para sua conservação, são congruentes espacialmente. O primeiro objetivo foi testado com um conjunto de 25 riachos distribuídos nas bacias hidrográficas dos Rios Araguaia (13) e Tocantins (12). Testamos as (dis)similaridades entre as assembleias de peixes do Araguaia e Tocantins com uma análise de similaridades (ANOSIM), e avaliamos o papel do espaço e do ambiente sobre a sua estrutura funcional com análises de RLQ e Fourthcorner. Encontramos uma dissimilaridade funcional entre as assembleias do Araguaia e Tocantins (R = 0.09, p = 0.03) e a RLQ foi significativa para as associações entre atributos/ambiente (p = 0.005), embora o ambiente espacialmente estruturado também pareça ser relevante. Altitude, profundidade do canal, temperatura da água, turbidez e condutividade são as variáveis do ambiente que influenciam: massa corporal, posição na coluna d'água, preferência pelo substrato, cuidado parental, local de forrageio e migração. Desta forma, a estrutura funcional das assembleias de peixes das bacias dos Rios Araguaia e Tocantins é influenciada tanto pelo espaço quanto pelas condições locais do ambiente. Para avaliar o segundo objetivo, calculamos os índices de parentesco líquido (NRI) de 22 rios e 27 riachos de cabeceira da bacia Tocantins-Araguaia e os relacionamos com as variáveis ambientais de cada curso d'água. Utilizamos ainda uma partição de variância para compreender o quanto da variação do NRI é explicada pelo ambiente e/ou pelo espaço. O padrão espacial do NRI indicou que as assembleias dos riachos de cabeceira tendem a ser funcionalmente agrupadas e as de rios sobredispersas, e a sua separação está associada a quatro variáveis ambientais: profundidade, largura, velocidade e oxigênio dissolvido. Porém, a partição de variância indicou um papel menor do componente ambiental na variação do NRI em relação aos componentes associados ao espaço. Portanto, a estruturação funcional de riachos e rios está associada a processos neutros, como os limites de dispersão intrínsecos de cada espécie. Avaliamos o terceiro objetivo utilizando 21 unidades formadas por: um rio e um riacho de cabeceira. Por meio de modelos nulos, verificamos se as unidades com maior riqueza de espécies possuíam maior diversidade funcional do que o esperado ao acaso. Criamos ainda cenários de conservação para riqueza de espécies e diversidade funcional com um algoritmo de complementaridade. Nenhuma unidade apresentou maior diversidade funcional do que o esperado pela riqueza de espécies, o que pode indicar a possibilidade de desenvolver uma única estratégia de conservação para ambos. Entretanto, a congruência entre os cenários para a riqueza de espécies e diversidade funcional parece ser resultado do algoritmo utilizado, selecionando áreas com espécies de ocorrência restrita, independente dos demais critérios utilizados.