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Ecology and Populations. What is ecology?. Ecology is the scientific study of interactions between organisms and their environment. Ecology. Ecological systems have both biotic and abiotic components. What are a few examples of biotic and abiotic factors?. Populations.

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what is ecology
What is ecology?
  • Ecology is the scientific study of interactions between organisms and their environment.
  • Ecological systems have both biotic and abiotic components.
  • What are a few examples of biotic and abiotic factors?
  • Individuals of the same species, at the same place, at the same time.
  • Demography- the study of populations and population processes
  • All populations have 3 characteristics: distribution, density, and growth rate or age structure.
  • Distribution- the range a population covers
  • Density- The number of individuals per unit area; measured by sampling or census
    • Sampling- measuring a portion of a population to estimate the whole population
    • Census- a full count of the population
  • Growth and Age Structure- Population sizes vary year by year. Members of a population are organized into an age structure, which separates members by gender and age.
  • Measuring growth-
    • Growth= Beginning pop+(birth-deaths)+(immigration-emigration)
      • Immigration= the number of individuals entering a population
      • Emigration= the number of individuals leaving a population
practice problem
Practice Problem
  • Suppose a population of cows with 523 members has 124 births, 94 deaths, 13 emigrations and 24 immigrations. What is the new size of the population?
  • A population of 307 sparrows lives in the fields surrounding the school. The following summer, the population was re-counted and there were 270 sparrows. Assuming there were 57 births, 0 immigrations, and 14 emigrations, how many deaths were there during the winter?
population growth
Population Growth
  • Age structure diagrams help to give a visual representation of how the population is made up in terms of age and gender.
  • There are 4 different types:
      • Rapid growth
      • Slow growth
      • Zero growth
      • Negative growth
population growth2
Population Growth
  • There are two types of growth models for populations: exponential and logistic.
  • Exponential: unregulated growth- the population can grow forever. (Ideal)
  • Logistic: limited growth with limiting factors. The population grows until it reaches the carrying capacity
population growth3
Population Growth
  • Growth factors:
    • Density dependent: factors that depend on how many individuals are in a given area.
    • Density independent: factors that are not affected by how dense the population is.
population growth4
Population Growth
  • Which of the following are density dependent? Density independent?
    • Food
    • Natural disaster
    • Weather and Climate
    • Disease
    • Predators
    • Human Activity
    • Living space
population growth5
Population Growth
  • Survival curves: Help to show the survivorship rates through different ages and stages of life.
  • 3 types:
    • Type I: High juvenile and adult survival, parental care, and low fecundity (numbers of offspring)
    • Type II: Constant survival/death rates throughout life
    • Type III: low juvenile survival rates, high fecundity, no parental care.
human population
Human Population
  • How does this all relate to the human population?
    • What growth pattern does the human population follow?
      • What will limit our growth eventually?
human population1
Human Population
  • The human population exhibits all 4 types of age structure:
human population2
Human Population
  • Consequences?
    • Ecological footprint is huge- too many demands with limited resources in the environment?
    • What are some of these ecological demands?
  • There are many resources I have posted online if you would like to, or need, more review.