Speciation

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


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


  Warning coloration in animals
• What color is the frog that Wallace studied as an example of warning coloration?


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


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

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


  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 is the significance of a geographical barrier in speciation?


  It prevents interbreeding between populations
• What are the stages of speciation as illustrated by the example of snails?


  1. Initial population can interbreed.
  2. A geographical barrier (e.g., river) separates the population.
  3. No interbreeding occurs between the two groups.
  4. Natural selection favors different alleles in each group.
  5. Mutations cannot spread between populations.
  6. Over generations, the populations change.
  7. If they can mix again, they may no longer reproduce fertile offspring, becoming different species.
• What happens to the populations of snails over time after being separated by a geographical barrier?


  They begin to change due to natural selection.
• What is the key point necessary for speciation to occur?


  A geographical barrier must separate a population.
• What is the result when two populations of snails can no longer reproduce to make fertile offspring?


  They are considered two different species.
• What does the term "interbreeding" refer to in the context of speciation?


  Breeding between individuals of the same species.
• How does natural selection affect the two separated populations of snails?


  It favors different alleles on each side of the barrier.
• What is the role of beneficial mutations in a population of snails?


  They spread through the whole population.