Parthenogenesis in whiptails is not a fallback used when males are scarce; it is the only mode available, because the lineage has no males at all. The hybrid origin matters mechanically: a hybrid genome contains two divergent chromosome sets, and the eggs undergo a premeiotic genome duplication that lets meiosis proceed with matching partners, so the resulting offspring retain the full hybrid heterozygosity rather than losing it.
The consequence is a clone lineage with unusually high genetic variation locked in from the founding hybridisation, spread across the descendants of each independent hybrid origin. Several unisexual Aspidoscelis species exist, some formed by a second hybridisation with a third species, producing triploid lineages.
A behaviour often reported deserves care. Captive whiptails perform mounting sequences resembling courtship, and this pseudocopulation has been shown to raise ovulation rates in some studies. It is not fertilisation and does not introduce genetic material; whether it plays a meaningful role in wild populations is less clear than the laboratory work sometimes implies.