Question

What prevents speciation in sympatric population?

Answer 1

Sympatric speciation occurs when a new species evolves from only one kind of ancestral species as both remain in the same geographic area. It entails the division of an ancestral species into two or more reproductively distinct groups that are not geographically separated. The main feature of sympatric speciation is that it can happen only by two or more incipient organisms coming into physical contact, potentially allowing them to interbreed and exchange genes.

Complete answer:
We will initially understand the definition of sympatric speciation and how it comes into being, then we will understand what prevents it from occurring .Remember that only when interbreeding between two subpopulations ceases, that is, when a natural reproductive barrier is erected, speciation come into play.

But we know that sympatric speciation occurs when a new species evolves from only one kind of ancestral species as both remain in the same geographic area. For this to happen it requires the division of ancestral species into two or more distinct reproductive groups that are not geographically separated.
Keep in mind that the main feature of sympatric speciation is that it can happen only by two or more incipient organisms coming into physical contact, potentially allowing them to interbreed and exchange genes.

So interbreeding is the main reason for speciation which is prevented particularly among such a population, a sympatric population.

Note: Sympatric populations undergoing speciation is uncommon and but can occur if certain conditions are met:
- Selection of the habitat: It is said that separation or mating preference are examples of habitat selection, which eventually contribute to the formation of such distinct sub-populations ( or demes). Speciation occurs when the gene flow among these demes ceases entirely. This can be observed in a variety of marine animals.
- Isolation of genes instantly: Commonly found in plants due to irregular meiosis, which causes polyploidy and other problems. When a chromosome in an inadvertently created flora doubles, a new species emerges in that same habitat.