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2.4 Ecological Tolerance, 2.5 Natural disruptions to ecosystems, 2.6 Adaptations
Ecological Range of tolerance
Range of conditions such as temperature, salinity, pH, or sunlight that an organism can endure before injury or death results
Optimal range
Range where organisms survive, grow, and reproduce
Zone of physiological stress
Range where organisms survive, but experience stress such as infertility lack of growth, decreased activity, etc.
Zone of intolerance
Range where the organisms will die
Natural disturbances
A natural event that disrupts the structure and or function of an ecosystem (can be greater than human disruptions)
Periodic
Occurs with regular frequency
Example of period natural disturbances
Dry-wet seasons
Episodic
Occasional events with irregular frequency
Example of Episodic natural disturbances
Hurricanes, droughts, fires
Random
No regular frequency
Examples of Random natural disturbances
Volcanoes, earthquakes, and asteroids
Natural Climate Change
Earth’s climate has varied over geologic time for numerous reasons
Major environment disturbances result in…
Widespread habitat changes and or loss
Migration
Wildlife may migrate to a new habitat as the result of natural disruptions
Adaptation
A new trait that increases an organism’s fitness
Fitness
Ability to survive and reproduce
Natural selection
Organisms that are better adapted to their environment survive and reproduce more offspring
Selective pressure/force
The environmental conditions that kills individuals without the adaptation
What does the environment determine for an organism?
The different traits may become adaptations and old traits may become disadvantages
Pace of evolution
The more rapidly an environment changes, the less likely a species in the environment will be able to adapt to those changes
What if there’s more genetic diversity in a population?
The better they’re able to adapt to environmental change
Note 
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