How does the rump marking of the Defassa waterbuck (*K. e. defassa*) differ from the common waterbuck (*K. e. ellipsiprymnus*)?

The Defassa waterbuck displays a more solid white patch that covers the entire rump area.

The division between the common waterbuck and the Defassa waterbuck is primarily defined by the pattern of white markings on the rump, which serves as a crucial external marker of their genetic divergence. The common waterbuck is characterized by a very distinct white ring encircling the tail. In sharp contrast, the Defassa waterbuck exhibits a much broader, solid white patch that encompasses the majority of the rump area, frequently without the defined circular boundary seen in the common subspecies. This morphological variation, arising from geographical isolation, suggests that distinct genetic backgrounds have become fixed within their separate ranges, even though their core ecological dependence on permanent water remains shared.