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Exam 4 review

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  • population

    • group of individuals of the same species living in the same geographic area.

  • Population density

    • Number of individuals :

    -per unit

    -area

    -volume

  • 1. Clumped

    Population distribution (dispersion)

    o Individuals occur in groups.

    o Most common pattern.

    o Occurs when resources are unevenly distributed.

  • 2. Uniform

    Population distribution (dispersion)

    • Individuals evenly spaced.

    1. Random

    Population distribution (dispersion)

    • Individuals distributed unpredictably.

  • Birth Rate (Natality)

    Number of individuals produced or born per unit, time

  • Death Rate (Mortality)

    Number of individuals dying per unit time.

  • Immigration

    Movement into a population.

  • Emigration

    Movement out of a population

  • Population Growth Equation

    Exponential Growth

    𝐺 = 𝑟𝑁

    𝐺 = 𝑟𝑁

    Where:

    • G = number of individuals added

    • r = per capita growth rate

    • N = population size

    Produces a J-shaped curve.

  • Carrying Capacity (K)

    The maximum population size that an environment can support.

    *Earth can hold up to 15 Billion people

    Produces a logistic (S-shaped) growth curve.

  • Density-Dependent Factors

    Effects increase as population density increases.

    Examples:

    • Disease

    • Predation

    • Competition

    • Parasitism

  • Density-Independent Factors

    Affect populations regardless of size.

    Examples:

    (Natural Disasters)

    • Frost

    • Fires

    • Floods

    • Hurricanes

    • Droughts

  • Type I

    Survivorship Curves

    Examples:

    • Humans

    • Elephants

    Characteristics:

    • Low juvenile mortality

    • High mortality late in life

  • Type Il

    Survivorship Curves

    Examples:

    • Songbirds

    Characteristics:

    • Equal chance of dying at any age.