BY5.5 Isolation and Speciation

Isolation and Speciation

• breeding subunits become isolated from one another and evolve along separate lines
• if reunited the sub units would be incapable of breeding successfully as they are separate species
• factors leading to the formation of new species:
  • geographical isoaltion
  • habitat changes
  • changes in body form
  • changes in breeding mechanisms

Speciation

• within a population breeding subunits are called demes
• individuals within a deme are more likely to breed with one another more often than with individuals of another deme
• new species arise when barriers to reproduction occur
• the gene pool is divided
• the flow of genes between separate demes stops
• this is known as an isolating mechanism

• long term speciation will lead to 2 new species that are incapable of interbreeding
• seperate species will have their own gene pool

Isolation leading to speciation:

• for a new species to develop from a population an isolating mechanism is needed

• 2 main forms of isolating mechanisms
  • geographical…