In Order for Allopatric Speciation to Occur,first There Must Be

Multiple Choice

In order for allopatric speciation to occur,first there must be a geographic separation of two populations of the same species.The second step requires:

A) additional extrinsic isolating mechanisms to become involved.
B) an increase in gene flow between the populations.
C) physical and behavioral changes that keep them from interbreeding.
D) physical and behavioral changes that permit occasional hybridization.