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13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
13a ecology
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13a ecology


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  • 1. Lecture 13a: Ecology Ecology
  • 2. Ecology
    • Definition: the study of interactions between all of the living and non-living components in an environment
    • So, discussion of ecology can include
      • Animals and plants
      • Soil and water qualities
      • Climate
      • Human impacts
  • 3. Communities
    • Definition: assemblage of populations of multiple species within a single environment
      • Ex: Fallen log
      • Ex: Forest
      • Fairly broad- can be small or large
  • 4. Communities
    • Because the organisms in a community have lived together over a long period of time, opportunity for coevolution
      • When an evolutionary change in one organism influences an evolutionary change in another organism
        • Ex: Many flowers and their pollinators
  • 5. Coevolution
  • 6. Interactions
    • Communities do not exist in a vacuum- the organisms interact with each other and with the environment-- this is an ecosystem
  • 7. Community Composition
    • Species richness : what species make up a community- basically just a list
    • Diversity : richness plus species distribution and relative abundance within the ecosystem
      • If different species spread throughout, more diverse than if only one is abundant
  • 8. Succession
    • Communities change over time- but can take decades to see the changes
    • Succession is the process of an ecosystem moving to a climax community after a disturbance
      • Each particular environment will lead to a stable climax community-a specific assemblage of plants and animals best suited to that environment
  • 9. Primary Succession Occurs when ‘new’ land becomes available- starts from bare rock or sand after glacier retreats, lava flows, etc.
  • 10. Secondary Succession Occurs after a disturbance- fire, agriculture, etc- there is already soil present
  • 11. Succession
    • In either case, first species are pioneer species - small, short-lived, and quick to mature (i.e. weeds)
      • First in primary are lichens and mosses- lichens help break down rocks into soil
    • Gradually, more equilibrium species move in- both plants and animals
  • 12. Ecological Niche
    • Niche : the specific ‘role’ of the organism in the ecosystem, including what it eats, where it lives, when it is active, how it interacts with others
    • Habitat : the part of the ecosystem that the organism in question lives in
      • Ex: Ecosystem for hippos is African savanna, habitat is the river and surrounding shorelines
  • 13. Interactions
    • Organisms interact with each other constantly, both within and outside of their species
    • Interactions, called symbiotic relationships , can be either positive or negative for each
  • 14. Competition
    • Competition can be for food, space, nutrients
    • Competitive exclusion principle : no two species can occupy the same niche at the same time
      • Leads to niche specialization , a way to reduce competition where different species use different resources, even though both could potentially use the same one
  • 15. Competition
    • Character displacement - organisms that have partitioned resources will evolve to suit their acquired niche, and thus the characteristics in question will become more different over time
      • Ex: bird beaks in birds that eat different foods
  • 16. Character displacement Spoonbill-uses bill like a shovel in sand Pelican- catches fish under water Heron- stabs larger fish Skimmer- uses bottom bill to scoop fish from surface
  • 17. Mutualism
    • A relationship in which both members benefit
    • Also very important
      • Ex. plants and pollinators
      • Ex. lichens (algae and fungus, living together)
      • Ex. Ants and caterpillars
  • 18.  
  • 19. Predation
    • When one animal eats another
    • Parasitism is a form of predation in which the predator lives in or on the prey, called the host
    • Ex: cheetahs and gazelles
    • Ex: owls and moles
    • Ex: hookworm and humans!
  • 20. Commensalism
    • Relationship when one organism benefits and the other is neutral
      • Ex: One animal transports another
      • Ex: Sea anemones and clown fish
  • 21. Fish: gets protection from predators Anemone: doesn’t care
  • 22. Name That Relationship! Microhylid frog + tarantula?
  • 23. Name That Relationship! Hermit crab + sea anemone
  • 24. Name That Relationship! Ants + acacia trees
  • 25. Name That Relationship! Cerambycid beetle + pseudoscorpion
  • 26. Community Stability
    • Really, communities are fragile, not stable- stability is hard to achieve because of natural disasters, human encroachment, etc.
    • Keystone species are species that help to stabilize community, other species’ survival can depend on this one species
      • Frequently not abundant
      • Ex: grizzly bears
      • Ex: bats in tropical forests
  • 27. Keystone Species: Sea Otter
    • Sea otters live in kelp forests
    • Eat lots of sea urchins, keep populations low so urchins don’t eat all the kelp
    • However, fishermen want to remove otters because they also eat abalone
    • But, if all otters are gone kelp forest will be gone and abalone will be gone because urchins will eat all the kelp and destroy the ecosystem
  • 28.  
  • 29. Role of Organisms
    • How an organism feeds is part of its niche:
      • Autotrophs: take in inorganic nutrients (CO2, minerals) and outside energy source
        • Plants, algae
    • These organisms are producers , because they produce food
  • 30. Role of Organisms
    • Heterotrophs: need a source of organic nutrients, release CO2
    • Called consumers , because they consume food
    • Four types:
      • Herbivores: eat plants
      • Carnivores: eat other animals
      • Omnivores: eat both plants and animals
      • Detritivores: decompose wastes and dead material
  • 31. Energy and Chemical Flow
    • Solar energy enters ecosystem through plants
    • Plants convert this into chemical energy via photosynthesis
    • Chemical energy is used by animals
  • 32.
    • At each level, some energy is used, some lost as heat
    • Less energy is available to the next level
  • 33. Chemical Cycles
    • Plants use nutrients in the soil to make organic compounds
    • Animals eat the plants and use those compounds
    • When animals die or eliminate waste, nutrients are broken down by detritivores and returned to soil, available to plants again
  • 34.  
  • 35. Food Webs and Energy/ Chemical Flow
    • Food webs represent energy flow from Producers to Primary Consumers to Secondary and Tertiary Consumers
    • Can also be drawn to represent detrital food webs, showing what eats waste
    • Important to realize where energy is stored- may be in living matter (rainforests) or in dead materials (temperate forests)
  • 36.  
  • 37.  
  • 38. Trophic Levels
    • There are always fewer consumers than there are producers, because energy is always lost as heat and used for cellular respiration and growth in every organism
    • As a general rule, only 10% of energy in one level is available to the next
  • 39.  
  • 40. Another way to see it
    • Biomass: it takes 10,000 g of grass to support 10g of snake
  • 41. Primary Productivity
    • Rate at which producers capture and store energy
    • Depends on species, temperature, moisture, soil
    • Highest in tropical environments, lowest at high altitudes, tundra, desert
    • Think of how this relates to high species richness and diversity in tropical rainforest vs. tundra
  • 42. Rainforest
  • 43. Tundra