4.4 - Ecological Tolerance

Question 1

What is ecological tolerance?

Answer 1

• Range of conditions such as temperature, salinity, pH, or sunlight that an organism can endure before injury or death results
• Species and individual organisms both have a range of tolerance for all the different environmental conditions
  of their habitat

Question 2

What is optimal range?

Answer 2

range where organisms survive, grow, and reproduce

Question 3

What is the zone of physiological stress?

Answer 3

range where organisms survive, but experience some stress such as infertility, lack of growth, decreased activity, etc.

Question 4

What is the zone of Intolerance

Answer 4

• range where the organism will die
• Ex: thermal shock, suffocation, lack of food/water/oxygen

Question 5

What are the 3 ecological tolerance zones?

Answer 5

1. Optimal Range
2. Zone of Physiological Stress
3. Sone of Intolerance

Question 6

FRQ writing tips

Answer 6

• On FRQs about human activities or natural events that cause environmental disturbance, connect answer to ecological range of tolerance
  - Global warming shifts temperature outside the range of tolerance for many tree species, causing their populations to decline
• Try to connect a shift in range of tolerance to a specific kind of physiological stress (suffocation, thermal shock, lack of water/food/nutrients/oxygen)
• Example: Global warming warms the ocean, shifting temperature outside range of tolerance for many fish species. Since global warming increases ocean temperature and warm water holds less oxygen, fish may suffocate due to lack of oxygen.