Mitochondrial DNA and the evolutionary genetics of higher animals

Mitochondrial DNA (mtDNA) in higher animals is rapidly becoming a well characterized genetic system at the molecular level. In this paper, I shift the focus to consider questions in organismal evolution that can be addressed by mtDNA assay. For the first time, it is possible to estimate empirically matriarchal phylogeny; to determine directionality in crosses producing hybrids; and to study the population genetic consequences of varying female demographies and life histories. The data obtainable from mtDNA may be especially well suited for studies of population genetic structure, dispersal, and historical zoogeography. The female-mediated, clonal transmission of mtDNA is also stimulating new ways of thinking about times to common ancestry of asexual lineages within otherwise sexually reproducing populations; about the possible relevance of mtDNA-nuclear DNA interactions to reproductive isolation; and about the very meaning of the phylogenetic status of related species with respect to particular kinds of genetic characters. These and other topics are reviewed.