An Inconsistency between Protein Resemblance and Taxonomic Resemblance: Immunological Comparison of Diverse Proteins from Gallinaceous Birds

The comparative study of proteins is being used with greater frequency to produce information concerning genetic differences among species. Such studies make it increasingly evident that there may not be a strict correlation between degree of genetic difference and degree of difference at the supramolecular or organismal level. This point can be illustrated by the results of comparing proteins from the Domestic Chicken (Gallus gaZZus) with those of the Domestic Turkey (Meleagris gallopavo) and the Ring-necked Pheasant ( Phasianus colchicus) . We present evidence from our studies at the protein level that appears to contrast with the evidence at the organismal level regarding the degree of resemblance among these species. According to most ornithologists, the pheasant is more similar in anatomy and way of life to the chicken than is the turkey. This view is reflected in the system of bird classification which traditionally puts pheasants together with the chicken in the subfamily Phasianinae of the family Phasianidae, whereas the turkey is assigned to another family, Meleagrididae (Wetmore 1960). In the last two decades, however, evidence from hybridization experiments (Asmundson and Lorenz 1957; Olsen 1960; Poole 1963), chromosome studies ( Stenius et al. 1962)) electrophoretic patterns of protein mixtures (Sibley 1960, Sibley and Ahlquist 1972)) immunological comparison of cell surfaces ( Mainardi 1963), and the study of additional anatomical characters (Holman 1964, Hudson et al. 1966) has made it less certain that the turkey is as distant from the chicken as once thought. Consequently, Brodkorb ( 1964)) Storer ( 1971), and Sibley and Ahlquist (1972) eliminated the family Meleagrididae and placed the turkey in the family Phasianidae. Nevertheless, these au-