Yet monandry does exist in short-lived invertebrates (Shuster 1989a,b; Robinson and Allgeyer 1996; Fischer and Fiedler 2000; Jones 2001), in certain birds (Mauck et al. 1995) and mammals (Sever and Mendelssohn 1985; Brotherton et al. 1997), as well as in protistan species in which sexuality is achieved by the transfer of genetic material from one cell to another (Raikov 1995; Dacks and Roger 1999).
Source: wiktionary