HL 1 Biology

5.3 Populations

182-184

<Population Growth>

  • S-shaped, growth curve: represents what happens when a population colonizes a new habitat
  • as pop. density increases, various density-dependent factors begin to limit pop. growth
  • *limiting factors: competition for resources, toxic by-products of metabolism, increase in predation, increase in disease
  • Transition phase: natality slows in relation to morality
  • max size of  population environment can support: carrying capacity
  • Plateau phase: when population reaches carrying capacity… population will stop growing, natality & morality equal
  • Some populations can go over the carrying capacity

==========DBQ===============================

Chapter 15 Questions (p.184)

4 (a) 1968

(b) Cormorants did not necessarily cause the decrease in the number of trout caught by the fishermen because there was a large decrease in the number of trout caught by fishermen before there was an increase in the number of cormorants. This can be seen in the 1960 or 1970s in which the number of trout caught by the fishermen had dropped significantly, but no cormorants were involved. Yet it is apparent in the data that the mass of trout caught by the fishermen remains low as the number of cormorants catching the trout seems to increase.

 

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