BLOOD GROUPS AND THE TAXONOMIC STATUS OF AMERICAN BUFFALO AND DOMESTIC CATTLE

The generally accepted taxonomic position of the American buffalo (Bison bison) and domestic cattle (specifically, Bos taurus) is that of separate genera in the subfamily Bovinae. That the two species might very well occupy positions in the same genus is suggested by one of several alternative taxonomic designations for the American buffalo, notably, Bos americanus (see Roe, 1951) . The two species are apparently fully cross-fertile, but only the females among the F1 hybrids seem to be fertile (Deakin et al., 1942). Attempts to differentiate the two species by means of the classical precipitin technique have not been uniformly successful (Wolfe, 1939) and even when turbidimetric methods of measuring precipitates are used, the two species always stand closely side by side (Boyden et al., 1951). In this connection the question arises whether more extreme differences in precipitin values might be found between and perhaps even within breeds of domestic cattle. Likewise, attempts to demonstrate a clearly definitive difference between the two species by means of cross-absorbing antisera produced in rabbits against both bison and cattle red cells yielded equivocal results (Owen et al., 1958). In the case of each antiserum, absorption with a pool of red cells from the heterologous species succeeded in removing the greater portion and sometimes all of the antibodies directed against the red cells of the homologous species. Such observations suggest that the antigenic structure of the red cells of bison and domestic cattle must be very similar, and this was borne out to a considerable degree by blood typing bison with a rather large battery of blood-typing antibodies (reagents) which had been developed specifically for the purpose of exploring individual differences in cattle. For example, Owen et al. observed antigenic factors in bison blood which appeared to be indistinguishable from the bovine blood factors named A, C, J, 5, W, X, and Z. Nevertheless, some rather marked differences were noted between the blood types of the two species, and those differences appeared to be significantly greater than any of the between-breed differences encountered in blood typing domestic cattle. For example, it appeared that the complex B locus of cattle is either not represented in bison or, if present, is occupied solely by alleles whose products (phenogroups) are essentially non-reactive with any of the 21 B system reagents used in that study. The data reported by Owen et al. (1958) were actually collected during the years 1945-47. Since then, we have had the opportunity to develop in this laboratory an entirely new battery of cattle bloodtyping reagents which derive from antisera independent of those used as sources of reagents by Owen et al. or by Miller and Stone (1955) in a further study of bison blood types. In connection with another study (Stormont and Suzuki, 1958), we had the opportunity to type three bison with our reagents. The results of those tests provided evidence which tended to narrow the magnitude of the blood-type differences between the two species. Further inquiry was therefore prompted and through the courtesy of Mr. Julian A. Howard, Refuge Manager of the Wichita Mountains Wild Life Refuge, Cache, Oklahoma, and Dr. D. C. Bostwick, we received 56 samples of citrated bison blood on October 29, 1959. (This was the same herd from which Owen et al. obtained 44 of the 69 samples used in their study, and it was also the same herd from which