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Five Common Graphs

Five Common Graphs. Several graphs are commonly seen in ecology. for example. Linear progressions J - CURVES S - CURVES Climb and collapse Bell shaped curve. An arithmetic number sequence grows by repeated additions of like amounts. and produces a linear graph. Examples.

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Five Common Graphs

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  1. Five Common Graphs

  2. Several graphs are commonly seen in ecology for example • Linear progressions • J - CURVES • S - CURVES • Climb and collapse • Bell shaped curve

  3. An arithmetic number sequence grows by repeated additions of like amounts and produces a linear graph Examples 1...2...3...4...5...6...7...8...9... 3...6...9...12...15...18...21 110...220...330...440...

  4. 1...2...3...4...5...6...7...8...9... 3...6...9...12...15...18...21 110...220...330...440... Each of these arithmetic progressions when graphed,produces a straight-line graph Such number sequences are predictable and easy to understand

  5. An exponential progression produces a classical J – CURVElike the one shown here

  6. J-curves are both powerful and deceptive They result from number sequences that growby repeated multiplications by like amounts Examples 1...2...4...8...16...32...64...128 1...3...9...27...81...243

  7. Most of the growth in an exponential sequence occurs at the end of the sequence Examples • A graph of a nuclear detonation • Populations undergoing ecological release • A graph of human population growth between 8000 BC and 2000 AD

  8. Many populations exhibit anS - CURVE

  9. An S-curve is also known as a Logisticgrowth pattern • Takes into account environmental factors limiting growth. • Contains 5 stages. • Initial Growth/slow • Exponential Growth/fast • Slowing Growth • Slower Growth • Steady State, which will fluctuate moderately.

  10. During the early stages of a population’s growth,theS-CURVE follows an exponential pattern As the population grows larger, competition and other limiting factors begin to slow its rate of growth

  11. Eventually, birth rates and death rates become equal and the population stabilizesnear the carrying capacity of its environment

  12. We often see S– CURVES in k-strategists such as whales and gorillas ..... unless they undergo ecological release .....

  13. This graph depicts a population pattern known as Climb and Collapse Can you see why?

  14. The population shown here grew exponentially for many generations This was eventually followed by a catastrophicdie-off over a relatively short span of time

  15. This graph shows the climb-and-collapse of a reindeer population on St. Matthews Island, Alaska In 1944, 29 reindeer were placed on the island

  16. Since the island had no competitors or predators The reindeer herd underwent ecological release (Definition?)

  17. By 1963, more than 6000 reindeerdamaged the vegetation needed to survive

  18. More than 99% of the herd died during the winter of 1963-1964 … only 42 individuals survived …

  19. In line graph form

  20. And with fewer reindeer, Santa had to try a different approach.

  21. Biologists who study populations often run across data that produce Bell-Shaped Curves

  22. Such data often involve patterns of variation within a population

  23. Example Suppose we analyze all the oranges on a given tree for their vitamin Ccontent per gram

  24. Some will have a very high amount of vitamin C per gram Others will have very little vitamin C per gram But most will have some average amount of vitamin C per gram

  25. producing a bell-shaped curve when graphed

  26. C’s B’s D’s A’s Bell shape curves are what we often use in education when evaluating student work. What’s fair about this? What’s not?

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