Complex sentence: The area that is used to define a sexual population is defined as the area where inter-breeding is potentially possible between any pair within the area, and where the probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas.
Split into simpler sentences: The area that is used to define a sexual population is defined as the area where inter-breeding is potentially possible between any pair within the area. The probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas.