Made available in DSpace on 2016-06-02T19:32:00Z (GMT). No. of bitstreams: 1 4125.pdf: 2555973 bytes, checksum: 6e384fbcd72f2a660b5bc6c0cf0c8739 (MD5) Previous issue date: 2012-02-10 / Financiadora de Estudos e Projetos / The studies related to the interactions among populations in the aquatic communities are essential for providing relevant information for the understanding of energy and matter pathways in the ecosystems and subsidize to the formulation of trophic web models.The occurrence of flexible diets is a marked feature of many species in the ichthyofauna of Tropical Rivers, where the same species can alternate the exploitation among food items according to the changes in the relative availability of food resources induced by temporal spatial and or ontogenetic changes. In this context, this study aimed to analyze the trophic interactions existing between the species Geophagus brasiliensis (Quoy & Gaimard, 1824) (Osteichthyes, Cichlidae), and benthic macroinvertebrate community in three reservoirs (Monjolinho Reservoir, Fazzari Reservoir, Broa Reservoir) in order to know its feeding mode, whether there is food selectivity or preference and which would be the most suitable trophic category for the species. Benthic macroinvertebrate communities in sediments sampled simultaneously to G. brasiliensis population were analysed and experiments were carried out in order to know the feeding mode of the species. Biometric measurements for ecomorphological analyses and analysis of stomach contents of the fishes were performed and based on qualitative and quantitative analyses of the macroinvertebrates consumed and their availability in the environment the values for the selectivity index of Paloheimo were calculated for the reservoirs sampled. The results showed that benthic macroinvertebrates are often used as food resource by the populations of G. brasiliensis with great participation in its diet, allowing us to characterize this species as a benthivore. Also, it was observed that G. brasiliensis has food preference for Chironomidae larvae. / Os estudos sobre as interações tróficas entre populações nas comunidades aquáticas são fundamentais por fornecerem informações relevantes para o entendimento dos caminhos do fluxo de energia e de matéria nos ecossistemas e subsidiar a formulação de modelos sobre teias tróficas. A ocorrência de dietas flexíveis é uma característica marcante de muitas espécies da ictiofauna fluvial tropical, onde uma mesma espécie pode alternar a exploração de itens alimentares em função das variações na disponibilidade relativa do recurso alimentar motivadas por alterações temporais, espaciais e ou ontogênicas. Neste contexto, este trabalho teve por objetivo analisar as interações tróficas existentes entre a espécie Geophagus brasiliensis (Quoy & Gaimard, 1824) (Osteichthyes, Cichlidae) e a comunidade de macroinvertebrados bentônicos em três represas (Represa do Monjolinho, Represa do Fazzari e Represa do Broa), a fim de avaliar seu modo de alimentação, verificar se existe seletividade ou preferência alimentar e em que categoria trófica esta espécie melhor se enquadra. Foi analisada a composição dos macroinvertebrados bentônicos em sedimentos coletados simultaneamente as amostragens das populações de G. brasiliensis, e foram realizados experimentos em laboratório para verificar o modo como a espécie se alimenta. Medidas biométricas para caracterização ecomorfológica e análises do conteúdo estomacal dos peixes foram feitas e com base nas análises qualitativas e quantitativas dos macroinvertebrados consumidos e sua disponibilidade no ambiente foram calculados os valores do índice de seletividade de Paloheimo para os reservatórios amostrados. Os resultados mostraram que os macroinvertebrados bentônicos são frequentemente utilizados como recurso alimentar pelas populações de G. brasiliensis, tendo grande participação em sua dieta, o que poderia caracterizá-la como uma espécie bentívora. Observou-se também que G. brasiliensis tem preferência alimentar por larvas de Chironomidae.

