Chapter 6

Question 1

Define the terms:

1. Carrying capacity
2. Overshoot
3. Population crash
4. Boom and bust

Answer 1

1. . The population of a species that can be supported in a specific area without depleting the available resources
2. when a population exceeds the carrying capacity of the environment and deaths result from a scarcity of resources
3. A rapid die-back in the population to a level below the carrying capacity
4. When a population undergoes repeated cycles of overshoots followed by crashes

Question 2

Population growth is described mathematically. N t = N0rt.

Describe N, T, and R

Answer 2

N= Population: Total number of all the members of a single species living in a specific area at the same time

T= Time: This is the unit of time upon which the rate is based

R= Rate: This is the rate of growth; the number of individuals which can be produced per unit of time under ideal conditions (with no limits to the population’s growth).

Question 3

What are logistic and exponential growth. How are they represented( as S-shaped or J-shaped curves)?

Answer 3

• Logistic Growth: S Shaped Curve: Sometimes population growth slows down as resources become scarce and a population nears its carrying capacity.
• Exponential Growth: J Shaped Curve: Growth at a constant rate of increase per unit time (geometric) ; has no limit. Tend to be for r-selected species.

Question 4

What is the difference between density-dependent and density-independent factors affecting population growth? Provide examples of both

Answer 4

• Density Dependent: The growth rate depends on population density. Many density dependent factors can influence population: Overcrowding can increase disease rate
• Density Independent: These are abiotic disturbances that affect population. Drought, fire, or habitat destruction

Question 5

List some characteristics of R-selected and K-selected species.

Answer 5

R-Selected: Rely on High Productive Rate to offset the high mortality rate of offspring with little or no parental care. Short life, early maturity, little investment in offspring.

K-Selected: Have fewer offspring. Longer life and high parental care or protection.Predators, regulated mainly by intrinsic factors. Adapted to stable environment. High investment in offspring. Few, large offspring.

Question 6

What is the meaning of this formula?

r=B+I-D-E

Answer 6

Rate of growth= Births+Immigration-Deaths-Emigration to other areas.

Question 7

Biotic regulatory factors tend to be?

Abiotic regulatory factors tend to be?

Answer 7

1. Biotic regulatory factors are Density Dependent

2. Abiotic regulatory factors tend to be Density Independent

Question 8

List examples of Biotic and Abiotic factors that regulate population growth

Answer 8

Biotic: Disease, physiological stress and predation

Abiotic: Drought, fire, habitat destruction. Weather