Final answer:
Hybrid speciation without a change in ploidy can occur via sympatric speciation, where genetic divergence arises within a shared habitat due to behavioral shifts like changes in resource utilization, leading to reproductive isolation and eventually speciation.
Step-by-step explanation:
Hybrid speciation can occur without a change in ploidy through mechanisms of sympatric speciation. This form of speciation does not require geographic separation and therefore allows species to diverge while sharing the same habitat. One example includes adaptative changes such as differential resource utilization within a population, leading to reproductive isolation without polyploidy.
For instance, a group of fish in a lake might find a new food source at a different depth. Over time, these fish would interact and breed mostly among themselves, encouraging genetic divergence from the original population. Despite living in the same environment, the new behaviors and feeding habits effectively isolate the two groups, fostering speciation.
In a hybrid zone, closely related species may interact and produce hybrids, but the viability of these hybrids can influence future speciation. Hybrids that are less fit reinforce divergence (reinforcement), while fit hybrids might lead to species fusion or stability with no significant net change.