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Ecosystems

Ecosystems. Communities and Ecosystems Ecosystem is one or more communities plus the non-living (abiotic) factors. Biodiversity is the variety of different kinds of organisms that make up a community. Ecosystems.

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Ecosystems

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  1. Ecosystems Communities and Ecosystems Ecosystem is one or more communities plus the non-living (abiotic) factors. Biodiversity is the variety of different kinds of organisms that make up a community

  2. Ecosystems A niche is the total of all the resources a species exploits for its survival, growth, and reproduction. Competition prevents species from occupying the same niche Principle of Competitive Exclusion: no two species can occupy the same niche.

  3. Ecosystems • Populations of two species cannot coexist in a community if their niches are nearly identical

  4. Ecosystems

  5. Ecosystems Competition between species with identical niches has two possible outcomes • One of the populations, using resources more efficiently and having a reproductive advantage, will eventually eliminate the other • Natural selection may lead to resource partitioning

  6. Ecosystems • Predation is an interaction where one species eats another • The consumer is called the predator and the food species is known as the prey • Parasitism can be considered a form of predation

  7. Ecosystems Camouflage is a very common defense in the animal kingdom • Example: the gray tree frog

  8. Ecosystems Batesian mimicry occurs when a palatable or harmless species mimics an unpalatable or harmful one • The mimicry can even involve behavior • This hawkmoth larva puffs up its head to mimic the head of a snake

  9. Ecosystems Müllerian mimicry is when two unpalatable species that inhabit the same community mimic each other • Example: the cuckoo bee and the yellow jacket

  10. Ecosystems Symbiotic relationships help structure communities Symbiosis: two or more species that can live together Mutualism + + Commensalism + 0 Parasitisim + - Parasatoidism + death

  11. Ecosystems Examples of commensalism • Algae that grow on the shells of sea turtles • Barnacles that attach to whales • Birds that feed on insects flushed out of the grass by grazing cattle

  12. Ecosystems • Disturbances include events such as storms, fires, floods, droughts, overgrazing, and human activities • They damagebiological communities • They remove organisms from communities • They alter the availability of resources

  13. Ecosystems • Primary succession is the gradual colonization of barren rocks by living organisms • Secondary succession occurs after a disturbance has removed the vegetation but left the soil intact

  14. Ecosystems

  15. Ecosystems Energy flow and chemical cycling are the two fundamental processes in ecosystems A community interacts with abioticfactors, forming an ecosystem Energy flows from the sun, through plants, animals, and decomposers, and is lost as heat Chemicals are recycled between air, water, soil, and organisms

  16. Ecosystems Energy Flow through an Ecosystem Food Web vs. Food Chain Producers, consumers, decomposers Autotrophs, Heterotrophs Herbivores, Carnivores

  17. Ecosystems • A food chain is the stepwise flow of energy and nutrients • from plants (producers) • to herbivores (primary consumers) • to carnivores (secondary and higher-level consumers)

  18. TROPHIC LEVEL Quaternaryconsumers Carnivore Carnivore Tertiaryconsumers Carnivore Carnivore Secondaryconsumers Carnivore Carnivore Primaryconsumers Herbivore Zooplankton Producers Plant Phytoplankton A TERRESTRIAL FOOD CHAIN AN AQUATIC FOOD CHAIN

  19. Ecosystems • A food web is a network of interconnecting food chains • It is a more realistic view of the trophic structure of an ecosystem than a food chain

  20. Ecosystems • What Limits the size of food chains? • Energy Supply • Biomass is the amount of living organic material in an ecosystem • Primary production is the rate at which producers convert sunlight to chemical energy • The primary production of the entire biosphere is about 170 billion tons of biomass per year

  21. Ecosystems A pyramid of production reveals the flow of energy from producers to primary consumers and to higher trophic levels Tertiaryconsumers 10 kcal Secondaryconsumers 100 kcal Primaryconsumers 1,000kcal Producers 10,000 kcal 1,000,000 kcal of sunlight

  22. Ecosystems Only about 10% of the energy in food is stored at each trophic level and available to the next level • This stepwise energy loss limits most food chains to 3 - 5 levels • There is simply not enough energy at the very top of an ecological pyramid to support another trophic level

  23. Ecosystems There are four main abiotic reservoirs • Water cycle • Carbon cycle • Nitrogen cycle • Phosphorus cycle

  24. Ecosystems Environmental Challenges Air : air pollution, acid deposition, thinning ozone layer, global warming Land: deforestation, desertification Water: chemical pollution, endangered estuaries, coral reefs, polluted oceans

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