Mitochondrial DNA Analyses and the Origin and Relative Age of Parthenogenetic Lizards (Genus Cnemidophorus )

Morphological, karyological, and allozyme analyses indicate that the parthenogenetic lizards Cnemidophorus neomexicanus and diploid C. tesselatus are hybrids formed, respectively, by crosses involving the bisexual species C. tigris and C. inornatus, and C. tigris and C. septemvittatus. Mitochondrial DNA, which is inherited maternally, was obtained from each of these species. Analyses of the mitochondrial DNA's and their restriction endonuclease digestion products by electron microscopy and agarose gel electrophoresis support the hybridization hypothesis by indicating that C. tigris (specifically the subspecies marmoratus) was the maternal parent species for both C. neomexicanus and C. tesselatus. Furthermore, these data imply that these two parthenogenetic species are younger than some races of C. tigris.