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Community and Ecosystem Ecology

Community and Ecosystem Ecology. Chapter 20. Community Ecology. Species living in same vicinity Potential interactions will occur Interspecific interactions Interactions between species Classified according to effect on populations Helpful (+) Harmful (-). Community Interactions.

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Community and Ecosystem Ecology

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  1. Community and Ecosystem Ecology Chapter 20

  2. Community Ecology • Species living in same vicinity • Potential interactions will occur • Interspecific interactions • Interactions between species • Classified according to effect on populations • Helpful (+) • Harmful (-)

  3. Community Interactions • Occurs in a few ways: • Competition • Mutualism • Predation • Herbivory • Parasites and pathogens

  4. 1. Competition (-/-) • Occurs when members of two different species try to utilize the same resource • Competitive Exclusion Principle: • No two species can occupy the same ecological niche at the same time

  5. Competition Between Two Species of Barnacles

  6. Competition • Competition can lead to resource partitioning • decreases competition between the two species • Character displacementis often viewed as evidence that competition and resource partitioning have taken place

  7. 2. Mutualism (+/+) • Both members of the association benefit

  8. 3. Predation (+/-) • Predator • Prey • 2 ways this regulates population growth: • A. Predator-Prey Population Dynamics • B. Antipredator Defenses

  9. 3. Predation • A. Predator-Prey Population Dynamics • Cycling of predator and prey populations • Occurs when either predators overkill prey, or when prey overuse resources and their numbers crash • In either case, predator numbers also decrease from a decrease in food source

  10. Predatory-Prey Cycling of a Lynx and a Snowshoe Hare

  11. Coevolution • Evolutionary change in one species results in an evolutionary change in the other • Organisms in symbiotic associations are especially prone to the process of coevolution • Also occurs between predators and prey • Example: Cheetah sprints forward to catch prey, and this behavior might be selective for those gazelles that jump high in the air

  12. 3. Predation • B. Antipredator Defenses • Cryptic coloration • Camouflage • Warning coloration • Association with undesirable consequences

  13. 3. Predation • B. Antipredator Defenses • Mimicry • One species resembles another species • Can help capture food or avoid being preyed upon • Batesian Mimicry • A prey that is not harmful mimics another species that has a successful antipredator defense • Warning colorations • Mullerian mimicry • Species that resemble each other all have successful defenses

  14. Mimicry Among Insects Mullerian Batesian

  15. Coral snake vs. Milk snake http://www.youtube.com/watch?v=LU8DDYz68kM

  16. 4. Herbivory (+/-) • Consumption of plants by an animal • Plant must expend energy to regenerate • Evolved defenses

  17. 5. Parasites & Pathogens (+/-) • Parasite • Lives on or in a host • Endoparasite • Ectoparasite • Pathogens • Disease-causing microorganisms

  18. Trophic Structures • Feeding relationships among species in a community • Determines the passage of energy and nutrients • Sequence of food transfer is a food chain • Unbranched

  19. Trophic Structure • Autotrophs (producers) • Require an energy source and inorganic nutrients to produce organic food molecules • Manufacture organic nutrients for all organisms • Green plants and algae carry on photosynthesis

  20. Trophic Structure • Heterotrophs (consumers) • Need a preformed source of organic nutrients • Herbivores • Graze directly on plants or algae • Carnivores • Feed on other animals • Omnivores • Feed on both plants and animals

  21. Trophic Structure • Decomposers • Heterotrophic bacteria and fungi • Break down nonliving organic matter • They release inorganic matter to be used by producers • Scavengers • Feed on dead remains

  22. Ecosystem Ecology • Possesses both abiotic and biotic components • Biotic • The various populations of organisms that form a community • Abiotic • Includes resources such as sunlight, inorganic nutrients, soil, water, temperature and wind • Two major processes sustain all ecosystems: • Energy flow • passage of energy through the components of the ecosystem • Chemical cycling • use and reuse of chemical elements within the ecosystem

  23. al c cy i cl m e in g Ch Energy flow Chemical energy Light energy Heat energy Chemical elements Bacteria, protists, and fungi

  24. Energy Flow • Biomass • Mass of living organic material in ecosystem • Ecological Pyramids • only about 10% of the energy of one trophic level is available to the next trophic level • Producers at the base • Most available energy • Energy is given off in less usable forms as producers are eaten by primary consumers, etc.

  25. Chemical Cycling • Biogeochemical cycles • Biotic and abiotic components of the chemical cycles in an ecosystem • 3 main cycles: • Carbon cycle • Phosphorus cycle • Nitrogen cycle

  26. CO2 in atmosphere Burning Photosynthesis Cellular respiration Higher-level consumers Plants, algae, cyanobacteria Primary consumers Wood and fossil fuels Decomposition Wastes; death Plant litter; death Decomposers (soil microbes) Detritus Figure 20.32

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