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Biology: Ecology_Populationgrowth

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Biology: Ecology_Populationgrowth

  1. 1. Population Models Chapter 16.1 section 1Population•All the individuals of a species in one place atone time.
  2. 2. Answer the following questions using the pictures on the next slide.1. What populations besides alligators could you find in this ecosystem?2. What do these these different populations taken together represent?3. What does the ecosystem include in additions to the living things you see here?
  3. 3. Answers are on next slide.
  4. 4. Check Your Answers1. What populations besides alligators could you find in this ecosystem? Grasses, fish, trees, owls, mangroves, bats, and other organisms2. What do these these different populations taken together represent? A community3. What does the ecosystem include in additions to the living things you see here? Abiotic factors, such as water, soil, and sunlight.
  5. 5. • Watch the first video titled, “World Populations”. (view it in full-screen-mode)• As you can see, human population will continue to grow exponentially if there are unlimited resources available. Look, Black Death that killed 50% of Europes population didn’t have a huge effect!
  6. 6. Using what you just learned, draw your own Exponential Grow Curve Number of individuals in a population TimeAnswer is available on next page, don’t erase your original answer.Make correction with another color pen.
  7. 7. Check your Exponential Growth Curve. It should look like thisAnswer is available on next page, don’t erase your original answer.Make correction with another color pen.Number of individuals in a populationWrite these down!•J-shape Time•Population doubling every year•Population will continue to grow exponentially if there areunlimited resources available.
  8. 8. Exponential growth is impossible to maintain in an ecosystem!!• Something would always limit the population’s growth.• Watch the second video titled, “Populations”
  9. 9. • As you saw in the video, an environment determines how many individuals of the species can be supported.• This is called Carrying Capacity.• Logistic growth curve would be used to show this.• Picture a population of grasshoppers that feed on meadow grasses. If a a fire burns part of the meadow, the insects’ food resources diminish, and grasshopper population would no longer grow.
  10. 10. Using what you just learned, draw a your own Logistic Growth Curve and label where carrying capacity is reached. Number of individuals in a population TimeAnswer is available on next page, don’t erase your original answer.Make correction with another color pen.
  11. 11. Your Logistic Growth Curve should look like thisMake correction with another color pen. Carrying Capacity Number of individuals in a population Write these down! Time S-shaped Carrying capacity is when Birth rate = Death rate
  12. 12. What could limit the population growth?1. Density dependent limiting factor– Affected by the number of individuals. Larger the number of population, more of the the resources are limited.– Examples: • competition, • predation (predator and prey relationship) • parasitism/disease Watch the third video titled, “Golden Eagle vs. Jackrabbit”
  13. 13. Predation is shown in aBoom and Bust Model • The population of a predator can be limited by the available prey. • The population of prey can be limited by being caught for food. • Over time, the two populations rise and fall in a pattern
  14. 14. Draw your own Boom and Bust CurveNumber ofindividuals in apopulation Time Use two different colors. One for predator population and one for the prey population.
  15. 15. What could limit the population growth? 2. Density independent liming factor –Aspect of the environment that limit a populations growth regardless of the density of the population. –Examples: • Unusual weather, • Natural disaster, • Human activities
  16. 16. Label the following scenarios as Population Density dependent or Population Density Independent limiting factor?1. Imagine that scientists introduced a disease into the rabbit populations of Australia, and the rabbit population crashed. Which type of limiting factor caused the crash?2. A species of beetle is in a period of exponential growth, but a competing species has started sharing the same space. Which type of limiting factor did this competition cause?3. A population of prairie dogs is experiencing high immigration and birthrate, but there are plentiful of resources available to support the population growth. A tornado hits the area and causes a huge destruction to a population of prairie grasses, their main food source. Which type of limiting factor would decrease the population? Answers are on next slide.
  17. 17. Check your answers! Population density dependent or independent?1. Population density dependent. Disease can spread more easily in a dense population2. Population density dependent. Increase in population of community causing them to compete for space.3. Population density independent Tornado hitting the area was not caused the increase in population. Bonus: Draw a graph to show this type of sudden decrease in population growth. (you can check your answer with Mrs. Majoros.

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