Biology 242: Lecture 12Spring 2001

Population Growth and Regulation

  1. Population models
    1. General growth equation
      1. Change in population size during time interval = Births during time interval - Deaths during time interval
      2. Problem: different population sizes
        Solution: per capita birth and death rates
      3. Let robs = b - d
      4. Equation: dN/dt = robsN
    2. Exponential growth
      1. Ideal conditions - let robs = rmax
      2. Equation: dN/dt = rmaxN
    3. Logistic growth
      1. Carrying capacity = K
      2. Buffering factor = (K-N)/K
      3. Let robs = rmax x buffering factor
      4. Equation: dN/dt = rmaxN(K-N)/K
    4. Accuracy of models

  2. Population regulation
    1. Density-dependent factors
      1. Competition for resources
      2. Predation
      3. Parasites/disease
      4. Waste products
    2. Density-independent factors
      1. Climate
      2. Weather
      3. Fires and hurricanes
    3. Interaction of density-dependent and density-independent factors
    4. Population cycles


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