Origin of the unisexual lizard Gymnophthalmus underwoodi (Gymnophthalmidae) inferred from mitochondrial DNA nucleotide sequences

Analysis of variation in nucleotide sequences in mitochondrial DNA genes am ong species of Gymnophthalmus supports three major conclusions. First, samp les of G. underwoodi, a unisexual species of hybrid origin, have identical nucleotide sequences, supporting the hypothesis that all individuals from l ocalities in the Guianan Region of South America and the Lesser Antilles de scended from a single hybridization event. Second, G. underwoodi and G. cry ptus share derived similarities in nucleotide sequences of the maternally i nherited mitochondrial DNA, suggesting that the female participant in the h ybridization event that produced the hybrid species was either G. cryptus o r most closely related to it. Last, phylogenetic analyses recovered histori cal structure among population samples of G. speciosus supporting previous claims that there is unrecognized diversity under that binomial, and some a nalyses suggest that G. speciosus does not comprise a natural group. (C) 19 99 Academic Press.