Resource variation and species interactions require organisms to respond behaviorally, physiologically, and morphologically within and among generations to compensate for spatial and temporal environmental variation. One successful evolutionary strategy to mitigate environmental variation is phenotypic plasticity: the production of alternative phenotypes in response to environmental variation. Phenotypic plasticity yields multiple characters that may enable organisms to better optimize phenotypic responses across environmental gradients. In this thesis, I trace the development of thought on phenotypic plasticity and present two empirical studies that implicate phenotypic plasticity in producing morphological variation in response to resource variation. The first empirical study addresses trophic plasticity, population divergence, and the effect of fine-scale environmental variation in western mosquitofish (Gambusia affinis). Offspring from two populations were fed either attached or unattached food items offered in three orientations: (1) water surface, (2) mid-water, (3) benthic, and (4) a daily rotation of the former three (fine-grained variation). Attached food induced wide heads, blunt snouts and rounded pectoral fins relative to morphology in the unattached treatment. Mid-water feeding induced elongated heads and deeper mid-bodies relative to benthic and surface feeding induced morphologies. The rotating treatment produced intermediate morphologies. Population divergence seemed related to both trophic and predation ecology. Ecomorphological consequences of induced morphologies and the need for inclusion of greater ecological complexity in studies of plasticity are discussed. The second study examines induced morphological plasticity and performance in red drum (Sciaenops ocellatus). I fed hatchery fish either hard or soft food for two months. Performance trials were designed to measure their ability to manipulate and consume hard food items. External morphology and the mass of pharyngeal crushing muscles were assessed for variation among treatments. A hard food diet induced deeper bodies and larger heads, more massive pharyngeal muscles, and initially more efficient consumption of hard food than fish receiving soft food. The observed morphological variation is in accordance with variation among species. Determining evolutionary mechanisms operating within red drum populations should eventually aid in developing and optimizing conservation efforts and ease the transition from hatchery facilities to estuaries.

Resource variation and species interactions require organisms to respond behaviorally, physiologically, and morphologically within and among generations to compensate for spatial and temporal environmental variation. One successful evolutionary strategy to mitigate environmental variation is phenotypic plasticity: the production of alternative phenotypes in response to environmental variation. Phenotypic plasticity yields multiple characters that may enable organisms to better optimize phenotypic responses across environmental gradients. In this thesis, I trace the development of thought on phenotypic plasticity and present two empirical studies that implicate phenotypic plasticity in producing morphological variation in response to resource variation. The first empirical study addresses trophic plasticity, population divergence, and the effect of fine-scale environmental variation in western mosquitofish (Gambusia affinis). Offspring from two populations were fed either attached or unattached food items offered in three orientations: (1) water surface, (2) mid-water, (3) benthic, and (4) a daily rotation of the former three (fine-grained variation). Attached food induced wide heads, blunt snouts and rounded pectoral fins relative to morphology in the unattached treatment. Mid-water feeding induced elongated heads and deeper mid-bodies relative to benthic and surface feeding induced morphologies. The rotating treatment produced intermediate morphologies. Population divergence seemed related to both trophic and predation ecology. Ecomorphological consequences of induced morphologies and the need for inclusion of greater ecological complexity in studies of plasticity are discussed. The second study examines induced morphological plasticity and performance in red drum (Sciaenops ocellatus). I fed hatchery fish either hard or soft food for two months. Performance trials were designed to measure their ability to manipulate and consume hard food items. External morphology and the mass of pharyngeal crushing muscles were assessed for variation among treatments. A hard food diet induced deeper bodies and larger heads, more massive pharyngeal muscles, and initially more efficient consumption of hard food than fish receiving soft food. The observed morphological variation is in accordance with variation among species. Determining evolutionary mechanisms operating within red drum populations should eventually aid in developing and optimizing conservation efforts and ease the transition from hatchery facilities to estuaries.

No description available.

