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Ecosystems Continually Change Over Time

This chapter explores natural changes in ecosystems, focusing on the Galapagos Islands' unique volcanic environment. Key topics include the adaptation and evolution of species such as the 13 finch species, which illustrate concepts like speciation, natural selection, and adaptive radiation. The chapter also discusses ecological succession, differentiating between primary and secondary succession, and examining how ecosystems recover from disturbances. By analyzing these processes, we gain insight into the intricate relationships among organisms and their habitats, highlighting the importance of biodiversity.

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Ecosystems Continually Change Over Time

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  1. Ecosystems Continually Change Over Time Chapter 3 (pages 106 -161)

  2. Galapagos Islands • Volcanic island; distributed around the equator in the Pacific Ocean (isolated) • 2 seasons: worm and dry • Finches (birds): There are 13 species on the island  primary food source: seeds

  3. 3.1 How Changes Occur Naturally in Ecosystems A. How Organism Change Q: How do these changes occur? Adaptation Characteristics that allow organisms to better survive and reproduce (3 types, chapter 1) Q: What if there is new environment? (eg. Forest fire)? • Speciation or extinction • Natural selection Evolution The process in which, over time, the best-adapted members of a species will survive and reproduce

  4. All the species are descended fromonefinch species on the mainland. • Each species has unique characteristics that allows them to thrive in their own niche, and not compete with other finches for resources. • Adaptive radiation: a form of natural selection when many different species appear from one original species.

  5. Activity 3.1A • 5 min • Page 109. DO “What to do”- “Mouth” and “eyes” • Match structural adaptation with correct advantage to the environment.

  6. Ecological Succession • Question: Which is more rapid: • Change from bare rock to a mature forest or • A burned down forest to an established forest? • Why? • Ecological succession: changes that take place over time in the types of organisms that live in an area

  7. Primary Succession • Occurs in an area where no soil exists such as bare rock • Takes a long time to complete ->up to several hundred years

  8. 1) Steps of Primary Succession • Starts with bare rock. • Wind carries spores of lichens that can survive on bare rock. • Weathering breaks down rock  soil begins to form

  9. d. Pioneer species make/improve soil; Insects and microorganism move in when soil forms • Pioneer Species are the first organisms to survive and reproduce. • Examples: Lichens and mosses

  10. As soil builds, other plants can grow (wildflowers and shrubs take root); More types of insects and microorganisms move in

  11. f. animals appear; tree seeds are transported to the area by birds or other animals Trees must be tolerant of lots of sunlight eg. Deciduous forest.

  12. g. Trees such as coniferous trees germinate and eventually shade out the deciduous trees I. A mature community form(stable and grows slowly.)

  13. 2. Secondary Succession: • when an area already has soil, but has had a disturbance like a forest fire or clearcut. • Happens more quickly than primary because there are already seeds, insects, worms etc. in the soil.

  14. Read page 115-117 • Complete “How natural events affect ecosystem” check at the end of the class HW. • Read page 3.2 complete “Human influence Ecosystem handout” • Pg 121 Q 2-5, 6, 9,11,

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