Vrijenhoek and Avise will survey mitochondrial DNA (mtDNA) variation and phylogeny in unisexual Poeciliopsis fishes and their bisexual progenitors in order to capitalize upon the unique advantages afforded by these atypical genetic systems for addressing two questions of broad significance to evolutionary biology: (1) is the inheritance of mtDNA strictly maternal? and (2) what are the evolutionary longevities and phylogenetic relationships of vertebrates that reproduce by asexual or semi- sexual means? The hybridogenetic strains will be studied for evidence of paternally-derived mtDNA indicative of occasional, low-level "paternal leakage" of mtDNA into zygotes. Both gynogenetic and hybridogenetic Poeciliopsis will be studied in terms of mtDNA phylogeny. By comparing mtDNA variability within and among the unisexual strains and their sexually-reproducing progenitors, the investigators will estimate the ages, clonal diversities, and phylogenetic origins of fishes complex. Results should help in addressing long-standing concerns about the evolutionary longevities of unisexual taxa, and hence about the evolutionary consequences of asexual reproduction.