Made available in DSpace on 2016-06-02T19:29:26Z (GMT). No. of bitstreams: 1 3114.pdf: 4153155 bytes, checksum: 9c4f4c3e1041563aa6254cc622f8352d (MD5) Previous issue date: 2010-05-28 / Financiadora de Estudos e Projetos / Studies on the feeding of fishes provide relevant information for understanding the mechanisms allowing the coexistence and exploitation of resources by several species of fishes and also by other components of the aquatic communities.. The objective of the present study was to analyze in detail the feeding habits and the ecomorphology of the fish species Pimelodus fur and Leporinus reinhardti as well as to preliminarily characterize the fedding habits and describe the morphological characteristics of other nine species of fish occurring in a stretch of the Upper São Francisco River Basin. Fishes were sampled in four periods: December 2006 and 2008 (rainy periods) and April 2007 and June 2008 (dry periods) using with gillnets, seine nets and sieve. The results on the feeding ecology of P.fur revealed that this species belong to the trophic gulid of the insectivores, since insects represent between 74.0% and 79.0% of its diet. There were seasonal changes in the diet of P. fur, with food items essentially authochtonous, as aquatic insects larvae being consumed in the dry periods and insects from terrestrial sources, as Araneae and Hymenoptera being added to its diet during the rainy periods, in both São Francisco River and its tributary Piumhi River. In these rivers P. fur displayed high trophic specialization, being a specialist in consuming aquatic insects. It was also observed great overlap in the food items consumed by the different size classes of P. population sampled in both rivers. L. reinhardti had intense feeding activity in both seasons dry and rainy periods. This species belong to the trophic guild of herbivores, being its diet composed mainly by plant material. The feeding spectrum of L. reinhardti is wider in São Francisco River than in the Piumhi River, what can be a consequence of the fact that the gallery forest in the São Francisco River is better preserved in this region than that of the Piumhi River. There were seasonal changes in the diet of L. reinhardt, with some food items as Trichoptera and Hymenoptera only being consumed in the rainy periods. There was no significant change in the diet of L. reinhardti along its development, with preference by plant material in all size classes. L. reinhardti is a feeding specialist with narrow niche breath. There was no feeding niche overlap between P. fur and L. reinhardti in any seasonal period or river stretch studied. Although feeding activity of both P. fur and L. reinhardti was intense during all periods analyzed, the narrow feeding niche breath and the large diet overlap among the size classes within each species population indicate that food sources are abundant in this part of the Upper São Francisco River basin. Regarding the morphological characteristics there was also trophic structuring of the species studied in Piumhi and São Francisco Rivers, with segregation between the body shape of the specialists (insectivores and piscivores) and the more generalist feeders (omnivores and herbivores). / Os estudos sobre a alimentação de peixes fornecem informações importantes para a compreensão dos mecanismos que permitem a coexistência e exploração dos recursos por várias espécies de peixes e pelos demais componentes das comunidades aquáticas. O objetivo deste estudo foi analisar detalhadamente o hábito alimentar e a ecomorfologia das espécies de peixe Pimelodus fur (mandi-branco) e Leporinus reinhardti (piau-de-três-pintas), bem como descrever preliminarmente os hábitos alimentares e as características morfológicas de outras nove espécies de peixes com ocorrência em um trecho da bacia do alto rio São Francisco. Os peixes foram coletados em dezembro de 2006 e dezembro de 2008 (períodos chuvosos) e abril de 2007 e junho de 2008 (períodos secos), utilizando-se redes de espera, redes de arrasto, tarrafas e peneiras. Os resultados sobre a alimentação de P. fur revelaram que esta espécie pertence à guilda trófica insetívora, sendo que os insetos representaram entre 74 a 70% de sua dieta. Foi observada variação estacional na alimentação de P. fur, com itens alimentares essencialmente autóctones sendo consumidos no período de seca (larvas de insetos aquáticos) e com artrópodos de origem terrestre (Araneae e Hymenoptera) sendo adicionados à sua dieta no período chuvoso em ambos os rios estudados, Rio São Francisco e Rio Piumhi. Nos rios estudados P. fur apresentou elevada especialização trófica, sendo uma espécie especialista no consumo de insetos aquáticos. Verificou-se também elevada sobreposição alimentar entre as diferentes classes de tamanho de P. fur na população amostrada em ambos os rios. L. reinhardti tem uma alta atividade alimentar em ambos os períodos climáticos, seca e cheia. A espécie L. reinhardti pertence à guilda alimentar herbívora, sendo a sua dieta composta preferencialmente por vegetais superiores. O espectro alimentar de L. reinhardti é mais amplo no Rio São Francisco, do que no Rio Piumhi, provavelmente pelo fato desse trecho do rio apresentar vegetação ciliar mais preservada. Verificou-se variação estacional na alimentação do piau-três-pintas, onde alguns itens como fragmentos de insetos, Trichoptera e Hymenoptera só foram consumidos na estação chuvosa. Não houve variação na dieta ao longo do desenvolvimento de L. reinhardti, sendo observada a preferência por material vegetal em todas as classes de tamanho. L. reinhardti é um peixe especialista, com pequena amplitude de nicho em todas as classes de tamanho. Não ocorreu sobreposição alimentar entre P. fur e L. reinhardti em nenhum dos períodos ou rio avaliados. Embora a atividade alimentar de P. fur e L. reinhardti tenha sido intensa em todos os períodos, a pequena amplitude do nicho e a grande sobreposição alimentar entre as diferentes classes de tamanho em cada espécie sugere que os recursos alimentares sejam abundantes neste trecho do Alto Rio São Francisco. Observou-se estruturação trófica quanto à morfologia das espécies estudadas nos rios Piumhi e São Francisco, com a separação entre as formas do corpo das espécies mais especialistas (insetívoros e piscívoros) daquelas das espécies mais generalistas (onívoro e herbívoro).

