Reproductive separation

• In order for evolution to occur the new species population must be?genetically?and?reproductively separated?from the pre-existing species population
  • When this happens, there can no longer be an?exchange?of?genes?between the two populations

   

• Reproductive separation occurs when changes in the?alleles?and?phenotypes?of some individuals in a population?prevent?them from successfully?breeding?with other individuals in the population that don't have these changed alleles or phenotypes
• Examples of allele or phenotype changes that can lead to reproductive separation include:
  • Seasonal?changes?- some individuals in a population may develop different?mating?or?flowering?seasons (becoming sexually active at different times of the year) to the rest of the population (i.e their?reproductive timings?no longer match up)
  • Mechanical changes?- some individuals in a population may develop changes in their?genitalia?that prevent them from?mating?successfully with individuals of the opposite sex (i.e. their?reproductive body parts?no longer match up)
  • Behavioural changes?- some individuals in a population may develop changes in their?courtship behaviours, meaning they can no longer?attract?individuals of the opposite sex for?mating?(i.e. their methods of attracting a mate are no longer effective)

   

Genetic isolation

• When two populations of the same species become reproductively isolated from each other, they can eventually become?genetically?isolated
  • If the two populations are no longer reproducing with each other, then they?do not interchange genes?with each other in the production of offspring
  • Changes that occur in the?allele?frequencies?of each group are not shared, so they?evolve independently?of each other, which can lead to the formation of two populations that are no longer successfully able to interbreed
  • When the genetic differences lead to an?inability?of members of the populations to?interbreed?and produce?fertile offspring,?speciation?has occurred

   

Reproductive separation of two populations can lead to speciation