A mecanismos fisiológicos é frequentemente usada para explicar fenômenos importantes da evolução (p.e. endotermia) e ecologia (p.e. limitações fisiológicas para ocupação de determinado microhabitat) dos vertebrados. Apesar de ser uma área promissora para fornecer explicações e mecanismo que tornam hipóteses evolutivas e ecológicas mais robustas, como já é amplamente praticado no estudo dos vertebrados, ela é raramente usada nas hipóteses elencadas para explicar a megadiversidade das aranhas de teia. Por outro lado, as leis da fisiologia são baseadas fortemente em dados de vertebrados que consistem em menos de 1% da biodiversidade existente no planeta. As aranhas são o sétimo maior táxon em número de espécies e são um bom modelo para testar a validade das regras gerais propostas para os vertebrados. Com insto em mente, o presente trabalho investigou três tipos de taxa metabólica - Metabolismo Padrão, Metabolismo Espontâneo Máximo e Metabolismo Diário - em aranhas de teia. Todas estas taxas foram obtidas através de respirometria intermitente Em um primeiro experimento, usando como modelo Loxosceles, um gênero de aranhas especialmente homogêneo em sua morfologia, testou-se o efeito de sedentarismo e intensidade de construção da teia nas taxas metabólicas. Em um segundo experimento, testou-se como as taxas metabólicas se apresentariam frente a grande diversidade das aranhas do clado Orbiculariae. Os resultados mostram que: as diferenças comportamentais analisadas não afetam significativamente as taxas metabólicas; as taxas metabólicas não possuem sinal filogenético; e o melhor modelo é o que ajusta uma relação alometrica diferente para cada gênero em detrimento de um coeficiente exponencial da massa único para toda a amostra. As diferenças comportamentais de Loxosceles provavelmente apresentam-se na distribuição de gasto energético ao longo do dia partindo de um mesmo montante energético. Os dados de diversidade de Orbiculariae provavelmente precisam ser investigados futuramente sob o aspecto das diferenças morfológicas subjacente à diversidade do clado. / The physiological mechanisms are often applied to explain important evolutionary adaptations (e.g. endothermy) and ecology (e.g. physiological limitations to occupy a particular microhabitat) of vertebrates. Despite the fact that it improves vertebrates ecological and evolutionary hypotheses with possible processes and mechanisms, it is scarcely used to understand the megadiversity of web spiders. On the other hand, the physiological rules are based mainly on vertebrates data, an animal group that represents less than 1% of the world biodiversity. Spiders group is the seventh most diverse taxon in terms of species number on the world and are a good model to test the validity of the general rules proposed for vertebrates. Accordingly, this study investigated three types of metabolic rate - Standard Metabolism, Maximum Spontaneous Metabolism, Daily Metabolism - on web spiders. All these rates were obtained by intermittent respirometry. In the first experiment, the Loxosceles model was chosen, a genus of spider with a especially homogeneous morphology, with whom we tested the differences on metabolic rates of spiders with different sedentarity and web building expenditure. In a second experiment we tested how metabolic rates would vary under the high diversity of Orbiculariae spiders clade. The results show that: behavioral differences do not affect significantly the metabolic rates examined, metabolic rates do not have any significant phylogenetic signal and the best model is the one that adjusts a separate allometric relation for each genus at the expense of an unique allometric model for the whole sample. The behavioral differences of Loxosceles probably could be explained by the distribution of energy expenditure throughout the day under the same amount of energy. The diversity of data of Orbiculariae clade probably need to be investigated in the future under the aspect of morphological differences underlying the diversity of the clade

