Approaches to Systematics

Bovids, being diverse animals that inhabit a spectrum of habitats from arid environments to wetlands, present an excellent resource with which to formulate and test evolutionary and paleoecological hypotheses. At the same time, their great diversity presents a serious challenge to morphological systematics. Homoplasy in bovid evolution is evidently rampant (Gentry 1992), and the application of comprehensive morphological cladistic methods to bovid systematics requires much more work, particularly as concerns the difficult task of character formulation and coding. Over recent years, morphological cladistic analyses using a selective set of characters and taxa (in contrast to 'total' methods) have had greater success in producing phylogenies commensurate with the fossil and molecular data (e.g., Vrba 1997; Geraads et al. 2008). Future phylogenetic work would benefit greatly from increased incorporation of ontogenetic data (e.g., Vrba et al. 1994).

Molecular systematics has over the last 20 years provided significant insight into the evolutionary history of, and interrelationships within, Bovidae. Molecular systematic work provided strong evidence for the existence of Antilopinae/Aegodontia (Lowenstein 1986; Hassanin and Douzery 1999b), the polyphyly of Neotragini (Hassanin and Douzery 1999b; Matthee and Robinson 1999; Rebholz and Harley 1999) and Ovibovini (Groves and Shields 1997; Hassanin et al. 1998; Ropiquet and Hassanin 2005). Molecular phylogenetic work has also advanced knowledge of living but enigmatic bovid species. Notable among these is the case of the saola, Pseudoryx nghetinhensis, a goat-like antelope living in the forests of Vietnam and Laos, only first described in 1993 (Dung et al. 1993; Kemp et al. 1997). Morphological comparisons (Thomas 1994) suggested inclusion within the Caprini while molecular work proposed affinity to Bovinae and Bovini (Dung et al. 1993; Hassanin and Douzery 1999a). A 'total evidence' approach using both morphological and molecular characters supported the previous contentions of the molecular evidence, that the saola was in fact a member of Bovinae and even nested deep within Bovini (Gatesy and Arctander 2000). Pseudonovibos spiralis, the linh duong, is another recently described bovid (Peter and Feiler 1994) of uncertain status. Pseudonovibos spiralis is known only from a number of horn sheaths collected from Vietnam, and controversy has raged over whether the characteristically spiraled and annulated horns are indeed indicative of a new species, or whether they are simply modified horn sheaths of cattle, Bos taurus. Molecular phylogenetic studies have made a strong case that Pseudonovibos spiralis is simply a synonym of Bos taurus (Peter and Feiler 1994; Olson and Hassanin 2003 and references therein).