14.5.3 Population Ecology: Population Strategy: r vs. K

Question 1

Population Ecology: Population Strategy: r vs. K

Answer 1

• The logistic population growth model predicts that a population’s growth rate changes as it approaches carrying capacity.
• The model predicts that populations with either low or high densities relative to carrying capacity will have different life-history strategies.
• High-density populations are called K-selected and have adaptations that enable them to survive and reproduce with few resources.
• Low-density populations are called r-selected and have adaptations for allowing rapid reproduction.

Question 2

logistic population growth model

Answer 2

• Review: The graph on the left depicts the logistic growth of a population. The population initially increases until it reaches the inflection point. At that point, the rate of increase slows until it reaches carrying capacity.
• The logistic population growth modelshows that population growth varies with population density. In real-life situations, scarce resources—such as food, mates, or shelter—limit population growth.
• One limitation of the model is that all individuals are
  considered equal regardless of their age. Adults have a greater impact on a population than young.
• The logistic population growth model predicts that
  populations with either low or high densities relative to carrying capacity will have different life-history strategies.
• Low-density populations are called r-selected and have adaptations that lead to rapid reproduction, like early maturation. Populations remain under the carrying capacity. Many insect species are considered to be r-selected.
• High-density populations are called K-selected. They have adaptations—like slow growth rate—that enable them to survive and reproduce with few resources. Populations increase and remain at carrying capacity. Many large mammals, like lions, are K-selected.

Question 3

r strategists have a __________ death rate and are ___________.

Answer 3

• high; small

Question 4

Which of the following is a good example of an r-selected organism?

Answer 4

• mayflies

Question 5

K strategists have a __________ maturation time and a __________ life span.

Answer 5

• long; long

Question 6

Which of the following are K-selected organisms?

Answer 6

• humans

Question 7

In terms of population strategies, how would you classify robins?

Answer 7

• Robins exhibit some characteristics of r strategists and some characteristics of K strategists and should be thought of laying somewhere along the continuum between the two strategies.

Question 8

True or false?

The categories of r and K strategies are useful because they allow all species to be classified into two groups.

Answer 8

• false