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Evolution of Populations

Evolution Unit. Evolution of Populations. What is a population?. Number of Individuals of the Same Species that Live together in one area or place. Population. Factors That Control Population Growth. A population’s biotic potential is the size it would be if nothing stopped it.

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Evolution of Populations

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  1. Evolution Unit Evolution of Populations

  2. What is a population? Number of Individuals of the Same Species that Live together in one area or place Population

  3. Factors That Control Population Growth • A population’s biotic potential is the size it would be if nothing stopped it. • Why don’t populations grow indefinitely?

  4. What determines the population number of an ecosystem (or planet)? (Think in terms the basics that plants, animals and ourselves need to survive.) Factors That ControlPopulation Growth

  5. Populations don’t grow indefinitely because of Limiting Factors. The major limiting factors are FWSS: Food Water Shelter Space Factors That Control Population Growth

  6. Carrying Capacity is the maximum number of individuals the environment can support. Carrying capacity is closely associated with the availability of limiting factors. Factors That Control Population Growth

  7. ? ? carrying capacity Factors That Control Population Growth • Does carrying capacity for an area ever change? Why or why not?

  8. Some populations start slow and then have a burst of growth. This is called EXPONENTIAL growth. What shape curve does it have? 70 60 50 40 30 20 10 0 Population 0 1 2 3 4 5 6 Time Population Growth RateExponential “J” Curve

  9. What is the slow almost flat growth called? What is the fast almost straight up growth called? 70 60 50 40 30 20 10 0 Population 0 1 2 3 4 5 6 Time Population Growth RateExponential “J” Curve Exponential B Lag A

  10. What is this phase? A. What is this phase? B. What is this curve called?

  11. Some populations start slow, have a burst of growth, then level off. This is called LOGISTIC growth. What shape is the curve? 600 500 400 300 200 100 0 Population 0 10 20 30 Time (in days) Population Growth RateLogistic “S” Curve

  12. Logistic curves have a lag phase and an exponential phase. Where are they on this graph? 600 500 400 300 200 100 0 A D Population C B 0 10 20 30 Time (in days) Population Growth RateLogistic “S” Curve

  13. The almost flat, slightly up/down line is called stabilization. What letter represents stabilization on the graph? 600 500 400 300 200 100 0 A D Population C B 0 10 20 30 Time (in days) Population Growth RateLogistic “S” Curve

  14. What is carrying capacity? What letter represents it? Why does the population stabilize at “A”? 600 500 400 300 200 100 0 A D Population C B 0 10 20 30 Time (in days) Population Growth RateLogistic “S” Curve

  15. What will happen to a population if it goes over the carrying capacity? What will happen to a population if it drops under the carrying capacity? 600 500 400 300 200 100 0 K carrying capacity K stabilization Population exponential lag 0 10 20 30 Time (in days) Population Growth RateLogistic “S” Curve

  16. Population Growth RateLogistic “S” Curve What is this? What is this? A. D. Why does it rise and fall slightly? What is this? B. What is this? C.

  17. Recall Darwin’s Concepts of Natural Selection variation exists in all species organisms produce more offspring than can survive competition for limited life resources survival of the fittest (most suited to the environment) descent with modification Natural Selectionand Populations

  18. Relate variation and offspring production to the population at B and C. Describe competition when the population reaches A. 600 500 400 300 200 100 0 A D Population C B 0 10 20 30 Time (in days) Natural Selectionand Populations

  19. Relate survival of the fittest with the population at D. Describe the population at D in terms of descent with modification and variation. 600 500 400 300 200 100 0 A D Population C B 0 10 20 30 Time (in days) Natural Selectionand Populations

  20. Relate the five concepts of natural selection to Graph #3. Variation Numbers increase Competition Survival of the fittest Descent with modification Event A Event B Event C Event D Natural Selectionand Populations

  21. Human Population • What kind of curve is world population growth?

  22. Human Population • Where is the lag phase? • The exponential phase?

  23. Human Population • Where is the carrying capacity?

  24. Human Population • What historical event could have caused the dip at the arrow?

  25. Consider the Black Death Plague as an environmental change. Describe the population after the Black Death (yellow arrow) in terms of variation and survival of the fittest. Human Population

  26. Why would the industrial revolution cause a population increase? (think in terms of FWSS and carrying capacity) Human Population

  27. Human Population • Where do we go from here? Children per Woman: High 2.5 Medium 2.0 Low 1.6

  28. What is the Earth’s carrying capacity? When will we reach it? Who will survive? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Human Population

  29. Works Cited • “Big Horn Sheep”, “Seabirds”. No date. Online Image. Free Stock Photos. June 15, 2004. <http://www.geekphilosopher.com/MainPage/bkgLinksPhotos.htm>

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