Comprendre comment évoluent les écosystèmes lors de perturbations majeures de l'environnement nécessite de prendre en compte l'histoire évolutive des espèces, c'est-à-dire leur phylogénie. Dans ce Mémoire de thèse, j'utilise une approche modélisatrice afin d'étudier l'évolution phénotypique en lien avec l'environnement (écomorphologie), approche incluant des données actuelles et fossiles et visant in fine à comprendre comment les écosystèmes se diversifient et s'organisent structurellement et fonctionnellement à l'échelle des temps géologiques. Le cadre historique, fourni par la phylogénie, définit une trame analytique commune à l'étude de taxons actuels et fossiles. Différents outils dédiés, d'une part au traitement de données morphométriques souvent incomplètes, et d'autre part aux études écomorphologiques évolutives dans un contexte phylogénétique, sont développés et discutés. Cette thèse s'articule autour de deux ateliers consacrés à l'étude macroévolutive et macroécologique de grands mammifères « ongulés » : Bovidae, Cervidae, et Equidae. Le premier atelier concerne les ruminants actuels, clade très diversifié et à l'écologie des espèces constitutives connue. Les analyses révèlent des modes évolutifs contrastés entre Cervidae et Bovidae actuels, en fonction des niches écologiques et des caractères écomorphologiques considérés. La diversification moi pliocène des Bovidae africains apparaît corrélée à des évènements globaux, tandis que leur évolution phénotypique révèle des modes de diversification différents selon les habitats. Le second atelier est focalisé sur l'impact d'un événement majeur ayant affecté l'ensemble du pourtour méditerranéen à la limite Miocène- Pliocène, il y a 5,3 millions d'années : la Crise de Salinité Messinienne. Il repose sur l'étude d' « ongulés » fossiles et apporte des précisions sur l'aspect temporel de l'évolution de ces mammifères avant et après cet événement. Les principaux résultats illustrent des variations rapides de la structure phylogénétique des assemblages d'ongulés qu'il est possible de relier au contexte biogéographique et aux variations climatiques locales et régionales. Les renouvellements fauniques (acteurs) et fonctionnels (rôles), initiés dès la fin du Miocène moyen, apparaissent progressifs et non soudains. Les résultats obtenus offrent une meilleure caractérisation et compréhension des réponses évolutives de ces mammifères, grands consommateurs primaires souvent parmi les premiers menacés lors de perturbations climatiques et environnementales majeures / Understanding how ecosystems evolve when facing severe climatic perturbations of the environment requires an historic perspective provided by species phylogenies. In this thesis, I use a modelling framework to investigate the question of the phenotypic evolution of species as an adaptation to the environment (ecomorphology). I combine extant and fossil data to study how ecosystems are diversifying and organizing structurally and functionally on a geological time scale. The historical context provided by the phylogeny defines a unified analytical framework for the study of extant and fossil taxa. Several analytical tools dedicated, on the one hand to deal with missing cases in morphometric studies, and on the other hand to ecomorphological studies in a phylogenetic context, are developed and discussed. This PhD thesis is organized along two main research axes dedicated to the macroevolutionary and macroecological study of three large mammals “ungulate” families: Bovidae, Cervidae, and Equidae. First I focus on extant ruminants, a well diversified clade for which species ecological preferences are well known. The analyses show contrasted evolutionary modes between extant cervids and bovids, depending on the ecological niche and ecomorphological traits under scrutiny. The Mio-Pliocene diversification of African bovids appears to be correlated with global climatic events while their phenotypic evolution shows contrasted evolutionary patterns depending on the habitat. The second axis focuses on the circum Méditerranean impact of a major event that took place at the Miocene-Pliocene boundary, 5.3 million years ago: the Messinian Salinity Crisis. The comparative study of extinct “ungulates” living before and after this event provides some clues about the evolutionary rates and spatial patterns of phylogenetic diversity of these large mammals. The phylogenetic structure of the ungulate communities shows abrupt changes related to the local and regional biogeographic context as well as variations in climate conditions. Meanwhile, progressive faunal (actors) and functional (roles) turnovers are depicted from the beginning of the Late Miocene onward. These results provide a better characterization and understanding of the evolutionary responses to broad climatic and environmental perturbations of these often-threatened, large primary consumer “ungulate” mammals

