Question

speciation caused by reduction of gene flow, not geography, is called

Answer 1

Speciation caused by gene flow is called SYMPATRIC SPECIATION.
Sympatric speciation is said to occur when speciation occurs in a population that live in the same geographical location. This type of speciation usually occur because of reduction in gene flow, that is caused by factors such as habitat differentiation, sexual selection and polyploidy.

Answer 2

Speciation Cause by Reduction of Gene Flow

Speciation caused by gene flow which is known as sympatric speciation.  Sympatric speciation happens when speciation occurs in a population that lives in the identical geological location. This kind of speciation often happens due to a reduction in gene flow which is created by agents example habitat differentiation, sexual selection, and polyploidy.