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Chapter 8 community ecology

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  1. Chapter 8community ecology

  2. How do organisms interact? • Fighting/ competition • Breeding • Predator/ prey • Symbiosis

  3. Interspecific competition • Different species compete for space or resources • Causes animals to shift niches, adapt, evolve, migrate, or go extinct

  4. Reducing competition • Animals become more specialized in what they eat/ where they live, when they are active • Resource partitioning • Character displacement

  5. Reducing competition • Resource partitioning: • Species evolve ways to share limited resources • Different times of day/ year • Different uses • Different places

  6. Resource Partitioning in 5 species of Warbler 9-5

  7. Resource partitioning via specialized feeding niches: Brown pelican dives for fish, which it locates from the air Herring gull is a tireless scarialavenger Black skimmer seizes small fish at water surface Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Ruddy turnstone searches under shells and pebbles for small invertebrates Flamingo feeds on minute organisms in mud Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Knot (a sandpiper) picks up worms and small crustaceans left by receding tide Piping plover feeds on insects and tiny crustaceans on sandy beaches Louisiana heron wades into water to seize small fish Reduces competition and allows sharing of limited resources

  8. Reducing competition • Character displacement: • Organisms change physical characteristics to become specialized • Finches develop different size and shape beaks to reduce competition

  9. predation • Predator eats prey species • Predators often feed on the old/ sickly/ weak/ least fit • This reduces competition among prey • Predators control prey populations

  10. Control hypotheses • Problem: both hypotheses assume too much. • Top-down- that lynx only eat rabbits and rabbits are only eaten by lynx • Bottom-up- that only rabbits eat veggies

  11. Top-down control hypothesis • Says that predators control prey pops • Ex: Lynx eat rabbits so rabbits decrease. Rabbits decrease so there is less food for the lynx so the lynx crash. Less lynx means less predators so rabbits increase which allows the lynx to increase.

  12. Bottom-UpControl Hypothesis • Food sources influence population • Ex: Rabbits eat too much vegetation so there isn’t enough food. Rabbits crash. Veggies grow back and then rabbits increase.

  13. predators • Pursuit: Fast runners, ability to see from above, hunt cooperatively in packs

  14. Predators • Ambush: use camouflage to hide in plain sight and surprise their prey

  15. Predators • Chemical warfare: bite and inject venom into prey

  16. Prey defense • Run, swim, fly fast • Highly developed sight/ smell/ hearing • Protective shells/ bark/ spines • Change colors • Mimicry • Camouflage • Chemical warfare

  17. Mimicry

  18. Behaviors

  19. plants • Plants develop many defense chemicals • Pepper, caffeine, cyanide, cocaine, opium, strychnine, peyote, nicotine, rotenone, mustard, nutmeg, oregano, cinnamon, mint

  20. parasitism • One organism lives on or in another organism and lives off of it

  21. parasitism • Some parasites have a different host for each life stage

  22. mutualism • Two species acting together so both benefit • Pollination: bees and flowers • Nutritional: coral and zooxanthellae • Food + protection: ox pecker birds and rhinos • Gut inhabitation: bacteria in termites/ humans to aid in digestion

  23. commensalism • Two species interact and one benefits while the other is basically unaffected

  24. Native species • Species that are normally found in a particular area and they thrive in that environment

  25. Nonnative/ invasive/ alien/ introduced/ exotic species • A species that is not originally found in that location • Some are harmful, others are benign, others are helpful

  26. Non-native species • A non-native species that DOES NOT harm it’s new environment • Usually plants • Ex: Goldfish

  27. Invasive species • Any non-native specie of plants, animals, etc that: • Is harmful to native critters • Negatively affects it’s new environment • Can hurt new environment economically • Examples: zebra mussels, brown anoles, African bees, Kudzu

  28. Invasive Species • Zebra mussels (Great Lakes): • Released via ship ballasts (1988) • Filter out nearly all the phytoplankton (and small zooplankton) • Bad and good

  29. invasive Species:Zebra Mussels Distribution

  30. Invasive Species:Zebra Mussels Distribution 2004!

  31. Invasive species • Asian green mussels in Tampa Bay

  32. Invasive Species African bees: • Introduced into the wild in South America (1956). • The Africanized bee escaped and began to dominate honey bee.

  33. Invasive Species: Africanized Killer Bees

  34. Invasive Species • Kudzu (from Japan)

  35. Introduced species • Can be on purpose or on accident • Monitor lizards and Burmese Pythons in South Florida/ Everglades • Pets that are released when they get too big to handle safely

  36. Introduced species • Lionfish in the FL Keys • Accidentally introduced during Hurricane Andrew • Massive efforts are underway to curb the population • Fishing, “delicacy” at restaurants, cookbooks

  37. Indicator species • Species that serve as an early warning system for damage/ danger/ pollution for a community

  38. Indicator species • Birds and butterflies • Sensitive to environmental changes • Both bird and butterfly populations are declining worldwide…

  39. Frogs • Great indicator species • Super vulnerable to environmental disruption at different points in their life cycles

  40. Frogs • Eat bugs (pesticides), no shell on eggs (UV radiation), thin permeable skin that easily absorbs pollutants from the water and air

  41. Frogs • Not just one thing • Declining in every region of the world • Habitat loss, prolonged drought, pollution, increase in UV radiation, increased parasitism, & overhunting

  42. Why do we care about the frogs? • Tells us environmental conditions are degrading • Amphibians are important parts of ecosystems • They might have genetic secrets humans want for Rx

  43. Keystone species • Have great effect on ecosystems • Loss can lead to population crashes or even extinction of other species

  44. Keystone species • Pollinators- bees, hummingbirds, butterflies, bats • Top predators- wolves, sharks, bears, alligators • Waste management- dung beetles

  45. Foundation species • Play a major role in shaping the community or habitat • Benefits other species • Ex: elephants knock down trees which allow grasses to grow. Antelopes eat the grass…