Overview
This lecture explains the concept of ecological range of tolerance, its significance, and strategies for incorporating it into written responses, focusing on examples like salmon and the impacts of climate change.
Ecological Range of Tolerance
- Ecological tolerance describes<u> the range of environmental conditions (e.g., temperature, salinity, pH, sunlight) an organism can survive before injury or death.</u>
- Both entire species and individual organisms have specific tolerance ranges for each environmental condition.
- Genetic diversity within a species, such as salmon, results in varied tolerance among individuals, increasing population resilience to environmental change.
Zones within Tolerance Range
- The <u>optimal zone is where organisms survive, grow, and reproduce best</u>; population size is largest here.
- The range of physiological stress is where<u> organisms survive but face challenges like infertility or stunted growth, </u>resulting in lower population sizes.
- The zone of intolerance occurs whe<u>n conditions cause death; </u>always cite specific causes (e.g., thermal shock, lack of oxygen) rather than just saying "organisms die."
Writing Tips for FRQs (Free Response Questions)
- Link human activities (electricity generation, transportation, agriculture) to ecological tolerance by discussing their contribution to climate change and altered environments.
- Specify how environmental changes (like global warming) push conditions outside species’ tolerance, possibly leading to population decline.
- Strengthen answers by identifying specific physiological stresses (e.g., suffocation due to low oxygen, thermal shock, dehydration) rather than general statements about death or extinction.
Examples of Applying Tolerance Concepts
- Rising ocean temperatures reduce dissolved oxygen, causing fish (like salmon) to potentially suffocate.
- Increased drought decreases soil moisture, preventing plant roots from absorbing water and causing plant death due to dehydration.
Practice Skill: Identifying Author Claims
- Practice reading a passage and write a sentence identifying a testable claim or hypothesis presented by the author.
Key Terms & Definitions
- Ecological Range of Tolerance — The span of environmental conditions an organism can withstand before being harmed or dying.
- Optimal Zone — The ideal range where organisms thrive and reproduce most effectively.
- Range of Physiological Stress — Suboptimal conditions where survival is possible but reproduction or growth is impaired.
- Zone of Intolerance — Conditions so extreme organisms cannot survive.
- Physiological Stressor — A specific cause of harm, such as lack of oxygen, food, water, or extreme temperature.
Action Items / Next Steps
- Read the provided passage on thermal tolerance in salmon.
- Identify the author’s claim by writing one testable hypothesis sentence.