Which characteristic of the waterbuck's environment is suggested to have been less intense, allowing for the conservation of the subspecies divergence?

The environmental pressures that drove speciation in other antelope lineages related to climate or vegetation shifts.

The analysis of the subspecies divergence in *Kobus ellipsiprymnus* suggests that while geographical isolation occurred, the environmental pressures that typically drive rapid speciation in other antelope groups—such as drastic shifts in overall climate or widespread, fundamental changes in dominant vegetation types across large areas—may have been less pronounced or intense in the waterbuck's core habitat. Because the non-negotiable constraint remains the reliance on permanent water, the environment surrounding these riparian zones may have remained relatively stable over evolutionary time. This stability allowed the core ecological requirements to be conserved across both the common and Defassa forms, focusing evolutionary divergence instead on localized adaptations like the external rump marking.