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COMMUNITIES AND ECOSYSTEMS

COMMUNITIES AND ECOSYSTEMS. Chapter 45. A. Community All populations of organisms living in a defined area. Habitat - the physical place where an organism lives. What is habitat of a koala? Niche - the role the organism has in the community (producer). What is niche of a koala?.

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COMMUNITIES AND ECOSYSTEMS

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  1. COMMUNITIES AND ECOSYSTEMS Chapter 45

  2. A. Community All populations of organisms living in a defined area. Habitat - the physical place where an organism lives. What is habitat of a koala? Niche - the role the organism has in the community (producer). What is niche of a koala?

  3. 1. Community Interactions Organisms in communities interact through competition, symbiosis or predation. • Interspecific Competition Individuals of different species compete for same resources (food, shelter, space). What are possible outcomes of interspecific competition?  one individual excludes the other(principle of competitive exclusion)  they coexist(resource partitioning)

  4. Principle of competitive exclusion Two species cannot coexist indefinitely in the same niche. When present alone, each has the same fundamental niche (all resources a species is capable of using). When present together, each has a different realized niche (all resources a species actually uses).

  5. When a new species enters an area, competition may lead to the extinction of a native population or species.

  6. Resource partitioning Competing species can coexist if they use the same resource in a slightly different way or at a different time.

  7. Symbiosis One species living in or on another. • mutualism - both species benefit. • commensalism - one species benefits with no apparent effect on the other.

  8. parasitism - one species benefits & the other is harmed. • parasitoidism - one species benefits & the other dies as a result.

  9. Predation One species (predator) kills another (prey) for food. Prey species often have adaptations that help them avoid being eaten. warning coloration camouflage mimicry

  10. 2. Ecological Succession Change in the species composition of a community over time. • Primary succession Occurs in an area where no community previously existed. • Caused by volcanoes, road cuts & glaciers. • Pioneer species are lichens & mosses. • Takes hundreds of years for a climax community to develop.

  11. Secondary succession Occurs in an area where a community is disturbed but not decimated (some soil & life remain). • Caused by fires, hurricanes & agriculture. • Pioneer species are herbs & weeds. • Occurs faster than primary succession. Few communities ever reach true climax conditions.

  12. Lupines • Lupines are legumes that add nitrogen to the soil • They are pioneer species in volcanic soil

  13. B. Ecosystem All the biotic (living organisms) and abiotic (nonliving environment) components in a defined area. • Ecosystems interact. • All ecosystems require a constant input of energy. • Chemicals are cycled within ecosystems.

  14. 1. Energy Flow Energy flows in one direction through an ecosystem. Route of energy flow is determined by an ecosystem’s trophic structure. animals that eat carnivores animals that eat herbivores animals that eat producers photo- or chemoautotrophs

  15. Food web - several species function at more than one trophic level.

  16. Test Your Cerebrum: • What is the niche of (think food chain) chemoautotrophic bacteria?

  17. Is all of the energy stored by individuals at one trophic level available to the next? No - energy needs of individual, second law of thermodynamics. On average, ~10% (2-30%) is transferred. Energy transfer in Cayuga Lake: humans store 1.5 kcal smelt fish store 15 kcal aquatic herbivores store 150 kcal algae store 1,500 kcal Food chains rarely extend beyond 4 trophic levels.

  18. Other types of pyramids can be used to describe ecosystems. • pyramid of numbers- shows number of organisms at each trophic level. • pyramid of biomass- shows total weight of organisms at each trophic level.

  19. Consider the food chain: hawk – rabbit – clover. Clover contains 10 calories of food value, rabbit 500 calories, hawk 1200 calories. Each species has a different daily caloric requirement: clover: sunlight rabbit: 100 calories of food hawk: 300 calories of food

  20. How many clover plants, per day, does it take to support a hawk? Hawk needs 300 calories from eating rabbits, so needs 3,000 rabbit calories available since only 10% moves up the food chain. 3,000 rabbit calories (where food energy is 500 calories per rabbit) means you need 6 rabbits to feed the hawk.

  21. 6 rabbits then need 100 calories of grass each, or 600 grass calories total. SO they feed on 6,000 calories of grass (since only 10% is available to them). Each clover plant is 10 calories so 600 clover plants = 6,000 calories. SO it takes 600 clover plants PER DAY to support one hawk!

  22. 2. Biogeochemical Cycles The biological & geological processes that recycle chemicals vital to life. • Water cycle

  23. Carbon cycle

  24. Nitrogen cycle

  25. N Cycle Quiz • What is the original source of nitrogen on Earth? • What fixes N from a gas into a usable form? (2 things) • In what form do plants take in N? • How do plants use N? • How do humans get N and why do they need it? • How does N return to the atmosphere?

  26. How do humans interrupt the N Cycle? • Fertilizer: producing N fertilizer started from leftover weapons • Runoff into water from crop fields • Causes birth defects • We overload the nitrate pool • Industry: air emissions • Domesticated cattle: farts & burps (maybe modify with kangaroo fart/intestinal bacteria DNA)

  27. New N Cycle Study • U of CA researchers have found that forest trees can use N found in sedimentary rock and boost their productivity. • Forests over N-rich rock were 50% more productive than forests over N-poor rock. • N was traced using radio-isotopes • Another factor in the N & C cycles!

  28. Phosphorous cycle

  29. Certain elements or compounds taken up by organisms cannot be metabolized or excreted. They accumulate in the organism (bioaccumulation) and may reach toxic levels. • heavy metals (lead, arsenic, mercury) • nonbiodegradable pesticides (DDT) The effects of bioaccumulated materials are magnified through the food web (biomagnification).

  30. of DDT

  31. What effect does DDT have on top predatory birds? DDT affects their ability to secrete a firm, calcium-rich eggshell.

  32. DDT Controversy DDT is used to kill female Anopheles mosquitos – most carry a plasmodium parasite that can infect and kill humans. (in 106 nations it is a problem) In sub-Saharan Africa, about 3,000 children die EACH DAY from malaria. In WW II, more people died from malaria than combat.

  33. DDT Use Today(read the handout!) • In 2006 the WHO approved DDT indoor use in African countries needing malaria control. • Sanaria in MD is the only company in the world working on a malaria vaccine: 30 scientists in a mini-mall lab. Artesunate is an anti-malarial drug for early treatment. • ALSO counterfeit drug trade is causing 20% of the 1 million malaria deaths each year.

  34. Let’s Review with a Problem • Food chain: • Bamboo (100 K) – needs sunlight • baby panda (2,500 K) – needs 500 K • snow leopard (6,000 K)–needs 1,500 K How many bamboo plants, per day, does it take to support a snow leopard? Note: snow leopards really eat goats & mountain sheep 

  35. Solution: • You need 6 baby pandas per day to feed a snow leopard • 6 baby pandas need 3,000 K total from bamboo • They feed on 30,000 calories of bamboo (to get the 10% or 3,000) • 30,000 bamboo K = 300 plants • It takes 300 bamboo plants per day to feed a snow leopard

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