Variable and invariable DNA repeat characters revealed by taxonprint approach are useful for molecular systematics.

A specially optimized restriction analysis of highly repetitive DNA elements, called DNA taxonprint, was applied for phylogenetic study of primates and lizards. It was shown that electrophoretic bands of DNA repeats revealed by the taxonprint technique have valuable properties for molecular systematics. Approximately half of taxonprint bands (TB) are invariable and do not disappear from the genomes during evolution or change spontaneously. Presumably these invariable bands are restriction fragments of dispersed DNA repeats. Another group represents variable taxonprint bands that differ even between closely related species. These variable bands are probably represented by tandem DNA repeats and could be used as species-specific markers. It was shown that taxonprint bands are independent characters since the appearance of a new taxonprint band does not change the previous band pattern. Phylogenetic reconstruction carried out on taxonprint data demonstrated that this approach could be of general utility for molecular systematics and species identification.

Restriction endonuclease analysis of highly repetitive DNA as a phylogenetic tool.

Multiple band patterns of DNA repeats in the 20-500-nucleotide range can be detected by digesting genomic DNA with short-cutting restriction endonucleases, followed by end labeling of the restriction fragments and fractionation in nondenaturing polyacrylamide gels. We call such band patterns obtained from genomic DNA "taxonprints" (Fedorov et al. 1992). Here we show that taxonprints for the taxonomic groups studied (mammals, reptiles, fish, insects-altogether more than 50 species) have the following properties: (1) All individuals from the same species have identical taxonprints. (2) Taxonprint bands can be subdivided into those specific for a single species and those specific for groups of closely related species, genera, and even families. (3) Each restriction endonuclease produces unique band patterns; thus, five to ten restriction enzymes (about 100 bands) may be sufficient for a statistical treatment of phylogenetic relationships based on polymorphisms of restriction endinuclease sites. We demonstrate that taxonprint analysis allows one to distinguish closely related species and to establish the degree of similarity among species and among genera. These characteristics make taxonprint analysis a valuable tool for taxonomic and phylogenetic studies.