PHYLOGENY OF PRIMATES AND OTHER EUTHERIAN ORDERS: A CLADISTIC ANALYSIS USING AMINO ACID AND NUCLEOTIDE SEQUENCE DATA

Abstract- Genealogical reconstructions carried out by the parsimony method on protein amino acid and DNA nucleotide sequence data are providing fresh evidence on cladistic branching patterns at taxonomic levels from the classes of Vertebrata and orders of Eutheria to the genera of Hominoidea. Minimum length trees constructed from amino acid sequence data group Mammalia with Archosauria (i.e., Aves plus Crocodilia), Amniota with Amphibia, and Tetrapoda with Teleostei. Within Mammalia, Edentata and Paenungulata (e.g., Proboscidea) appear as the most anciently separated from other eutherians. Another superordinal eutherian clade consists of Artiodactyla, Cetacea, and Perissodactyla. A third consistently contains Primates, Lagomorpha, and Tupaia. The cladistic positions of such orders as Carnivora, Chiroptera, Insectivora, and Rodentia are not well resolved by the currently still sparse body of sequence data. However, recent dramatic progress in the technology of gene cloning and nucleotide sequencing has opened the way for so enlarging the body of sequence data that it should become possible to solve almost any problem concerning the phylogenetic systematice of extant mammals. An example is provided by hominoid genera. Minimum length trees constructed from mitochondrial DNA nucleotide sequence data very strongly group Pan, Homo, and Gorilla into Homininae and then join Homininae and Ponginae (pongo) into Hominidae as the sister family of Hylobatidae (Hylobates). Resolution of the hominine trichotomy into two dichotomous branchings should be forthcoming as kilobase sequencing of nuclear genes progresses.