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Biology 102 Ecosystems

Biology 102 Ecosystems. Dave McShaffrey Harla Ray Eggleston Department of Biology, Marietta College. Lecture based on Chapters 56 and 57 Raven, Johnson et al. 2008 Also Chapter 44 - Life, 6th Ed. By Lewis, Parker, Gaffin, and Hoefnagels 2007.

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Biology 102 Ecosystems

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  1. Biology 102Ecosystems Dave McShaffrey Harla Ray Eggleston Department of Biology, Marietta College

  2. Lecture based on Chapters 56 and 57 Raven, Johnson et al. 2008 Also Chapter 44 - Life, 6th Ed. By Lewis, Parker, Gaffin, and Hoefnagels 2007

  3. Chapter 44 describes how organisms interact to form living communities.

  4. To get the most benefit from these slides, have your textbook open and follow along looking at the illustrations and reading the accompanying text.

  5. Niche:the way an organism makes its way in the world: • What it eats • What eats it • Parasites • Diseases • Activity Patterns • Habitat • Etc. • When organisms try to obtain the same resources – food, water, nesting sites – they compete with each other. • Competition hurts both competitors and should be avoided • The closer two niches are, the stronger the competition • Two species cannot share the same niche. • Fundamental Niche – the niche the organism can occupy • Realized Niche – the niche the organism actually occupies due to biogeography, evolutionary history, predation and competition.

  6. Fig. 56.4

  7. By foraging on different parts of the tree (and at different seasons), these birds reduce competition and are able to coexist.

  8. Fig. 56.5a Competition

  9. Fig. 56.5b Competition

  10. Fig. 56.5c Competition

  11. Fig. 56.8 Competition

  12. Predation

  13. Producers and Consumers: Organisms fall into one of 2 categories: • Producers – convert energy from the environment into carbon-carbon bonds • Consumers – get their energy by breaking the carbon-carbon bonds made by producers.

  14. Producers : • AKA Autotrophs • Includes plants and other photosynthetic organisms • Includes bacteria that are chemosynthetic

  15. Consumers : • AKA Heterotrophs • Includes animals, fungi and some bacteria

  16. Fig. 57.8

  17. To summarize: In the flow of energy and inorganic nutrients through the ecosystem, a few generalizations can be made: • The ultimate source of energy (for most ecosystems) is the sun. • Theultimate fate of energy in ecosystems is for it to be lost as heat. • Energy and nutrients are passed from organism to organism through the food chain as one organism eats another. • Decomposers remove the last energy from the remains of organisms. • Inorganic nutrients are cycled, energy is not.

  18. A food chain is the path of food from a given final consumer back to a producer.

  19. A food web is real-life, complicated path of energy through the organisms of the ecosystem

  20. Look back at the previous two slides and the food webs – how many links in a food chain are there at a maximum? Why is this?

  21. Figure 44.11a As you move up a food chain from producer to final consumer, less energy is available. This forms a pyramid of biomass. Less energy is available for 3 reasons: Consumers do not consume all of the organisms on the trophic levels below them, not all of what is consumed is digested and assimilated, and some of the energy is used in respiration before the organism is consumed.

  22. As you move up a food chain from producer to final consumer, less energy is available for 3 reasons: • Consumers do not consume all of the organisms on the trophic levels below them. • Not all of what is consumed is digested and assimilated. • Some of the energy is used in respiration before the organism is consumed.

  23. Fig. 57.9

  24. Fig. 57.10

  25. Figure 44.11b This illustrates the fate of energy in an ecosystem. At each level, less energy is available due to the 3 reasons listed on the previous slide. Overall, more energy is available to lower trophic levels, thus the Earth can support more humans if we feed as secondary rather than tertiary consumers.

  26. Fig. 57.12

  27. Figure 44.12a Pyramids of biomass are often accompanied by pyramids of numbers, particularly when the producers are small and the consumers are progressively larger. On the other hand, a single oak tree (producer) can support many consumers at several trophic levels.

  28. Fig. 57.13a

  29. Fig. 57.13b

  30. Fig. 57.13c

  31. Fig. 57.13d

  32. We’ve touched upon the fact that nutrients cycle through the ecosystem; other materials do so as well. One of the best known of these biogeochemical cycles is the water cycle. We will take up some of the other cycles later.

  33. Figure 44.7 The process of succession from bare rock to a climax community (biome). This sequence is called a sere; each stage is called a seral stage. We will study succession in detail later.

  34. The End

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