Anfíbios anuros representam um grupo de vertebrados cujo plano corpóreo apresenta uma série de modificações associadas ao desempenho locomotor através de saltos, sendo estas especializações muito antigas e conservadas filogeneticamente. Embora estudos comparativos venham demonstrando associações entre desempenho de salto e diversidade de habitat e história de vida para esse grupo filogenético, as relações entre o desempenho locomotor e o comportamento antipredatório dentro do contexto da diversificação do uso do micro-habitat permanecem inexploradas. Primeiramente, nós testamos modelos adaptativos de evolução morfológica associados com a diversidade do uso do micro-habitat (aquático, arborícola, fossorial, reofílico e terrestre) em espécies de anuros e foi examinada a relação da distância máxima do salto como uma função dos componentes das variáveis morfológicas e do uso do micro-habitat. Nós também investigamos, tanto em nível intra quanto interespecífico a influência da complexidade do microambiente (arena vazia, arena com folhiços ou arena com folhiço e arbustos) e do tipo de estímulo (aproximação versus toque) na manifestação do comportamento antipredatório em anuros. Adicionalmente, nós investigamos o efeito do uso de diferentes tipos de refúgio pelos anuros quando sujeitos aos testes de simulação predatória no laboratório. Nossos resultados demostram a existência de múltiplos ótimos adaptativos para os comprimentos dos membros associados aos diferentes usos do micro-habitat, com uma tendência de aumento dos membros posteriores em espécies reofílicas, arborícolas e aquáticas quando comparadas com espécies terrestres e fossoriais, as quais evoluíram em direção ao ótimo adaptativo com membros posteriores mais curtos. Além disso, espécies reofílicas, arborícolas e aquáticas apresentaram maior desempenho para o salto e membros posteriores mais longos quando comparadas com espécies terrestres e fossoriais. Em seguida foi abordada a influencia da complexidade do ambiente no comportamento antipredatório e nossas análises intraspecíficas mostraram que o número de respostas ativas (salto) e passivas é fortemente dependente do tipo de estímulo e varia de acordo com a complexidade estrutural do ambiente. Simultaneamente, nossas análises comparativas interespecíficas mostraram que anuros modulam a distância saltada em resposta ao toque do predador de acordo com a complexidade ambiental, e nós ressaltamos uma variação interespecífica associada ao uso de micro-habitat. Por fim, foi investigado o uso de refúgios pelos anuros expostos a testes de simulação predatória. Nossos resultados mostram que os anuros usam a vegetação arbustiva, o folhiço e a água como areas de refúgio quando sujeitadas a simulação predatória. Além disso, ocorreu variação interespecífica na escolha de refúgios potencialmente associados à diversificação do uso de microhábitat / Anuran amphibians represent a group of vertebrates whose body plan presents a series of changes associated with jumping locomotor performance; these specializations are very old and phylogenetically conserved. Although comparative studies have shown associations among jumping performance, habitat diversity and life history for this phylogenetic group, the relationship between locomotor performance and antipredator behavior remains unexplored within the context of diversification of microhabitat use and habitat. First, we tested adaptive models of morphological evolution associated with the diversity of microhabitat use (aquatic, arboreal, fossorial, torrent and terrestrial) in species of anurans and examined the relation of the maximum distance jumped as a function of components of morphological variables and microhabitat use. We also investigated, both at intra and interspecific levels, the influence of the complexity of microenvironment (empty arena, with leaf litter or bushes) and stimulus type (approach versus touch) on the manifestation of antipredator behavior in anurans. In addition, we investigated the effect of the use of different types of refuges by anurans when subjected to simulated predator tests in the laboratory. Our results demonstrate the existence of multiple optima of limb lengths associated to different microhabitats, with a trend of increasing hindlimbs in torrent, arboreal, aquatic species whereas fossorial and terrestrial species evolve toward optima with shorter hindlimbs. Moreover, arboreal, aquatic and torrent anurans have higher jumping performance and longer hindlimbs, when compared to terrestrial and fossorial species. Then, was addressed the influence of the complexity of environment on antipredator behavior and our intraspecific analyzes showed that the number of active responses (jump) and passive responses is strongly dependent on stimulus type and varies according to the structural complexity of the environment. At the same time, our interspecific comparative analyzes showed that anurans modulate the distance jumped in response to the predator\'s touch according to environmental complexity, and we highlight an interspecific variation associated with the use of microhabitat. Lastly, was investigated the use of refuges by anurans exposed to simulated predation events. Our results show that anurans use bushes, leaf litter and water as refuge areas when subjected to simulated predator. Moreover, there is interspecific variation in the choice of refuges potentially associated to diversification of microhabitat use