A mecanismos fisiológicos é frequentemente usada para explicar fenômenos importantes da evolução (p.e. endotermia) e ecologia (p.e. limitações fisiológicas para ocupação de determinado microhabitat) dos vertebrados. Apesar de ser uma área promissora para fornecer explicações e mecanismo que tornam hipóteses evolutivas e ecológicas mais robustas, como já é amplamente praticado no estudo dos vertebrados, ela é raramente usada nas hipóteses elencadas para explicar a megadiversidade das aranhas de teia. Por outro lado, as leis da fisiologia são baseadas fortemente em dados de vertebrados que consistem em menos de 1% da biodiversidade existente no planeta. As aranhas são o sétimo maior táxon em número de espécies e são um bom modelo para testar a validade das regras gerais propostas para os vertebrados. Com insto em mente, o presente trabalho investigou três tipos de taxa metabólica - Metabolismo Padrão, Metabolismo Espontâneo Máximo e Metabolismo Diário - em aranhas de teia. Todas estas taxas foram obtidas através de respirometria intermitente Em um primeiro experimento, usando como modelo Loxosceles, um gênero de aranhas especialmente homogêneo em sua morfologia, testou-se o efeito de sedentarismo e intensidade de construção da teia nas taxas metabólicas. Em um segundo experimento, testou-se como as taxas metabólicas se apresentariam frente a grande diversidade das aranhas do clado Orbiculariae. Os resultados mostram que: as diferenças comportamentais analisadas não afetam significativamente as taxas metabólicas; as taxas metabólicas não possuem sinal filogenético; e o melhor modelo é o que ajusta uma relação alometrica diferente para cada gênero em detrimento de um coeficiente exponencial da massa único para toda a amostra. As diferenças comportamentais de Loxosceles provavelmente apresentam-se na distribuição de gasto energético ao longo do dia partindo de um mesmo montante energético. Os dados de diversidade de Orbiculariae provavelmente precisam ser investigados futuramente sob o aspecto das diferenças morfológicas subjacente à diversidade do clado. / The physiological mechanisms are often applied to explain important evolutionary adaptations (e.g. endothermy) and ecology (e.g. physiological limitations to occupy a particular microhabitat) of vertebrates. Despite the fact that it improves vertebrates ecological and evolutionary hypotheses with possible processes and mechanisms, it is scarcely used to understand the megadiversity of web spiders. On the other hand, the physiological rules are based mainly on vertebrates data, an animal group that represents less than 1% of the world biodiversity. Spiders group is the seventh most diverse taxon in terms of species number on the world and are a good model to test the validity of the general rules proposed for vertebrates. Accordingly, this study investigated three types of metabolic rate - Standard Metabolism, Maximum Spontaneous Metabolism, Daily Metabolism - on web spiders. All these rates were obtained by intermittent respirometry. In the first experiment, the Loxosceles model was chosen, a genus of spider with a especially homogeneous morphology, with whom we tested the differences on metabolic rates of spiders with different sedentarity and web building expenditure. In a second experiment we tested how metabolic rates would vary under the high diversity of Orbiculariae spiders clade. The results show that: behavioral differences do not affect significantly the metabolic rates examined, metabolic rates do not have any significant phylogenetic signal and the best model is the one that adjusts a separate allometric relation for each genus at the expense of an unique allometric model for the whole sample. The behavioral differences of Loxosceles probably could be explained by the distribution of energy expenditure throughout the day under the same amount of energy. The diversity of data of Orbiculariae clade probably need to be investigated in the future under the aspect of morphological differences underlying the diversity of the clade

Les poissons vivant au sein d’une rivière sont soumis à des variations circadiennes de température pouvant influencer la croissance, la digestion et le métabolisme standard. Les modèles bioénergétiques utilisant les fonctions métaboliques pour déterminer la croissance d’un poisson ont souvent été élaborés avec des poissons acclimatés à des températures constantes. Ces modèles pourraient sous-estimer l’énergie dépensée par un poisson soumis à des températures fluctuantes. En utilisant la respirométrie par débit intermittent, les objectifs de ce travail étaient : (1) de quantifier les différences entre les taux métaboliques standards de poissons acclimatés à une température constante (20.2 oC ± 0.5 oC) et à des fluctuations circadiennes de température (19.8 oC ± 2.0 oC; 19.5 oC ± 3.0 oC) et (2) comparer deux méthodologies pour calculer les taux métaboliques standards de poissons sujets aux fluctuations circadiennes de températures : respirométrie (a) en température constante ou (b) en température fluctuante. Les poissons acclimatés à des fluctuations circadiennes de température ont des taux métaboliques standards plus élevés que des poissons acclimatés à une