Morphological Divergence and Genetic Variation in the Triploid Parthenogenetic Teiid Lizard, Aspidoscelis neotesselata

The parthenogenetic triploid lizard Aspidoscelis neotesselata originated from a hybridization event between a female of diploid parthenogenetic Aspidoscelis tesselata (pattern class C) and a male of Aspidoscelis sexlineata viridis, and A. neotesselata is morphologically more similar to its maternal progenitor, A. tesselata. The geographic distribution of A. neotesselata is characterized by localized arrays of individuals located within a four-county area in southeastern Colorado, and postorigin divergence is visually evident in its four allopatric color pattern classes (A, B, C, and D). A fundamental pattern of morphological divergence was revealed by a multivariate partitioning of its four color pattern classes into two basic groups: an A group (pattern classes A and D) and a B group (pattern classes B and C). A problem introduced by this grouping is the incongruence between the multivariate similarity of pattern classes A and D and the closer geographic proximity of other color pattern classes to each of A and D. All four color-pattern classes of A. neotesselata had a modified triploid karyotype of 69 + 1 chromosomes (3n = 70). Electrophoretic assessment of 31 nuclear gene loci across the four color-pattern classes revealed postorigin genetic variation only at the mannose-6-phosphate isomerase (MPI) locus, but A. neotesselata had a remarkable heterozygosity of 71% based on these loci.