Speciation

• Who contributed to our understanding of evolution alongside Charles Darwin?

  Alfred Russel Wallace
• What did Alfred Russel Wallace study in relation to animals?

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

  Bright red
• What did Wallace independently propose based on his studies?

  The theory of evolution by natural selection
• In what year did Darwin and Wallace jointly publish their findings?

  1858
• What significant work did Darwin publish the following year after 1858?

  On the Origin of Species
• What process do scientists call the formation of new species?

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

  A wide river
• What happens to the populations of snails when a river separates them?

  They can no longer interbreed
• How does natural selection affect the two separated populations of snails?

  It favors different alleles on each side
• What is the result of mutations occurring in the separated populations of snails?

  Mutations cannot spread between populations
• What happens when the river changes course again and the two populations can mix?

  They can no longer reproduce fertile offspring
• What is a key requirement for speciation to occur?

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

  1. Original population can interbreed.
  2. Geographical barrier (e.g., river) separates populations.
  3. No interbreeding occurs between groups.
  4. Natural selection favors different traits.
  5. Mutations cannot spread between populations.
  6. Over generations, populations diverge.
  7. If they mix again, they cannot produce fertile offspring.
• What are the contributions of Alfred Russel Wallace to evolution?

  • Studied warning coloration in animals
  • Proposed theory of evolution by natural selection
  • Jointly published findings with Darwin in 1858
  • Focused on the process of speciation