Answer:
Selectivity in choosing a mates
Geographic barriers separating subpopulations.
Step-by-step explanation:
Selectivity in choosing a mates is a factor in which individuals can mate with each other. Some individuals tend to choose a sexual mates that posses some traits or characteristics that attract them to each other and because of the observable character, similar individuals attracted to each other mates.
Geographic barriers separating subpopulations is another factor that make similar organism or individuals to mates.
When there is geographic separations or demarcation between individuals in a species and they are separated from other subpopulations .. They tend to mate with each other in the same geographic location and cannot mate with other subpopulations that is outside their own geographic location. These is common in animals.