Close Relationship between the Lizard Genus Sator and Sceloporus utiformis (Reptilia, Lacertilia, Iguanidae): Electrophoretic and Immunological Evidence

Abstract

Horizontal starch gel electrophoresis was employed in analysis of lactic dehydrogenase isozymes for two species of Sator, 22 species of Sceloporus, and representatives of all other sceloporine genera. Sator was compared electrophoretically to 12 species of Sceloporus for six additional presumptive gene loci. Albumin of Sator was compared immunologically to 38 species of Sceloporus and representatives of all other sceloporine genera. The findings indicate a close genetic relationship between the two insular species of Sator and the mainland Mexican Sceloporus utiformis. * * * The lizard genus Sator is comprised of two species restricted to three islands in the Gulf of California: Sator grandaevus on Cerralvo, and Sator angustus on Santa Cruz and San Diego islands. Sator is the only recognized endemic genus of terrestrial vertebrates restricted to the Gulf of California islands. Clarification of its phylogenetic relationships is important to furthering our understanding of the historical and ecological biogeography of the Baja California peninsula and its associated islands. Its present distribution suggests that it is a relict, and there are strong implications of competitive exclusion. On the three islands where it occurs, Uta, Urosaurus, and Sceloporus are all absent, although at least one member of these three genera occurs on virtually all other Gulf islands (Soule and Sloan, 1966). Since the description of Sator by Dickerson (1919), the taxonomic and biogeographic status of this genus has aroused interest. Dickerson believed that the affinities of Sator were with mainland Mexican Sceloporus of the utiformis group. Subsequent analyses of the relationships of Sator have dealt with morphological characters (Etheridge, 1962, 1964; Larsen and Tanner, 1975; Mittleman, 1942; Savage, 1958). This study provides additional evidence based upon independent sets of characters, electrophoretic mobilities of proteins and immuno- logical distances of serum albumins.