Ecosystems continually change over time
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Ecosystems continually change over time . Chapter 3 – Science 10. Ecosystems continually change. 3.1 How Changes Occur Naturally in Ecosystems 3.2 How Humans I nfluence E cosystems 3.3 How Introduced Species Affect Ecosystems. Natural Selection.

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Ecosystems continually change
Ecosystems continually change

  • 3.1 How Changes Occur Naturally in Ecosystems

  • 3.2 How Humans Influence Ecosystems

  • 3.3 How Introduced Species Affect Ecosystems

Natural selection
Natural Selection

  • When an organism is born, it belongs to a species, but it also is born with unique characteristics.

    • Sometimes, these unique characteristics give organisms an advantage within their niche. For example, a salmon with a slightly larger tail may be able to swim a little faster or a little farther in a river.

  • Natural selection is the process where individuals with advantages are better able to reproduce and pass along their traits.

    • Those with unfavourable characteristics have less chance to reproduce and pass along their traits.

      • A salmon with a smaller tail may never have a chance

        to spawn because it cannot swim to the correct location.

A salmon with a large tail may be able to swim faster and farther.

3 1 how changes occur naturally in ecosystems
3.1 How changes occur naturally in ecosystems

  • Natural Selection

    • Change is possible in living things

  • Adaptive Radiation

    • Different species have “radiated” out from a common ancestor to inhabit different niches.

  • Lake Victoria Cichlid

Natural selection1
Natural Selection

  • Natural selection is the process that enables organisms to change in response to changes in abiotic and biotic components of an ecosystem.

Adaptive radiation
Adaptive Radiation

  • Adaptive radiation is the change from a common ancestor into a number of different species that can inhabit different niches.

How ecosystems change over time ecological succession
How ecosystems change over time: Ecological Succession

  • A connection with Chapter 12: Mt. St. Helens


Ecological succession
Ecological Succession

  • Two types:

  • Primary Succession

    • Occurs in an area where NO SOIL exists

    • Slow

    • First organisms to appear are called pioneer species

      • Lichens, mosses etc…

  • Secondary Succession

    • After a disturbance in an area that already had soil and organisms

      • Fire, floods, building a road through a forest etc…

    • Much faster than primary succession

Primary succession mature community
Primary Succession: Mature Community

  • From Bare Rock to Mature Communities

  • A mature community is also called a climax community but a mature community is a preferred term because forests are constantly changing.

  • A forest is an example of a mature community.

Primary succession pioneer species
Primary Succession: Pioneer Species

  • Pioneer Species take advantage of bare rock.

    • Pioneer species decay and create soil.

    • Pioneer species provide food for other organisms, introducing new animals to the community.

  • New plants take over the new soil area until….

  • The next species succeeds the previous species and so on until a mature community is established.

How natural events affect ecosystems
How natural events affect ecosystems

  • Natural events can change the abiotic and biotic conditions of an ecosystem

  • Some examples:

    • Flooding

    • Tsunamis

    • Drought

    • Insect infestations


  • Can cause soil erosion and wash away nutrients

  • Can cause the spread of disease in human populations

    • Bacteria and toxins polluting the water supply

  • Climate change

    • May be causing increase around the world


  • Huge rapidly moving ocean wave

  • Caused by earthquakes or underwater volcanic eruptions *Ch. 12/13

  • Salt water kills the plants on shore *remember the NaCl lab?


  • Below average precipitation

  • Crop failure, animal death

  • Made worse from climate change

Insect infestation
Insect Infestation

  • Insect infestations

    • Many insects play important roles in their ecosystems.

    • Even insects that appear destructive, such as the

      mountain pine beetle, actually play a role in the

      renewal of the forest.

      • The beetles have a symbiotic relationship with a species of fungus that inhibits the trees’ ability to use resin for protection.

    • However, when normal conditions are changed, infestations can occur.

      • Trees can be stressed from overcrowding drought or animal grazing and do not resist the insects as effectively.

      • A warmer climate and lack of forest fires allows the insects to spread much more effectively than in the past.

    • Not only are the trees affected, but so is the entire forest ecosystem, as well as any human industries relying on the forest.

Mountain pine beetle.

Insect infestation1
Insect Infestation

  • Mountain pine beetle example:

  • Forests are no longer exposed to sustained periods with temperature below -30°C

    • Climate change

  • Too many beetles attack stressed out trees.

  • A fungus symbiotic with the beetle is passed from tree to tree.

    • Blue stain fungus prevents the tree from making protective resin and destroys tissues

  • Trees die!

  • Many habitats are destroyed for organisms depending on the trees.