Learning Objective- 14. Community Ecology PDF

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Professor Stockwell ...

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Community Ecology Learning objectives for BILD 3, Fall 2017 Dr. Sarah Stockwell You should be able to: 1. Define ecological community: Scientific study of the interactions between species in communities 2. Define ecological niche and distinguish it from habitat. - Ecological niche: An ecological niche is the way a particular species makes its living and the biotic and abiotic resources it uses. - It’s not just the habitat that a species occupies. It’s the ways in which it interacts with other species and the physical environment.

3. Contrast fundamental and realized niches, explain what factors may drive these to be different, and interpret the results of an experiment to determine whether a particular population is occupying all of its fundamental niche. (This is in the reading.)

4. Distinguish between interspecific competition and intraspecific competition, and give an example of each. Interspecific Competition • Different species compete for a particular resource that limits growth or survival. • Limiting resources include light, space, and nutrients. • Competition can decrease population growth rates.

Intraspecific Competition -

competition among individuals of the same species.

Ex. Hynas compete with each other (Intraspecific) Lion compete with Hynas ( Interspecific)

5. Understand which (if any) species benefits and which (if any) species is harmed in each of the following interactions: Parasitism, Predation, Competition, Mutualism, Commensalism. Be able to give an example of each from nature. (Some of this is from the reading.)

Parasitism: Parasites vs. Host (+/-) Predation:(+/-) White Rabbit and Wild Cat, evolve to their benefit Competition: (-/-) not enough resources for both mutualism: +/0 deer carries the seeds wherever they go

Commensalism: (+/0) Cattle stir up flies for bird to eat

6. Compare and contrast two potential outcomes of competitive interactions between species: competitive exclusion and resource partitioning. competitive exclusion: 2 species cannot grow together on the same limiting resources (will exclude one out) resource partitioning: co-exist but occupy diff. niches ( lizards on same trees but one on trunk and other on leaves) 7. Describe mechanisms (adaptations) species use to avoid predation (including herbivory).

8. Define cryptic and aposematic coloration and explain how they protect against predation.

9. Given a diagram of a food chain and information about whether it is a topdown or bottom-up system, predict how a change in the population size of one species would affect the population size of another species in the chain.

10.Compare and contrast top-down and bottom-up control of communities. Bottom-up: producers control food chain Top Down- Predators control food chain (wolves in Yellowstone)

11.Given some basic information, be able to draw a food web. Understand what type of relationships are represented in a food web. Identify organisms based on their trophic level as producers (autotrophs), consumers (heterotrophs; primary, secondary or tertiary consumers), or decomposers (detritovores).

12.Explain how the addition of wolves to Yellowstone affected the biotic and abiotic components of the ecosystem described in the video. Draw a food web of the trophic relationships described in the video.

13.Understand and give examples of species that have a strong influence on communities (dominant and keystone species). (This is in the reading.) Dominant species in a community are the species that are the most abundant or that collectively have the highest biomass  Impact when it dies: lead to extinction - in contrast, keystone species are not usually abundant in a community. Ex. American Chestnut tree – led to extinction of 7 species of moths and butterflies...