Population ecology

Question 1

Explain why the carrying capacity of a population is determined by limiting factors

Answer 1

• Limiting factors cause environmental resistance
• Environmental resistance causes the growth of the population to slow
• This can lead to growth ceasing all together where growth rate = declining rate and carrying capacity is reached

Question 2

Describe environmental resistance

Answer 2

The sumof all environment limiting facors

Causes population growth to slow and possibly cease

Question 3

List the density-dependant limiting factors

Answer 3

(Effects increase as population increases)

• Competition: for food, shelter, mates
• Predaction: Increase prey = increase food = increase predators = decrease food
• Crowding: increase stress = decrease reproductive rate = decrease immune system
• infectious disease: spread more easily in high density population

Question 4

List the density- independant factors

Answer 4

Regular abiotic conditions:
- water availability
- Temp
- Salinity

Irregular disturbances:
- flood
- fire
- drought

Question 5

Explain the J- curve

Answer 5

Exponental growth

• if resources within an ecosystem were unlimited, the population could continue to grow exponentially (“Boom”)
• Growth may be stopped suddenly by a limiting factor causing a population crash (“bust”)

Question 6

Explain the s-curve

Answer 6

Logistic growth

• resources are always limited and ecosystems cannot sustain an infinite number of organisms
• carrying capacity is dynamic: it is determined by the most limiting factor