| Abstract: | Phylogenetic relationships among Sceloporine genera are briefly discussed. Species relationships within the genus Sceloporus are analyzed, and evolutionary lines of descent are proposed. The genus Sceloporus is composed of three monophyletic groups: Group I, the most primitive, probably developed from Sator - like ancestral stock in Miocene times. This group speciated from stock similar to Sceloporus gadoviae in southern Mexico to S. merriami in the North and contains 7 species in 3 species groups. We propose that these species be included in the genus Lysoptychus Cope. Group II arose from Group I and evolved from centrally located Sceloporus pictus in all directions throughout Mexico. This intermediate group contains approximately 19 species in 5 species groups. Group III also arose from the primitive stock of Group I and radiated from several desert refugia created by Pleistocene glaciation. Evolution of this group in Mexico was generally from north to south with Sceloporus malachiticus extending as far south as Panama. This group contains approximately 33 species in 5 species groups. |
