1.Review- What is a niche Use Analogies- How is a niche like a profession. In ecological terms, describe your niche. 2.Review- What is symbiosis. What are the major type of symbiosis. Explain- Bacteria living in a cow’s stomach help the cow break down the cellulose in grass, gaining nutrients in the process. Is this an example of commensalism or mutualism- explain. Apply Concepts- What is the difference between a predator and a parasite- explain 3.Review- What is a keystone species. Infer- How might a dramatic decrease in vegetation lead to a decrease in a predator species.

Ch 4 Ecosystems and Communities 4.2 Niches and Community Interactions

Community Ecosystem Interacting populations at the same time and place The community and its environment (abiotic factors).

No two organisms share exactly the same niche in the same habitat Role in community, it’s job or what it does Includes biotic and abiotic factors Habitat Physical place where it lives No two organisms share exactly the same niche in the same habitat Niche and Habitat of Your pet dog Spot Oak tree You.

Tolerance Ability to survive and reproduce under a range of environmental circumstances Farther than the optimal the greater the stress More energy to maintain homeostasis and less energy left for growth and reproduction.

Competition Occurs when organisms attempt to use the same limited ecological resource in the same place at the same time Intraspecific Competition Between members of the same species Interspecific Competition Between members of different species.

The Competitive Exclusion Principle No two species can occupy exactly the same niche in exactly the same habitat at exactly the same time One species will be better at competing for limited resources and will eventually exclude the other species.

The Competitive Exclusion Principle Dashed Lines- Cultures grown separately Solid Lines- Cultures grown together.

Dividing Resources Species usually divide resources rather than compete over them Using slightly different resources results in different niches.

Predator-Prey Relationships Predation One organism kills and eats the other one Predators can affect the size of prey populations in a community and determine the places prey can live and feed.

Herbivore-Plant Relationships Herbivory Interaction where a herbivore feeds on producers Can affect both the size and distribution of plant populations and determine where certain plants can survive and grow.

Keystone Species Species that plays major role in the structure of the entire community Beaver.

Relationships Review Symbiosis Predator-prey Parasitism Organisms of different species that live in direct physical contact Predator-prey Relationship where one organism kills and eats the other one Win/lose (+,-) Parasitism Relationship where one organism lives off another one without trying to kill it Win/lose (+,-).

Relationships Review Competition Mutualism Commensalisms More types Relationship where both organism want the same resource- food, habitat Lose/lose (-,-) Mutualism Relationship where both organisms benefit Win/win (+,+) Commensalisms Relationship where one organism benefits and the other is unaffected Win/nothing (+,0) More types Lose/win (-,+).