SPECIATION

• WHAT DOES SPECIATION RESULT IN?

  creation of a new species
• WHEN DOES SPECIATION OCCUR?

  when one original population of the same species becomes reproductively isolated leading to two populations of the same species that cannot breed together
• HOW DOES REPRODUCTIVE ISOLATION OCCUR?

  allopatric/ sympatric
• WHAT IS ALLOPATRIC SPECIATION?

  separated geographically leads to reproductive isolation
• WHAT IS SYMPATRIC SPECIATION?

  differences in behaviour lead to reproductive isolation
• WHAT IS SPECIATION?

  new species arise from an existing species
• REASONS FOR REPRODUCTIVE ISOLATION?

  • different courtship behaviours
  • different breeding seasons
  • ecological differences
  • mechanical differences
  • gametic differences
  • hybrid sterility
• WHAT IS THE IMPORTANCE OF COURTSHIP BEHAVIOURS?

  • recognise members of same species
  • recognise opposite gender
  • recognise sexual maturity
• PROCESS OF ALLOPATRIC SPECIATION?

  1. Geographical barrier
  2. Organisms of one population now separated
  3. Reproductively isolated
  4. No gene flow between organisms
  5. Different selection pressures in each area
  6. Natural selection occurs in each area
  7. Organisms experience change in allele frequencies
  8. Over many generations, populations become phenotypically different
  9. Organisms cannot reproduce to produce fertile offspring
• PROCESS OF SYMPATRIC SPECIATION?

  1. No geographical barrier (live in same environment)
  2. Reproductively isolated
  3. No gene flow between organisms
  4. Natural selection occurs
  5. Organisms experience change in allele frequencies
  6. Over many generations, populations become phenotypically different
  7. Organisms cannot reproduce to produce fertile offspring
• WHY ARE ORGANISMS IN SYMPATRIC SPECIATION REPRODUCTIVELY ISOLATED?

  • different courtship behaviour
  • mating seasons do not coincide
  • genitalia are not compatible