Population Interactions Ch. 51

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

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

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

Fight for the Right to Survive Interspecific competition  competing between different species – IntRAspecific  competition inside a population of one species 1)Interference  species directly limit access to resources – Lions chase away hyenas 2)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

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

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

Symbiotic Interactions Symbiosis  physical ecological interactions 1)Commensalism  one species benefits and one species is not affected – Grass eaters stir up insects that birds will eat 2)Mutualism  both species benefit – E. coli in your intestine gets nutrients from us and gives us vitamins 3)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

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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