Population Interactions Ch. 51

1. Population InteractionsCh. 51

2. Ecological Community • Interactions between all living things in an area • Coevolution changes encourages by interactions between two or more species • Predator vs. Prey • Herbivore vs. Plant • Food Availability creates complex interactions: • Optimal Foraging Theory animal must balance the energy spent to get food with the energy they get from eating it; determines diet • Specialist eat one or few types • Generalist eat almost anything

3. Arms Race • Prey must adapt methods to protect themselves if they are to survive • Hiding places; physical defenses; poisons • Aposematic coloration bright, contrasting color patterns that act as a warning of poison • Predators must learn to over come these methods too • Recognize poisonous prey; hunting skills; immunity to poisons • Cryptic coloration camouflage to help hide predators and prey

4. Copy Cat • Mimicry resembling the appearance of a another species to gain an advantage • Batesian harmless species mimics a dangerous species • Mimic gains protection but does not commit energy like the model does • Mullerian dangerous species have similarities; predators learn of danger much faster

5. Fight for the Right to Survive • Interspecific competition competing between different species • IntRAspecific competition inside a population of one species • Interference species directly limit access to resources • Lions chase away hyenas • Exploitative species lower amount of resources so they are harder to find • Birds eat seeds so it is harder for squirrels to find them • Competitive Exclusion Principle if two population require the same limited resources in the same way, one will destroy the other

6. You Need a Niche • Niche specific way a species interacts with its environment • All successful businesses need a market in order to survive • Ecological niche the food type, amount, and space required for a species to survive • Fundamental all possible resources that CAN be used • Realized all possible resources ACTUALLY used • Competition can occur when fundamental niches overlap

7. Cant We All Just Get Along • Not all overlapping parts of niches lead to competition • All animals breath air but rarely have to compete for it • Resource partitioning different species can use the same resources but can get them or use them in different ways • Birds species can feed on the same insects but get them different parts of the tree • Character Displacement • Sympatric species living in the same area are more morphologically different • Darwin’s Finches • Allopatric species living in different areas are less morphologically different

8. Symbiotic Interactions • Symbiosis physical ecological interactions • Commensalism one species benefits and one species is not affected • Grass eaters stir up insects that birds will eat • Mutualism both species benefit • E. coli in your intestine gets nutrients from us and gives us vitamins • Parasitism one species benefits (parasite) and one species is negatively affected (host) • Tapeworm takes nutrition from our intestine and decreases our health • Endoparasites live inside the body • Ectoparasites live outside the body

9. Defining A Community • Some see communities as “super-organisms”; species in the community are so well connected they require each other to exist and to exist in certain amounts • Species composition could reach equilibrium and shifts with major changes • Others think communities constantly change and have no strict boundaries or composition • Some biomes do have clear boundaries though; Water vs. Land, Aerobic vs. Anaerobic • Ecotones edges where communities meet; full of biodiversity • ESSAY!!! • Explain which of these ideas you most agree with; support with reference material

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