Unlimited, constant, favorable environment (i.e., population growth rate remains constant).
Age-specific birth and death rates remain constant (i.e., population has a stable-age distribution).
Overview (see Peterson 1977 )
Exponential Growth Model
Limited environments cause age-specific birth and/or survival rates to decline with increasing population size.
Logistic Growth Model
Birth and/or survival rate is/are a decreasing linear function of population size
C. Stochastic Processes
Stochastic: involving a random variable; a random outcome
A random variable (e.g., number of offspring) is one that can take more than one value in which the values are determined by probabilities.
Statistical Distributions and random outcomes
Examples: uniform, normal, log-normal
An organism's physiology, age, body size, behavior, prior experience, anatomy, location in time and space, etc. are all complexities that result in ecological processes such as birth and death rates being stochastic
Demographic stochasticity - individual variation of some characteristic (e.g., birth rate, mortality rate)
"Mean" birth rate
Variation in the mean birth rate = Standard error of the mean
Environmental stochasticity
Demographic stochasticity becomes less and less a factor as population size increases
Environmental stochasticity is unaffected by population size
Begon, M., and M. Mortimer. 1986. Population ecology: A unified study of animals and plants. Blackwell Scientific Publ., Boston, Mass. 220pp.
Caughley, G., and L. C. Birch. 1971. Rate of increase. J. Wildl. Manage. 35:658-663.
Elseth, G. D., and K. D. Baumgardner. 1981. Population biology. D. Van Nostrand Co., New York. 623pp.
Johnson, D. H. 1994. Population analysis. Pages 419-444 in T. A. Bookhout, ed. Research and management techniques for wildlife and habitats. Fifth ed. The Wildlife Society, Bethesda, Md.
Krebs, C. J. 1989. Ecological methodology. Harper & Row, Publ., New York. 654pp.
Wilson, E. O., and W. H. Bossert. 1971. A primer of population biology. Sinauer Assoc., Inc., Sunderland, Mass. 192pp.