Orientador: Igor Paiva Ramos / Resumo: Empreendimentos hidroelétricos podem desencadear alterações no ciclo hidrológico, desequilíbrio dos ecossistemas aquáticos e facilitar a introdução de espécies de peixes não-nativas. Contudo, essas espécies também podem apresentar grande representatividade na pesca artesanal e esportiva, tornando-se uma importante fonte de renda local. Dessa forma, o estudo de espécies não-nativas, suas origens, hábitos e posições tróficas, além de suas habilidades que garantem a permanência e o sucesso no estabelecimento em novos ambientes, são relevantes. Dentre tais espécies não-nativas, Geophagus sveni destaca-se como uma das espécies mais importantes para pesca artesanal na região Noroeste do estado de São Paulo. O presente trabalho teve como objetivo caracterizar e correlacionar a composição alimentar, composição bromatológica do tecido muscular, perfil de ácidos graxos do tecido muscular e hepático, além de identificar possíveis parasitos musculares em G. sveni nos períodos chuvoso e seco, no reservatório de Jupiá, alto rio Paraná, Brasil. Foram realizadas duas coletas, uma ao final do período chuvoso (março/2018) e outra ao final do período seco (agosto/2018), no reservatório de Jupiá (20°30'33.4"S 51°27'19.7"W). Os espécimes coletados foram eutanasiados e, em seguida, tiveram mensuradas massa total, comprimento padrão e o sexo determinado visualmente. Geophagus sveni apresentou hábito alimentar detritívoro, além de plasticidade e oportunismo trófico. Sua composição alimentar foi sign... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hydroelectric developments can trigger changes in the hydrological cycle, imbalance in aquatic ecosystems and facilitate the introduction of non-native fish species. However, these species can also be highly representative in artisanal and sport fishing, becoming an important source of local income. Thus, the study of non-native species, their origins, habits and trophic positions, in addition to their skills that guarantee permanence and success in the establishment of new environments, are relevant. Among these non-native species, Geophagus sveni is provided as one of the most important species for artisanal fisheries in the Northwest region of the state of São Paulo. This study aimed to characterize and correlate the food composition, the bromatological composition of muscle tissue, the fatty acid profile of the muscle and liver tissue, in addition to identifying possible muscle parasites of Geophagus sveni in the rainy and dry periods, in the Jupiá reservoir, on the Paraná River, Brazil. Two collections were made, one at the end of the rainy period (March/2018) and another at the end of the dry period (August/2018), at the Jupiá reservoir (20°30'33.4"S 51°27'19.7"W). The collected specimens were euthanized and, afterwards, total mass and standard length were measured, as well as sex determined visually. Geophagus sveni presented detritivorous eating habits, in addition to plasticity and trophic opportunism. Their food composition was significantly different only between t... (Complete abstract click electronic access below) / Mestre

Le refroidissement global et les oscillations entre cycles glaciaires et interglaciaires du Pléistocène inférieur ont pour conséquence une alternance entre milieux steppiques et forestiers, favorisant par là-même renouvellements et dispersions fauniques dont celui du genre Homo.Dans les interprétations paléoenvironnementales basées sur les assemblages fauniques, les cervidés, parmi les plus abondants mammifères, sont classiquement considérés comme forestiers, mais ce paradigme ne reflète pas la complexité de la diversité écologique réelle des cervidés.L'analyse texturale de 921 spécimens représentant les 5 cervidés actuels à l'écologie référencée a permis d'établir une robuste base de données et d'attester du lien significatif entre micro-usure dentaire et ressources végétales. L'analyse de 547 cervidés fossiles issus de 15 localités européennes souligne leur grande diversité écologique. Eucladoceros ctenoides et Metacervoceros rhenanus présentent une alimentation plastique. Leur analyse permet l'identification de réponses alimentaires adaptatives aux modifications environnementales liées aux oscillations climatiques. Ces deux cervidés, eurytopiques, constituent des indicateurs écologiques incontournables. La composante forestière supportée par la présence des cervidés est ici remise en cause ; les cervidés étant plus diversifiés écologiquement. L'analyse de la texture de la micro-usure dentaire des cervidés présents dans des sites européens, où la présence du genre Homo a été avancée, vise à identifier le type potentiel d'habitat favorable à sa dispersion en Eurasie. / The early Pleistocene is a period of global cooling and climatic oscillations punctuated by glacial and interglacial cycles. This period of climatic instability leads to an alternation of steppe and forest habitats resulting in faunal renewals and dispersals, including Homo dispersal.In paleoenvironmental reconstructions based on faunal assemblages, deer, which are among the most abundant mammals, are traditionally considered forest dwellers. However, this paradigm is far from reflecting the real complexity of deer ecological diversity.Via the textural analysis of 921 representatives of the 5 extant European deer with known ecology, a solid reference database has been setup. It attests of the significative link existing between dental micro-wear and vegetal resources. The analysis of 547 fossils from 15 European localities underlines the ecological diversity among fossil deer. Eucladoceros ctenoides and Metacervoceros rhenanus are plastic in their diet. The analysis of such deer allows the identification of dietary adaptive answers to environmental modifications resulting from climatic oscillations. Being eurytopic, they constitute essential proxies for paleoenvironmental reconstructions. The results challenge the link existing between the occurrence of deer and the presence of forest habitats, as deer are ecologically more diversified.The textural analysis of deer from European human bearing localities aims at characterizing potential habitats favorable toward Homo dispersion in Eurasia.