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Exploring Speciation: Mechanisms and Spectacular Cases

Understand the process of speciation through isolating mechanisms, natural selection tests, and the fascinating evolution of Galapagos finches. Learn about the importance of reproductive isolation and the impact of natural selection on the development of new species.

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Exploring Speciation: Mechanisms and Spectacular Cases

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Presentation Transcript

  1. The Process of Speciation Objectives: Define species and speciation. Explain 4 isolating mechanisms that result in speciation. Describe how natural selection has been tested in nature. Explain how the speciation of the Galapagos finches occurred.

  2. Remember… • Natural selection and chance events can change the relative frequencies of alleles in a population.

  3. But… • How does natural selection lead to speciation, the formation of a new species?

  4. What’s a species? • A species is a group of organisms that can breed with each other and produce fertile offspring.

  5. What must happen for a new species to evolve? • Populations of organisms must become reproductively isolated from each other. • Reproductive isolation is when the members of two populations cannot interbreed and produce fertile offspring.

  6. Hybrid Animals…

  7. Three ways in which reproductive isolation can occur… • Behavioral isolation • Geographic isolation • Temporal isolation

  8. Behavioral Isolation • When two species are capable of interbreeding but have differences in behavior.

  9. Behavioral Isolation • Eastern Meadowlark Western Meadowlark

  10. Geographic Isolation • When populations are separated by geographic barriers such as rivers or mountains.

  11. Geographic Isolation • Abert’s Squirrel Kaibab Squirrel

  12. Temporal Isolation • When populations reproduce at different times.

  13. Testing Natural Selection • Does natural selection really happen? • Can it actually lead to speciation?

  14. Galapagos Finches

  15. What do we need? • Natural Variation

  16. Beak Size & Survival

  17. Change over time • Increase in beak size during drought

  18. Speciation in Galapagos Finches • Galapagos Islands South America

  19. Speciation in Galapagos Finches

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