Neuroethology and ecomorphology seek to understand ecology and behaviour from the perspective of specialised adaptations of sensory systems, such as vision. Sharks display a large variety of visual specialisations reflecting the diversity of different ecological niches they occupy. Many shark species are long-lived and wide ranging and often select different habitats for reproduction, growth, and feeding. Habitat complexity, ambient lighting conditions and feeding strategies can therefore change throughout a shark’s lifetime or between populations. Few comprehensive investigations of visual function exist for sharks as studies typically focus on a narrow aspect of visual function or a particular life history stage. Consequently, there is limited data on within-species plasticity of visual function in response to acclimation to different visual environments or ontogenetic development. The aim of this thesis is to undertake a functional analysis of the shark visual system. An integrated approach is employed to investigate optical, anatomical and physiological specialisations, linking such specialisations to known habitat and/or behavioural traits, with particular emphasis on ontogenetic, inter-population and inter-specific variability. Fundamental capabilities of the visual system are examined, including optical quality, eye morphology, spectral range, irradiance sensitivity, spatial and temporal resolution, contrast discrimination, and temporal and spatial summation. The main study species is the sandbar shark (<i>Carcharhinis plumbeus</i>; Carcharhinidae), a cosmopolitan species of ecological and economic importance. <i>C. plumbeus</i> occupies a wide range of natural habitats from highly turbid coastal estuaries, to relatively clear waters off the outer continental shelves and near pristine clear waters over the slopes of oceanic islands. This provides an opportunity to explore the relationship between habitat variability and the adaptation of visual specialisations and subsequent behaviour. For inter-specific comparison, the visual systems of two other species of shark with contrasting ecological niches are also assessed: the shortspine spurdog (<i>Squalus mitsukurii</i>; Squalidae) and the tiger shark (<i>Galeocerdo cuvier</i>; Carcharhinidae). The study finds marked differences in visual specialisations of the three species studied. The eyes of <i>S. mitsukurii</i> are adapted to enhance retinal illumination within a dim light environment with a large eye, immobile pupil, reflective tapetum and a relatively high optical sensitivity (2.72 μm² steradians). Visual features include a short wavelength lenticular filter, a high spatial resolving power (7.2 cycles/degree) and a large binocular overlap in the dorsal visual field, suggesting adaptations may facilitate the visualisation of bioluminescent prey. In contrast, the eyes of <i>C. plumbeus</i> are optimised for vision under variable light conditions with a mobile pupil and an occlusible tapetum. The sandbar shark shows an optical sensitivity of 1.11 μm² steradians. Visual resolution is highest in the lateral visual field, reaching a peak spatial resolution of 8.9 cycles/degree. An ERG derived spectral response curve for this species indicates maximal response to blue light between 460-490 nm. Interestingly, the tiger shark is maximally sensitive to a brighter range of light intensities compared to sandbar sharks, implying that tiger sharks occupy a more photopic light environment. However, sandbar sharks have a visual system with higher temporal resolution, as evaluated by the ERG response, (54 Hz) than tiger sharks (38 Hz). These results may reflect a difference in the importance of motion perception between <i>C. plumbeus</i> and <i>G. cuvier</i>. Phenotypic variability in visual function is shown between different populations of <i>C. plumbeus</i> occupying habitats with different ambient light conditions. This study provides new evidence of plasticity of visual function in response to acclimation to different visual environments within the same species. Sandbar sharks show an adaptive plasticity in visual sensitivity and temporal resolution, which appears to enable both temporal and population-specific adaptations to local light environments. In addition, the eyes of <i>C. plumbeus</i> and <i>S. mitsukurii</i> continue to grow even in adulthood. Visual performance, with respect to spatial resolving power and optical sensitivity, improve with eye growth. For example, peak spatial resolution increases with eye growth from 4.3 to 8.9 cycles/degree in <i>C. plumbeus</i> and from 5.7 to 7.2 cycles/degree in <i>S. mitsukurii</i>. These studies suggest that the light environment strongly influences visual function in this ancient class of vertebrates. Anthropogenically induced changes in water clarity may, therefore, impact on visually-mediated behaviours such as prey detection, agonistic signals or vertical migration. Anatomical and physiological parameters obtained from these studies provide a platform from which to model visual behaviours such as 1). Prey detection capabilities, 2). The impacts of water clarity on the limits of visually-mediated behaviour, and 3). The visual strategies that would allow sharks to maximise visual function, such as spatial and temporal summation under low light conditions. In conclusion, neuroethological studies can be a useful means to enrich information obtained from life-history and tagging studies and, together, can inform us of the functional role of sharks in marine ecosystems.

No description available.

No description available.