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Evolution and Biodiversity: Origins, Niches, and Adaptations

Evolution and Biodiversity: Origins, Niches, and Adaptations. G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 5. Dr. Richard Clements Chattanooga State Technical Community College. Key Concepts. Origins of life. Evolutionary processes . Ecological niches.

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Evolution and Biodiversity: Origins, Niches, and Adaptations

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  1. Evolution and Biodiversity: Origins, Niches, and Adaptations G. Tyler Miller’s Living in the Environment 13th Edition Chapter 5 Dr. Richard Clements Chattanooga State Technical Community College

  2. Key Concepts • Origins of life • Evolutionary processes • Ecological niches • Species formation • Species extinction

  3. Origins of Life • Chemical evolution • Biological evolution Fig. 5-2 p. 96; Refer to Fig. 5-4 p. 98

  4. Chemical Evolution Dust cloud condenses to form molten Earth (4.7 bya) a) 1st atmosphere forms, no oxygen (4.4 bya) b) CO2, N2, H2O, CH4, etc exposed to lightning and UV form organic molecules, including amino acids (Miller’s primordial soup)

  5. b) Earth cools sufficiently to form crust (3.7 bya) volcanic eruptions, meteorites allow water vapor to escape inner earth b) vapor cools ---> rain ---> dissolved minerals ---> oceans, mud ponds c) 1st prokaryotic cells (bacteria) (3.5 bya) a) no ozone so lived 10m below sea surface d) 1st photosynthesis: cyanobacteria (2.3-2.5 bya) (Gaia hypothesis) e) O2 levels increase (2 bya) f) O2 at current levels (1.5 bya)

  6. g) 1st eukaryotic cells (1.2 bya) h) O3 formed and UV levels were low enough for life (plants) on land (780 mya)

  7. Evolution Mutations: random changes in DNA that lead to new traits. When environmental conditions change, certain offspring may be better suited to changes because of a beneficial mutation. That individual will be likely to produce more offspring than organisms without that trait. Those offspring will also produce more offspring and eventually through this natural selection process that trait will become part of the genetic makeup of the entire species. This change in the genetic makeup of the species is called evolution.

  8. e.g fox > rabbit population up, speed is no advantage V rabbit population is down, speed is advantage

  9. microevolution (one population) vs macroevolution (groups of species) a) microevolution mutations (alleles) ---> adaptation (adaptive trait) ---> differential reproduction ---> natural selection environmental cond. change---> adaption, migration, extinction artificial selection ( selective breeding)

  10. b) three types of natural selection 1) directional natural selection low frequency alleles --> high frequency (resistance to pesticides) 2) stabilizing natural selection high freq alleles dominate (no envir change) 3) diversifying natural selection low freq alleles at either end become favorable (new food supply)

  11. Evolution and Adaptation • Macroevolution • Microevolution • Gene pool Refer to Spotlight p. 99 • Mutation • Natural selection • Gene flow • Genetic drift

  12. c) coevolution (pos feedback loop) change in one population makes a certain trait more favorable in another species (e.g owls and mice: Drought--> loss of food for mice --> mouse pop declines. Certain owls become better hunters, then certain mice survive (faster, better hider). As population of mice decreases, owls must be faster, have better eyesight to survive. (adaptation)

  13. Natural Selection • Differential reproduction • Adaptive trait • Directional selection • Stabilizing selection • Diversifying selection Fig. 5-5 p. 101 • Coevolution Refer to Fig. 5-6 p. 102

  14. d) Niche vs habitat 1) fundamental niche vs realized niche -niche overlap leads to competition 2) generalist vs specialist species (cockroaches vs giant panda, spotted owl) 3) convergent evolution -similar niches lead to similar traits in otherwise unrelated species that are geographically isolated

  15. Ecological Niches and Adaptation • Ecological niche • Fundamental niche • Habitat • Realized niche Fig. 5-7 p. 104

  16. d) speciation 1) geographic isolation 2) reproductive isolation -mutations and natural selection occur independently in 2 populations that are geographically isolated (divergence)

  17. e) Macroevolution gradualist model vs punctuated equilibrium hypothesis

  18. Broad and Narrow Niches • Generalist species • Specialist species Refer to Spotlight p. 105

  19. Speciation, Extinction, and Biodiversity Fig. 5-8 p. 105 • Speciation • Geographic isolation • Reproductive isolation

  20. f) Extinction due to changing environmental conditions caused by 1) continental drift 2) gradual climate change 3) abrupt, catastrophic climate change g) all species become extinct (4-22 million years); mammals (2-5 million years)

  21. Extinction • Background extinction • Mass extinction • Adaptive radiation

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