BIO 311D 2nd Edition Lecture 36 Outline of Last Lecture I. Measuring population growthII. Population growth modelsIII. Human population growthIV. Index Card Questions Outline of Current Lecture I. Introduction to Community EcologyII. Biotic Interactions among speciesIII. In-class exercise: Yellowstone wolves Current LectureI. Introduction to Community EcologyA. Carrying capacitya. Exponential Growth: J-shaped, unlimitedb. Logistic Growth: S-shapedB. Organismal Population (single species) Community (interactions between species, biotic factors) Ecosystem (abiotic and biotic factors) Landscape (practical for management) Globala. Species interactions comparisons through physiologyb. Involves evolution C. Community: all the populations of different species living close enough to interact with each othera. General goal: be able to relate population and community ecology to evolution and physiologyb. Community ecology: the study of interactions between species1. What is a community’s “tropic structure”?2. How do species interact?3. What is the “ecological niche”?D. Tropic structurea. A community’s tropic structure- the set of all feeding relationships in the community, food chains, food websb. Energy and most chemical nutrients enter the food chain at a primary producer (algae, grass, oak trees, protist algae, etc.) c. Energy is transferred to consumers by predation and parasitismd. Decomposers release inorganic materials (source of food= dead organisms) e. Figure 53.12 Terrestrial and marine food chains II. Biotic interactionsA. Two species live in the same place. Do they interact? Is the interaction sufficient that one species affects the evolution of the other? Competitors? Adaptations? a. Chart types of interactions in a community:1. A species benefits +2. Species is harmed –3. No effect on a species 0 B. Types of Interactionsa. Predation (predator-prey)1. One species benefits, the other is harmed 2. How to test if this is the only factor regulating the population? – Large controlled 3. How could you test whether predators are regulating prey populations?- Experiment: Manipulate hare food supply. Exclude predators - Keystone species b. Herbivory (plant-herbivore)c. Parasitism (pathogen-host)d. Mutualisme. Competitionf. Commensalismg. Amensalism III. Case Study: Wolves at Yellowstone A. Wolves became extinct in the park by the early 1940s. What do you think happened to other populations in this community?a. Grizzly bear could increaseb. Elk increase, coyote increase B. 1974 Wolves protected by law in WyomingC. 1995 Begin re-introduction of wolves into Yellowstone – 14 from CanadaD. 1996 17 more wolves from another Canadian
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