Ecosystems continually change over timeChapter 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 Ecosyste

ms Change

and Species Adapt

Introduced Species

Natural Phenome

naHuman

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.

http://www.youtube.com/watch?v=AMtT5_AQmLg

How ecosystems change over time: Ecological Succession

▪ A connection with Chapter 12: Mt. St. Helens▪ http://www.youtube.com/watch?v=BaRAGzjSkzo

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

http://www.youtube.com/watch?v=V49IovRSJDs

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

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

http://www.youtube.com/watch?v=anxJsQ7GEV4