Nuclear integrations: challenges for mitochondrial DNA markers.

The combined use of mitochondrial DNA markers and polymerase chain reaction (PCR) techniques has greatly enhanced evolutionary studies. These techniques have also promoted the discovery of mitochondrial-like sequences in the nuclear genomes of many animals. While the nuclear sequences themselves are interesting, and capable of serving as valuable molecular tools, they can also confound phylogenetic and population genetic studies. Clearly, a better understanding of these phenomena and vigilance towards misleading data are needed.