Cladistic Relationships Among Anoles (Sauria: Iguanidae)

Relationships among lizards of the anole genera Chamaeleolis, Chamaelinorops, Phenacosaurus, and Anolis (sensu lato) are discussed based upon a cladistic analysis of osteological, karyological, and albumin immunological data. Osteological data support a sister-group relationship of carolinensis subsection and beta section anoles, while anoles of the bimaculatus-tatellus-cybotes, cuvieri series, and latifrons series are sequentially more distantly related to terminal cluster. Karyological data support five major groupings. One of these groups represents those forms with the primitive karyotype for lizards and includes: Chamaeleolis, Chamaelinorops, and Phenacosaurus; the cuvieri, cybotes, and latifrons series; and most of the carolinensis subsection. Two groups with advanced karyotypes characterize the cristatellus and bimaculatus series, spectively. The remaining two groups of karyotypes characterize the beta subsection. One population of beta anoles possesses the modal karyotype of both of these groups suggesting a saltatorial evolution of chromosomes within anoles and making difficult the determination of relations among the five groupings of karyotypes. Albumin immunological data support a close sister-group relationship among the beta section, and the cristatellus and bimaculatus series, the carolinensis series and latifrons series are sequentially more distantly related. Within Anolis (sensu lato), five distinct monophyletic lineages are recognized as genera. The latifrons series (placed in the genus Dactyloa) is derived relative to the primitive anole genera in the presence of autotomic septa on the caudal vertebrae and reduced numbers of aseptate caudal vertebrae. The cuvieri series (placed in Semiurus) shares with other advanced anoles derived conditions for the shape of the parietal, parietal cresting, total number of parasternal ribs, and number of attached parasternal ribs, but lacks the derived condition of occipital region of more advanced anoles. The bimaculatus-cristatellus-cybotes series (placed in Ctenonotus) sents a lineage possessing a derived condition of the occipital region and a derived total number of parasternal ribs but lacks the derived shape of the interclavicle. The most derived lineages—the carolinensis subsection and beta section—are linked by the derived shape of the interclavicle The carolinensis subsection is diagnosed by derived numbers of lumbar vertebrae and constitutes the genus Anolis. The beta section is diagnosed by derived processes on the caudal vertebrae and is placed in the genus Norops. This systematic arrangement eliminates the paraphyletic nature of the alpha section and punctatus subsection. Although some aspects of current distribution patterns of anoles must be due to dispersal events, it appears that vicariant events provided the impetus for the separation of the anole genera into their current ranges. On the basis of a cladogram of areas and recent geological evidence of vicariant and accretional events in the Caribbean, it seems that a widespread ancestral distribution of anoles throughout Central and South America, connected by a proto-Greater Antilles bridge, was fragmented by geological events forcing part of the proto-Greater Antilles northeastward towards their present location. This fragmented the distribution of primitive anoles in South America (Phenacosaurus and Dactyloa), and on Hispaniola and Cuba maelinorops and Chamaeleolis, respectively) from the ancestors of the advanced forms on America and associated portions of the rest of the proto-Greater Antilles. More advanced anole genera were added to the Caribbean by additional geological activity which separated the remainder of the proto-Greater Antilles into a Hispaniolan-Puerto Rican block and a Cuban-Hispaniolan block. Separation and accretion of these blocks brought Semiurus, Ctenonotus,Anolis to their present distributions, leaving Norops on Central America as well as on an attached block that later separated to become Jamaica. The closing of the Panamanian portal allowed extensive invasion of South America by Norops and less extensive invasion of Central America by Dactyloa.