Ecological Range of Tolerance - Notes

  • Introduction to Ecological Range of Tolerance

    • Ecological range of tolerance refers to the range of environmental conditions an organism can tolerate before experiencing injury or death.
    • Conditions include:
    • Temperature
    • Salinity
    • pH
    • Sunlight
    • Both species and individual organisms possess a range of tolerance for various environmental factors.

  • Example of Salmon

    • Basic temperature tolerance range: 6 to 22 degrees Celsius.
    • Individual salmon may have adaptations allowing them to survive slightly outside this range.
    • Adaptations result from genetic diversity within the species, contributing to resilience against changes like global warming.

  • Variation Among Species

    • Different salmon subspecies exhibit varying temperature tolerance ranges.
    • Graphical representation shows temperature (x-axis) vs. aerobic scope (y-axis), illustrating species-specific tolerance ranges.

  • Zones Within the Range of Tolerance

    • Optimal Zone:
    • Ideal range for survival, growth, and reproduction.
    • Maximum organism population occurs in this zone.
    • Range of Physiological Stress:
    • Organisms can survive but experience stress (e.g., infertility, slow growth).
    • Population size diminishes as conditions move beyond optimal range.
    • Zone of Intolerance:
    • Conditions are lethal to organisms.
    • Important to specify cause of die-off (e.g., thermal shock, food shortage).

  • Writing Tips for Free Response Questions (FRQs)

    • Connect answers to ecological range of tolerance, especially concerning human activities or natural events that disturb ecosystems.
    • Examples of disturbances:
    • Electricity generation, transportation, and agriculture contributing to climate change (increased CO2 levels).
    • Consequences of global warming:
    • Increased temperatures leading to stresses beyond species’ tolerance ranges.
    • Example: Ocean temperature rises affecting aquatic species leading to die-offs from physiological stresses, e.g., decreased oxygen levels.

  • Citing Physiological Stressors

    • Strengthen FRQ responses by identifying specific physiological stress rather than general outcomes.
    • Examples:
    • Fish suffocating from lack of dissolved oxygen due to warm water temperatures.
    • Plants dying from drought conditions leading to insufficient soil moisture and roots unable to absorb water.

  • Practice Skill

    • Identify the author's claim regarding thermal tolerance in a passage about salmon.
    • The claim should be a testable hypothesis that can be examined through experimentation.