Biochemical Characters and the Reconstruction of Turtle Phylogenies: Relationships Among Bataguirine Genera

Abstract

Phenetic and cladistic approaches were used to assess relationships among 22 spp. representing 17 genera of batagurine turtles, and 2 spp. representing 2 genera of emydine turtles. Phenograms and cladograms were constructed from a total of 90 variable enzyme products (electromorphs) of 14 gene loci. Phenograms were generated by UPGMA [unweighted pair-group methods with arithmetic averages] clustering using genetic similarity, identity and distance matrices; a Wagner tree was constructed from a binary-coded character matrix. A qualitative locus-by-locus cladistic approach was also attempted. In this as well as in the application of the Wagner algorithm, a species of the sister group family Testudinidae was used as the outgroup taxon. Results of the 3 approaches are evaluated relative to each other, and relative to relationships that previously have been proposed with other lines of evidence. Some of the clades generated by 1 or more of the approaches used in this study are particularly strongly corroborated by chromosomal and osteological data sets. High genetic distances between some taxa, and high levels of inferred homoplasy suggest that divergence among many species approaches the limits of electrophoretic resolution and, as a result, several cladistic hypotheses are presented for some taxa. Where results are inconclusive, they are useful to the extent that they draw attention to contradictory data sets and alternative hypotheses of intergeneric relationships.