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Chapter 19

25 February, 2016 - 11:05
  1. Figure 19.2 Smaller animals require less food and others resources, so the environment can support more of them per unit area.
  2. Figure 19.6 A: The carrying capacity of seals would decrease, as would the seal population.
  3. Figure 19.11 Stage 4 represents a population that is decreasing.
  4. C
  5. D
  6. A
  7. A
  8. C
  9. B
  10. A
  11. B
  12. C
  13. B
  14. B
  15. D
  16. C
  17. D
  18. The researcher would mark a certain number of penguins with a tag, release them back into the population, and, at a later time, recapture penguins to see what percentage was tagged. This percentage would allow an estimation of the size of the penguin population.
  19. In the first part of the curve, when few individuals of the species are present and resources are plentiful, growth is exponential, similar to a J-shaped curve. Later, growth slows due to the species using up resources. Finally, the population levels off at the carrying capacity of the environment, and it is relatively stable over time.
  20. If a natural disaster such as a fire happened in the winter, when populations are low, it would have a greater effect on the overall population and its recovery than if the same disaster occurred during the summer, when population levels are high.
  21. Rapidly growing countries have a large segment of the population at reproductive age or younger. Slower growing populations have a lower percentage of these individuals, and countries with zero population growth have an even lower percentage. On the other hand, a high proportion of older individuals is seen mostly in countries with zero growth, and a low proportion is most common in rapidly growing countries.
  22. The competitive exclusion principles states that no two species competing for the same resources at the same time and place can co-exist over time. Thus, one of the competing species will eventually dominate. On the other hand, if the species evolve such that they use resources from different parts of the habitat or at different times of day, the two species can exist together indefinitely.
  23. Removing a keystone species will have dramatic effects on the abundance of individuals in other populations, increasing some and decreasing others. This affects the interactions between populations such as competition and predator-prey relationships. In addition, the community may show a loss of diversity.