What prevents speciation from occurring in sympatric populations?

Question

Julian Aguilar · Accepted Answer

Interbreeding.

Speciation can occur only when such interbreeding stops between two sub-populations, i.e. a natural reproductive barrier is erected.

Sympatric population occupies one habitat, where organisms interbreed. Thus there is no physical barrier working to separate sub-populations. As long as random interbreeding between all members continue, sympatric speciation will not occur.

Speciation in sympatric population is rare and may occur by different means: e.g.

Habitat selection- This includes separation and mate choice preference, ultimately leading to establishment of separate sub-populations (=demes). When gene flow between these demes completely stop, speciation is achieved. This is seen in many marine fauna.
- Instantaneous genetic isolation- This is very common in plants due to appearance of polyploidy, etc. due to abnormal meiosis. Chromosome doubling in accidentally generated flora immediately establishes a new species in same habitat.

Natalie Ahrens · Answer

undefined Factors such as gene flow, hybridization, and natural selection can prevent speciation from occurring in sympatric populations. These factors promote genetic mixing and the maintenance of a single gene pool, inhibiting the development of distinct species within the same geographic area.