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Population Ecology and Growth Models

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  • What defines a population in biology?
    A population is a group of individuals of a single species living in the same general area.
  • What is population density?
    Population density is the number of individuals per unit area or volume.
  • What is dispersion in population ecology?
    Dispersion is the pattern of spacing among individuals within a population.
  • Name three common patterns of dispersion.
    Clumped, uniform, and random dispersion.
  • What influences clumped dispersion?
    Resource availability and social behavior often cause individuals to aggregate in patches.
  • What causes uniform dispersion?
    Social interactions like territoriality, where individuals defend bounded spaces, lead to even spacing.
  • What characterizes random dispersion?
    Individuals are spaced unpredictably, with no strong attractions or repulsions.
  • What is a life table in population ecology?
    An age-specific summary of the survival pattern of a population, often following a cohort.
  • What are the three types of survivorship curves?
    Type I: low early death rates; Type II: constant death rate; Type III: high early death rates.
  • What is a reproductive table or fertility schedule?
    An age-specific summary of the reproductive rates in a population, often focusing on females.
  • How is population growth rate (r) calculated ignoring immigration and emigration?
    r = birth rate (b) minus death rate (m).
  • What is zero population growth (ZPG)?
    When the birth rate equals the death rate, resulting in r = 0 and no population size change.
  • Write the exponential growth equation for population size N.
    dN/dt = rmax N, where rmax is the maximum per capita growth rate.
  • What shape does the exponential growth curve have?
    A J-shaped curve representing rapid population increase under ideal conditions.
  • What is carrying capacity (K)?
    The maximum population size that the environment can sustainably support.
  • How does the logistic growth model modify exponential growth?
    It adds a term to reduce growth rate as population size (N) approaches carrying capacity (K).
  • Write the logistic growth equation.
    dN/dt = rmax N (K - N) / K.
  • What happens to the per capita growth rate as N approaches K in logistic growth?
    The per capita growth rate declines, slowing population growth.
  • What is the Allee effect?
    A phenomenon where individuals have difficulty surviving or reproducing at low population sizes.
  • Name four factors that determine population size and density.
    Births, deaths, immigration, and emigration.