Ecosystems continually change over time Chapter 3 – Science 10

Ecosystems continually change ▪ 3.1 How Changes Occur Naturally in Ecosystems ▪ 3.2 How Humans Influence Ecosystems ▪ 3.3 How Introduced Species Affect Ecosystems Ecosystems Change and Species Adapt Introduced Species Natural Phenomena Human Activities

▪ 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. Natural Selection

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

Cichlid – an example of adaptive radiation

Galapagos Finches & Charles Darwin

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

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 ▪ 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 ▪ 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.

Primary Succession: hundreds of years

Secondary Succession: tens of years

How natural events affect ecosystems ▪ Natural events can change the abiotic and biotic conditions of an ecosystem ▪ Some examples: ▪ Flooding ▪ Tsunamis ▪ Drought ▪ Insect infestations

Flooding ▪ 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

Tsunamis ▪ 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?

Drought ▪ Below average precipitation ▪ Crop failure, animal death ▪ Made worse from climate change

▪ 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 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.

Insect Infestation: Mountain Pine Beetle