African rhinos share retroviruses not found in Asian rhinos or other related species

Rhinoceros belong to a mammalian order called odd-toed ungulates that also include horses and tapirs. They are found in Africa and Asia. Until recently, evidence suggested that throughout their evolutionary history, gamma-retroviruses such as Murine leukemia virus had not colonized their genomes, unlike most other mammalian orders. The colonization process is called retroviral endogenization and has resulted in most mammalian genomes being comprised of up to ten percent retroviral like sequences.

Source: ScienceDaily.com