Overview
This lecture covers ecological range of tolerance, including its definition, examples, importance of genetic diversity, and strategies for answering related free-response questions (FRQs) with a focus on specificity.
Ecological Range of Tolerance
- Ecological tolerance is the range of environmental conditions an organism can survive before injury or death.
- Conditions include temperature, salinity, pH, and sunlight.
- Both species and individual organisms have specific tolerance ranges for these conditions.
- Genetic diversity within a species allows some individuals to survive outside the typical range.
Zones within the Range of Tolerance
- The optimal zone is where organisms survive, grow, and reproduce best; population size is highest here.
- The zone of physiological stress is where organisms survive but experience stress like infertility or reduced growth.
- The zone of intolerance is where conditions cause death due to factors like thermal shock or lack of resources.
Importance of Genetic Diversity
- Genetic diversity causes variation in tolerance ranges among individuals in a species.
- Populations with higher genetic diversity are more resistant to environmental changes, such as global warming.
FRQ Answering Strategies
- When answering FRQs about disturbances, connect the impact to ecological range of tolerance.
- Make answers stronger by linking human activities to climate change and altered tolerance ranges.
- Cite specific physiological stressors (e.g., suffocation from low oxygen, thermal shock, lack of water) rather than just stating death.
Example Connections and Applications
- Global warming raises water temperature, which may reduce dissolved oxygen and suffocate fish.
- Changes in rainfall patterns can decrease soil moisture, causing plant roots to absorb insufficient water and leading to plant death.
FRQ Skill Practice
- Practice identifying the author's claim in a passage about thermal tolerance in salmon, writing it as a testable hypothesis.
Key Terms & Definitions
- Ecological range of tolerance — range of environmental conditions an organism can endure before stress or death.
- Optimal zone — range where organisms thrive and reproduce.
- Zone of physiological stress — range where organisms survive with stress.
- Zone of intolerance — range where organisms cannot survive.
- Genetic diversity — variation in genetics within a species, allowing different tolerance abilities.
Action Items / Next Steps
- Read the passage about thermal tolerance in salmon and write a one-sentence testable claim by the author.