BIO 311D 2nd Edition Lecture 36 Outline of Last Lecture I Measuring population growth II Population growth models III Human population growth IV Index Card Questions Outline of Current Lecture I Introduction to Community Ecology II Biotic Interactions among species III In class exercise Yellowstone wolves Current Lecture I Introduction to Community Ecology A Carrying capacity a Exponential Growth J shaped unlimited b Logistic Growth S shaped B Organismal Population single species Community interactions between species biotic factors Ecosystem abiotic and biotic factors Landscape practical for management Global a Species interactions comparisons through physiology b Involves evolution C Community all the populations of different species living close enough to interact with each other a General goal be able to relate population and community ecology to evolution and physiology b Community ecology the study of interactions between species 1 What is a community s tropic structure 2 How do species interact 3 What is the ecological niche D Tropic structure a A community s tropic structure the set of all feeding relationships in the community food chains food webs b 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 parasitism II III d Decomposers release inorganic materials source of food dead organisms e Figure 53 12 Terrestrial and marine food chains Biotic interactions A 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 Interactions a 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 Mutualism e Competition f Commensalism g Amensalism 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 increase b Elk increase coyote increase B 1974 Wolves protected by law in Wyoming C 1995 Begin re introduction of wolves into Yellowstone 14 from Canada D 1996 17 more wolves from another Canadian population
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