What is Speciation?

• What is Speciation?:

  • Over a long period of time the phenotype of an organism changes so much because of natural selection that a completely new species is formed
• Speciation is the development of new species
• What is speciation?

  development of species
• Figure 5 shows:

  • the two species of finch live on Isabela Island

  • only one of the species lives on Daphne Island

  • only one of the species lives on Crossman Island. Suggest why both species of finch are able to live on Isabela Island:

  • The island is large enough to have two species
  • therefore less competition for food
• One of the genes codes for an enzyme used in fat metabolism.

  A mutation in this gene causes a reduction in milk fat. The mutation changes one amino acid in the enzyme molecule.

  Explain how a change in one amino acid in an enzyme molecule could stop the enzyme working:

  • A different protein is made
  • as the active site changes
  • so the substrate doesn't fit
• Describe how the ancestors of modern lemurs may have evolved into the species shown in Figure 3.:

  • isolation of different populations
  • habitat variation between lemur populations
  • genetic variation or mutation (in each population)
  • better adapted survive (reproduce) and pass on (favourable) allele(s) to offspring
  • (eventually) cannot produce fertile offspring with other populations