température constante. À 20.2 oC ± 0.5 oC, les taux métabolique standards ont été de 25% à 32% plus bas pour des poissons maintenus à une température constante que pour des poissons gardés sous des fluctuations circadiennes de température. Les méthodologies utilisées pour estimer les taux métaboliques standards de poissons sujets aux fluctuations de température offrent des résultats similaires. / Fish that inhabits river are subjected to circadian fluctuations in water temperature. These fluctuations can influence growth, digestion and metabolic processes. Bioenergetic models are traditionally modeled using data recorded from fish kept at constant water temperatures. These models could underestimate the energy spent by fish subjected to fluctuating temperatures. Thus, with intermittent-flow respirometry, the objectives of this study were to: (1) quantify the differences between standard metabolic rates of fish acclimatized to a constant temperature (20.2 oC ± 0.5 oC) and two circadian fluctuating temperatures (19.8 oC ± 2.0 oC; 19.5 oC ± 3.0 oC) and (2) compare two methodology for calculate standard metabolic rates of fish subjected to circadian fluctuating temperatures: intermittent-flow respirometry with (a) constant temperature or (b) fluctuating temperatures. Fish held at circadian fluctuating temperatures have higher standard metabolic rates than fish acclimatized to a constant temperature. At 20.2 oC ± 0.5 oC, standard metabolic rates was 25% to 32% lower for fish held at constant temperature than for fish held under circadian fluctuations. However, results of the two different strategies used to calculate standard metabolic rates of fish subjected to circadian fluctuating temperatures did not differ.

Les poissons vivant au sein d’une rivière sont soumis à des variations circadiennes de température pouvant influencer la croissance, la digestion et le métabolisme standard. Les modèles bioénergétiques utilisant les fonctions métaboliques pour déterminer la croissance d’un poisson ont souvent été élaborés avec des poissons acclimatés à des températures constantes. Ces modèles pourraient sous-estimer l’énergie dépensée par un poisson soumis à des températures fluctuantes. En utilisant la respirométrie par débit intermittent, les objectifs de ce travail étaient : (1) de quantifier les différences entre les taux métaboliques standards de poissons acclimatés à une température constante (20.2 oC ± 0.5 oC) et à des fluctuations circadiennes de température (19.8 oC ± 2.0 oC; 19.5 oC ± 3.0 oC) et (2) comparer deux méthodologies pour calculer les taux métaboliques standards de poissons sujets aux fluctuations circadiennes de températures : respirométrie (a) en température constante ou (b) en température fluctuante. Les poissons acclimatés à des fluctuations circadiennes de température ont des taux métaboliques standards plus élevés que des poissons acclimatés à une température constante. À 20.2 oC ± 0.5 oC, les taux métabolique standards ont été de 25% à 32% plus bas pour des poissons maintenus à une température constante que pour des poissons gardés sous des fluctuations circadiennes de température. Les méthodologies utilisées pour estimer les taux métaboliques standards de poissons sujets aux fluctuations de température offrent des résultats similaires. / Fish that inhabits river are subjected to circadian fluctuations in water temperature. These fluctuations can influence growth, digestion and metabolic processes. Bioenergetic models are traditionally modeled using data recorded from fish kept at constant water temperatures. These models could underestimate the energy spent by fish subjected to fluctuating temperatures. Thus, with intermittent-flow respirometry, the objectives of this study were to: (1) quantify the differences between standard metabolic rates of fish acclimatized to a constant temperature (20.2 oC ± 0.5 oC) and two circadian fluctuating temperatures (19.8 oC ± 2.0 oC; 19.5 oC ± 3.0 oC) and (2) compare two methodology for calculate standard metabolic rates of fish subjected to circadian fluctuating temperatures: intermittent-flow respirometry with (a) constant temperature or (b) fluctuating temperatures. Fish held at circadian fluctuating temperatures have higher standard metabolic rates than fish acclimatized to a constant temperature. At 20.2 oC ± 0.5 oC, standard metabolic rates was 25% to 32% lower for fish held at constant temperature than for fish held under circadian fluctuations. However, results of the two different strategies used to calculate standard metabolic rates of fish subjected to circadian fluctuating temperatures did not differ.