MOLECULAR INSIGHTS INTO THE RELATIONSHIPS AND BIOGEOGRAPHY OF WEST-INDIAN ANOLINE LIZARDS

The realization that the present day positions of continents and island arcs are a result of continental drift led to the proposal that the extant West Indian fauna reflect an ancient (Cretaceous) land connection between the proto-Antilles and North and South America. Movements of the Antillean islands throughout the Cenozoic are hypothesized to have further fragmented the fauna present on the proto-Antilles when it separated from the mainland 70-80 million years ago. This proposed vicariant origin of the West Indian fauna challenged the previous theory that some or most of the fauna arrived in the Antilles by overwater dispersal from mainland sources. The virtual absence of appropriate fossils in the West Indies has hampered testing these alternative hypotheses for the origin of the present day West Indian fauna. We present evidence from two types of molecular data, one providing indirect estimates of amino acid sequence divergence for the protein serum albumin, and the other direct DNA sequence information from a mitochondrial ribosomal RNA gene. Our new data provide insights into the origin and relationships of two enigmatic lizard genera, Chamaeleolis and Chamaelinorops, and suggest they are recent derivatives within the genus Anolis. These data, along with molecular data presented elsewhere, strongly implicate an origin by overwater dispersal for most of the Antillean vertebrate fauna.