A model of dietary fiber utilization by small mammalian herbivores, with empirical results for Neotoma
Article Abstract:
Evidence indicates that rodents can derive energy from plant fiber. However, allometric analysis implies that small herbivores can extract little, if any, of their energy requirements from structural carbohydrates. A model of structural carbohydrate utilization of small mammals is generated to resolve this contradiction. The model indicates that small mammals can extract considerable amount of energy from the microbial fermentation of fiber in their hindguts. Actual experiments have proven that Neotoma can extract as much as 21.3% of its energy requirement from fiber fermentation.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1992
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Optimal resource allocation and the marginal value of organs
Article Abstract:
A modification of the optimal control theory function P/(r* + Mu), where P is productivity, r* is the per capita rate of increase of optimal strategists and Mu is the mortality rate, is presented. In the original formula, r* is a measure of fitness and is based on one state variable, the organism's body mass. In the modified function, fitness is decribed by several state variables to reflect the various body components which affect P and Mu in different ways. The results could explain dynamic optimization patterns in resource allocation to reproduction and to somatic structures.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1992
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Diving birds in cold water: do Archimedes and Boyle determine energy costs?
Article Abstract:
The energetic costs of working against buoyancy in diving birds were investigated. Water displacement experiments were performed to determine the body density and the volume of trapped air in the feathers of 36 species of waterfowl, and the results showed that in species wherein foraging depended more on diving, body density was higher and the volume of trapped air in plumage was lower. A model of the energetic costs of working against buoyancy was developed to show the linkage between waterfowl foraging ecology and the volume of trapped air in the feathers.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1992
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- Abstracts: An experimental calibration of the nickel in garnet geothermometer with applications: reply. Non-ideal mixing in the phlogopite-annite binary: constraints from experimental data on Mg-Fe partitioning and a reformulation of the biotite-garnet geothermometer
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