SNAKE RELATIONSHIPS REVEALED BY SLOW-EVOLVING PROTEINS - A PRELIMINARY SURVEY

We present an initial evaluation of relationships among a diverse samp le of 215 species of snakes (8% of the world snake fauna) representing nine of the 16 commonly-recognized families. Allelic variation at fou r slow-evolving, protein-coding loci. detected by starch pel electroph oresis, was Found to be informative for estimating relationships among these species at several levels. The numerous alleles detected at the se loci [Acp-2 (42 alleles), Ldh-2 (43). Mdh-1 (29), Pgm (25)] provide d unexpected clarity in partitioning these taxa. Most congeneric speci es and several closely-related genera have the same allele at all four loci or differ at only a single locus. At the other extreme are those species with three or four unique alleles, these taxa cannot be place d in this analysis. Species sharing two or three distinctive alleles a re those most clearly separated into clades. Typhlopids, pythonids, vi perids, and elapids were resolved into individual clades, whereas boid s were separated into boines and erycines, and colubrids appeared as s everal distinct clades (colubrines, natricines, psammophines, homalops ines, and xenodontines). Viperids were recognized as a major division containing three separate clades: Asian and American crotalines, Palae arctic and Oriental viperines, and Ethiopian causines. The typhlopids were found to be the basal clade with the North American erycine bold Charina and the West Indian woodsnakes Tropidophis near the base. A nu mber of species and some small clades were not allocated because of un informative (common, unique, or conflicting) alleles. Of the 215 speci es examined, five to eight appear to have been misplaced in the analys is of these electrophoretic data.