1. 24.2 Speciation can take place with or without Geographic Isolation

2. Allopatric Speciation
Geographic barriers cause a stop to gene flow.

3. Sympatric Speciation Rarer the allopatric speciation.
Speciation occurs without a geographic barrier typically through polyploidy, sexual selection, and habitat differentiation.

4. Polyploidy
Polyploidy: cell division accident causing extra sets of chromosomes to appear. (Typically this happens more in plants)
In rare cases, a sexually created polyploidy hybrid can self replicate asexually and over a few generations create a new fertile offspring that can breed only with it’s own kind.

5. Sexual Selection
Differences in food selection can cause organisms, (through mate choice) to mate with others that share the same food source.

6. Habitat Selection
In some cases, offspring of a parent organism can cause new species to arise because the offspring exploit new habitats or resources.