4.2.1

3. Habitat– The area where an

organism lives

4. Niche– The range of physical

and biological conditions in which an organism lives.

E. Symbiosis

1. Any relationship where two organisms are living closely together.

2. Commensalism

• A symbiotic relationship where one organism benefits and the other is neither benefited nor harmed.

Eyelash mites Wolf in shade

3. Mutualism

• A symbiotic relationship where both organisms benefit mutually.

Clown fish and sea anemoneAnts and acacia tree

4. Parasitism

• A symbiotic relationship where one organism benefits and the other suffers.

Wasp parasite on caterpillar

Daily Trivia

• The sidewinder is a desert snake that moves in a way that only 2 parts of it’s body are touching the sand at a time.

• This prevents the snake from getting burned on the hot sand.

What Shapes an Ecosystem?

The Niche

• What is included in a niche?– the range of temperatures that an organism needs

to survive– the organisms place in the food web– the time of year it reproduces– how many offspring it produces– the type of shelter it occupies

• No two species can share the same niche in the same habitat. • Different species can occupy niches that are very similar.

Community Interactions

Community Interactions– When organisms live together in ecological communities,

they interact constantly.

– Community interactions, such as competition, predation, and various forms of symbiosis, can affect an ecosystem.

Community Interactions

Competition- when organisms of the same or different species attempt to use an ecological resource in the same place at the same time.

Competitive Exclusion principle

• Resources are limited. • No 2 species can occupy the same niche in the

same ecosystem at the same time. • Direct competition will result in a winner and

loser. The loser will fail to survive.

Community Interactions

The distribution of these warblers avoids direct competition, because each species feeds in a different part of the tree.

Yellow-Rumped Warbler

Bay-Breasted Warbler

Feed

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ht (m

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0

6

12

18

Cape May Warbler

Community Interactions

Predation• An interaction in which one organism captures and

feeds on another organism is called predation. • The organism that does the killing and eating is

called the predator, and the food organism is the prey.

Antipredator adaptations (crypsis)

• Disruptive Coloration– Animals, like the zebra, use their

coloration patterns to make it hard to see them.

• Counter Shading– Counter shading is seen mostly

in aquatic animals. They are light on the bottom and dark on the top.

Antipredator adaptations (crypsis)• Color Change– Some animals can even change their coloring to try

and fool predators.• Camouflage (appropriate background)– Another group of animals look like something

commonly in their environment.

Antipredator adaptations (crypsis)• Warning Coloration– Animals that are poisonous often

advertise this by using bright colors and patterns to discourage predators.

• Mimicry– An organism copiesthe crypsis of anothermore dangerous organism

4.2.2

DAILY TRIVIA

• Mount Saint Helens summit was 9,677 feet before the eruption and 8,363 feet after

1,314 feet were removed by the blast.

Ecological Succession

What is ecological succession? Ecosystems are constantly changing in response to

natural and human disturbances. As an ecosystem changes, older inhabitants

gradually die out and new organisms move in, causing further changes in the community.

D. Ecological Succession1. Predictable changes

that occur in a community over time.

2. Primary Succession– No exposed

soil

3. Pioneer Species– The first

species to populate a new area.

Ecological Succession

Ecological successionThe gradual, sequential re-growth of a species in an area

o Sometimes, an ecosystem changes in response to an abrupt natural or man-made abrupt disturbance.

o At other times, change occurs as a more gradual response to natural fluctuations in the environment.

Ecological Succession

Pioneer SpeciesThe first species to grow after an ecological disturbance.

o tend to be small, fast growing and fast reproducing

• Each stage of succession alters the physical environment in ways that make it less favorable for their own survival but more favorable for the organisms that will replace them

Climax CommunityA stable, mature community that marks the “end” of succession.

Ecological Succession

In this example, a volcanic eruption has destroyed the previous ecosystem.

Ecological SuccessionThe first organisms to appear are lichens.

Ecological SuccessionMosses soon appear, and grasses take root in the thin layer of soil.

Ecological SuccessionEventually, tree seedlings and shrubs sprout among the plant community.

Ecological Succession

Secondary SuccessionOccurs where an existing community has been cleared by a disturbance, natural or man-made, but the soil has been left intact.

What would be some examples of disturbances that would result in secondary succession?

The Eruption of Mount Saint Helens

http://www.youtube.com/watch?v=rbgAOfv-W20

Homework