Phylogenetic relationships and rates of allozyme evolution among the lineages of sceloporine sand lizards

Parsimony analysis of characters derived from an electrophoretic survey of allozyme variation in the sceloporine sand lizards indicates that Uma is outside of a clade formed by the rest of the sand Uzards and that Cophosaurus and Holbrookia share a more recent common ancestor with one another than either does with Callisaurus. Previous electrophoretic studies used phenetic clustering based on genetic distance data to assess relationships among these taxa. The resulting dendrograms were used to argue that Holbrookia is the sister group of all other sand lizards and that Callisaurus and Cophosaurus are sister taxa. When reanalysed using parsimony methods, the data from these previous studies are found to support the conclusions of the present study, namely, that Uma rather than Holbrookia is the sister group of all other sand lizards and that Cophosaurus is the sister taxon of Holbrookia rather than of Callisaurus. Relative rate tests indicate that the incongruencies between branching diagrams derived from phenetic clustering of genetic distances versus those derived from parsimony analysis of electrophoretic characters are attributable to increased rates of protem evolution in the Holbrookia lineage.