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Speciation & Patterns of Evolution

Speciation & Patterns of Evolution. *. Objectives. Explain how the isolation (physical or genetic) of populations can lead to speciation. *. Vocabualry. Species Speciation Geographic isolation Allopatric Speciation Reproductive Isolation. Sympatric Speciation Gradualism

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Speciation & Patterns of Evolution

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  1. Speciation & Patterns of Evolution *

  2. Objectives • Explain how the isolation (physical or genetic) of populations can lead to speciation. *

  3. Vocabualry • Species • Speciation • Geographic isolation • Allopatric Speciation • Reproductive Isolation • Sympatric Speciation • Gradualism • Punctuated equilibrium • Adaptive Radiation/Divergent Evolution • Convergent Evolution *

  4. What is speciation? • Species: a group of organisms that look alike and can interbreed to produce fertile offspring in nature. • SPECIATION: when members of Similar populations can no longer interbreed to produce fertile offspring.

  5. What can cause speciation? 1. GEOGRAPHIC ISOLATION • Physical barrier separates a population • Allopatric Speciation: New species arise as a result of geographic isolation

  6. What can cause speciation? 2. REPRODUCTIVE ISOLATION • Organisms can no longer mate to produce offspring • Timing • Behavior • Habitat • Infertile Hybrid offspring • Sympatric Speciation • New species arise as a result of reproductive isolation

  7. How fast does speciation occur? • Gradualism • species originate through a gradual change of adaptations • Punctuated equilibrium • speciation occurs relatively quickly, in rapid bursts, with long periods of genetic equilibrium in between.

  8. Comparing Gradualism vs. Punctuated Equilibrium

  9. How does environment affect speciation? • Divergent evolution/Adaptive Radiation: • when populations change as they adapt to different environmental conditions, eventually resulting in new species. • Convergent evolution: • distantly related organisms evolve similar traits • occurs when unrelated species occupy similar environments in different parts of the world

  10. ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTION

  11. CONVERGENT EVOLUTION EXAMPLE Psst: this is an example of Analogous Structures

  12. Question #1 Natural processes such as speciation and gradualism provide the genetic basis for _____. • evolution • biogenesis • spontaneous generation • sexual reproduction

  13. Question #1 Natural processes such as speciation and gradualism provide the genetic basis for _____. • evolution • biogenesis • spontaneous generation • sexual reproduction

  14. Question #2 A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____. • disruptive selection • directional selection • convergent evolution • divergent evolution

  15. Question #2 A pattern of evolution that results when two unrelated species begin to appear similar because of environmental conditions is _____. • disruptive selection • directional selection • convergent evolution • divergent evolution

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