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Biology Faculty & Staff Publications

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Body size

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Effects Of Body Size And Temperature On Population Growth, Van M. Savage, James F. Gillooly, James H. Brown, Geoffrey B. West, Eric Charnov Mar 2004

Effects Of Body Size And Temperature On Population Growth, Van M. Savage, James F. Gillooly, James H. Brown, Geoffrey B. West, Eric Charnov

Biology Faculty & Staff Publications

For at least 200 years, since the time of Malthus, population growth has been recognized as providing a critical link between the performance of individual organisms and the ecology and evolution of species.We present a theory that shows how the intrinsic rate of exponential population growth, , and the carrying capacity, rmax K, depend on individual metabolic rate and resource supply rate. To do this, we construct equations for the metabolic rates of entire populations by summing over individuals, and then we combine these population-level equations with Malthusian growth. Thus, the theory makes explicit the relationship between rates of resource …


Size And Temperature In The Evolution Of Fish Life Histories, Eric Charnov, James Gillooly Jan 2004

Size And Temperature In The Evolution Of Fish Life Histories, Eric Charnov, James Gillooly

Biology Faculty & Staff Publications

Body size and temperature are the two most important variables affecting nearly all biological rates and times, especially individual growth or production rates. By favoring an optimal maturation age and reproductive allocation, natural selection links individual growth to the mortality schedule. A recent model for evolution of life histories for species with indeterminate growth, which includes most fish, successfully predicts the numeric values of two key dimensionless numbers and the allometry of the average reproductive allocation versus maturation size across species. Here we use this new model to predict the relationships of age-at-maturity, adult mortality and reproductive effort to environmental …


Effects Of Size And Temperature On Developmental Time, James Gillooly, Eric Charnov, Geoffrey West, Van Savage, James Brown May 2002

Effects Of Size And Temperature On Developmental Time, James Gillooly, Eric Charnov, Geoffrey West, Van Savage, James Brown

Biology Faculty & Staff Publications

Body size and temperature are the two most important variables affecting nearly all biological rates and times. The relationship of size and temperature to development is of particular interest, because during ontogeny size changes and temperature often varies. Here we derive a general model, based on first principles of allometry and biochemical kinetics, that predicts the time of ontogenetic development as a function of body mass and temperature. The model fits embryonic development times spanning a wide range of egg sizes and incubation temperatures for birds and aquatic ectotherms (fish, amphibians, aquatic insects and zooplankton). The model also describes nearly …


Effects Of Size And Temperature On Metabolic Rate, James Gillooly, James Brown, Geoffrey West, Van Savage, Eric Charnov Sep 2001

Effects Of Size And Temperature On Metabolic Rate, James Gillooly, James Brown, Geoffrey West, Van Savage, Eric Charnov

Biology Faculty & Staff Publications

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on metabolic rate. The model fits metabolic rates of microbes, ectotherms, endotherms (including those in hibernation), and plants in temperatures ranging from 0 to 40C. Mass - and temperature - compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular organisms and plants) is separated from the highest (for endothermic vertebrates) by a factor of about 20. Temperature and body size are primary determinants of biological time and ecological roles.