Final answer:
In biology, if populations have diverged significantly, hybrids will typically have lower fitness. This results in assortative mating and reinforcement, which further increases reproductive isolation and divergence between the species.
Step-by-step explanation:
If populations sufficiently diverged in genetics and phenotypic traits, hybrids should have lower fitness; there should be strong selection for assortative mating; selection that reduces the frequency of hybrids is reinforcement. This process leads to a decrease in the reproduction between two species, nudging them to diverge further. Over time, as adaptive evolution occurs, the reproductive isolation between the populations increases, and they may continue diverging until hybridization is no longer possible. Reinforcement plays a crucial role by enhancing differences that prevent interbreeding, thereby maintaining or increasing the divergence between species.