Bio 004,CH19, College of the Desert

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  1. Community
    Collection of interacting organisms of different species within an ecosystem.
  2. Diversity
    • The variety of different kinds of organisms.
    • 1. Species richness
    • 2. Relative abundance
    • 3. Species diversity
  3. Species richness
    Total number of different spp in the community
  4. Relative abundance
    Size of populations of different spp in the community
  5. Species diversity
    The number and relative abundance of spp in a community.
  6. Other Properties of a Community

    • 1. Prevalent Form of Vegetation.
    • 2. Stability.
    • 3. Trophic Structure.
  7. Interspecific Interactions
    • Encounters be-tween members of different species.

    • Three main types of interspecific interactions: Competition, Predation, Symbiosis

  8. Competitive Exclusion Principle
    Populations of two spp cannot coexist in a community if their niches are nearly identical. Usually results in one spp dying out, moving out, or adapting to occupy another niche. Possible mechanism for natural selection.
  9. Interspecific Competition
    • When populations of two or more spp in a community rely on similar limiting resources.
    • 1. Niche
    • 2. Resource partitioning
  10. Niche
    Sum total of spp use of biotic and abiotic resources in the environment (eco-logical role in nature - job). Example: birds of prey - diurnal v. nocturnal.
  11. Resource partitioning
    Differentiation of niches that enables similar spp to co-exist in a community (Darwin’s finches).
  12. Predation
    • Predator: Organism that eats another.
    • Prey: Organism that gets eaten by another (food).
  13. Predator Adaptations
    • 1. Acute senses
    • 2. Ability to catch and subdue prey.
    • 3. Fast and agile (pursuit).
    • 4. Camouflage (ambush).
  14. Plant Defenses v.
    • 1. Chemical weapons: Poisonous (nicotine) or distasteful (peppermint).
    • 2. Mechanical weapons: Spines or thorns.
  15. Animal Defenses v. Predators

    • 1. Hiding, fleeing (passive).
    • 2. Alarm calls distraction (active).
    • 3. Cryptic coloration (camouflage).
    • 4. Mechanical, chemical defenses.
  16. Specialized Animal
    Defenses v. Predators
    • 1. Aposematic coloration: Bright-color warning. Frog.
    • 2. Batesian mimicry: Copy a harmful spp. Camouflage.
    • 3. Mullerian mimicry: Shared copies of distasting spp. Monarch taste bad so Bisoroy (spelling) must taste bad because they look similar.
  17. Symbiotic Relationships
    • Interaction between two or more spp that live in close contact.
    • 1. Parasitism: Parasite, Host
    • 2. Mutualism
  18. Parasite
    Organism that lives on or in another organism – usually smaller; benefits.
  19. Host
    Organism supporting another organism living on or in it –usually bigger; harmed.
  20. Mutualism
    Interaction between two or more species in which both benefit. Methanogens & N-fixing bacteria, Acacia trees and ants, Coevolution usually occurs between mutualistic spp.
  21. Disturbance
    Episodes that damage biological communities temporarily or long term by destroying organisms and affecting the availability of resources. Examples: storms, fires, floods, droughts, & humans.
  22. Ecological Succession
    Transition in spp composition of a community following an ecological disturbance.
  23. Primary succession
    Occurs in a virtually lifeless area where no original organisms exist; no soil is present.
  24. Secondary succession
    Occurs where an existing community has been cleared by a disturbance, but the soil is left in tact.
  25. Trophic Levels and
    Food Chains
    • 1. Trophic level
    • 2. Food chain
    • 3. Producers
    • 4. Consumers
    • 5. Omnivores
    • 6. Decomposers
  26. Trophic level
    Feeding relationship.
  27. Food chain
    Logical sequence of food transfer from one trophic level to another.
  28. Producers
    Organisms that use sunlight for photosynthesis and produce organic molecules from inorganic molecules. Examples: cyanobacteria, algae, & plants.
  29. Consumers
    • Organisms that obtain energy as organic material from other organisms. Examples: herbivores (plant eaters - primary) & carnivores (meat eaters - secondary).
  30. Omnivores
    Organisms which feed on both plants and animals.
  31. Decomposers
    Organisms which feed on dead and decaying material.
  32. Food Web:
    A system of interwoven food chains creating a more stable community.
  33. Pyramids
    • 1. Pyramid Base; Producers.
    • 2. 1st Level: 1° Consumers.
    • 3. 2nd Level: Consumers
  34. Biomass
    Dry weight of all organisms at a specific trophic level.
  35. Chemical Cycles
    • Include carbon, nitrogen, phosphorous, and water.
    • 1. All cycles have an abiotic reservoir and can bypass the biotic components.
  36. Chemical Cycles –
    • 1. Certain cycles (N) require microorganisms in order to enter biotic components.
    • a)80% of atmosphere is N, but plants cannot utilize N directly (N-fixing bacteria).
    • b)Animals obtain N from their diet.
  37. Biomes
    Large regional communities primarily determined by climate (temperatures & rainfall as well as altitude and latitude (terrestrial).
  38. Aquatic Biomes –
    • 1. Standing bodies of water (lakes & ponds).
    • 2. Flowing water (rivers & streams).
  39. Estuaries
    Where freshwater merges with salt. Marine life distributed according to depth, degree of light penetration, distance from shore & surface, and temperature.
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Bio 004,CH19, College of the Desert
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