Support for the Hypothesis of Anguimorph Ancestry for the Suborder Serpentes from Phylogenetic Analysis of Mitochondrial DNA Sequences

Snakes represent one of the most ubiquitous and successful groups of terrestrial vertebrates; however, many aspects of their evolutionary relationships remain uncertain. Previous research, which utilized morphological and immunological data, has not resolved the origin of snakes or clearly delineated the relationships between snakes and other lizards. A DNA sequence data set from the mitochondrial ND4 gene and the histidine, serine, and leucine tRNAs has been generated for use in the examination of these relationships. Parsimony analyses employing multiple outgroups resolve snakes within the lizard clade. Varanus is the sister group to the snakes in 81% of bootstrap replications using Bos as the outgroup specified, 85% using Trachemys, 57% using Alligator, and 80% using all three outgroups. The primitive, fossorial snake genera Leptotyphlops and Typhlops are basal to the other snakes and provide tentative molecular evidence in support of a fossorial or subfossorial origin of limblessness for the suborder Serpentes. (c) 1995 Academic Press, Inc.