Speciation

• Who contributed to our understanding of evolution alongside Darwin?

  Alfred Russel Wallace
• What was Alfred Russel Wallace interested in regarding animals?

  Warning coloration in animals
• What color is the frog that warns predators of its poison?

  Bright red
• What did Wallace want to know about warning coloration?

  How warning colors evolved
• In what year did Darwin and Wallace jointly publish their findings?

  1858
• What did Darwin publish the following year after their joint findings?

  On the Origin of Species
• What process did Wallace study that leads to the formation of new species?

  Speciation
• What geographical feature did Wallace notice separating closely related species?

  A wide river
• What is required for speciation to occur?

  A geographical barrier
• What are the stages of speciation in snails?

  1. Initial population can interbreed.
  2. Geographical barrier (e.g., river) separates populations.
  3. No interbreeding occurs between groups.
  4. Natural selection favors different alleles.
  5. Mutations cannot spread between populations.
  6. Over generations, populations change.
  7. If they can mix again, they may be different species.
• Why is the river considered a geographical barrier in speciation?

  It prevents interbreeding between populations
• What happens to the populations of snails over many generations?

  They begin to change significantly
• What occurs when the two populations of snails can mix again?

  They may no longer reproduce fertile offspring
• What is the key point for speciation to take place?

  A geographical barrier must separate populations
• Where can students find more questions on speciation?

  In the revision workbook