The living world: biodiversity

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