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Speciation and Extinction

Speciation and Extinction. Big Idea 1: The process of Evolution drives the diversity and unity of life. Essential Knowledge. 1C1: Speciation and extinction have occurred throughout the Earth’s history.

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Speciation and Extinction

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  1. Speciation and Extinction Big Idea 1: The process of Evolution drives the diversity and unity of life

  2. Essential Knowledge • 1C1: Speciation and extinction have occurred throughout the Earth’s history. • 1C2: Speciation may occur when two populations become reproductively isolated from each other. • 1C3: Populations in nature continue to evolve.

  3. A group of individuals capable of interbreeding and exchanging genetic info to produce viable, fertile offspring. Species YES Panda Babies! NO Dog-Cat Babies!

  4. Speciation • Creation of a new species • Usually occurs when 2 pops diverge from a common ancestor

  5. Speciation Can Be Slow…. • Very gradually, over a long time, the population changes (gradualism). Change is slow, constant, and consistent (Darwin).

  6. Speciation Can Be Fast… • Bursts of change followed by quiet periods (Punctuated Equilibrium, Eldredge and Gould, 1972)

  7. What Could Cause Bursts?? • Sudden, quick changes in the environment leads to more available niches!

  8. Speciation is the reason for diversity of life!

  9. Geographic Isolation Separation of pops by a geographic barrier exposes species to new environmental conditions.

  10. TPS: What Other Items May Be Geographic Barriers?

  11. Reproductive Isolation • Biological factors (barriers) that stop 2 species from producing viable, fertile offspring • Can be pre/post zygotic barriers

  12. Example: Polyploidy • More than 1 set of chromosomes. • Ex: Wheat: strains that are diploid(2 sets),tetraploid(4 sets) durum or macaroni wheat, hexaploid(6 sets) bread wheat. • Will not interbreed with each other.

  13. Prezygotic Barriers Goal: To impede mating/fertilization! • Habitat isolation: no/rare contact • Temporal isolation: mate at diff. times of yr. • Behavioral isolation: behavior mating rituals. • Mechanical isolation: Morphological differences

  14. What Kind of Prezygotic Barrier is This?

  15. Postzygotic Barriers Goal: Prevent a hybrid zygote from being a viable adult • Frail/Weak Hybrids • Sterile Hybrids

  16. Extinction • Occurs rapidly at times of ecological stress.

  17. Habitat Loss/ Habitat Fragmentation

  18. Hunting/Poaching

  19. Overfishing

  20. 5 Major Mass Extinctions

  21. On a Positive Note.. • Extinction opens up available niches (jobs) and leads to new species creation.

  22. Evolution Continues to Occur… • Activity in class…

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