37 resultados para Lithobates


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The objective of this work was to determine nutrient deposition on the carcass of bullfrog (Lithobates catesbeianus) tadpoles using a nonlinear model. A total of 2,700 tadpoles with an average weight of 0.039 g were used. Commercial ground feed containing 55% crude protein was offered ad libitum. The animals were weighed and evaluated every ten days for analysis of crude protein, ether extract, water, and mineral salt contents. The parameters of the Gompertz model were estimated by the modified Gauss-Newton method, and the deposition rates (g per day) over time were calculated by the resulting equation. The values found for the parameters of the Gompertz equation, used to describe nutrient deposition on tadpole carcass, showed biological interpretation. Maximum deposition rate (t*) was observed on the 36.2331th day for protein, on the 37.1420th day for water, on the 35.2971th day for mineral salt, and on the 41.3547th day for fat. Nutrient intake from the diet is higher than the deposition rate on the tadpole carcass.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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A central question in evolutionary biology is how interactions between organisms and the environment shape genetic differentiation. The pathogen Batrachochytrium dendrobatidis (Bd) has caused variable population declines in the lowland leopard frog (Lithobates yavapaiensis); thus, disease has potentially shaped, or been shaped by, host genetic diversity. Environmental factors can also influence both amphibian immunity and Bd virulence, confounding our ability to assess the genetic effects on disease dynamics. Here, we used genetics, pathogen dynamics, and environmental data to characterize L.yavapaiensis populations, estimate migration, and determine relative contributions of genetic and environmental factors in predicting Bd dynamics. We found that the two uninfected populations belonged to a single genetic deme, whereas each infected population was genetically unique. We detected an outlier locus that deviated from neutral expectations and was significantly correlated with mortality within populations. Across populations, only environmental variables predicted infection intensity, whereas environment and genetics predicted infection prevalence, and genetic diversity alone predicted mortality. At one locality with geothermally elevated water temperatures, migration estimates revealed source-sink dynamics that have likely prevented local adaptation. We conclude that integrating genetic and environmental variation among populations provides a better understanding of Bd spatial epidemiology, generating more effective conservation management strategies for mitigating amphibian declines.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)