Phylogeny of the Dipus sagitta Species Complex by Nuclear Gene Sequences.

The northern three-toed jerboa Dipus sagitta had long been considered to be a single polytypic species. High genetic diversity of D. sagitta was earlier revealed on the basis of several mitochondrial and nuclear genes, and several separate species were hypothesized to occur within the taxon. However, the relationships between phylogenetic lineages have not been established because of the small sample size of nuclear genes. In the present work, a far larger set of nuclear DNA loci was used, and thus, a higher resolution of the phylogenetic tree was achieved for ten D. sagitta forms. The structure revealed for the species mainly confirmed the topology and relationships of the mtDNA lineages. Yet the mitochondrial and nuclear phylogenies were not completely consistent. Some of the D. sagitta genetic lineages were therefore assumed to be a product of reticular evolutionary processes. The taxon was concluded to be the diverse species complex D. sagitta sensu lato, in which long-diverged lineages are not always reproductively isolated.

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.