Ecology: Odds and Ends

Question 1

Geographic Distribution or Range

Answer 1

the area inhabited by a population

Question 2

Population Density

Answer 2

• the number of individuals per unit area

- varies depending upon the species and its ecosystem

Question 3

Population Growth: Factors Affecting Population Size

Answer 3

a population will increase or decrease in size depending on how many individuals are added to it or removed from it

Question 4

Number of Births / Birth Rate

Answer 4

• can involve egg hatching or seed/spore germination, as well as single cell divisions (binary fission)
• if birth rate exceeds death rate, the population will increase

Question 5

Immigration

Answer 5

movement of individuals into an area; can cause populations to increase

Question 6

Emigration

Answer 6

movement of individuals out of an area; can cause populations to decrease

Question 7

Carrying Capacity

Answer 7

the largest number of individuals an ecosystem can support

Question 8

Limiting Factors

Answer 8

• any factor that causes population growth to decrease
• example: competition, predation, parasitism and disease, climate extremes, human disturbances, density dependent factors, density independent factors

Question 9

Density Dependent Factors

Answer 9

• those that become limiting only when the population density reaches a certain level
• operate most strongly when the population is large and dense

Question 10

Density Independent Factors

Answer 10

• those that affect all populations in similar ways, regardless of population size
• example: unusual weather, natural disasters, seasonal cycles, certain human activities

Question 11

Biological Magnification

Answer 11

process by which the concentration of a pollution- such as DDT- is multiplied as it passes up the food chain from producers to consumers