Evolution: Speciation

Evolution: Speciation

1. Speciation: The production of a new species

   • To produce a new species we need to produce a group that can no longer breed with the original species. Has to become reproductively isolated
     • Reproductive Isolation- the inability of 2 populations to interbreed
       • There are many reasons for this : different courtship behaviour, sperm and eggs may not be compatible, different chromosome numbers
   • Difficult to study as it is a long process and often cannot watch the process all the way through. Can look at existing species and pick up patterns

2. Geographic Isolation plays a big role in speciation

   • 2 populations of the same species separate by a geographical barrier - body of water or a mountain range
     • Because the environment for each population is different, they will have different selection pressures therefore different adaptations
       • May cause heritable changes in the characteristics of one or both populations & eventually the populations become so different they can no longer be able to interbreed. This is called allopatric speciation
         • Allopatric Speciation - Speciation due to geographically factors

3. Sympatric speciation- the production of a new species living in the same location

   • E.g Flies in Canada whose maggots feed on apples and hawthorn berries. Used to just feed on the berries and then some started to feed on the apples. Adult flies then gre up on apples and lay their eggs on apples and mate which other flies that grew up on apples the same is true for those of the berries
     • Eventually the 2 population will become so distinct they can longer interbreed