Eutherian phylogeny from a primate perspective

Determinant formulas for up to 22 serum proteins from nineteen species in seven Eutherian orders (Chiroptera, Carnivora, Artiodactyla, Perrissodactyl, Rodentia, Proboscidea, Xenarthra) and Metatheria were derived by comparative determinant analysis from a primate (human) perspective. Plesiomorphic character states for taxon-pairs were inferred, including epitope patterns of the putative last common ancestor of Primates and non-primate Eutheria. Our approach, comparative determinant analysis, is exceptional among immunological methods in being able to define molecular character states for cladistic systematics. Average degrees of phylogenetic conservation of protein determinants varied between loci by 6.5-fold. Against the background of possible lineage-specific rates of molecular substitution, the clear immunological differentiation of the Asiatic elephant from (other) ungulates is discussed as to its phylogenetic relevance, as are the well-marked distances between guinea-pig and myomorph rodents, fissipeds and harbour seal, Mega- and Microchiroptera, or pig and ruminants. It is concluded that genetic drift influenced the rate of molecular evolution of mammalian orders to a different extent, e.g. more in the Proboscidean lineage than in the clade leading to the horse. It is concluded that the substitution rate of antigenic determinants of serum proteins correlates positively with speciation frequency in a phyletic lineage.