Final answer:
Genetic isolation leads to a barrier to gene flow.
Step-by-step explanation:
True. Genetic isolation leads to a barrier to gene flow. When populations are isolated, such as by physical barriers or reproductive barriers, the exchange of genes between the populations is limited or prevented. This can result in the populations evolving independently and developing distinct genetic characteristics over time. For example, if a river separates two populations of a species, individuals from one population may not be able to physically reach the other population to reproduce, leading to genetic isolation and a lack of gene flow.